William Sager- The Largest Volcano in the World-Mid Pacific Ocean

I appreciate it I'm really happy to give the talk to the society having just recently joined and so this is kind of interesting story you may have heard about it last year there was all this stuff in the news about the world's largest single volcano in quotes is he up there and it was really quite an interesting ride in so to speak because it was a bit of science that I thought really wasn't all that important but it had this little hook to it largest volcano in the world suddenly everybody picked up on it and it went viral all over the world and it got a lot of attention which is good although honestly that and a couple of bucks to get you a cup of coffee at Starbucks but it has submit there's an interesting story here an interesting bit of science and also some interesting background and I thought I would was shared with you and by the way this is a neat graphic but has absolutely nothing to do with my talk this is from the Discovery Channel program on the Yellowstone supervolcano but it's the best thing I could find so this is a story about hard work and a lucky break I've been working on this for 20 years lucky break because last year actually it was almost like in a fit I finally I had got a paper published in a journal called Nature Geoscience which has a very broad readership and in order or to get that well they've been rejected four different times twice by another journal and then twice by this journal and finally I was at the point where the editor said it's a big volcano so what an ass slacker it's the biggest volcano I know about and that became the hook so that became what we publicized and like I say it wasn't even the basis of what we were doing out there research wise it was just one of those things I thought it was an interesting fact but anyway it's also a tale about a name and institutional pride so 20 years ago we went out to study this mountain range it's called chatsky rise I'll show it to you here shortly and it has these mountains in and well it's kind of like going to Himalayas and you could say well there is that one on the right and that one on the left and so he gave them names and so I was a Texas A&M at the time and was my cruise so I said well we're naming the biggest one Taman I'm for Texas A&M there's another one that we call Orie after Ocean Research Institute University of Tokyo a colleague who was there another one named shirshov after the pp cherche offense to to oceanology but that was the smallest one Tam who was the biggest one so 20 years later Tam who gets to have the biggest volcano in the world named after all so this story highlights difficulty of ocean exploration it's all over the news right now they want somebody to find an airplane maybe in the middle of the ocean they're not gonna be able to do it you just can't do it physically and the ocean is a very large place is very hard to explore for years we hit our nuclear weapons under in submarines under the under the ocean we probably still do it is hard to find things under the ocean a lot of people asked well why do we just discoveries because it took years and years to get the right kind of equipment out there to collect the right kind of data stuff that most you guys who work in industry do all the time by the way all right so one of the real questions is the ocean basins are littered with thousands of sea mounts which are undersea volcanoes most of them are inactive and as you look at the seafloor and I'm sorry I forgot my laser printer so I have to drag around the cursor here but there is the Hawaiian Emperor chain there's a bunch of sea mounts over and there there's a bunch over in here here's some of the in the Atlantic they're all over the place has been estimated it may be a hundred thousand of them out there so how the heck did they get out there well that's one of the question that we'd really like to know as geologists because that the stuff that they form from the magma has to come from the earth's mantle somehow so it has to represent a flux from the Earth's interior to the exterior and one of those big things out there there's there's a big volcano cursor went away there it is there's a big one that's why and there's a wine upper chain but they're there and there's a bunch of little ones out there but well what's what's that thing that's called chatsky rise right there we're going to talk about that that one's called Hesse rise there's the mid-pacific mountain is he big complexes big volcanic mountains out there that are much bigger than anything else and again how the heck did they get out there well that's something we would like to know so just sorry about the geology primer here what when I say the biggest single volcano what do I mean by that well this is typically what we mean by a volcano it is a magma and lava come out of us typically a central vent and they come out and they form a conical land form and we could we would call that a volcano if we had a whole bunch of them together maybe we call it a volcanic complex and so what do we mean by magma and lava well you probably are very familiar with with lava flows on the right there there's a Hawaiian lava flow from the air you can see event where there's a lava fountain in out because of the gas in the in the lava and it's running down like a river over the landscape and it eventually builds up the volcano lava flow by lava flow that cools down and on the left-hand side you see an up close picture of a lava flow a little low but lava flow that will go out and solidify and the next will come down and bury it the next one will come down bury that slowly building up the volcano by the stacking of these lava flows so all volcanoes the same well no they aren't on the right-hand side we see what's called a stratovolcano they're typically very steep sided very pretty volcanoes Mount Fuji is one of these they're built up by alternating layers of ash which is broken up lava ash and lava on the right-hand side is I can't pronounce the name but it's in Iceland volcano and then notice it has this shape of like an inverted shields they're called shield volcanoes and they're typically made out of basalt whereas the the Aaron all volcano the stratovolcano is made out of andesite in the oceans mostly we have both basaltic volcanoes so here is Mauna Loa in Hawaii from the air and that is the largest active volcano and it's also a shield volcano you can see the shape basaltic lava is not very viscous and so when it D gases it forms these fire fountains maybe but it doesn't blow up like like the Yellowstone volcano like those up like the andesite volcanoes and so typically what happens is you get a vent and lava flows roll out from the vent and they slide down the mountainside and build it up and if you if you look over here on on montolo ofor example you can see a lot of the the eruptions happen here on the rift zone you can see a lava flow going down the side of the volcano there one coming down over there and that's how you'd expect these volcanoes to build up so oceanic plateaus are a different thing there's those big things we're talking about and the one that I'm going to talk about is a ski rise I pointed out Hess rise the mid-pacific mountains the largest one in the world is long Tong Java Plateau over here which is about the size of France then there's somewhat several others man ahiki over here Magellan right in there but they are big and they look different notice lots of these little volcanoes there's well little they might be 20 30 40 kilometers across and a few kilometers high by contrast these are hundreds of kilometers across no higher but but still hundreds of kilometers across so how do those things get out there they have areas that are in millions of cubic kilometers our sorry square kilometers and one question we would have is do they form like the common sea mounts that we see everywhere most sea mounts form at at plate boundaries so we have a plate we have plates being formed at the mid-ocean ridges and so we get volcanoes formed at the mid-ocean ridge in fact the mid-ocean ridge itself is in essence a huge linear volcano we also get volcanoes where plates come together at convergent margins boundaries and make volcanic arcs so that's the two big source of plate tectonic volcanoes when we go to the middle of the oceans we have there are some that are formed in plate interiors not at the edges in Hawaii is is a classic example of one of those and it's thought that Hawaii formed over what we call a hotspot an area of melting beneath the plate and as a plate drifted over the top it forms a chain of volcanoes and if you look at this diagram and the lower left you see the ages of the Hawaiian volcanoes and you say Hawaii is essentially zero age and the farther you go up the chain the older the islands get to go to a lot of it's 2 to 4 million years you go to Kauai is 5 million years but Hawaii itself is is still active with Kilauea volcano here and Wan Aloha volcano over here now here's also another important point Mauna Loa volcano right here come on curser is that is the largest active volcano in the world and that's sitting in the middle of this island but there are actually five six if you count we evoke a nose as a part of this complex there is there is mana logo maybe we won't see that okay there's Mon Aloha there's Mauna Kea maka Kona who will Ally kill away over here then Louie he is an active submarine volcano just off the flank over there so even though Hawaii itself is a big volcanic complex it is not a single volcano and I say that because we're going to go see a large single volcano so where does Hawaii come from so 30 years ago the idea was was introduced that it came from what's called a mantle plume deep inside the mantle hot material would rise buoyant in a column like you see here and when it got to the surface it would cause an eruption and so this mantle plume idea has stuck around for a long time there's a lot of debate about it and in fact that's one of the primary hypotheses for how we get these volcanoes at the Earth's surface but it can't form all of them a lot of the volcanoes just don't don't fit this hypothesis very well for forming the oceanic plateau is one very popular idea is that they form by what's called a plume head so the plume forms of the core mantle boundary at the bottom there the yellow part and it forms a big buoyant blob and that blob rises up through the mantle there it is right there as a plume head and when that arrives at the lithosphere it causes a huge eruption and what we call a flood basalt up there basically a large eruption that covers a large area and some of these have been actually associated with mass extinctions like the Deccan Traps formed at the same time that dinosaurs died out the Siberian traps in Russia formed at the same time the greatest mass extinction of all time in the Permian at the end of the Permian and then it's thought that after after you get the plume head exhausted that then you have this plume rising up through the mantle and then you get the plume tail and you get a series of seamounts coming away from it to form a volcanic chain now the the only problem with that is that nobody's yet actually documented that there are big oceanic plateaus and there are sea mount chains but no one has actually been able to connect those so this is a very popular idea the plume head hypothesis it's widely accepted if for no better reason then it's an easy way to explain that suddenly you have this big eruption but there are others who disagree as I say hitter the trouble is there is yet no in vertical evidence this is right and some questions question some scientists question the number and or even existence of the mantle plumes maybe there's only a small number of mantle plumes and other researchers suggest that it may be more complex it may not be just thermal plumes for the maybe thermochemical plumes there may be plumes of different sizes and different types the biggest thing is we just really don't know what's going on deep within the earth so we have to take whatever clues that we can get so Shasti rise is the oceanic plateau that i've been studying and the question we went out to try to address is was it formed by a plume head or some other mechanism now chatsky rise has some of the characteristics that you would expect for the plume head model so on the right hand side of the plume head bottom see the blob and then you see it coming up to the lithosphere it makes a uplifts the lithosphere it causes a big eruption and then on the lower right over here you see that idea that forms a flood basalt so that would be the biggest eruption at first and then it would trail away with time with smaller eruptions and we see that chaski Rockies the oldest volcano appears to be big and then it gets smaller as it as it moves along so we thought also that it might show uplift because it must have stuck up out of the ocean we were going to try to test that it looked like you had this transition from the plume head to smaller volcanoes the plume tail it obviously had to have a large source volume so all that seemed to fit but there are some other things that didn't fit one idea is that if you have this magma that comes up from deep within the earth well then you ought to see a signature that looks like it came from the deep mantle so geochemist and I'm not a geochemist so you chemists still argue about what that might be and so that's a problem but everything that we all the rocks we have from this place look like well they look like the mid-ocean ridge it's shallow not fault of not deep volcanism also this same formed right right around the time of the Jurassic Cretaceous boundary and even though there is a boundary there there is no obvious mass extinction or or that you might expect from such a large eruption so that part of the puzzle doesn't seem to fit very well there are some pieces there and some pieces that aren't there so here's a bathymetric map of chaski rise and you see the different names so Tambu Massif is the large one on the bottom Horry Massif and then shirshov Massif then you see a ridge tailing up going off to the to the northeast down over here on the very lower left is a typical large female and so you can see how much smaller it is then then Tama Massif for example so this whole thing has an area about the size of California Tama Massif itself has an area about the size of New Mexico so it's a big thing so we see these we see these blobs and so a long time ago I thought gee that looks to me like one volcano doesn't it's one mount it must be one volcano but what would happen is when I would sell that to other scientists they would go no no you can't say that it could be these things must erupt on fissures they must be multiple eruption centers so it'd be more like Hawaii lots of volcanoes that are all strung together so I couldn't prove that for for many years but we'll talk about that a little bit later a little bit more about the size here so there's Tama massive the kind of big green blob on the lower left and next to it is Olympus Mons on Mars the largest volcano in the solar system at the same scale and so you see they're not that different Olympus Mons is still the largest but it's Tama massive isn't far from it now look to be fair Olympus Mons is 24 kilometers high but Tama Massif is only 3 to 4 kilometers high except that Olympus Mons sits on very thick rigid lithosphere so it's mostly above the surface and kamu massive is like an iceberg it's 30 kilometers thick so most of Tambu massif is down in the mantle so it looks like one big volcano but until recently we didn't know what the interior structure looked like so here's tama Massey first Mon Aloha on a Mercator map just so you can see the see the - you can see how much bigger taboo is then then long low up and so as I said we weren't really looking for the biggest volcano our project was to understand the origin of shad ski rise and so what do we know about chatsky rise formation let me give you a little bit of a history of how we think the clues that we have about about chaski rise that is formation so I understand Dave riches in the audience Dave I'd be happy to meet here after all these years day there you are ok so when I was a young professor at Texas A&M thirty years ago one of the first theses I read was one that they did he he was a student at Texas A&M and worked for a guy had the office next to me he studied the magnetic anomalies in this area so Dave here's the magnetic anomalies 30 years later what you see is two sets of you see that this is the Pithom 'try of shafts key rise up the middle and these red lines are the magnetic anomalies from the EM sequence these were formed at the Pacific Farallon Ridge these over here were formed at the Pacific is a nagi ridge so there were two ridges that came together because one went in that direction the other one went in this direction and you see they come together right where shad ski Rises and so that's a very interesting observation it says it's a ski rise had to form along the trace of where these ridges met where you have two ridges you actually have to have a third it's called a triple Junction and okay so there it is this is the triple Junction before in this set of plots the dark shows what's existing at the time this is M 22 time about 105 50 million years ago and so there was a triple junction of three ridges that came together and it was happily going in the direction of the arrow to the northwest let me jump back I missed something on that slide when I accidentally hit the button at currently we only have one radiometric age for Forsch ASCII Rison it's where that arm circle is site 1213 it was drilled in nineteen No 2001 and is dated at 140 4.6 million years which is essentially the age of the magnetic anomalies under it and so what that means is that this volcano had to form right at at the same time as those magnetic anomalies so it had to form right at the ridge so here's the triple Junction at 122 million years ago it's going to Northwest and then chaski rise begin to form shortly thereafter a few million years later at 144 million years at m17 time now you see the two the triple Junction is at the center of shafts key rise it followed the blue arrow it jumped actually 800 kilometers to the east and then began following chatsky Rockies more likely what was happening is there was some volcanic process that took the triple Junction and stopped it going from the direction that should go and made it follow the volcanism and then we go a little bit later 139 to eight years at 131 million years you see that the triple Junction follows a ski rise right on up as it as it forms and so these large volcanoes were formed in the plateau at along the wake of this triple Junction Sochi a ski rise in some ways fits the plume head model it begins with a massive eruption that is we estimated 2.4 million cubic kilometres the initial eruption was followed by transition to a smaller eruptive all usako from the bigger one to the smaller ones to the little ridge that goes off to the northeast so and also the triple junctions seem to be captured by volcanism so it seems like there must be some Keit there that keeps the triple junction willing to go now remember what is a triple junction of ridges is just retake threes place and he split them apart so it's a crack so basically it's going to follow the line at weakness also we had dredge shallow water fossils back in 1994 from the from the summit of Tama massive and so we knew that had been in shallow water so that suggested well we must have been high enough at least to get up to be maybe it was an island although we'll get back to that and I'll disagree with myself here a little bit but there were some observations that didn't fit and one of them is I promise to only show you this one geochemistry slide our geochemists what they like to do is they like to find isotopes that have different behaviors so these are do divyam isotopes versus lead isotope sources strontium and then lead anyway you plot these things and you hope that your samples fall into groups so one of the groups you see here is the East Pacific Rise these Pacific Rise is there it's there it's there and it's there so these Pacific Rise is what you get from shallow volcanism at the mid-ocean ridge and you see them these are some the symbols are from shafts key rise back in 2005 from that one hole we had you see if they plot the same place so by this geochemistry it looks very ridged like it doesn't look like a plume hmm so that doesn't fit very well then there's just a logical argument if you have a plume and it comes up from the core-mantle boundary and it doesn't care what's going on the surface and it just rises up and there's a triple Junction up here what's the odds it's going to come up and hit right near that triple Junction well the odds that of a plume head a random plume hitting within 800 kilometers of a random triple Junction is about four tenths of a percent not very good percentage okay so coincidences happen but as a scientist we don't like coincidences or maybe the plume does know and care maybe the plume is following one idea is that the add a triple Junction you have upwelling beneath the ridges the plume might come up and and follow that follow that in here's a another interesting observation so she a ski rise is just one of many plateaus and it looks like many of them follow fall along a triple junctions so this one triple Junction that I mentioned earlier went up this way got the shaft ski rise went over here eventually went up this way and we think the lights went out during the Cretaceous quiet period come back there but there was another one another plateau over here near where it eventually came out another triple Junction went this way near the mid-pacific Mountains near the Magellan rise and near man ahiki plateau so goodness gracious if we have if there's only one less than 1% chance that that a random plume will find a random triple Junction that's an awful lot of coincidences and it makes me think that there must be some kind of Ridge control that that hook that makes these things happen so why study shot ski rocks I mean it's just one many out there we went there because it had a couple of characteristics one is it has those magnetic anomalies that I mentioned that's rare it turns out that many of these were formed during the Cretaceous during a period of time and there were no magnetic reversals so this is the only large plateau that's formed at the time of magnetic reversals it also has this sort of tantalizing combination of things that fit both of those sort of end member hypotheses and so maybe it's a special class of sorry I didn't explain large igneous province that's the lib acronym formed at reorganising ridges or maybe it's characteristic of all we didn't really know that without going out there so I was able after many years to convince some people to put some money into it and so in 2009 I was a co-chief scientist for an expedition on the integrated ocean drilling program it's still called IO DP with the change to the International national ocean Discovery Program okay god I have a new acronym even if it's the same thing and we went out there just because we specifically want to try to get a basalt there'd only been one set of cores cord from the basalts of shad ski rise we want to test the age and want to test the age progressions we also want to look at the geochemistry when look at evidence for paleo water depth so this was a this was 15 years in the making I first submitted this proposal in in 1995 shortly after my first cruise and it was finally granted in 2008 it was a it took it was a long time coming so there's there's a photo prove that I was there at the drill ship and so we went out and we drilled where you see the red dots or where we drilled so we drilled one up on cherche off to a nori 2 on Tam ooh and then we already had the one cause site 12 13 it was drilled in another expedition before that there a bunch of other little holes have been drilled but none of them had gone into the igneous part of the of the volcanic complex so we want to and that was particularly what we want to look at so once again this is the path inventory map and it shows the Magnetic litigations around it and one interesting thing is that notice how the magnetically ations go through parts of Schad ski rise which is really interesting it doesn't go through some parts like the middle of Tama but it goes through the flank of Tama hmm so that suggests that again a link with with the ridge formation so when we drilled at as chad ski rise we found we found a massive flow so these are the different sites that we drilled and i know you can't see it all at once sitting here within the short time on show it to you but these are the different sites these are Tama Massif right here this is another plateau called Hong Kong Java Plateau this dark green here represents massive flows these are flows that are tens of meters thick this lighter green here come back here oh that lighter green represents they are the sort of normals low fusion lavas that form under seeds so like squeezing toothpaste out of a tube they come out like that and they form they form little things that look like pillows when you cut them cut them open and so what we found was that Tambu massive right over here this one we just got explosive volcanism but here we found alternating massive flows here we found here we found massive flows and very similar lithology on ontong Java Plateau which is the world's largest plateau and the thickest flow that we found here in this short section of about 150 meters that we were able to drill into the in the India's part 23 meters thick 75 feet so think of a lava flow 75 feet thick on the flank of a volcano suggest that you have to have a massive amount of magma pouring out lava pouring out in order to do that there's no reason to think that there was a pond of lava we think that there are lava flows because as we drill this on the flank this is what one of those massive lava flows look like in core so that's a core without nine and a half meter core you're seeing half of it's been split so it was cylindrical it's been split and you're seeing it sections of it laid out and mainly what you see it it all looks the same that's because it's very homogeneous inside this massive massive float so important points from drilling that we learned are is at a mu massive looks like a typical flood basalt I forgot to mention those massive flows are seen on land they're seen on lands in places like Deccan Traps Siberian traps and other places where flood basalts have happened so it's we see the typical lava flows from flood basalts and we also make the connection with Hong Kong Java Plateau so it looks like the formation mechanisms are are similar the one thing I forgot to mention on that is that you didn't see those massive when you go farther up shot ski rise so there does seem to be a transition from massive flows on taboo to smaller flows as you go up to the smaller edifice so there's a does appear to be a waning of volcanism or at least a diminution of the fusion of magma coming out also wherever we drilled we found evidence that the wherever drilled near the summit we found that we were getting shallow water sediments we didn't find any strong evidence of actually being severely exposed but we found lots of lots of evidence for shallow water and then again from the geochemistry nothing really looks that much different from ontong Java or mid-ocean ridge basalt sorry about the acronyms MORB is mid-ocean ridge of salt okay so I mentioned seismic in the title yes there's ively data so it actually after the drilling crews and this could only happen with what the government right because I've been trying for about five or six years to get the u.s. academic seismic ship out to shot ski rise to get new data to see inside the thing but we got the drilling proposal funded with only a year's lead time and we and we couldn't get out there so then the next proposal I said well we got the drilling we really need to get the seismic data so then I got and so I was able to go out and collect the seismic data the year after anyway and it was on a ship called the Marcus Langseth which you'll see here in a moment yeah there's the Marcus Lange set if it looks vaguely familiar it ought to it's actually an old western gqo ship and it had been sitting around for a while I think because it's just covered with rust it this was the first cruise out of drydock when they were fitting it up it looks pretty from this angle and there's a rainbow there it's in Honolulu and the guys I felt sorry us for were the poor seamen that had to paint because I every day I'll go out there and young they'd be painting yeah and they're trying to paint over all that rust and if you ever seen a seismic ship it's got a million in ters disease and cracks and thing in places where it rust can hide I really felt sorry for those guys anyway so we got to go out on this ship but there were some wrinkles with this cruise because like I said it's the first cruise coming out of drydock so I'm going to tell you about some some issues that came up all the cruises but mine got canceled why did mine go forward because was funded with ARRA that Obama's recovery money money so NSF got a little bit of money they put it into this this cruise and they couldn't cancel it because that you know they had to spend it anyway so so we had to go from Honolulu which is Honolulu is a great place to go I highly recommend it but it's ten days away from from chaski rice so we had to sail ten days out to get there red sail ten days back to get there so there's 20 days to start with and then this cruise was the unluckiest cruise I've ever been on and I've spent probably about four years of my life at sea on Gary's cruises 41 cruises cruise was delayed six weeks in the shipyard delayed another two weeks because of engine control problems you know seismic ships they have to have precise engine control the cruise was assigned 20 days of transit because other cruises were postponed so the cruise not only did it shift by about two months it also grew by 20 days one of my colleagues who's seismologist of lamont-doherty passed away from a heart ailment in the middle of the summer I suppose the lucky thing is that he would have been on the ship but I guess it wasn't really that lucky anyway the cruise was delayed two days waiting for incidental hazard assessment and those of you in industry might recognize that that's your permission to go out and annoy the whales the crews have delayed another 10 hours because of a technicians plane being late and then we got out and started doing our work and then we had another day we had a senior Marine Mammal observer passed away from a heart attack and so we had to take his body to Japan so Japan is four days away so we went to Japan we dropped him off we came back and we started working then we had a second medical evacuation it was a captain's first time being captain I think he was so traumatized that he that cook had a problem with his leg and he was afraid that the cook might have phlebitis I think and so we took off again and back to Japan so another but we didn't actually go into the harbor this time so it was only seven and a half days so at the end of the cruise in September they got a Hawaiian Kahuna which is a religious shaman to come and bless bless the ship and chase away the evil spirits and the project was finished actually two years later after the grant money had already run out two years later they gave us another short cruise to go back and finish it like I say this can only happen with the government so our survey plan looked like this the blue line was a seismic refraction line that we shot across the center of Tambu the red lines were all multi-channel lines basically the ones on Tam ooh we did in the first cruise and then we went back and to finish up the northern part of Jammu and go across Ori on the second cruise the mg/l 1 0 0 4 is the to 2010 cruise mg/l 1206 and 2012 cruise and I'm glad that NSF stuck with us and gave us another cruise which was very expensive because I don't think it had we not had the data from the northern part of camu that I would have been able to got get this paper published in the prestigious journal that I did so here's a quick snapshot of the OBS data published by a colleague of mine and what you see at the top is a cross-section of camu Massif and that's a velocity profile on the upper left that says sea there and so basically what you see is Tambu Massey because this low-rise with a with like an iceberg keel at the base so it shows that a mu Massif is is huge it's very thick but it's just most of that is hidden beneath the beneath the crust now I'm going to start showing you some seismic profiles the bright red line shows you where this one's going to come from I show you close-up of one line to show you what we're interpreting so on the left hand side is raw data and on the right hand side is interpretation and what you see is if you look at the top part you see nicely layered sediments that's what you'd see if you were looking for a while of course there's no source rock around here so that's not a worry in this neighborhood and you see and then you see these sort of lower frequency but clearly layered sequences much deeper in the section and those we interpret as being the tops of lava flow packages now one thing I have to mention about this is that by the time the seismic wave gets into the igneous crust we're looking at wavelengths that are probably on the order of 100 150 meters something like that so we're not going to detect an individual lava flow we're going to detect changes in lethargy rate related to lava flows and I'll show you that in a minute but the exciting thing here is that you're seeing reflections from things that we can interpret as lava flows that are more than a second deep in this one right here we've seen them as deep as about two two and a half seconds which is 45 kilometers deep inside the volcano which is really a really outstanding so this is we do have did get some walking data when we went drilling so on the left-hand side is a lithology for one of the sites we went across the sites with our seismic and then you see a velocity and a density log and then you see a synthetic record and then you see on the right hand side the actual multi-channel traces in essence what you're seeing is we have the top of the igneous basement is right there it gives us a big reflection because there's a big rise in both density and and velocity and then you get to a section no pillow lavas where you have lower density material there's also a few sections where we have the red arrows or where we have sediment layers that are intercalated that are approximately 5 meters and so you see a low velocity zone in here another low velocity zone in here that basically gives rise to your reflections those gradients in there and we get a pretty good our synthetic matches the the actual trace is pretty well except for this one spike right here that gives us a reflection of the synthetic but doesn't appear in the actual multi-channel traces and who knows that could be a bad data some bad data points in the log or it could be that very thin layer that shows up in the logs it doesn't show up in the seismics really can't can't tell now let me show you a line that goes all the way across Tama Massey this is our most complete line and so this is Tama massive and profile and so what you see is a large rounded mound and I should tell you that the vertical exaggeration here is about thirty to one so it looks steep but it's not at all steamed up there you see the seafloor slope and most of the slopes are a degree or half degree or less that you get down on the lower flanks it is the slopes are so shallow within if you were blindfolded and walking across it you'd have trouble telling which way is down shoot without the blindfold you might have trouble telling which way is down one very interesting thing here so this is the interpretation down here these are the lava flows that you see here in here and this is a late-stage volcanic peak that sticks up you'll see it in some subsequent figures that's sediments on the top but you see what you see is is broad dome and we see the lava flows come out though that way they come out and go that way there's no obvious secondary source of volcanism except this very late stage then here and we won't see it on other profiles and if we look at the pattern of lava flows that go there kind of pretty much right there right on through it so that is that is the evidence for which we say that looks like this Tama Massey is a central volcano volcano where the lavas come out from the center will see other profiles and basically the main point is going to be that no matter how we cut this thing in half we're always going to see the same picture okay so this next profile goes up the length of Tambu Massif kind of a convoluted profile but we're trying to follow the axis and so you see a similar sort of pattern you see a broad dome and you see lava flows that go in places very deep now there are some places like these arrows down here there are local highs that maybe they were a center at one time most everything comes from the top of the volcano so that last profile cut a crop right about there and so you saw that same pattern in two different directions now and there are you can see there are things here some buried cones right there we found lots of cones there is another cone that's buried over there there's another one on the flank over there this next profile is going to be down on this side on the west side and again you see a very similar pattern you see some interesting faults in here we still don't understand these faults but they appear to have happened later but basically you see a big mound with lava flows going away to the sides and then this one goes across the north side and once again you see the same sort of same sort of picture there is the sediment cap right there now I forgot to put point this out on another one but there is a caldera right there so that many volcanoes we see a caldera at the summit if you go to Kilauea montolo you'll see a caldera the summit so we we found a buried caldera in there and we do see we do see one of the interesting things because this thing is so low and so broad these secondary cones look major mountains but they're not there a few tens of kilometers across maybe a kilometer high sitting on the flanks and they look like these daggers sticking out but it's just because the vertical exaggeration is so high but once again lava flows go that way lava flows go that way this one goes across or a masse which is the other one the next biggest one and it's a basically a similar pattern we see it looks like it's symmetric around the middle and so no matter where we go we see that same that same picture so that's that that's the origin of the idea that this is we're looking at one massive volcano and probably Laurie is one massive volcano so this thing however whatever mechanism made it happen it can generate huge volcanoes in one place this slide talks about the about how shallow was was chatsky rise how shallow was the top of Tamron Massey one idea is that remember if you have this big blob coming up from yours buoyant blood coming up in the Earth's mantle it ought to push things up high Iceland today is thought to be a at the top of mantle plume and it sticks up it's a high ion that sticks up by a kilometer or two so did Shasta your eyes do that the answer is not really so in these diagrams what we plot it is we plotted this is the depth where we drilled the volcanic s-- in each diagram these are different holes one for each hole this is backtracking as lithosphere ages it subsides and so these are the subsidence models curves for that and you see they all backtrack up so that they're in pretty shallow water remember we when we drilled we found shallow water settings but no evidence of emergence and so indeed that's what that fits the the analysis of the sedimentary data and also look this profile this is that same profile again if you look at the Hawaiian volcanoes they come out of the water and within a few million years and waves plane them right off and they're gone we don't see any of that there's no evidence for sub-aerial for wave erosion at the top of Tama Massey and what's more this thing actually sticks up so we think that this same form first the main peak this one must have formed later after it is subsided but neither of them show any evidence of wave erosion so we think that it was never highly emergent so that doesn't really fit the plume model very well at least not the classic plume model as being a thermal pluton ok so let me summarize a little bit so why is the world's biggest volcano important I got that question a lot it was important because I got the paper ok so that would that was an immediate thing and then I had to think about all right so why is it really important ok tell massive is vastly larger than the common sea mountain so it's a different class of volcano you saw those little sea mounts little pimples all over the place this is a much different thing it has a different morphology instead of Pekin it's it has very broad shape to it in any case lava flows we think that indicates a lava flows that travel along this is a very fluid very massive lava flows that basically go along hundreds of kilometers and so we have high fusion rate low viscosity flows so why is tama Massey if a single volcano as I said has a large emplacement at the single near the center and why do we see that well we think that what happened was the plate was drifting over this source and it formed Tambu within the plate that drifted away then it formed or E and then formed shear soft so there was a gap and the plate moved in between just like there is in Hawaii except on a bigger scale so what does Tambu really mean besides the acronym Plateau formation relies on a large extraction of magma from the mantle to typically we think at the base of the mantle there might be partial melt of a couple of percent to 3 percent you have to even at 10 20 percent you have to evacuate a tremendous amount of mantle to pull that amount of magma out of the mantle they are similar flows to continental flood basalts that's a CFP an aunt on Java Plateau and that suggests the common Lane that's been suggested for these and so oceanic plateaus have can have the single sources and a single edifice can be much larger than previously thought as I said until this time we really didn't know of volcanoes of this size on earth so that's one of the reasons why it was important to recognize kind of like we're going to have a dinosaur lecture it's kind of like we found a t-rex is ten times bigger actually 50 times bigger than the then the other biggest t-rex that we knew about so what about this argument of is it a plume or is it a plate well the jury is still out there is no one observation that clinches the argument but this is the way science works we're going to chew on these data for a long time I'm a geophysicist that I can see what's at the surface and all I can tell you is what the volcano looks like at the top not where it came from down down below so maybe the massive size that suggests to a lot of people that it must have been a plume you got to bring up some heat or something to make it happen and it fits the plume head to plume tail model that's that's still there there's a strong link to spreading ridges in a triple Junction and so there's a link to plate boundaries and so the idea that these things are disconnected maybe that's just wrong maybe there is a connection maybe we just don't understand that connection yet geochemistry so far is still similar to Hong Kong Java and mid-ocean ridge basalts but my colleague geochemistry colleagues are arguing about what that means some say well you can see the same variability see the same things on the mid-ocean ridges some say no it's only anyway it's it's over my head and I'm waiting for them to to come to decision and like I say perhaps we just don't understand the problem we have a tendency to go out and say well it could be this or could be that and reality is it could be something else in that's maybe related to both of those things so the story was of course one of the big things about this it was a great it was a great opportunity for outreach I've done many things over 30 years of my career and actually until this time a funny story is my biggest claim to fame was seeing a squid so back in 2000 I went down I was studying oil seeps the Gulf of Mexico went on a dive on the Alvin we got down to the bottom and if you ever been an Alvin it's just a little 6-foot titanium sphere and the only person who can really see is the sub pilot so you get to the bottom would clip on the lights cruise around a bit the sub pilot says what the heck is that and that's not what you want to hear Bob so he got the video camera on it I'm looking over his shoulder and there's this weird squid there and unlike most kids that take off it just kind of slowly flap like hey submersibles happen all the time now these spaghetti like arms I took videos of it then we went on did our business later on I gave the videos to guide the Smithsonian and I ended up being 7th author on a science article I don't know why people called me and I was on TV on CBS on NBC I was in the newspaper even local news and College Station thought they'd better interview me they don't like to really bother people with science and so that was great it was great except I you know I kept saying I'm not a cephalopod biologist I am not tell us about the giant squid this is something I actually did so I'm proud of that it was a great it was a great opportunity because it had that little hook biggest volcano in the world that made people go oh and they would look up from their smartphones for a few seconds and it also showed a huge difference in the way that news has changed in the intervening 12 years 13 years back in the old days that was newspapers and TV now it's all the way we put out a few press releases I'll EP did one UHT one Texas A&M did one and those things got copied there Eric burger and The Chronicle did an article there's a few newspapers did that interviews did articles and then those things got cloned all over the web's we would kind of lost count at about 400 web articles something like that so it was great you H was just loving it Tammy was just loving it story appeared on like 400 websites with it but maybe there are only about 15 different interviews there's about it it's always interesting on both of these things I get interviews by talk radio I guess talk radio has airspace to film and so they you know they call people like me in the middle of night and and keeping people awake or something the story appeared on TV mostly as a short headline often attributed to scientists without mention of the affiliation and one of the things that I did in all this was try to to hot spotlight the IO DP and also National Science Foundation because both of these things that ocean drilling program and this seismic ship are under intense budgetary pressure and they're not a given that they're going to stick around and very very nicely it was also ranked by Discover Magazine as a number 11 in their top 100 science and the highest-ranked Geoscience story for the year so that that's neat it's on the wall of my office now there's also just weird stuff somebody wrote us on on YouTube I guess that just proves that some people have more time on their hands than they really need there's a story in the onion so the onion went out and I don't know whether is real or not but they have interviews of three people on the streets basically proving that they do absolutely nothing about discs like I hate mail somebody objected really strenuously to the fact that I named it Tamara masse after the eggs and it wasn't even a long horn it was from somewhere in Washington State and it's just that you know it's I guess I should feel lucky that it was only one bit of hate mail because you know any time you look at any story posted on the way of the people who are author medications come out hand they know they're they make all these rude and inappropriate comments anyway and my sister tells me she was watching a program that I've never seen called million second quiz which I have no idea what that is but it must be a quiz of some sight what did scientists recently discovered largest up so even they it made it onto a quiz show so anyway I think that's that's it so I'd be happy to answer questions definitely I noticed on many of your seismic profiles gap not all open but the majority of the seismic profile she showed can the thickest sedimentary overlay at the crest of the stretch right adjusting that the initial growth started from a basic the initial growth of the masses well the sediments the sediments accumulate unevenly for two reasons one is that current swirl around the summit they tend to clear it off but also it's above the calcium calcite compensation depth once you get down to 4500 meters in the Pacific all that carbonates going to go away nor those are large that carbonate sediments pelagic sediments on the time 25 what's at 2500 meters 445 I think 4500 is you know I don't know exactly because I'm not a chemical oceanographer but I think it's 4,000 4,500 meters is a CCD in the Pacific yeah I'm sorry somebody back here yes thank you not all mid-ocean ridge this walls are similar and be done detail to be a showing and you look for regret recreate my collar I remember I'm not a geochemist and my colleagues are doing that if you're interested give me a card and I can get you the papers and yes they're looking for not only at the at the major elements but also at and and the trace elements but also at the different flavors of of isotopes and their ratios in the Gulf of Mexico most certainly I one of things i study is the gulf of mexico and so you know i have trouble holding onto my students are very long because they're all they're all off working for oil companies in this area there's really not there's there's no hydrocarbons because there's there there are some the sediment cap does have some black shales but that's about as close as you'll never be economic to go after them and manganese nodules is there's covered with manganese nodules but so far it hasn't proven economically feasible to dredge up manganese nodules not to mention the environmental disaster that it would be to like scrape them all up off the seafloor but there is there that people have been researching that for a couple decades but nobody's actually done it yet yes good any heat flow studies using satellite data to see if there's any remnant higher thermal activity in the area thank you for asking that because you you reminded me that I forgot a very key thing remember this thing happened 145 million years ago it is as dead and stone-cold dead as any volcano can be but know that nobody has done any heat flow on it that I know of but there's also no reason they would never get the funding to go out and do it because the wait actually I'm wrong about that on one of the holes drilled I think we did we took some temperature readings and it's just a very it's an old ocean he flowed nothing no real heat source there we did find a lot of evidence of hydrothermal circulation in the basement rocks suggesting that when it formed there was lots of heat and lots of circulation of seawater probably probably through cracks that deposited leached out a lot of minerals so you could see a lot of these and of course that are geochemist hated that because it just wreaked havoc with the chemistry of rocks so but no there's nobody's looked at any pretty recent eclip yeah Dave for that one things that we look at when I was working the problem was the place all the same great bright wall fractures on that it eventually did Plateau right it was it because it's moving at the same rate this stable configuration and that would even if it was weak transform that is still basically correct and I only gave part of the story because it's simplest part when I said that triple Junction should have gone to the northwest that was a direction it was going because you can see that with the magnetic bytes but that's also the stable direction if it's a Ridge Ridge Ridge if it's a Ridge Ridge fault which is a possibility then it could have been going in I think it would be go I I don't remember it's been years since I looked at it but I think you're you're right about that and I ignored that part part of the problem is that all we have left is a record on the Pacific plate as you know and so we don't actually know what was on on that other that other boundary and we can only speculate it's all been subducted beneath Asia yeah are you going back to the same area or well actually actually I am and it's another weird twist of this tale so I figured there's no way I'm going to get NSF to give me any more money go out there they've given me millions of dollars to go out with these two cruises somebody else has turned and also to get NSF funding you have to prove that something is transformational and not just the next the next step but they are Google billionaires that have made a an oceanographic institution in California called the Schmidt Ocean Institute and they have their own ship and so last year I saw a call they said send us your proposals so I sent or false it will go out and the thing that Dave I want to do is magnetics have been ignored through all of this the problem is that most of data that were magnetic data are collected in the 60s and 70s there's really not much new dad you got so I suggest I said we really need to go out and look at those magnetic lineage ins and how they come together and lo and behold they gave me they say they're giving me a cruise but here's the interesting part I don't have any money to get there I know now no I'm going to get get there or bring my magnetometer along but that's details to be worked out micron so next year next summer maybe I'll be going back out again and I did get a outreach coordinator to try to we're going to try to get looked out hooked up so this time beforehand maybe you can come along and watch this on the web it's Google remember so they got a good web connection dinner is you know when you go to Google Earth and you open up the bathymetric picture of your right it just seems like we know everything you know everything looks mapped and it looks clear but the fact are we the data for each of these areas varies you know tremendously between you know how much control we really haven't we really do know and so how how do you is how do you recognize that or reconcile that when you're going in and exploring inside Google Earth imagery you know how well do we really know areas like most of the most livable with imagery comes from a satellite measurement and I know I told you earlier that you can't do with satellite but you can fake it and so what they do is a satellite flies over the ocean and it uses a radar beam microwave beam to sense where the sea level is and so it's a big big spot so it's not the waves are averaged out and that's an equipotential surface basically it's gravity and so they can derive the gravity in the oceans and from that making some assumptions they can derive the bathymetry so what they've done is they've gone through used actual with imagery soundings Plus this gravity and done basically a transformation function to convert gravitated with imagery so that's mostly what you're seeing the great thing about that is it fills in all these gaps and it's pretty good it's really good showed me pretty good but it doesn't have much detail actual modern both imagery soundings that we have in the old day the ship will go over to just take a sounding sounding sounding sounding nowadays a multi-beam ship goes over does a swath of soundings and we have maybe 20% of ash a ski ride covered with with actual real data the rest is filled in with the satellite and so there's still a tremendous amount to be learned in fact they collect morpeth imagery data on this on this next next cruise it is one of the frustrating things about being a deep ocean marine geophysicist because in areas like this this is actually well surveyed go to the southern ocean there are whole states there gaps that are big enough to throw you know throw Ted well maybe not Texas but there gaps big enough to throw a large state in and not hit anything and it's just because they're a long way from anything and most of the explorations on the oceans we've done in the 60s 70s and early 80's since then it's all been very targeted and so not only is it not much data but most of that data is old data that's very badly navigate long before GPS so half the time we don't know really where we are yep and look like circles your shadow plateaus were sometimes marvelous right so should be huge oceanic hunters to be massive massacres Church I guess I guess I would say depends on how you define anomalous but I would say yes probably so they don't they don't fit within our classic plate tectonics so if we use that our baseline yes they clearly are outside that and and that's in fact why we I get to study them because they are anomalous and so and so you're right another point that a good point to make is Tama Massif is just one part of chatsky rise and it's the biggest volcano that I know of there are bigger plateaus out there I carry very curious about Hong Kong Java like I say it's as big roundish thing the size of France but nobody has got enough survey data over it yet to say with any to say with any certainty is it one or many volcanoes that's the our classic problem was studying the oceans going back to the knees is question you know I get this all the time for reviewers of articles you know I spent two months at sea and I have few postage stamps then they say well you only have these small areas how can you make the well my job is to do that from the small boats geologists that's right that's a desta geology isn't it and and you know in marine geology is especially bad because we're never we never have enough data that doesn't stop us yet or question yep has there been any hypothesis put out that these plateaus are my hip originally cores of crayons in the early primordial earth that's that is certainly one idea and it's it's hard obviously hard to prove because if it's a crate on now it's been so massively metamorphosed and most around that it's hard to say we think that these plateaus they are too buoyant to subduct so when they hit the edge of a continent they'll just get scraped off into the continent and so that may well be exactly well that's one idea of how you get your old bull crate ons initially yes okay I'm sorry I didn't I didn't quite catch that which could you repeat it again I'd have missed it that's actually that's actually a really good point maybe maybe not the gravity doesn't show well one very interesting thing about the gravity is that this thing is so I so statically compensated there's practically no gravity anomaly and I've had I had two masters students work on a gravity model and they both came up with kind of different conclusions so I kind of okay I'll have a third do it then I'll take the average I think and then but one things about the magnetics is remember I showed you that there are places where the the magnetic linens go through we wouldn't expect that if we have a volcano that spews lava over large distances because Iceland we do Iceland forms at the mid-ocean ridge and we do see the magnetic stripes come up and they get Wiggly but they go through and what's happening there is the lava SB is it's coming up in volcanoes right along the rift then they split and they go their different ways but it's not like this and in fact that's the basis of my latest proposal is we need to find out why we even look at that transition between where we have we think we have the magnetic stripes and where we don't and see if we can figure out a good reason for that suggests that this thing is maybe half-and-half or something like that so that's a very good point but no it's not all tidy yet very good well that's everybody's gushin if you have more questions stick around after I think we'll be I'm not willing to sure it answer some more questions we'd like to thank you for coming out this evening you very much you have a little gift for you it's a paperweight so you'll remember us and maybe oh how could I forget come back and give us another chapter okay certainly thanks very much thank you

Channel: HGSGeoEducation

Views: 155,617

Keywords: geology, volcanoes, Pacific Ocean (Body Of Water), mantle, plumes, plate tectonics

Id: 8bhUEYNNr1Y

Length: 68min 6sec (4086 seconds)

Published: Sun Mar 23 2014