Intermezzo

Post by Geolurking, based on a repost

I have been tasked to revisit something I covered years ago.  And update it with a bit of fresh info.  The original publish date was 20 Feb 2012.

The first thing I need to cover, mainly in order to bring every one up to speed… is the compass rose. The compass rose appears on many navigational charts and a method of calculating direction from one point to another. When coupled with an actual compass, you can find your way from one point on the chart to another.

The rose is noted in degrees from 000° to 359° (actually 359.99….) which is a full circle. North is 000°, due South is 180°. Many features having to do with the earth are discussed in the bearing that the feature lies in or has moved.

Image by GeoLurking: Compass rose.

(In actuality, this is really a scan of a Maneuvering Board, but it has the same increments as an actual rose as they appear on nautical charts.)

Which brings us to a definition:

“Lineament n (often plural)

3. (Earth Sciences / Physical Geography) Geology any long natural feature on the surface of the earth, such as a fault, esp as revealed by aerial photography.”

On Carl’s “Earthquakes – What’s the fuzz?” post from even longer ago, that stunning picture of the San Andreas is a Lineament, or a linear feature. It’s a surface manifestation of the thousands of years of slip along that section of the San Andreas. In some places, you can find creeks that have had their channels offset by several meters… in other words, they don’t line up across the fault. It has shifted that much since the creek bed was formed.

San Andreas fault

Not all lineaments are formed this way, remember, a lineament is just an odd linear feature. In the New Madrid Seismic Zone (NMSZ) there are several lineaments that were un-explained until modern research revealed them for what they are. (Well, at least to the point that we can talk intelligently about them.) Crowley’s ridge is one of them.

Crowley’s ridge is a linear structure sitting right in the middle of the flood plain of the Mississippi river. It’s a raised structure made up of loess, which is wind blown silt.  A lot of loess deposits are ultimately of volcanic origin, being the fall-out of some of the larger eruptions that North America has had over the millennia. But primarily, they are glacial sediments.   So… how is a 170 meter high ridge of silt able to exist in the middle the flood plain of one of the more powerful rivers on the planet? In all likelihood, it’s from uplift due to the mechanics of the NMSZ. (If you wonder what this has to do with volcanoes, the NMSZ has several plutonic structures scattered along its extent… those are “failed” volcanoes along the “failed” rift structure)

Now to bring this into something more on the subject. (That was all lead-in.)

Generally, when a quake occurs, it is along a fault plane that is oriented in relation to the stress on the rock.  In the case of the San Andreas, it’s from the westward moving North American plate and the northward moving Pacific plate (relative motions).  When the quakes occur, they usually are oriented along the trend of the fault. The focal solutions usually show a fault plane oriented on a line from the Northwest to the Southeast.

Faults are not two dimensional structures. Most are a diagonal break in the rock that angles down as you go deeper. This is called the “dip” of the fault. Dip angles that are less than 180° are normal faults, those that are angled greater than 180° are reverse faults. Which side the fault is measured from depends on which side is the headwall, or the part that rises relative to the other side. Those that principally slide past  one another without one side lifting, are transform faults. The dip angle is usually pretty close to vertical (near 180°)

This is all represented in a neat little graphical construct called a “Focal Mechanism.” A common name for them are beach balls because that’s what they look like.

Here is one for a recent quake in California.

 

Image by GeoLurking. Focal Beach Ball, the name is really self evident.

For this graphic, the extensional part of the quake is shown by the shaded region.  Seismic stations in that area would have shown the “first motion” on the traces to be going up as the wave arrived. Stations in the unshaded quadrant would have seen the “first motion” as going down. The best way to read this, is to think of the two unshaded regions moving towards the middle of the ball, and the two shaded regions being pushed away from the ball. The orientation of it illustrated the fault orientation. In this case, the dip angle is 23° from vertical. The NP1 solution (mathematically derived) shows the fault plane to be oriented along a bearing of 11°. The alternate solution, NP2, shows 226° NP1 being the most likely explanation of how it happened. (Note, this is subject to correction since that is the best that I can find… but could be wrong)

Now… I mentioned lineaments earlier. Here’s why. A fault that is oriented at 11° is also oriented along 191° (11+180). If you draw a line along those two bearings from a point on a map, say where the epicenter is at, that would describe the fault plane as represented by the focal mechanism.

You can  explore this more at the USGS explanation of it here: http://earthquake.usgs.gov/learn/topics/beachball.php  or at http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/faults.html.   For an authoritative discussion about it from an actual geologist, I recommend http://all-geo.org/highlyallochthonous/2009/12/5-focal-mechanisms/.

Now that I’ve covered that, a word about volcanic quakes. Magma forcing its way into a segment of rock usually will not always generate “double couple” solutions, or if they are there, they will be either too small or too chaotic in order to pull this sort of data off of a lot of seismographs. Magma intrusion causes most of the first motion traces to be upward as the overall volume increases and the rock splits apart. This means that pretty much all of the waves in all directions will be compressive waves. That was why that 1996 Bardabunga quake was so weird… the math and the motions pointed at no net volume change, and no double couple that matched something tectonic.  In hindsight, that appears, to have been the start of the events leading to the Gjálp eruption.

Remember, not all quakes will have a focal mechanism solution in the quake report, only the larger ones. This is mainly due to the large number of reporting stations that have to be used to derive it. Smaller quakes just don’t register on as many stations. Usually you will find the ‘beach balls’ in the technical details for the quake at the USGS event page.

Well, I hope this helped. In order to get anything more detailed than this you’re gonna have to poke at a real geologist to pony up more info. This is just a layman’s understanding of it.

Now for something “new”.  It’s not really new, just an illustration for you to ruminate upon.

This just happened in my backyard as recorded on my accelerometer.

It is NOT an earthquake.  It is the impact signature of a 10 lb weight dropped from 2 meters onto partially damp sandy soil at a distance of 2 meters from the sensor.  (approx 88.9 Joules).  Let’s zoom in and look at the “first motion” of the event.

Notice that the “First Motion” is in the downward direction.  This indicates that the waveform was in the tension sector of the event.  Initially, the ground was pulling away from the sensor.  Had I stuck a firecracker into the ground and detonated it, the motion would have been positive, indicating a compression wave had passed by.  (And in about 20 minutes, the Sheriff’s department would have arrived and asked me what the @#%$ I was doing setting off fireworks here, issued a citation, probably put me on a watch-list, and left.)

I don’t have a way to confirm it, but I imagine that any sort of meteoric impact would generate a tensile indicating negative first motion.  Do note, that any magmatic induced earthquake will likely be “normal mode” faulting.  However, due to the extremely small size, a focal solution likely won’t be available.  My little thump event is in the fractional Twinkie realm and if I had not specifically set up a sensor to get the waveform, no one would have seen it.

The big thing you have to do when reading a beach ball, is to figure out which quadrants indicate tension waveforms, and which one indicate compression waveforms.  I’ve seen the solid color indicate either one depending on who generated the plot.

For a more detailed discussion about seismology and focal mechanisms, I recommend “AN INTRODUCTION TO SEISMOLOGY, EARTHQUAKES, AND EARTH STRUCTURE” by Stein and Wysession, (2003) Blackwell Publishing.  You will also find quite a lot of information about waveform picks and the different paths that a quake waveform can travel.

This is an explanatory image from that reference.

Figure 4.2-4 from “An Introduction to
Seismology, Earthquakes, and Earth Structure”

This is a USGS generated graphic that indicates the various orientations.  For them, solid indicates tensile waveforms (negative first motions)

 

Final thought.  When a magmatic intrusion occurs in conjunction with a quake, by all rights, you should see and overall “Normal Mode” faulting as the two sides move apart.  The large quake in Hawaii during the opening phase of the Lower Puna eruption did not show this.  In all likelihood, a complex stress field was in play that opened up the feed system of Kilauea to the Rift Zone.  If I remember, the moment tensor for that quake showed thrust faulting. (the two sides moving towards each other)  And I repeat my lament, usually for the small earthquakes, you don’t get moment tensor solutions (Beach Balls) Due to the lack of stations observing the event.

 

 

 

149 thoughts on “Intermezzo

  1. In all honesty. The teaser for this mentioned a quake in my backyard… it was self induced. When I first thought of getting a waveform I had considered dropping an engine block on the ground, having felt that sort of thud first hand when salvaging an engine from a junkyard. Since I’m not 17 anymore and don’t have a spare block up on a chain, I opted for a weight to see if I could detect something that small.

    As for seismicity here in my corner of Florida. There has been a small cluster going off up near Century Fl and Flomaton AL. Unfortunately for the anti-frack crowd, there is no fracking going on in the nearby gas field. It is even advised against by some field exploration experts since it could actually decrease the productivity of the gas bearing strata. What is likely going on is stress along the Port St Joe fault. An ancient transform fault associated with the opening of the Gulf of Mexico occurred coincidental to the Atlantic opening up. On top of that. This is also the southern end of the South Georgia rift. A competing structure that also lost out to the Atlantic. By all rights there should be a dead triple junction somewhere around here. But I have no idea how to track it down.

  2. must be a pretty small triple juction because the triple by Japan has huge consequences. Or do i have this incorrect? Whats the temp?? Granddaughter heading to Florida but south of You in a bit. i keep telling her she will die of heat but not too worried about her… her boyfriend is a medic and he will keep a close eye on her. Best!motsfo (enjoying the summer heat here…. it’s 55F)

    • 95 or so. Humidity up around 40% during the day. Hot enough to make you seek shade.

    • As for the triple junction. My only evidence for it is logic. We’ve got transforms dominating the region and an ancient rift coming in at an angle to them. There had to have been some sort of junction trying to form since the features were most active at about the same frame. If it did actually exist. It’s likely sutured shut by now.

  3. Thanks very much – as an absolute amateur whose interest in volcanoes is limited to seeing things go bang and wondering what the Daleks do, I never had any idea what people meant when they said “Beach ball”, and I was too embarrassed to ask.

    • The only stupid question one that is repeatedly asked after it has just been answered. Scratch that. If it’s still a genuine question, then it was answered incorrectly.

      Prior to the comp tests in the various “modules” I used to teach, I used to preface the test with this statement. “Read the question, the whole question, and don’t read anything into the question. If you are unclear about what the question is asking. Raise your hand.”

    • Since you are a functional volcanophile. Do note that the “wet” quakes you occasionally hear mentioned here. Are quakes with drawn out codas. In other words. The body of the shaking wave-form is a bit drawn out and doesn’t decay as fast as a tectonic style quake. This likely comes from some sort of fluid movement in conjunction with the quake. On seismos with a spectral output, they will look like a quake with a harmonic component.

      • And as I’ve noted before, for anyone with experience of working with sound…
        The transient/wave form of a drumstick striking a plain old block of wood…. Dry quake… Almost instant “attack” followed by almost instant “decay”.
        Wave form of a drumstick striking a cymbal… Wet quake, characterised by the slow dying off of the sound… long decay.

        That might help a few people understand the difference.

  4. Always exciting for a Missouri resident like me to see mention of Crowley’s Ridge, amazed anyone outside of the Midwest ever heard of it in the first place. Missouri has a lot of hidden geology but you have to ‘dig’ to find it, if you can pardon the pun, it’s not obvious like Hawaii or Iceland.

    • Crowley’s ridge was part of the discussion about the NMSZ in a paper I read about 20 years ago. Likely my first deep dive into a geologic topic… and resulted in my first plots. I sent a misguided comment about my plot and a copy of it to SLU but they blew it off and thanked me for my interest. At the time I was thinking of crustal blocks but I had the mechanics wrong. So, I went and learned more just to find out where I had erred. No ill will towards SLU, it was good motivation.

  5. Thank you for that beachball refresher. Now all I have to do is remember to pin the included diagram to my fridge door to deal with the incipient dementia.

    • What it boils down to. Is that when a fault breaks. If you have enough seismos scattered around it. You can determine just how the fault failed. All the beach ball does is to provide a method of communicating that data. If you match the beach ball displayed by USGS with the diagram on this post. You can understand what they are trying to communicate.

      Most quakes are going to be a combination of normal or reverse mode plus a strike-slip component. These are called oblique faulting. There will generally be a dominant failure mode that is determined by what the most stresses were that caused it.

    • The three important types of failure for what we do here are strike-slip mode… the two sides moving horizontally, normal mode … the two sides moving apart and reverse mode… the two sides moving towards each other.

      Reverse mode is also called thrust faulting, usually caused along subduction zones.

      Strike-slip is typical of transform faults like the San Andreas.

      • …and the deeper SISZ area. SISZ is essentially a forming transform fault since it still exhibits flower structures. These can be seen in the sprungar (cracks) that do not align with the parent transform. As you go deeper, these cracks rotate to match the motion of the transform. Essentially what you should see are the smaller, shallower quakes there showing normal mode faulting while the stronger deeper quakes would show more sttike-slip.

      • Actually, the forces in normal mode are as you describe, but the movement in response is downward (or upward if reverse).

      • You got to love transform faults, the definitive proof the earth is a globe, well that and others, if the surface of the earth was flat, transform faults wouldn’t curve left or right as the reached for the equator, I suppose flatards even have an explanation for that, but some people have their beliefs and then their facts and others have their facts and then their beliefs. You have to be careful with how and where you apply your facts, as the hitchhikers guide would let you know, since the population of the universe is finite and the space infinite anyone you might of met today must of been a figment of your imagination since a finite number divided by infinity is zero.

  6. Albert I haves a question
    What is the density of the solar photosphere?
    ( plasma gas pressure ) compared to earths sealevel pressure

    The photosphere is under the much less dense cromosphere.
    The photosphere is the lowest layer of the solar atmosphere. It is essentially the solar “surface”

    • Attn other dragons. Though this is OT. Please don’t sanction it. It’s a well targeted question.

      Albert will probably get to it if he has time.

    • Do you want the density or the pressure? They are different things.

      The density at the photosphere is around 10^-13 kg/m^3

        • Density and pressure are different things. They also depend on temperature and on composition. You also need to reaize that the photosphere is not a single surface: it has depth.

          The pressure of the photosphere varies from roughly 100 mb at the bottom to 1 mb at the top. Our atmosphere has around 1000 mb.

          The density I gave before is wrong. I am not sure where I got it from. The correct value seems to 10^-9 gm/cm^3 for the top of photosphere which converts to 10^-6 kg/m^3. The bottom of the photosphere is about 100 times more dense. That is still only about 0.01% of our atmosphere.

          • Given how low density the sun actually is, I wonder how far something solid falling into it would actually get, I mean the sun is very hot but it takes a huge amount of energy to heat a solid to its evaporation point especially so for things above 3000 C, so a big object might make it pretty far?

            Most things probably not very far, but there are some really refractory compounds like hafnium carbide that have high density and melting points that are within 1000 C of the suns surface temperature, so I would imagine these would be able to fall quite far into the sun before melting or evaporating. Maybe not far by the overall size of the sun, certainly not to the center (only a neutron star would survive that), but maybe hundreds of km or thousands, or even several earth radii. It takes a lot of energy to heat a large mass up to 5500 C, a big solid block of tungsten or hafnium carbide would probably fall a very long way before being destroyed. I have seen theories that very massive terrestrial planets may survive their stars red giant stage and orbit the remnant as a mostly iron core. 5000 C matter can be ‘cold’ if it is very diffuse (eg thermosphere, technically 2500 C but practically it has no real temperature and ou would freeze in it if anything). The corona is an even better example, 1 million degrees but it is basically a vacuum so things can survive going inside it like comets often do.

            Then again, common sense doesnt always work in space so I might be very wrong about all this.

            (I didnt talk about carbon because it is very low density while HfC and WC are very high density at comparable maximum solid temperature, the high density means it will have more speed and go deeper through kinetic energy, maybe)

          • 1/100th of earths surface pressure is still quite dense for a stars outer edge

            A fiery death ocean of plasma
            Hot enough to boil solid iron!

          • Turtlebirdman
            The sun is still quite dense
            Most of its volume is 1000 s millions of of earths atmospheres in pressure
            Its outer edge is already 1/100 th of earths surface pressure

            Much denser inside
            Earth or an Asteorid placed inside woud be turned into hot plasma

            Very diffrent from Red Giants thats are very much hot vaccums

          • The photosphere is much much much denser than the Corona

            Photosphere is very much like fiery furnace plasma air similar to mars surface pressure
            Curiosity woud not stand a chance in souch conditions even with heat shields

          • But a planet like Mercury thats is a large object to heat up
            Woud likely fall quite some distance into the sun
            IF it was dropped inside
            Before turning into rock vapour plasma

            Still the sun is quite dense

            But a Red Dwarf Star is much much much denser at its outer edges. Density of a very small red dwarf star is 57,000 kg/m3 for its surface! And crushing 250 G gravity

          • A blowtorch is at about atmospheric pressure, 100 times the pressure of that part of the sun, it is 1/4 as hot but that should mean that with no other factors the rate of heat transfer is 25 times higher for a torch than sun photosphere plasma.
            If you put a piece of steel in a propane furnace (basically the same thing as a blowtorch in this situation, a high temperature atmosphere) it does not melt, and it only starts to glow after about 5 minutes or much longer if it is a big bit (ive watched a lot of blacksmithing videos 🙂 ) despite the adiabatic flame temperature of propane in air being 1970 C which is a lot higher than the melting point of steel. Eventually it will melt but not for a very long time that is dangerous to operate. Even aluminium which melts at 600 C will not melt in such an atmosphere for several minutes.

            Still im interested to hear what Albert has to say about this, he knows this area much better than we do.

          • That number seems about right for heating directly by the plasma. But in much of the Sun the heating by radiation would be more important. Say you are at a depth where the temperature is 100,000 K. (I do not recommend this. Dropping the Earth into he Sun is very dangerous.) The atmosphere will disappear very quickly, of course. The radiation heats the surface with a power
            of a bit over 10^12 W/m^2. (Just about enough to cover our entire energy usage from about 1 square meter). Ignoring latent heat, assume the surface should heat to 3000 K to turn the rock into atmosphere, at 1 kJ per Kelvin per kilogram. That gives me 9 GJ to vaporise a cubic meter of rock (not counting the latent heat). So the surface could evaporate at a rate of about 100 m/s. In practice it is not quite as fast as the evaporating rock carries off much of the deposited energy, acting as shield for the lower rock. Still, the Earth would be gone within months. I’ll blame you.

          • Radiation also heats things
            Sunlight itself is likley extremely intense and destructive at photosphere

            This is why the solar probe use a heatshield

          • Albert, if I may make a small correction to your post:

            The multiplier from m3 to cm3 is actually X^6, because cm3 is the second level from m3. First you reduce to dm3 by ^3, and then another level ^3 from dm3 to cm3.

            So your numbers corrected are actually “10^-9 gm/cm^3 for the top of photosphere which converts to 10^-15 kg/m^3.” If you go from cm3 to m3 that reduces the number by 6 power, so -9 to -15. 😉

          • It goes the other way. If the density is say 1 gm/cm^3, then the mass of 1 m^3 is 10^6 gm which is 10^3 kg. 1gm/cm^3 is about the density of water, and you know from experience how heavy a cubic meter of water is. An aquarium of 1000 liters is unmovable – unless the floor isn’t strong enough.

          • Yeah. Floor loading can be a problem. I had a server room that had to have its floor reinforced before we moved gear in. Thing gave me chills when inspecting it prior to install. Far more deflection than I was comfortable with when walking on it. I could just see the servers and equipment racks landing in that computer shop beneath us.

          • The question now is how far into the sun could the earth go in a few months? I guess it will sto on its own somewhere wherever the density is higher than 5.5 g/cm3 but that is probably getting closer to the core than the surface.

            Probably if the earth hit the sun though it would explode, and be like an enormous meteor but on a scale we can only slightly imagine. It wouldnt do anything long term to the sun but in that moment it would be profound. A hit like that would probably blow off some of the outer layers of the sun in that area and expose the way hotter stuff underneath and make a massive flash of light, maybe even increasing the brightness several times. Ive seen something that impacting comets can reach nearly 1 million km/hour before they hit the sun, imagine a planet doing that…

            Or completely different, if a white dwarf hit the sun. Chandarsekar limit is aboht 1.4 suns, and I dont think white dwarfs smaller than 0.4 suns are possible to form directly (probably wrong) so the combined mass would go above the chandarsekar limit and you would get a supernova… D:
            Maybe it would just turn into a neutron star more passively though, and then you get a very disorganised solar system orbiting a tiny glowing thing. theres a lot of other suff do go with that topic but not for right now 🙂

          • Neither the earth nor the sun would notice too much at the surface. The earth’s magnetic field might briefly connect to that of the sun, giving a nice solar flare. Inside the surface there would be some energy and angular momentum deposition, slightly inflating the sun and perhaps causing quite a large flare from the perturbed magnetic field. But the earth is tiny and neither the energy nor the mass are going to do much compared to what is already there. Jupiter would make more of a mouthful and if the sun were to swallow a brown dwarf, it could potentially cause a FU Orionis type outburst.

            I thought I had warned you not the throw the earth into the sun..but if you still insist, I doubt that the Earth would make it far. Even the outer convective zone quickly reaches a million degrees, far higher than what I used in the estimations. Perhaps it could last as far as 20% inside the outer radius. Not worth sacrificing our home for. I recommend using Venus.

          • Oh.. yep, my mistake. I saw cubics, and I instantly thought volume and ignored density. Of course. 🙂

          • Remember this because almost everyone underestimates the density of air. This means that a largish room, 5m x 4m x3m has no less than about 70kg of air in it

  7. If you still find the beach balls a bit confusing, maybe this video can help. It says basically the same thing as the current post, but with excellent (although a bit childish) animations.

    • That’s actually a really good video on the topic. The only thing I will add is that the term “hypocenter” is the same as “epicenter” but expressed in 3 dimensions.

      In other words, lat-lon go with an epicenter.
      Lat-lon+depth = hypocenter.

      Thank you for the vid link. 😀

      • “Hypocenter” and thank you to the Dragon that fixed that typo. I was sitting in the middle of a parking lot at NavHosp and didn’t have access to my PC. (Lab-work)

        And since that is taken care of, something from local news;

        A South Florida couple having a picnic were charged by a Gator that was watching them from the nearby water. Gator ate all the salami, a block of cheese, and all the guacamole dip. The couple backed away from the food as the gator did his thing. The male of the pair started hopping around waving his arms yelling at the gator. The gator, having completed its mission, retreated back to the water.

        https://www.wthr.com/article/watch-gator-crashes-florida-picnic


        And the Gator vs Kitchen thing from a few days ago.

        https://www.wral.com/woman-delivering-newspapers-witnesses-gator-breaking-into-florida-home/18424689/

        All of this is in South Florida and nowhere near here. However, Gators do live in the area of the Florida Volcano that Albert wrote about a couple of months ago. I was going to head down into the area where the “volcano” was likely at for a few pics, but have not had a call down in that region for quite some time now, even with that it is a bit off my normal path. Tates Hell is a bit further East than I normally go. Lots of Flatwood forest in that area, even the lowlands near the Choctawhatchee River between Bruce and Ebro along State Road 20. The boat landing and campsites at Cowford get inundated quite regularly when the river is up. I think Ebro‘s primary industries are a dog track and and a beer distributor.

  8. another line eq swarm on Torfajokull west end. Is Carl watching this from distance?

  9. As Greip rests after a heavy month, Torfajokul rumbles again, this time again teasing with unzip patterns on the Veidivotn fissure line. And that can at some point start to get dangerous if persistent for enough time. We can see an older (dark blue dot) quake further up the same line, which confirms the fissure line pattern. It could mean nothing, but it could also mean everything.

    • How deep are these quakes (and the older ones too)? If they are very deep then it is probably generic, or a deep feed of hekla, but if it is crustal then yes it is probably exactly what it looks like… 😀

      • All are crustal in Iceland generally, deep and shallow, all above the MOHO.
        Not all are corrected yet, but its usually the deep ones that spark most attention in Iceland, depth wise. Its usually the shallow lower magnitude tectonics that are considered generic in Iceland.

        A deep feed of Hekla? You for real? 😀

        • The fact this has happened twice now and there was apparently some inflation of about 70 cm northeast of hekla oved the last year that happened last year in december… 😀

          This looks very promising 🙂

      • If my plotting accuracy is correct, it follows a line between veidivötn and vatnaoldur:

  10. An M3 more than 100 km deep below Hawai’i. Wow. I guess the depth may be recalculated

    • Right under kailua kona, if this is real that is a record I think.

      • 107 km depth is impossible in Hawaii!
        Hawaii is the worlds hottest hotspot
        Makes sense they cancel that quake

        At 107 km down is pretty much the astenospheric Hawaii hotspot partial melting pool where the crust/ litosphere maybe competely molten and close to 1600 C
        Hawaiian plume head melts as it rise into the uppermost mantle
        Big Island and close areras around contains many 1000 s of km3 of semi molten materials
        Deep in the litosphere
        ( astenospheric melting source )

        • A certain faux geological prophet on Youtube will be positively gushing FUD… Just saying tin foil on hand 🙂

          • Oh yes at 32 minutes into his most recent video… 🙂

            At that point though it was still there so I dont know what he will say when he sees it has been deleted… lol

            Anyway jesper is right a quake is basically impossible at 100 km underneath any ocean let alone within a mantle plume that is 500 C hotter than the normal mantle. You get quakes hundreds of km deep in subducting plates not hotspots coming from the core…
            Think of it like a piece of solid wax that has been submerged in melted wax, that is a subduction zone and descending plate, while a hotspot is a pool of melted wax inside solid wax, and you dont get fractures inside a liquid…

      • That will get the conspiracy lunacies going. USGS deleting earthquakes! What do they have to hide? When did they develop this capability? Is it a military secret and could it be used to create earthquakes as well?

          • The earth is 0.3% flat and 99.7% round 🙂

            Unless I did the maths wrong (12742 km diameter, 30 km longer to core from equator than to the poles)

            0.3% of the earths population is 21 million, that is a lot of flat earthers D:

          • Since it is the poles that are flatter, the number of people may be overestimated.

        • It’s not a quake. It’s our alien overlord Lizard’s motherships surfacing from their eons of slumber to come and eat us all.

          HAARP is being used even now to try and neutarlise their shields and allow the ships to be crushed at depth.

          Luckily the lizards are allergic to tin-foil and a simple hat should prevent you from becoming lunch – however as the top-secret notes on tin-foil date from WW2, you probably need real tin-foil and not aluminium.

  11. The cost of internet: here is an image taken at the Lowell Observatory, shortly after the launch of the starlink satellites. These are the first 60 or so of over 10,000 planned satellites, and several other companies want to put up competing systems. We don’t yet know how bad it is going to get, as it depends on how reflective the satellites will be which seems unplanned (the company apparently doesn’t know and it varies between satellites). Radio astronomers are also extremely worried.

    • Who needs to sweat the Kessler syndrome when Ego Musk can do it as a side project?

      Ecce Homo Stultus.

    • There was already a problem keeping the lookouts doing their job as iridium flares kept distracting them on watch at night. Turning the night sky into a snow globe is beneficial how?

      Just so smartphone zombies can wander off cliffs?

      • “Just so smartphone zombies can wander off cliffs?”

        Yes, but the idea has disadvantages too 🙂

    • I think it’s too early to say this is going to be a serious problem. I’m old enough to remember that the exact same worries were voiced about Iridium satellites, and GPS too, back in the day.

      The first batch of satellites created these trains of light as they were all extremely close together – far closer together than they ever will be once they’re in service as part of the full constellation. Then, they will only be lit against dark sky in a very small portion of the time and space of the sky, as the ground needs to be dark and the satellites at 550km be in the sun. Noctilucent clouds are a (lower-down) example of that problem, and are seen as a wonderful thing.

      Remember, the sky is huge – 360 degrees by 360 degrees – and the window that earthbound telescopes are looking at is very, VERY small against that size. There are 1,679,616,000,000 square arc-second areas in the whole sky, suddenly 10,000 satellites doesn’t seem so intrusive. A lot of the big telescopes are looking at patches of sky considerably smaller than that.

      Also, Elon has said that the design is very much still fluid – making them non-reflective doesn’t seem a hard problem.

      I think in the long run, more and more telescopes will be in higher orbit or on the moon anyway – why struggle to look through the atmosphere if you don’t really have to?

      • I remember iridium well. They caused flashes which were 50 times brighter than Venus, in the general area of the sky we use for calibration. We ran software to predict these flashes to avoid accidentally looking at them and ruining the data, and potentially the CCD for the night.

        And you forget that these satellites move. A typical telescope nowadays looks at half a square degree of sky, and may integrate for 30 minutes before reading the CCD. The satellites are in 90-min orbits, and so in 30 minutes each covers a trajectory of 120 degrees. Multiply by the field of view of the telescope, and a single satellite pollutes around 80 square degrees. The full sky has 45,000 square degrees, so over 30minutes each telescope exposure will have 20 of these satellite tracks. Suddenly 10,000 satellites sounds like quite a lot.

        If I have done my math correctly, the ones directly overhead will stop being illuminated by the sun when it is 12 degrees below the horizon, more or less when we start our real work. The ones closer to the horizon will be illuminated longer and this will mean that that part of the sky is problematic until the sun has set to some 18 degrees below.

        There is a reason satellites are made with a reflective shielding.

        We cannot observe through noctilucent clouds. I have seen plenty of exposures ruined by cirrus illuminated even just by moon light.

        And space telescopes are the exception, not the rule. It is very expensive to put telescopes in orbit, and we can only launch small ones (the Hubble is only a 2.5 meter while we have 10 meter mirrors on Earth). We can also nowadays get better resolution from the ground, so space is used only for wavelengths we cannot do from the ground. Telescopes on the Moon is a dream: the US can’t at the moment even get a person in orbit and Europe has never had that capability.

        • Opinion. Ego Musk should be held financially responsible for reduction in usable time each of those multimillion dollar telescopes suffer. To be paid to each entity that financed the construction.

          • Sadly there are no legal protections of the night sky. You’d need something like the law of the seas and only the UN has the clout to get this off the ground (puns intended). It can be done but in the US you would have the problem that the companies involved are rather integrated into the political scene – politicians need company money to get elected, and Americans are honest enough to stay loyal to the people that bought them.

            There are other companies planning to do the same thing as Musk is starting. I still think it would be cheaper to put optical fibres across the world! What we are really concerned about is the plan for mirrors in space to provide nighttime illumination – and advertising. That would end astronomy.

  12. Because hawaii isnt doing anything right now, I have recently been looking at a lot of stuff regarding mt etna, also because it has been erupting recently. I have noticed something that might have some rather profound implications.
    1669 is considered the type example of the worst case scenario eruption from etna. Before 1669 there was a lot of very large scale activity in the preceding 60 years, the two biggest eruptions being from 1614-24 and 1651-56. Both these eruptions were slow and very large pahoehoe eruptions, the latter eruption upslope of the town of bronte is as thick as 200 meters!
    The flow I calculated has a volume of somewhere around 2 km3, maybe even 3 km3, the other flow of 1614 is similar, a bit smaller but still well over 1 km3. Two other flows in 1607 and 1646 were also long lived flows, not as big as before but still very substantial. Then there was 1669 which was a vigorous lava flood eruption that was probably very similar to kilaueas eruption last year at the start. The maximum eruption rates were over 600 m3/s.
    The reason I bring this up now is that in the last few decades there has been very significant effusive eruptions as well as a marked increase in eruption rate and rapid summit crater growth since 1950. The cone of monti centanari in the valle del bove was symmetrical and 100 meters tall when it forned in 1856 but now is nearly buried, so 100 meters of lava has piled up in that area mostly in the 21 century. There was also 1991-93 that was 0.3 km3 of lava, and there has also been a number of intrusions to the south that could be forming a conduit in that area to potentially allow a large low altitude eruption, the last big intrusion happened in december last year. The frequent rift activity between 1955 and 2018 on kilauea was what allowed a conduit to form so far through its rift and made last years eruption so big, the same process might occur on etna too.

    2-3 km3 in 6 years is also about 30 m3/s average which I have seen in some sources showing average eruption rates of 17th century eruptions, so these numbers might not actually be so far off.

    • Etna is a crazy active volcano
      And coud be the most productive subduction zone basaltic stratovolcano on the entire planet.
      Under my 24 years its been an eruption almost every year.
      Etna is also much larger than most other subduction zone stratovolcanoes.
      Etna does near constant strombolian activity
      And near constant short lava flow episodes of diffrent sizes. In 1900 s there been plentiful of large flank flows and 2000 s been intense.
      Etnas current eruptive rates and frequency and sizes gives a yearly supply of 0,08km3 every year: thats more than almost any other volcano. Etna is 500 000 years old and 700km3 in volume, so the supply may been much lower before.
      For now the volcano is very very active and haves very high supply.

      Etna is in a very complicated tectonic setting
      For more complicated than a normal subduction zone as magma source

      • Etna is probably not a subduction volcano, I dont know what it is otherwise but the area is rather tectonically complicated and there are other ways it could generate magma.
        It is probably more of a small hotspot or a rift volcano, it is very interesting that for how long we have known about it and studied it that even today the exact reason there is a volcano in that spot is not fully understood.

        There is probably someone else better able to answer this than me though.

        • There is not just one volcano in that region. There are a LOT of volcanoes in the region, many of them quite sizable and active. Etna, Stromboli, Vulcano, Campi Flegrei, Vesuvio, Marsilis (big seamount), Ischia, and the islands south of Sicily.

          Also some suspicious looking round lakes going in a line northward.

    • Indeed the pahoehoe flow near Bronte Etnas west side is enormous
      This is one of few examples of 100% real and true slow pahoehoe on Etna that haves the skinn ropes and general smoothness of true pahoehoe
      Still Etnas bronte lavas are not as smooth as hawaiian pahoehoe due to lower temps.
      Bronte pahoehoe lavas are known as peanut lava for the small crystals in that lava
      Bronte magma batch as already cooled a little before breaking out in eruption.
      Still Bronte lavas are defentivly one of the most fluid historical Etna eruptions it formed true pahoehoe thats rare in Etnas subduction zone basalts.
      Bronte lavas where also hot 1140 C been suggested. Bronte is indeed a huge enormous flow field and was likley feed by lava lake vent something like a land surtsey
      There is enormous lava tubes and some collapse pits in Bronte in Google Earth

    • Etna 1669 ”Monti Rossi” was a fast Aa flow eruption it likley produced some hell of impressive fountains likley larger than Tolbalcick 1975 Most of the 1669 lava flow field have been urbanized.
      Monti Rossi cone is around 1,2 km wide and many 100 s of meters high. The fountains must have been many 100 s of meters tall.
      And likley even more impressive at curtains of start. Still the lack of cone row around Monti Rossi suggest it may have started more like Fissure 8 or Paricutin. The lava rivers from Rossi woud been channelized Aa lava on flat ground and moving quite quickly at slow walk speed when it was most intense and much much faster near the fountain vent.

      If 1669 happens today in Catania it woud be a material disaster beyond imagination!
      And likley will happen soon again after all … most of Etnas monogentic cinder cones are towards Catania side and weast.

      Monti Rossi 1669 is equal in severity to placing Holuhraun or Fissure 8 inside Rome

      • Before 1669 there was also the 1030 eruption that formed monti ilice, the lava flow from which also reached the ocean, a nearby cone formed in 1329 that was somewhat smaller eruption as its flow was more limited, and an eruption very far downslope that happened in 1160 that was more gentle but within current city limits of cantania. The average time period between 1669, 1329 and 1030 is 639 years, it has been 350 years since 1669, the eruptions above happened on average 320 years apart, so if etna is vaguely cyclical an eruption of this type happening now would be not that surprising. Probably a lot more likely now than most of the last 300 years.

        • I can only stress again: volcanoes don’t do schedules (well, except maybe grimsvötn). But also, you can’t extrapolate a pattern from three data points. It seems likely, but Etna is such a complex system that it is virtually unpredictable what it will do next.

          • Very true, that is why I only went as far as to say that an eruption like 1669 is only more likely now than it was in the 18 or 19 centuries, on account of recent significant increases in magma production in the 1950s and near continuous activity since then, which happened in the 17th century but not so much in the 18th or 19th. During that time it was probably not uncommon for etna to go years between eruptions while that is basically unheard of now.

  13. A period Albert posted about recently.

    https://phys.org/news/2019-06-bacterial-diversity-justinianic-plague.html

    Researchers discover bacterial diversity in Justinianic Plague

    A large international team of researchers has discovered a previously unknown level of diversity in the Justinianic Plague (also known as the First Pandemic). In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of the bacteria Yersinia pestis and what they learned about it.

    …The team reports that they did find evidence of Y. pestis in Britain (at a site called Edix Hill), confirming that the pandemic reached the British Isles. They also found diversity in strains of the bacteria that had not been seen before. They report that they found eight from Germany, Britain, Spain and France. The researchers note that their findings show that there were multiple strains of the bacteria involved in the pandemic and that they were all closely related. They also report that despite their success in finding new strains of the bacteria, they were still unable to pin down the onset of the First Pandemic. They suggest the bacteria likely got its start in Central Asia, long before the pandemic got underway.

  14. Greip and Grims Grumbling Ongoing ..

    Interesting study

    https://www.smithsonianmag.com/smart-news/rock-art-footprints-reveal-how-ancient-humans-responded-volcanic-eruption-180972337/

    Thousands of years ago, hominins living in what is now western Turkey witnessed the eruption of the Çakallar volcano. Intrigued by the spectacular sight, walking stick-wielding locals and their canine companions ventured closer, leaving a trail of footprints
    Read more: https://www.smithsonianmag.com/smart-news/rock-art-footprints-reveal-how-ancient-humans-responded-volcanic-eruption-180972337/#xEtI6Wrm2zpdIa5T.99
    Give the gift of Smithsonian magazine for only $12! http://bit.ly/1cGUiGv
    Follow us: @SmithsonianMag on Twitter

    • I think I’m casually going to be predicting a winter/spring eruption for Grimsvötn.
      Not an expert here or anything though, just going by reading the numbers, graphs and whatnot.

    • Wow de har redan skurit en väg genom spricka 8 s lavakanal var nog väldigt hett att plöja igenom
      Fortfarande väldigt hett efter utbrottet och ryker mycket efter det regnat

    • Like Jesper, I’m amazed roads are already cut across the flow! Human resilience…
      Thanks for the video!

    • Don’t you need a doomed city in the right location for that?

      Lacking that it’s just a potential eruption.

  15. Quick Qu – is the seismic activity at Sangeang Api anything above the usual?

      • I look at the MAGMA Indonesia graphs periodically. Sangeang Api usually looks like that but this example has slightly more than usual.

    • Depends on what you meant by “usual”. Sangeang Api has been very active since at least 2018…and I suspect this just a continuation of it’s current eruptive episode(s).

  16. I need some help with in a certain area, (Nothing related to money). A certain group of people around me believe in certain fringe group part of a larger controversial religion. I am not what you’d call an aggressive atheist, I love talking to religious people. Christian, Jew, Muslim, whatever. But this group takes the cake as it is utterly ridiculous and hateful. I don’t even think this group of people really believes in it as They don’t follow it completely

    This group of people believes that Mountains were made through bombs being detonated from within the crust of the earth. I have told how impossible this but perhaps not as well as my elders and scientists.

    • Here’s a good link that shows the effects of an underground explosion at various depths. You could use this to show that we have actually tested that theory, and that there are at least 2 main problems with it. 1: At best it creates a circular mountain of loosely compacted rock surrounding a depression (Most mountains form peaks(not rings), and the ranges tend to be non-circular). 2. At greater depths, explosions form collapse pits rather than mountains.
      I suspect what they have in mind is a giant explosion waaaay down under which bulges the surface upward to form a peak. In that scenario, a pit actually forms.

      https://nuclearweaponarchive.org/Library/Effects/UndergroundEffects.html

    • forget it……………. it’s impossible to talk logic to the illogical……………. and sadly, if You are an atheist, i can’t even suggest You say a prayer for them… 😉 (( Dragons, Hope You see and understand this little joke from motsfo)) Find Your own peace and don’t engage them. Hopefully they will find their own way……. Still hoping for the Best!motsfo

      • I don’t understand atheists. Do they still believe in purpose or not? If they do, what’s the point of correction or thinking correctly? Shouldn’t chaos be as meaningless as order or reason as meaningless as nonsense? If not, why not?

        • As an atheist, I don’t believe in religious systems because that is not going to bring one closer to God. God is a mystery as there is no proof that he could or couldn’t exist. A being that created the universe could do essentially whatever he wills including keeping his existence hidden. If God does exist and did send messengers for humanity then that would not change the fact that religious systems are incapable of remaining rigid in one way.

          Edited. Rule 1: Be nice. We do not attack our readers (or non-readers) for what they believe or do not believe in. – admin

        • A fair comment and inevitably can only be answered from a personal point of view, even when that view is set down by others.

          As an atheist, who was very religious as a child/young man, I have a bunch of theological reasons why god doesn’t exist or affect this universe.

          So then you have to ask how an evolved hominid invented him/them and conclude that its an innate need to codify/enforce ethical behavior within a society. This has a profound genetic influence, even monkeys have ethics of ‘fairness’.

          As a consequence its in the end quite simple to see how an atheist should behave ethically even without a god.

          I hope that, although short and skimpy, is food for your consideration.

        • I’m an atheist and I have no issue in accepting that we (humans) are an insignificant mass of various atoms amongst a vast sea of stars and galaxies. My existence has no consequence or meaning amongst the continual processes of the universe. Maybe I’m more nihilistic than Nietzsche… Life and its interactions with other life and the environment is a chaotic system with a purpose of replication at a molecular level. This replication is also chaotic and open to mutations. The only true source of order is death, whether that’s life or the eventual heat death of the universe. I certainly don’t class chaos as bad and order as good, they both have their good and bad points! Just because I fail to see a grander spiritual purpose doesn’t stop me from correcting myself and being nice to others, that should be a fundamental of any social organism.

        • There are atheists, agnostics and anti-theists. One can get very bogged down in semantics… add in dogma, emotion and social factors and we have a potent brew.
          ‘When God invented man…she was only joking…’

      • That would seem to be the case but giving up isn’t my vocabulary, ever since I was a sperm cell, I only had one goal and this to achieve what ever i set my mind to. BUUUTTTT I don’t really think that this is the case with this duo. I am planning my final siege with a partner to show how deluded this “Nation of Islam” stuff is.

        Seriously, they don’t believe God created the earth while claiming to be muslim…

        • Don’t argue with idiots. They’ll drag you down to their level and beat you with experience.

      • I second motsfo. People can be challenged on what they do but not on what they think. And atheists too have their fundamentalists and their agnostics. Our local humanists became fundamentalist, to the degree of proposing to ban people from teaching if they hold religious beliefs – they had to turn that down a bit as it was against the law, but they tried several times. Some people seem to be following political leaders who go against everything their beliefs stand for. On the other hand, in Africa I saw plenty of explicitly religious organisations providing aid – but never an explicitly atheist one. People are funny creatures – I guess someone had great fun designing them.

        • Of course there is a really, really good way of tweaking the tail of an fundamentalist atheist: tell them it’s nice that they’re so religious in their beliefs. After all saying that is semantically and literally correct. Religious as in scrupulously faithful and conscientious and religion as in a specific fundamental set of beliefs and practices generally agreed upon by a number of persons or sects.

          Not quite the primary meaning of both those words, but hardly a non-mainstream one either. The blustering as they try and claim they’re not religious in their beliefs can be quite funny.

          • Why are we talking about religion on a science blog? They don’t mix! Plus it’s very off-topic!

            Edited. Rule 1: Be nice. We do not attack our readers (or non-readers) for what they believe or do not believe in. – admin

          • This is what I usually say. The true scientific perspective re whether God exists is “I don’t know”. Any profession of belief yea or nay is an expression of faith.

    • You could point out that mountains were built millions of years before bombs were invented.

      • I can assure you that won’t mean a thing to them. As the cult believes that monkey came from white people trying to make themselves black again. in Europe. ALL THE MONKEYS.

    • To summarize our opinions: you are probably on a no-hope with this one. You are unlikely to be able to convince them of anything. I also found this discussion very civilized and focussed on own opinions and experiences, while respecting others. That was nice to see. But this is quite far OT and it is probably best to move on! Anything happening in Etna?

      • I’d say so but i will continue with my final siege(Name taken).
        I didn’t know that there could be civil disscussion on a racist fringe religious group and religion in general on the internet.

        I don’t think Etna is going to do anything special but the Tatun volcanic group has been proven active and has a large chamber and is actually restless.
        https://www.taiwannews.com.tw/en/news/3712982
        Rather cool and scary. This just shows that there should(!) be a study to understand the dynamics of Phlegrean fields magma chamber. The entire system is getting hotter and that could be due to the gathering of eruptible or molten magma.

      • No etna stopped 🙁

        Since 2015 etna has been relatively quiet, at least compared to 1996-2015, where it was probably erupting more often than it wasnt.
        My guess is that possibly there is a magma body forming within the more shallow areas of the volcano, so less continuous eruptions for now as the magma isbt going straight out but this sort of activity does bring a greatly increased risk of an event like 1669 happening later on. This was theorised even in 2001 and the old etna articles on the eruptions blog from 2007 talk about it too though a bit different to today as it was 12 years ago and things were rather lively on etna back then. The 2002 eruption did push the flank out, if etna behaves even slightly like kilauea probably magma is filling some of that space.

        Since mid 1999 when things really started going big there has probably been 2-3 km3 of lava erupted on etna which is a lot, likely more than any other volcano on earth in that time frame, except probably kilauea. Big difference to kilauea though is that etna is doing most of its eruptions at or near its summit 3 km above sea level and 2300 meters higher than puu oo, and when it comes to basaltic volcanoes lots of magma erupting at high elevation is always a risk of a vent opening low down and draining it all. The fact that every eruption after the may 2016 paroxysms has nearly immediately started leaking out of the upper south flank before proper fountaing has a chance to start at the summit, and there was a failed eccentric eruption last year, is probably not the best sign…

  17. The general mantra from most highway Patrols and Emergency operations centers when it comes to flooding conditions is “Turn around, don’t drown” Wise slogan. However, according to what various “news” outlets have said about some of these water rescues is that the rain came so suddenly and intense that the driver could not see they were driving into a pond that used to be a road until they were in it. This particular lady over in Louisiana was saved by the two guys trying to break into her car.

    • BTW, this is the water from Invest 91L that never made the jump to Tropical Storm status.

      The projection is for a few more days of rain. Here, that is not really out of the ordinary. We are used to being wet.

      • Yes indeed.

        Southern england was having a summer, but now its back to rain and cold, probably for the rest of the year.

        Ah well, glad I cut the lawn yesterday ….

  18. The name of this Article
    Sounds like the name of a Secret Military ”Black Operation” sabotage mission

    🤣🤣🤣
    ”Intermezzo”
    Date —-————— 1965
    Location————-
    —————
    Classifyed……

    • The next VC article should be named ”Spectre” or
      ”AC-130” 🙂

        • Well most active volcanoes do have an extensively-deployed censor network so that’s hardly surprising.

    • Origin of the name. Originally, I was going to use “Thump” since the sequential Ruminarian ones were handy and descriptive, but I had lost count. Since Carl is into music, the name popped into my head since this is an “in-between” article in a couple of on going series. The Black-Ops characteristic is coincidental. I never was in or associated that particular species of highly skilled operators. My military experience involved sitting at a console calling off radars that I could see. The closest civilian job description: “Sensor Operator,” though we were sort of unique in that we maintained and repaired our own gear.

  19. We did have a deep quake this morning on the Big Island.

    2019-06-07 11:26:33 2.1 29.1

    Funny thing is all the seismographs went sort of blank around an hour after the quake. I don’t think that they are related but most likely a data problem with the network.

    Mac

      • Still there, changed a little since it was reviewed.

        1km E of Pahala, Hawaii
        It is located just above the seismograph 2812 along the highway

        2019-06-07 11:26:33 1.8 30.7

        • You said big island, so I of course looked at Iceland. 😉
          If you would say small island, then I would look at Hawaii. 😀

          • Yet the hawaiian volcanoes are the largest, most massive and tallest volcanoes on the entire planet…
            all other volcanoes are pretty much grains of salt in comparsion when it comes to edifice size in km3.

            These shield volcanoes are grew very very fast.
            The Big Islands enormous
            350 000km3 is only around 600 000 years old oldest parts
            Absoutley enormous ammounts of materials in a very short time indeed: All of Kilauea and Mauna Loa, Mauna Kea are latest pleistocene as oldest.

            By many sources hawaiian hotspot
            Is the hottest and deepest and most bouyant of any plume on Earth.
            Hawaii is a very strong presistent magma source
            Making the worlds largest deep sea volcanoes very quickly from a 6 km deep ocean
            For 70 million years its been burning a trail through the moving seafloor litosphere

          • Yes Jesper, thats cute and all. 😉 But Iceland is still the bigger island and explosive, and with potential to have global effects, at least economy-wise. And with potential health hazards reaching far into Europe.

            200.000km3 of edifice wont keep me up at night, I need a 20km+ ash column for that. And we all know you aint gonna get one from Hawaii, so… 😀

          • Over 300 000 km3 of edifice in just around 600 000 to 750 000 years
            And once souch load every Half million years roughly
            And most of the shields during a short 190 000 years timespann
            Hawaii haves an insane magma production
            ( most of Mauna Loa is only
            200 000 years old )

            And Kilauea can defentivly do
            20 km tall steam and tephra columns if it goes really crazy
            Kilaueas summit ( despite extremely hot very fluid basalts can get gas rich enough for Tarawera like fountain episodes.
            Lots of basalt pumice in halemaumau from very very tall fountains long ago.
            And Mauna Loa does ( Laki sized lava eruptions in speed and volume ) Last time 1400 years ago Panawea

          • Yea, wake me up when Hawaii does an Oraefajokull VEI6, or Saksunarvatn. 😉

          • Hawaiis lavas are acually extremely gas rich
            Its just so extremely runny that most of the gases just bubbles out

            All these ash and reculite ( gold pumice ) around halemaumau is the result from very tall intra caldera or ring fault fountains or even true plinians.
            Indeed Kilauea coud be the worlds most gassy basaltic lava and the hottest too.
            Halemaumau lava lake had a daily sulfur output that was larger than all US coal power plants combined. And fissure 8 relased 50 000 tons of Sulfur every day. Even in her sleep Kilauea release around 100 tons of Sulfur everyday a sign just how massive the magma input is for this volcano its very gassy. it makes sense despite the lavas are very fluid and release its gas
            When Kilauea been sleeping and magma pressure pent up ( we can get very very tall fountains indeed ). There are huge deposits of reculite pumice around halemaumau from earlier gas rich fountain events.
            With a 200 million cubic meters yearly supply its not strange at all if Kilauea does a Tarawera or Masaya or basaltic plinian or Grimsvötn 2011 Ice Free when a huge load of 1250 C to 1300 C gas rich basalt emerge from the mantle or from a growing magma chamber. These things happen after a major caldera drainage when the volcano been sleeping for a while when there is No lava lake to release gas pressure or when its having a sourge in magma supply.
            Or after the caldera been sleeping for a while and the gas and magma pressure been pent up. All this enormous ammounts of gas is signs of a very very very prolific magma source indeed… And indeed imagine when Kilauea pents up gas and magma pressure.

          • Hawaii is though much smaller than iceland, about 9 times smaller. So hawaii is the ‘small’ island and iceland is the ‘big’ island. Kilauea is also the only subaerial volcano that is younger than 250,000 years (‘late pleistocene’), kohala is over 1 million years old, hualalai maybe 900,000 years, mauna kea is probably about 700,000 years old, mauna loa is 400,000 years old. Loihi is probably much less than 100,000 years old but it will be about 150,000 years old when it surfaces.

            Area covered by holocene lava is though fairly comparable for both iceland and hawaii, 7,130 km2 for big island, and about 11,000 km2 for iceland. Erupted volumes seem to differ though, about 1755 km3 for hawaii (if observed rates in recent decades are ‘normal’) and apparently about 600 km3 for iceland, which is a ratio of 2.9, which is comparable to the ratio of erupted volume in the last 70 years since 1950 (5 km3 for iceland? and ~13 km3 for hawaii, ratio of 2.6).

            There is evidence that recent centuries in both hawaii and iceland could be more active than the holocene average though so this might not matter at all.

          • Size of Hawaii and Iceland

            Iceland is larger than Hawaii
            Because a less hot .. hotspot
            Is fused with a slow spreading ocean ridge. That lifts up the seafloor and allows Iceland Hotspot rise more land over the ocean.
            This have made Iceland into the largest volcanic Island on the planet
            The sea around Iceland is quite shallow beacuse the spreading mid ocean ridge swell
            The ridge is very slow too and that allows the Icelandic Hotspot to pile on materials on the Iceland plateau

            Hawaii hotspot
            Is hidden inside a oceanic plate
            On the Abyssal plain on one of the deepest oceans on the planet.
            The sea around Big Island is so deep it can swallow Kilimanjaros summit
            No mid ocean ridge here
            ( you see less of Hawaii than Iceland )
            Hawaii sits on pacific plate and its moving pretty fast constantly removing the volcanic piles from Hawaii Hotspot.
            Yet during the short time the Islands speed over the 1550 C Hawaii plume they grow into the largest volcanic mountains on Earth.
            Had Hawaii been on a slow moving plate
            It woud pretty quickly grow to bigger than Olympus Mons size. As materials piles up
            If Hawaiis hotspot was in Iceland
            Hawaii woud become much larger over 14 million years

          • Hawaii also will never do an eruption bigger than VEI 5, the eruption magma storage is too small, though effusive eruptions can probably exceed that by a lot, though not quite thorsjahraun level.

            The only way an eruption of enormous size might happen in hawaii is if a volcano falls into the ocean and its deep rift ends up in the ocean with a lot of water around it, then you get your VEI 8, but that apparently hasn’t actually happened before, so…

            Hawaii winds by lava output over time but iceland has larger potential eruptions, sometimes much larger… That thing I mentioned a while ago about kilaueas version of the saksunarvatn tephra turned out to be much less, probably as expected (still not small but not a comparison). Was based off 3 feet of kilauea tephra in a well near hilo but the jet stream blows that way so this makes sense and gives an overestimate, and the pahala ash seems to be a long timescale formation not one eruption. Biggest known explosive eruption in hawaii in the holocene stands at a borderline VEI 5 for the lower kulanaokuaiki tephra in 800 AD, which has been solidly exceeded by eruptions in iceland even within the past decade (2011).

          • Thats explosive eruptions
            Still Hawaii can easly do a VEI 6 volume as a very fast channelized Aa flow like Panawea eruption
            Leilani on steroids and more like 1950 on steroids
            Panawea was Hawaiis Laki

  20. https://en.m.wikipedia.org/wiki/North_Arch_volcanic_field

    Yes it is wikipedia but it has really updated some time recently, theres way more information here than what was there before.

    One thing that is strange though, the field is 25000 km2, and ranges at average of 10-50 meters but apparently has a volume of 1000 km3, if it was that dimension and 10 meters thick it would be 2500 km3 and if 50 meters thick it would be 12500 km3. Given the heat conducting properties of water I would expect the latter (higher) thickness to be more likely especially if the flows are over 100 km long.

    I also expect that the field extends further east following the arch, why it would exist only on this section is unlikely, the part most studied formed largely as maui nui was at its apex, holocene flows probably exist east and north of the big island, even the original map strongly indicates the field extended outside the study area. There is probably thousands of km3 of lava erupted out of vents on the whole hawaiian arch and still ongoing to recent time. If there are holocene flows of similar proportion to the mapped areas then I think those probably represent the biggest holocene lava flows on earth by wide margins, maybe 10 times the volume of thorsjahraun.

    • Makes alot of sense
      Since Hawaii is indeed the most vigorous / strongest hotspot on Earth for the moment and have been for a long time
      No other hotspot is that hot or so bouyant as Hawaii is
      Or release so much thermal energy as Hawaii do

    • Lava extracted from the South Arch Volcanic Field was dated in 14-20 ka, it is most likely still active and it is possible that there are more recent holocene flows there.

      The most recent lavas that have been dated from the much larger North Arch Volcanic Field are about 0.5 million years old, one interpretation is that the North Arch formed due to loading into the crust of the massive Kea trend volcanoes of East Molokai, Haleakala and Kohala. After the construction of Kohala and as its subsidence into the crust slowed down it is possible that the volcanism in the North Arch stopped or more likely just declined down a lot. This view would also explain the active volcanism of the South Arch, due to loading of Mauna Loa it has caused flexure and volcanism to its south which is probably currently peaking. If this is correct then as Kilauea rapidly grows it could cause another pulse of volcanism into the North Arch in the future probably extending it southeastward.

      Since studying volcanoes that are 4-5 km underwater is complicated some flows to the east of the mapped North Arch Volcanic Field and in other areas of the recent Hawaiian Arch could have been missed but I would doubt anything close to the volume of the biggest eruptions from the North Arch, those are easy to spot in the bathymetry.

      In general there are still a lot of things not known about submarine volcanism, if one looks around Hawaii the entire seafloor is covered in volcanic fields, central volcanoes and some weird narrow long ridge-like volcanoes, up to 700 km long and 4 km high (Necker Ridge), I am not saying these are in any way related to the Hawaiian Hotspot, the crust around Hawaii is of Cretaceous age they have had plenty of time to form before Hawaii showed up, it is just to show that what is going down there is still poorly understood. Regarding the ridge-like volcanoes they could be called “Mata” volcanoes since West Mata is a well studied and observed erupting volcano of this kind, it is a surprisingly common morphology of submarine volcanoes.

      And also I would be careful with giving volume estimates, yours usually shoot up far above the estimates given in publications. 1000 km³ spreaded over 25000 km² is 40 m thick flows which is reasonable.

  21. Have patience with one last comment from me, please: my son says he is a Multi-Atheist as there are many ‘gods’ in which he does not believe. Everybody, have a Good Day/Night! Best!motsfo

    • Y’all should head over and read it. Its really nice. It’s got plots 😀

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