Yellowstone Volcano Observatory Scientists Host Facebook Live Event

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USGS–Yellowstone Volcano Observatory Scientist-in-Charge Mike Poland, Deputy Scientist-in-Charge Wendy Stovall, and Chief Seismologist Jamie Farrell answer questions from the public about Yellowstone earthquakes, deformation, eruptive history, the magmatic plumbing system, and more, during a USGS Volcanoes Facebook Live event recorded on March 7, 2018, at the USGS–Cascades Volcano Observatory seismic operations room in Vancouver, Washington.


Date Taken:

Length: 00:42:27

Location Taken: Yellowstone Caldera, WY, US

Video Credits

Comments addressed by USGS–Yellowstone Volcano Observatory Scientist-in-Charge Mike Poland, Deputy Scientist-in-Charge Wendy Stovall and Chief Seismologist Jamie Farrell.


Wendy: Hi, world!

Welcome to the first ever Yellowstone Volcano Observatory Facebook live event.  We have three people here – two in person and one virtual, and as this lovely picture on the back wall.  I'm Wendy Stovall, Deputy Scientist-in-Charge and my specialty is geology.


Mike: I'm Mike Poland, the Scientist-in-Charge of the Yellowstone Volcano Observatory and my specialty is in geodesy.  Jamie, do you want to introduce yourself?


Jamie: Yeah, hi, I'm Jamie Farrell with the University of Utah.  We operate the seismic network in Yellowstone National Park, and I'm also the Chief Seismologist for the Yellowstone Volcano Observatory.


Mike: Just so you know a little bit about YVO – it's not a physical volcano observatory the same way that many other places are - like the Hawaiian Volcano Observatory or even the Cascades Volcano Observatory.  Instead it's a consortium of organizations: The United States Geological Survey, the Park Service, the University of Utah, University of Wyoming, UNAVCO – a group that runs deformation stations, and the state geologic surveys of Idaho, Wyoming and Montana.  So it's actually a nice grouping of scientists that are all focused on better understanding of how Yellowstone works.


Wendy: yeah.


Mike: With that in mind, we hope you send us your questions.  We're going to get started with some questions that were previously posted in response to some of the announcements. The first one we'd like to deal with involves some of the earthquake activity that’s happened recently.  So, we'll send this one over to Jamie to answer.  "What's up with the earthquake swarm?  Can Yellowstone have a really big >6 Magnitude earthquake?  If so, what would the effets be?"


Jamie:  That's a good question.  I can tell you right now that earthquake swarms at Yellowstone are pretty common.  We get a lot of earthquake swarms in and around the park.  Overall at Yellowstone about ½ the seismicity occurs as part of earthquake swarms.  IT's not just a Yellowstone thing, they are pretty common at all volcanic systems.  We've had some pretty large earthquakes in the past.  The image that you're seeing now, that Wendy is holding up, is a seismicity map of Yellowstone.  All the red dots are earthquakes that have been located since 1972 to the current time.  All the blue dots are events that we have identified as part of earthquake swarms. Earthquake swarms happen almost any place we have seismicity, and on that map is a total of about 48,000 earthquakes located on that map.  But as far as recent times, last year we had the second largest earthquake swarm that we have ever recorded at Yellowstone.  We call it the Maple Creek Swarm, and we located about a little over 2400 earthquakes in that swarm. It began in June and ended around September, though it had some continuing activity after that.  This year we had a continuation of that swarm that started up in February and we located about a little over 700 earthquakes – they were mostly really small.  As a matter of fact, the swarm that was happening earlier this year, the largest was a M 3.1 and there have been no reported events of any being felt.  There were some reports for last year's swarm. Now to go on to the part of the question about can Yellowstone have a large earthquake.  The answer to that is definitely yes.  We have had a couple earthquakes in the Yellowstone area that have been larger than magnitude 6.  In 1975 we had a magnitude 6.1 near the Norris geyser basin.  It's that circle on the map that she's trying to point to.  It's the largest event that's happened inside the park and in the caldera.  And of course in 1959 we had the magnitude 7.3 Hebdgen Lake earthquake – which is the star just west of the park boundary in Montana.  To answer your question as to what the effects they would have.  Both had a lot of effects in the park – a lot of rockfalls blocked the roads. There were some changes to the hydrothermal system, some temporary, some permanent.  There were, as far as the Hebgden Lake event, M 7.3, there was some damage to the buildings, mainly West Yellowstone, MT, and the Old Faithful Inn.  There might have been some damage from the 1975 event, but the biggest impacts to visitors would be the rockfalls and landslides that would block transportation, definitely for a Magnitude 6.  I hope that answered your question.


Wendy: Great, thank you Jamie.  So just so you guys know.  If you have questions, please just throw them into the chat and we will get to them as we can. If we don't get to all the questions, we will try to follow up later as well.


Mike: Yeah, we'll put some posts together that answer the questions we didn't get to.


So, the next question is one I'd like to handle.  Someone had asked, "I hear you're monitoring elevation in the caldera, and is it rising?" I've got some plots I can show of that.  In fact, we are measuring how the ground deforms, and the best measurements by far are the GPS stations scattered throughout the park. There's over a dozen GPS stations scattered in various places including within the caldera, outside the caldera, and even outside the Yellowstone system in total.  I'd like to show a plot of some of these GPS data and how to interpret them.  This is data from a station near Norris Geyser Basin. This is the East deformation, the North deformation, and the up.  The way you interpret it is the East plot, if you see it going positive, the station is actually moving to the east, and if it goes negative, it's moving west.  In the north plot, if it is going down, it means the station is moving south, and if it goes up, it's moving north.  And in the up plot, this is the vertical deformation down here – if it goes down, it means the station is subsiding, and if it goes up, it means the station is uplifting.  See here at Norris, there was an event in about 2014 where the station went up, to the south, and to the east, before all of those reversed.  And right now, Norris is in a period of uplift, moving to the south, and moving to the east.  So, that's the way you interpret these GPS plots, and you can get these on the YVO website or in lots of other places.


In terms of what's happening overall in the caldera, this is a plot put together by our colleague Christine Poskus from UNAVCO.  She organized a number of GPS sites that are in the caldera, some sites that are sort of along the rim of the caldera, and then here's Norris.  This is just the vertical plot, and what you can see here is since 2010, so the last 8 years or so, the caldera actually went down then it went up – there was inflation – and right now it's subsiding.  Outside the caldera, we really don't see much vertical deformation, it's very flat – that's to be expected, because it's outside the range of the active magmatic system.  And at Norris it has these interesting events where it goes uplift, subsidence, uplift, there was a bit of subsidence event in December, and now we're back to uplift.  This is one of the more dynamic places in the park, perhaps because of all the water that's coming to the surface there.  So, yes, we are monitoring deformation, the GPS data are some of the most interesting ways of tracking that, and right now the caldera is going down, it's subsiding, and Norris area is uplifting.


Wendy, do you want to take the next question?


Wendy: yeah.


Mike: Are there any signs that Yellowstone will erupt soon? Is it overdue?  Randy asks, Will it erupt in the next 6 years? And Madeline wants to know what are the signs that an eruption might occur.


Wendy: Okay. So, this is a question that we get a lot.  The question of whether Yellowstone is overdue is kind of an interesting one.  I'm going to show you a map here that shows you the hot spot trace. So, Yellowstone is a hot spot volcano.  You can see its evidence across the Snake River Plain.  This is a map that shows the state of Idaho here, and this is the current Yellowstone Volcanic Field, and this is the state of Wyoming.  The numbers you are seeing here are basically the number of million years ago that these volcanic centers erupted.  If you take into account just to here, just back through the last 6 million years, the average recurrence interval is about 900,000 years, 996,000 years actually. And if you really only look at the Yellowstone Volcanic Field, this is the number that people cite most often – they say it erupts every 600,000 years – that's not actually true.  The average of these two intervals, between 2.0 and 0.6, and 1.2 and 2.0 is 740,000 years if you just take those.  But, you can't really get statistically accurate if you look at only two intervals.  And the way that it works, is this volcanic field will…there are cycles that it goes through.  It erupts rhyolite lava flows, and then it will erupt in a super eruption, and then more rhyolite lava flows will come in and fill in the caldera – the super eruption formed a caldera.  This is the Yellowstone National Park, and all the pink stuff is rhyolite lava flows that erupted since the last supereruption, which was 600,000 years ago.  So, if that interval is correct – 740,000 years, and it's been 600,000 years since the last one, then we're really 140,000 years away from another eruption.  That's one aspect of it.  The other aspect is that if it does erupt again, more than likely we would see more of those lava flows.  The lava flows will have an impact inside the park – they are really big.  The last one was 70,000 years ago and it erupted an area that's about the size of Washington DC called the Pitchstone Plateau.  In addition to the lava flows, there were mild explosive eruptions that were not putting ash high up into the atmosphere, but definitely things that would impact the National Park area.  We are not seeing any signs presently that Yellowstone is doing anything different than it has.  We have had lots of indications – all the seismic swarms have been happening since we've been monitoring and it hasn't erupted yet.  We don't expect that it will erupt anytime soon.


Mike: Okay – so let's see, there's a question from John Graves.  What happens if it goes off when you're travelling, will they ground flights.  Do you want to handle any of the ash aspects?


Wendy: Yeah, so, now that I've covered the it's probably not going to happen aspect, we'll go into the what if aspect. So, what if there were a supereruption?  Yes, ash would go high up into the atmosphere, it would cover a lot of area.  This is a map of the deposits of ash that have occurred from Yellowstone. The Mesa Falls ash bed was the smallest of the last 3 caldera forming eruptions, and that one wasn't actually a supereruption. A supereruption has to be 1000 cubic km of ash, and this one was not that big at all.  1,000 cubic kilometers of ash, just so you guys know, would cover the state of Texas to 5 feet thick – that's kind of a lot.  Huckleberry Ridge and Lava Creek ash beds were much larger.  And you can see, yeah, ash is going to fall out here, but that distal part – really far out – it's only a few millimeters thick.  IT's going to make it pretty annoying to drive around, but closer in to the park, there would be a lot of ash.  So yes, airplanes would be grounded during the eruption, but not after.


Mike: Jamie, I think we've got one for you – about how earthquakes affect the geyser basins and other geothermal features.


Jamie: Yeah, in fact that's a good question, I think it's coming from Yellowstone National Park, actually.  So, what happens is, actually, to preface this I would say that geyser basins actually need earthquakes to stay alive.  The reason for that is the hydrothermal fluids are moving through the ground in these small fractures in this network of fractures.  That's how water's getting from deep up to the surface, and you need earthquakes to shake that up and not only create those fractures but also to keep them open.  The hydrothermal systems – this hydrothermal water is heavy with minerals that deposit as they move through these systems that tend to clog themselves up. When you get large ground shaking from earthquakes you break that up and allow these things to happen. What we've seen in the past with the earthquakes can affect these things in many ways.  Two of the main ways I'll talk about now.  One, the ground shaking causes a change in the stress field. And these hydrothermal systems are almost stressed and ready to go, they are almost ready to erupt at any time and they just need this little push from these seismic waves as they travel through to cause them to erupt.  When we had this big earthquake in 2002 at Denali in Alaska, when those seismic waves reached Yellowstone, they caused all these features to erupt all at once as those big seismic waves passed through.  Those tend to be temporary changes. Now there can be permanent changes as well if we have a big earthquake that actually causes new fractures or closes up old fractures. A previous active system could die out or change from being a geyser to a fumarole. Or a new system could pop up – you could have a new geyser or you could have a system that used to be a hot spring that could start geysering.  There could be a number of changes from earthquakes both from new fractures opening up or from changes in the stress of seismic waves passing through. 


Mike:  Thanks Jamie.  We have another question from Larry and Karen Brown. Is the bottom of Yellowstone Lake still rising? I'd like to address this one.  It's pretty neat. There was a report some time ago of sort of a dome on the floor of Yellowstone Lake based upon the mapping of lake bathymetry.  The suggestion was that there had been some sort of buildup of pressure beneath the lake surface.  That was never known to be actively rising, because we didn't have measurements of deformation of the lake floor. But what's happening right now in the park actiually, and over the last couple of years, is some research – a project called HDY Lake – which is focused on understanding the dynamics of Yellowstone Lake, including looking at the hydrothermal systems.  There are hydrothermal systems that look almost like the sorts of spires and hydrothermal vents that you'd see at mid-ocean ridges on the floor of Yellowstone Lake.  It's a very active hydrothermal system, quite a hot one as well.  They are putting pressure sensors and seismometers on the floor of the lake to detect what type of activity might be happening there. We actually expect to have some pretty neat new results about what's happening on the floor of Yellowstone lake in the next months to years.


Alright, what else we have…let's see.  "Can you describe some of the different ways you monitor Yellowstone and tell us about the ongoing activity?"


Wendy: We monitor Yellowstone in lots of different ways.  There's GPS, which Mike has touched on a bit and there are permanent stations that are out there.  So GPS sensors, it's like a sophisticated version of what's in your car or on your phone. They are sensors that sit out in the field.  They are there all the time, and they measure things that are going up and down, north and south, and east and west just like Mike showed in the plots earlier.  Those measurements come in via satellite to our computer systems.


Mike: This is, by the way, a map of all the GPS stations we have in the park. There's different types of stations and they are scattered all over the region.


Wendy: Yep.  And then we have seismometers, which is Jamie's forte.  This is a map of all the seismometers in the park.  There's different types of seismometers that are out there, and they measure earthquakes. Earthquakes tell us lots of things.  One of the other things that earthquakes do, is that they can tell us what's going on deep in the system.  Seismic tomography is used to make a map of the subsurface, and Jamie can probably talk more about this in a minute.  We also have heat sensors, temperature sensors at Norris Geyser Basin. That's one of the hottest areas of the park and there are many geysers that erupt there. it's been the site of hydrothermal explosions in the past.  Hydrothermal explosions are second to earthquakes in the most hazardous type of volcanic activity that could occur in the park.  They are steam and rock explosions that would eject rocks out at high velocity and could hurt people if they were to occur.  It's happened at Norris in the past.  It's happened at Biscuit Basin, and we know it's happened at Mary's Bay in the north end of Yellowstone National Park – it's the largest hydrothermal explosion in the world.


Mike: In the lake…


Wendy: In the lake.  It's two miles across.  Let's see, what else do we monitor for.  Let's see…


Mike: Geochemistry of the water… and looking at major river systems.


Wendy: Yup, those tell us the chemical components of the rocks and can tell us about magma underground.  Then we have strain meters, which we wrote a YCC – Yellowstone Caldera Chronicles article about.  They measure the amount of strain…


Mike: Yeah, how the rock is deforming.


Wendy: And then there's tilt meters…you want to talk a little about that?


Mike: Tiltmeters are actually measuring the tilt of the ground's surface.  It's a bit ambiguous sometimes because if the ground is tilting like this, you don't know if this side of the ground is uplifting or if this side is sinking.  But tiltmeters are very good over short time scales for looking at subtle changes.  Over long time scales, they tend to drift.  The instruments sort of are unsettled, which is why we prefer to look at GPS for long time series deformation.  


We also do a lot of spot measurements – sampling of springs to look at geochemistry of the gases or water chemistry.  Hopefully over the year or two, we'll get a permanent gas station installed.  We've done some spot measurements over the course of a few days to weeks to even months of gas, but unfortunately, we haven't been able to install a system that can operate year round. But I think we're going to be able to get one online in the next year or two.  And those data will be on the website when we get it. 


Wendy: All of the data we collect is available on our website.  If you click on monitoring, you'll see our monitoring map and you can access all of our data.


Mike: Jamie, do you want to talk just real quickly about this topography image that you were part of creating?


Jamie: Sure. So one good thing that earthquakes are good for is imaging the subsurface of the Earth.  The way we do that, as many of you guys know, is the exact same technique they use to image the body.  Sort of like when you get a CAT scan of your body or an MRI.  They are using the same technique, only we use earthquakes.  What we do is that we have this whole network of seismometers in and around Yellowstone, as we showed earlier, and then we have all these earthquakes that are happening, and we know exactly when and where those earthquakes are occurring so we can locate them.  What we do is we measure the time it takes for those seismic waves to go from that earthquake at depth up to one of our stations at the surface.  We do this for many many earthquakes, all around Yellowstone, and we record this at all of the seismic stations that we can throughout the Park.  What we can tell is you can tell places where the seismic waves are traveling faster or slower.  When seismic waves travel through hot or partially molten material they slow down, they travel slower through that material.  We can do this for many earthquakes and many seismic stations throughout time, and we can basically map out where these slow seismic velocity areas are.  We can say those are where the magma reservoir, or the area of partial melt is.  What you can see in this image that we’ve come up with showing what we call the complete plumbing system of Yellowstone volcano.  What we’ve found is that basically we have what we call the upper crustal magma reservoir which is that top kind of reddish orange boy up there.  Below that, in the lower crust, we have this larger magma reservoir which is labeled on there as “basaltic partial melt”.  Below that, you get into the mantle and you have the hotspot or the plume coming up from deep in the mantle and feeding energy up to Yellowstone.  There’s kind of a misconception about what a magma reservoir is beneath the volcanic system.  Just to give you an idea, these aren’t just giant voids within the Earth that are full of magma.  These are areas of what we call partial melt, and I like to tell people it’s kind of like a sponge.  If you have a sponge, most of the material in that sponge is solid, and you have these pore spaces in there that in the case of the sponge get filled up with water.  Similar to a magma reservoir, most of the material in there is solid although its hot, but you might have pore spaces in there that could be filled with magma.  Now the upper reservoir, we estimate to be anywhere from 10 to 15 percent melt.  That lower reservoir would even be less, maybe 2 to 5 percent melt.  The rest of that is probably solid material, although it’s still hot. 


Mike: Thanks, Jamie.  There are actually some questions coming in that are relevant to this kind of thing.  Let’s see, I just had them here.  Well there were some questions about the depth of magma beneath places like Norris and so forth.  The upper magma chamber is somewhere on the order of about 5 kilometers down, the top of that reservoir.  We’re talking somewhere in the neighborhood of 3 miles below the surface before you start to get to this mushy zone that Jamie was talking about as being the magma reservoir.  Remember, it’s not a void, or a big balloon, of magma; it’s a mushy zone that’s only a few percent melt.


There’s some questions coming in about drilling from Janie Schoop and Lenny Sinsiri.  “What do you think about geothermal drilling and would the Park be affected by changes in drilling.”  Some of these questions may come from a NASA or a Jet Propulsion Laboratory report that was released some months ago. We tried to address this in the FAQs on our website.  There’s actually no plan to do any drilling at Yellowstone.  This was just sort of a concept that was put forward.  More like a thought exercise and calculations.  There’s no plan to do any drilling at Yellowstone and I can’t imagine that it would ever be allowed given that it’s a National Park.  It wouldn’t actually have the intended effects on trying to cool the magma body anyway, so it’s not really even a good idea.  And it would have the potential drawbacks of affecting all of the wonderful natural features that we go to Yellowstone to see.  In other places in the world where geothermal wells have been drilled near geysers and thermal activity it’s actually muted that activity.  So it’s not something that’s likely to happen at Yellowstone.


There’s also some questions coming in from Steven and Randy about animal behavior. 


Wendy: Right.


Mike: Which is something we see a lot about in terms of questions.  I’m not aware of any reports that actually say animal behavior changed prior to an eruption.  There was a YouTube video, I think a few years ago, that showed, like, animals running out of the park, or something like that.


Wendy: Yeah, and they were actually running in the Park.


Mike: Yes, they were actually running in the Park, not out, which was sort of funny.


Wendy: Yep.  That happens.  That happens, where things get turned around.


Mike: Apparently the animals get turned around, too.


Wendy: They do.


Mike: There’s a question from Anne.  “Are there other places on Earth that are like Yellowstone, and that behave in the same way.”  In fact, yes, there are many many caldera systems around the world.  Rabaul, in Papua New Guinea.  Campi Flegrei, in Italy.  Long Valley caldera in eastern California.  The Toba system, in Indonesia.  Taupo, New Zealand.  There’s a great many of them.  They often have similar characteristics, in that they have an upward bulge at the center of the caldera, a thing we call a resurgent dome, which happens shortly after the caldera forms, that you get this upward doming.  Some of them are very active, and some of them still experience eruptions.  Rabaul, I think, is erupting either right now or recently.  Campi Flegrei last had an eruption in 1538.  Toba erupted 74,000 years ago in an eruption that was larger than Yellowstone’s most recent but explosion.  So yeah, there are calderas around the world, and we can learn a lot about Yellowstone by studying those other calderas, and we can learn a lot about those other calderas by studying Yellowstone.  So looking at these big volcanic systems is sort of a theme among some volcanologists.


Let’s see.  We have a question about…  Jamie – does an increase in seismic activity mean an eruption is imminent?  This from Leah Dingman.  St. Helens was a bit of a surprise, so how are we able to fine tune our eruption predictions today?


Jamie: This is a common question we get.  Just because we have a big seismic swarm going on does that mean Yellowstone is going to erupt?  The answer is definitely no.  Luckily, for volcanic eruptions, there are typically is precursory activity to volcanic eruptions, seismic activity being one of those.  Other things are ground deformation, which we talked about earlier, and changes in the hydrothermal system, or increased gas output.  We monitor for these things for that purpose.  What I like to tell people is just because you have an increase in seismicity doesn’t necessarily mean that there’s magma moving through the crust, getting ready to erupt.  It’s only one of the precursory signals.  If you’re only seeing changes in seismicity that probably doesn’t mean that there’s an eruption happening.  It’s not likely that there’s an eruption that’s gonna happen.  If you start these seeing changes in all of these things, and they’re all pointing to the same thing, then you might want to look into it more and get a better idea of what’s going on.  But if all we’re seeing right now is changes in the seismicity rate it likely does not mean there’s magma moving through the shallow crust. 


I’d like to combine this.  There’s another question on there that says “if it was to blow, how much time would people have in advance to get out of the area, and I think this pertains to what we’re talking about now, these precursory signals.  Other volcanic events have been predicted pretty well, that these things are gonna erupt.  I would say, as far as Mount St. Helens I don’t think it was much of a surprise.  There was a lot of warning for that volcano.  Pinatubo, there was a lot of warning.  They knew it was going to erupt and they got people out in time.  As far as Yellowstone and these large caldera systems, we’ve never really witness one of these things with any instrumentation or even live, so we don’t know exactly how these behave when they start ramping up to an eruption.  But if we take these small eruptions, relatively small eruptions and scale them up to Yellowstone, we do believe that there would be precursory activity before an eruption, that we would know something was happening.  But I don’t think I could tell you how much time you would have to know this thing was going to erupt.  That could be days, weeks, months.  I can’t tell you that right now just because we’ve never seen that.


Mike: Yeah, I think there’s an important aspect to about what constitutes background activity.  Volcanoes are kind of like people.  They have personalities.  Some volcanoes are very very active, and they have a lot of background activity so at a place like Yellowstone there are thousands of earthquakes a year.  If you put that same kind of activity at a place like Mount Rainier, we would be thinking this is abnormal.  But in a place like Yellowstone, the background is that it’s a very active place, because of all the fluids moving around in the subsurface, and it’s sitting in an environment that’s very prone to earthquake activity.


Wendy: Yeah.


Mike: So what constitutes background in one place, and would be an alarming increase in seismicity or deformation or other indicators in one place is not going to be the same for what you see in another.


Jamie: Yeah, we’re really looking at relative changes in these things.  So how has it changed compared to what’s been happening previously or in the long term.  Or the long-term average.


Mike: Yeah, that’s a good point.


We have a question from Michael about “will I be safe at Yellowstone?”  Stay on the boardwalks!


Wendy: Yeah. That is actually true.  In Yellowstone National Park, and the Park can probably chime in here, the most dangerous thing is walking off the boardwalk and falling in a hot spring.  Don’t do that!


Mike: It could ruin your whole day.  But there’s a lot of folks that worry about visiting the Park because maybe there’s an earthquake swarm or something like that.  There’s nothing different today than there was yesterday or a month ago or a year ago or ten years ago in terms of our concern of a potential eruption.  So absolutely, you should go enjoy Yellowstone.  We try to go as often as we can. 


Wendy: Yeah.


Mike:  It’s an amazing, fantastic place.


I wanted to address too, it looks like Brittany Paddock’s 6th grade science class has chimed in with a couple of questions.  “When do we think Yellowstone will erupt again, like a big explosion, and how much ash would be released?”  And this sort of gets back to what Wendy was addressing at the very beginning.


Wendy: Yeah, so we really don’t even know if the Yellowstone Plateau volcanic field as it is now will ever erupt in a super eruption again.  It’s gone through three caldera-forming cycles, it could mean that it’s done.  We do know that there’s magma under the ground, we know there’s basaltic magma coming in and sitting underneath the larger rhyolite body.  This is the basaltic magma.  When the Yellowstone volcanic field is done, we will see eruptions kind of like the ones that are in Hawaii at the surface inside the caldera.  We’ll know that it’s done then.  The volcanic field that is a little bit to the west of Yellowstone, the Heise volcanic field, that was the one that erupted just before this Yellowstone volcanic field, and there have been basaltic eruptions in that.  So that’s kind of the next stage in the cycle.


Mike: The basalt sort of squirts through up to the surface.


Wendy: Yeah, and the reason why it can get up to the surface is because the rhyolite body, that spongy body of partial melt isn’t sitting there blocking the basalts to get up to the surface.  But right now it’s preventing it from getting there, so it’s supplying heat by there’s no sign that it’s gonna erupt.  We’re not sure if it will.  And the ash will, depending on the size of the next super eruption, which may be hundreds of thousands of years if not millions of years away, go much further to the west [east] than we are currently seeing activity now, who knows if people will be here, but the next super eruption form that system will send ash into the atmosphere, and yeah, it’ll be a nuisance for people thousands of miles away, but it won’t be life ending.


Mike: One question I’d like to grab here.  “Does the slow slip event,” Larry’s asking “does the slow slip event on the west coast affect what’s happening in Yellowstone?”  So slow slip is occurring on the boundary of the tectonic plates that are intersecting off the coast of Oregon and Washington, where one plate is diving beneath another.  And when that occurs you can get these very large megathrust earthquakes, magnitude 9-style earthquakes, but there are also every, I think, 14 or 15 months, there’s a two-week period where the plate sort of slides a bit.  We call those slow earthquakes because they’re smeared out over thus couple-week period.  If it happened all at once it would be a magnitude six or seven earthquake.  Those don’t have any effect on Yellowstone that we know of.  And it raises a bigger question about triggering, and can big earthquakes trigger eruptions at Yellowstone.  And Jamie talked earlier about how seismic waves from large earthquakes elsewhere in the world can cause some changes, for example in the thermal activity, geyser activity.  But what I like to think of is, you know, the last eruption of lava getting to the surface at Yellowstone was 70,000 years ago.  How many magnitude-nine earthquakes have happened off the coast of Oregon and Washington in the last 70,000 years? 


Wendy: Lots.  We don’t know.


Mike: Dozens?  And none of those triggered an eruption at Yellowstone.  So the question of whether or not eruptions can be triggered by earthquakes is one that’s very active in the literature right now.  There’s statistical tests, and observations that suggest there are effects, like the ones Jamie mentioned, but it’s difficult to really put your finger on whether or not there are effects.  Statistically for Yellowstone, since it hasn’t erupted in 70,000 years, and there was a magnitude 7.3 right next to Yellowstone in 1959, it doesn’t appear that the system is primed enough for any kind of big earthquake even nearby to do much damage.


Wendy: So we’re about 5 minutes over what we said we were gonna do.  Which is great!  That means that you guys are interested, and we’re really enjoying talking to you. 


Mike: We’re having fun.


Wendy: Yeah.  I think we’re gonna take one last question, and after this we will follow up by, well, I’ll read you the question.  So we have a question that came in from Matthew and he was wondering whether, well, he said that it seems now that people know more about Yellowstone than, say, we did in the 1980s.  And he’s wondering that corresponding with that it seems like there’s more people, YouTubers and tabloids and stuff, that are starting to also chime in about what’s going on at Yellowstone.  So I’m going to use this opportunity to talk about this.  We do get lots of questions, and we love getting the questions because we love…




Mike: Ha!


Wendy: We have no viewers now, but we are back.


Mike: Well, we can record this and play it back later.  So, Wendy was going to answer a question about all the information that’s out there.


Wendy: Yep. 


Mike: So, starting over for the 2 people that just joined back…  Sorry about that, technical difficulties.


Wendy: Yeah, so technical difficulties.


Mike: Not a conspiracy!


Wendy: At a very interesting time.  We were just about to talk about the amount of information that we have now about Yellowstone versus what we knew in the past.  Just how far we’ve come in the past 30 years, 50 years or so, and then also why are there so many other people out there that seem like they know a lot about Yellowstone.  So I think there is a couple of things.  One is that yes, we do know a lot more about Yellowstone.  There’s been lots more instruments, technology advances, so technology is moving forward, and the way that we monitor Yellowstone is moving forward and becoming more sophisticated.  We have learned a lot.  There’s a lot more researchers involved in pushing out information about Yellowstone.  So we’re active in doing that, and we do love to share information about Yellowstone.  The other thing that’s happened is the Internet has been born.  So, since 1980, hey, we have the Internet!  We didn’t have the Internet in 1980.  And because of that there’s new and different ways of sharing and getting information and along with the advances in the Internet have come more advances in Internet technology, communications technology.  Hey, we couldn’t have done this FaceBook Live event.  You would be watching us in a scripted interview on a news channel instead of an unscripted technically challenged FaceBook Live event.  So, we see lots of people coming to us scared because they’ve seen information that’s been promoted by people out there who claim to be experts in Yellowstone.  We can’t do anything to convince you that we actually are the experts in Yellowstone, so we just hope that you’ll trust us.  Look, we’re people.  As Mike was saying earlier, if you were our neighbor you wouldn’t know any different.  We’d just be normal people.  We’re not hiding anything. 


Mike: Yeah, I don’t take a black helicopter when I go to Yellowstone.  I drive like everyone else. 


Wendy: I wish I had an invisible airplane, though.  That would be cool. 


Mike: But I think the point is that we love to…if you have questions, please ask them.  We’ll try to answer some of the questions that we weren’t able to get to today in a Facebook post and we have an email account as well. 


Wendy: Yes.  Yvowebteam, all one word, at usgs dot gov.


Mike: And I think you’ll find that, I mean, friends of mind that know me know that I love talking.  Endlessly.  Especially about volcanoes.  Thanks for the endorsement [reference to Wendy pointing].  We love talking about volcanoes.  And so if you have a question, we’d love to try to help you understand more.  And we can even maybe in the future do some podcasts on how to access the data yourselves.  Because a lot of these data are out there as solid numbers.  You don’t have to rely on plots that we provide, or that are provided by UNAVCO or other places.  You can actually get the data, download it, look at the numbers yourself and sort of teach yourself.  That’s a really cool aspect of what the Internet brings, is this availability of data.  It’s sort of a horrible thing to say, it’s an “explosion” of data, but it is.


Wendy: But there you go. 


Mike: So we hope that if you have questions you’ll ask, and we hope to be able to provide more information to you in the future, both online, as part of our Caldera Chronicles, which is our weekly series of information about Yellowstone, posted to our website every Monday.  And if you have a question, please write in, either to Facebook or through our email account and we’ll do our best to answer your questions.


Wendy: Yeah.  And if we didn’t get to your question today then we will follow up with the answers to your questions in another post. 


Mike: And if it seems like there’s interest in doing this again we can do it again.


Wendy: We will.  Yes.


Mike: Yeah, especially if there’s interesting stuff to talk about like earthquake swarms, deformation, and perhaps some of the research on Yellowstone Lake.  Or after the summer field season we get some more results.


So anyway, thanks everyone.  Appreciate you stopping by.  Hope you found it interesting.


Wendy: Thanks for tuning back in after we went out there.  At an inopportune time.


Mike: Yeah, yeah.  Accident!  Yeah, and hope to see you around Yellowstone.  Take care.


Wendy:  Bye.