Hank Heasler Intro: Bob’s recent interests are in seismology, tectonophysics, crustal deformation using global positioning systems, and active tectonics. Current research projects include: Geodynamics of and Evolution of the Yellowstone Hotspot; Yellowstone Caldera; The Seismicity and Volcanic Hazards of Yellowstone; and the Operation of the Yellowstone Seismic Network. Bob has done an immense amount of work in Yellowstone. He has over 50 published papers on Yellowstone, refereed; he has had six PhD students, two are not finished right now, and there titles are Teleseismic Tomography and Anisotoropy imaging of the Yellowstone Hotspot; Dynamic Modeling of the Lithospheric Deformation from GPS, Fault-Loading and Seismic Moment Rates for the Yellowstone Hotspot and Surrounding Region of the Western U.S. using Finite Element Methods; then and a combined study of Yellowstone Seismicity and the Development of a Dynamic GIS Database for the Yellowstone GeoGIS System.

With that, with those topics, of course today, Bob is discussing the Yellowstone Hotspot—Shaking and Baking: Plumes, Plums, the Norris Disturbance and Earth Scope.

So please join me in welcoming Bob Smith.

Bob Smith: Well, it’s like coming home and I appreciate coming back. I see a lot of people in the audience who are friends of mine. I think a lot of us are in Yellowstone because of our long-term sensitivities in the sense of where we’ve come from, and Yellowstone did get me started in 1956 and I’ve been here ever since then.

Yes, I still enjoy teaching, and yes, I still enjoy students, and I still enjoy coming up and meeting folks and doing my research. Frankly, it’s a lot of fun. I wouldn’t do it otherwise.

My title today is “Yellowstone: Plumes, Plums, Norris Disturbances and Scoping the Earth.” Now plums means the difference between a hotspot and a plume, or is it a plume? A plum I will show you in a moment. I might say this is by me (referring to an illustration of a cross section of the earth showing geothermal processes) but I have had a long set of students. I’ve just graduated my 65th graduate student, and we have a had a long career. I’ve had several post docs, and my technicians whom many of you know, everyone has contributed in a team effort, and I view this very much that way.

I am going to give you an overview of the system. I think you have already heard a lot about the geology of Yellowstone, so I won’t belabor the volcanic history too much.

I want to get in why it works, what are the processes, something about Norris that we did last fall, and about this famous hotspot and why a telescope is going to look down on the Earth.

I would like to acknowledge that my research from day one has been supported by the Park Service, the National Science Foundation, U.S.G.S Volcano Observatory, and by the university (Montana State University).

Now, I am going to start off with a punchline. In 2003 Yellowstone lived up to its reputation as one of the Earth’s most dynamic volcanic, hydrothermal, earthquake systems. We certainly had new disturbances at Norris Geyser Basin. We found from GPS the caldera had been uplifting in the northwest side of Yellowstone, while the southwest side was going down. This (referring to a slide on screen) is the continuation of I record I am going to show you--it goes clear back to 192--about a caldera that is living and breathing.

That’s one of the nice things about Yellowstone, in a geologic career I can see all of this. Earthquakes are actually quite normal now. There was a magnitude 4.4 earthquake just south of the park in August. It helped set off some of the sensational tremors, and, of course, we have some of the highlights of Yellowstone Lake that were done by recent U.S.G.S. surveys that highlighted basically the same results of previous surveys, coupled with this earthquake and Norris of course brought a great deal of press to Yellowstone, and I say these phenomenon, however are within the norm.

The press and the internet, particularly the after-midnight discussion groups, have portrayed some of these (events) as precursors to volcanic eruptions.

Current data at Yellewstone do not support those interpretations. There are no indications of increased potential for volcanic eruption. That’s a statement that the Volcano Observatory has made, and a paragraph was sent to Senator Gail Gordon in January.

However, I am going to talk to you about new things, that is, there is a deep hotspot or plume source for Yellowstone, but it’s not under Yellowstone. It’s somewhere else, and I’m going to show you where it is.

I like to show this (referring to a slide) because I was a student in 1959 when the Hebgen Lake Earthquake ruptured and of course this was a rude awakening to the fact that Yellowstone has active earthquakes and volcanoes and this Hebgen Lake fault system is simply one of those elements.

Reading from the slide:
“The ground started shaking. I thought it was a bear. Someone shouted it’s a tornado, it’s an earthquake. Outside I saw the whole mountain collapse. A huge waterfall.”

These are some of the recent quotes I’ve gotten from the survivors. And of course in that earthquake we lost 28 people, it destroyed the infrastructure of the region, and it made huge, permanent changes in the Yellowstone hydrothermal system.

That was 12 million dollars in damage in ’59. That’s worth about a 100 now days, in just damage itself. But this is kind of quintessential, this is the maximum credible earthquake , and you can see the displacement that three geology students saw (referring to a photo showing part of the fault).

That’s what you’d expect in an active, large earthquake system in Yellowstone.

I always remind people that the Earth is 4.5 billion years old, and if we take 4.5 billion and put it into human terms of one day how much of the history is equivalent to Yellowstone. Well, essentially, the first 38 minutes of Yellowstone countryside is occupied by mountain building, pre-Cambrian time, oceans that cover the western United States, active mountain building in the Laramide and the Rocky Mountains. Finally, the Yellowstone got started in volcanic eruptions in northern Nevada. Each one of these red dots isa big volcanic center, much like a Yellowstone volcanic center.

Getting progressively younger—here’s the date 16 million 12, 8, finally down to the Yellowstone three giant volcanic systems, one, two and three. Yellowstone one, two and three are in the last five seconds. 1.6 million years old Yellowstone caldera to 1.2 million years, and finally the Yellowstone caldera we call today 630,000. Since then we’ve had about 30 post-caldera eruptions, we’ve had glaciation, and we’ve had continuous faulting and large earthquakes on the Teton Fault and related Yellowstone faults. The point being, Yellowstone is a very young system in terms of Earth’s history and it is active today. It is one of the most active hotspot systems and volcanic systems in the world and the largest in North America.

Many of you have seen my picture showing the progression of these volcanic centers. They started out here 60 million years ago. Each circle represents upwards of 10 to 20 Yellowstone-equivalent eruptions. I’ve plotted on her the three Yellowstone calderas.

The oldest one is this bigger one right here. This is the Yellowstone caldera today. Each one of these centers may have five, up to ten Yellowstone eruptions. And they get progressively older down the Snake River Plain to where they began. And of course it is because the North American Plate moves across this system. There’s a young system that goes up through southeastern Oregon and that’s because there’s return flow in the mantle that drives up magma. But the percentage of melt here is maybe one to five percent of the percentage of melt here—even less than one percent.

We have this surrounding zone of active earthquakes shown in red. We call that the tectonic parabola, that’s the high topographic shoulder and the low Snake River plain which is the subsiding part of the system. Of course we lost the roof support in all these volcanic eruptions, the ground has subsided, the edges have swelled upward, just like the bow waves in a boat passing over some kind of a thermal source, namely, the hotspot.

The North America plate moves at two centimeters per year. The analogy is good to put your hand over a candle and let the hand move across the candle and it burns its way through. So the plates moving from northeast to southwest, ages get younger from southwest to northeast. It is a dynamic system.

So basically here is the plume. It’s fixed in the upper mantle. It’s at a depth of about 80 miles. The material comes up. I haven’t said what the source here is, and parts of it get sheared off because the upper part of the Earth is brittle, called the lithosphere, it moves along roughly and inch a year, and so this candle gets sheared off, like a candle gets sheared off when you move it under a plate. Some of the material leaks out. It comes up and it forms magma systems in the upper mantle, finally the very shallow ones beneath Yellowstone today. But as the plate moves this whole process burns a new hole…a new hole…a new hole, so there are old Yellowstones all the way down the Snake River Plain, clear to Boise. Now the real question is, what’s a hotspot. They were defined in the late 60s when plate tectonics became envogue and were defined (‘65 and ’70). Hotspots are defined as volcanic centers of enduring points of weakness or long-lived hot upwellings. They do not say thay have to be at the core-mantle boundary. Nonetheless, for Yellowstone, this heat that’s finally leaking up and coming out here produces almost one-and-a-half watts per square meter of heat flux. It’s the heat that drives Yellowstone. That’s more than 30 times the world average, and of course, it’s accompanied by volcanism and earthquakes.

Now, you are used to seeing….runny basalts. These are the basalts you see on TV. They come from Hawaii (this is a picture from Hawaii) or from Iceland or Mount Etna. These basalt eruptions are all over the globe. They are the normal, what we call normal background basaltic volcanism. There much less explosive than the volcanism we see, however, related to Yellowstone.

In Yellowstone we have the situation where we have a charged magma system at depth, and the magma system is a met, here it’s modeled as a resin with acetone, we pressureize this guy and then we release the pressure suddenly and you have a solution of fluid, of hot gases and oxygen, CO2 that blow up to the surface and this is basically Yellowstone in a test tube.

This is time lapse photography, but it’s instantaneous when you take the lid off the sytem. You can see the gas bubbles, the CO2 coming out, there’s a big one right there. When they come out they blow very, very high plumes of ashes, particulates are producing these cataclysmic flows of material. These are just particles and aerosols. They get up to 80,000 feet and get captured in the jet stream and go around the world, but most of it falls back down on the Earth, and it covers Yellowstone with a blanket of ashes and rhyolite flows, ryholite being the dominant type of volcanism of this type of rock.

So what happens is that you know have where have before Teton ranges that came across Yellowstone, Gallatin ranges that came across Yellowstone, the Washburn Range, the Red Mountain Range, Big Game Ridge, probably the Madison Range, all were probably looking much like the Tetons today. But during the three giant eruptions starting 2 million years ago—this is the outline of the southern boundary of caldera one, the northern caldera boundary we now know actually is at the base of Mount Holmes—we can see it from seismic tomography. That’s caldera one, here’s caldera two, Henry’s Fork Caldera and finally Yellowstone caldera itself. One thing that’s interesting, not only have we destroyed the mountain topography, these mountain systems have blown into the atmosphere and part of them have been subsumed back into the active magma chambers, but the average elevation here is about 1,500 feet higher than the surrounding terrain, and that’s because it’s held up by magma systems in the upper mantle, in the hotspot, which are low density because they are hot, and they are buoyant. They just lift things up and so we have the Yellowstone Plateau.

Now, how do they work? Well, magma comes into the upper chamber, and I’m just showing you the end results, material comes up vertically in a conduit, it starts to expand because it is trapped here because of all the material that is too cold and brittle that acts as a permeable trap, so the material spreads laterally, creating this elliptical-shaped dome, and the magma is going to fill this chamber. It fills the chamber until it finally gets so high in pressure that something creates a leak to the surface. Now in the filling, of course, it uplifts the surface itself. So you can think of this on the scale of Yellowstone magma chamber of 15 kilometers or at 100 kilometers at the base of the lithosphere. Finally, it does release and material flows to the surface. Roof support is relaxed, we draw the material out and the lid is going to fall. The surface drops down, creating a circular caldera, which is simply a round topographic depression. The walls are what we like to map geologically. This is the Yellowstone caldera. Of course it’s been filled in since this last eruption 630,000 years ago with about 30 smaller eruptions. We see pieces (of the caldera) here and there. Bob Christianson has done a nice job of mapping, first of all, caldera one. This is its extent, with its flow of material which is Huckleberry Ridge tuff. Huckleberry Ridge is a mountain peak south of the park. Roughly 1.3 million years ago we had the Henry’s Fort Caldera, which is a smaller system; its erupted material. covers this part of Island Park and some of the Yellowstone. We finally get the Yellowstone caldera 630,000 years ago. There’s the extent of the caldera, and the material from the Lava Creek tuff is spread out over most of the park. These are the three giant eruptions that have created the plateau itself.

I want to point out since then, starting in at 640 million years ago, plotted by age here in color, cold to the oldest, red to the warmest, all the individual flows. There are about 30 of them. The oldest upper here (north), the younger to the southwest at the Madison Plateau and the Pitchstone Plateau, and the vents of the volcanoes that erupted and the ryholites that erupted are shown by the yellow stars.

The youngest being the Pitchstone Plateau, so this whole plateau system, if you wish, has been covered by these flows, that flowed in and covered it much like toothpaste—so most of the exposures of the caldera boundary have been covered or eroded away.

Nonetheless, these are the volcanic rocks that we see primarily at the surface.

How big are these (eruptions)? Here’s Mt. St. Helens, it erupted in 1980, that produced point 3 cubic kilometer of erupted material. The magma chamber was high up in Mt. St. Helens, a magnitude 4.5 earthquake shook, it was enough to release pressure because a little landslide occurred on the surface, decreased the overburden pressure, just like in a steaming kettle, and it exploded violently. It killed people. And you can it was 3/10ths of a cubic kilometer. In 1991, we had the eruption of the Pinatubo Volcano in the southwest Philippines, and Mt. Pinatubo, which used to be a mountain, was right here. You can see the edges of the mountains here. That’s seven cubic kilometers (of erupted material), so many times larger than Mt. St. Helens. Pyroclastic flows went out several, almost hundreds, of kilometers. This thing killed 700 people. And the ashes were 47 centimeters deep up to 60 kilometers away.

These eruptions that you are seeing here are even smaller than these typical post-caldera eruptions. They are five to 10 times bigger than a Pinatubo. It gives you a sense that even the smaller eruptions are still very large and devastating.

What’s left here is the boundary of the northwest rim of the caldera, that’s the Madison Canyon, Madison Junction, the road to Old Faithful, and this cliff, the top purple mountain where we have a seismic station down to the floor right here is about 300 meters, 900 feet.

The caldera collapsed, this would have been a sharp fault—the boundary of the fault came around to the Madison Plateau, wraps around to the east. So this is the caldera boundary from the most recent eruption. But the caldera boundary from the first eruption, I can tell you is right here on the south end of Mt. Holmes and Holmes Hill.

That’s the first one that actually chopped off Mt. Holmes. So these are active systems that are easy to see. When you drive up the Firehole Canyon Road, I want you stop here, and next time, instead of going swimming here, before you swim take a look at the rocks. This is one of the best exposures of these rhyolites. This is a rhyolite flow and you can see the flow pattern of this material, and while it flowed somewhat like basalt, it’s about a million times more viscous than basaltic magma, which means it flows very slow, it’s very resistant to gases, so gases are deflected in these materials, and because this material has very low viscosity, the gas pressure gets very, very high before it’s finally raised; thus the explosive nature of the rhyolite systems of Yellowstone are many, many times greater than they are for the typical basalt systems.

If you go down to the Bechler country, here is the Bechler meadows, these are some of the rhyolite flows coming off the Pitchstone Plateau. These are same kind of flows you see coming down, for example, from Hawaii Volcano Park which are the order of a few hundred meters wide and kilometers long, were several kilometers wide and several kilometers long. So the cliffs are the ends of the ends of these flows that flowed off the Pitchstone Plateau. This is the youngest of the post-caldera eruptions.

What remains, of course, is you still have magma at depth and one of the remaining features of the system is that magma pushes upward like the piston of a car and it pushes up the ground, creating a domal structure. This is the Mallard Lake resurgent dome. This is the Upper Geyser Basin, (indicating) Old Faithful, looking back into the Mallard Lake Hill as I call it. This hill is transected by a valley. Here’s Rabbit Creek, and Mallard Lake is over here. This is a fault system here that faces north. This is a fault system shown by the snow facing south. If you lift up the Angel Food cake too high, the center collapses. So these faults are simply the collapsed structures of this dome that’s lifted at least 500 meters in the last 150,000 years. This is one that probably has magma beneath it today.

I have to say something about the hydrothermal systems. The heat from the shallow magma heats the underlying water system which is brine in this case, which finally serves to heat the shallow recirculating ground waters that produces the geysers and hot springs. I am not going into this subject except to say of course this is what makes Yellowstone famous, but the geysers and hot springs are the end result of this complex volcanic process.

So we want to know what’s really going on here, guys. This is my reminder (referring to a Calvin and Hobbs cartoon in which Calvin is saying to Hobbs: “C’mon Hobbs, these guys want to know what’s shaking and baking.”)

I want to talk to you about the processes. I don’t like to describe things, I like to show you how things work, because I am kind of physicist to, you know—am a physicist, geophysicist, geologist, whatever (jokingly), computer scientist, I put them altogether.

What drives it all is Yellowstone’s heat. Here’s a map showing he values of heat, and we use the number, milli-watts per square meter, and you say what the heck does that mean.

Well, 40 watts is what’s in a small light bulb. These light bulbs are more like 200 watts or 100 watts, that’s what you use to replace the ones at home. So this is 1.5 watts per square meter. So that’s the amount of heat that comes out of just a square meter on the ground. The average heat flow for the caldera is 1,500. I point out that in the western side of Yellowstone the heat flux combined, the upper and lower geyser basin and Norris, is 58,000, 42,000, 44,000. Now that’s the combined heat. Over in the Lake area it starts out at 125, 500, and 1000 up to 3,500. The background is 50, in the Absarokas 80. The Snake River Plain 105.

Yellowstone is an immense release of heat, despite the fact that it is cold. I am not talking about temperature, it’s how much energy, how many calories are coming out of the ground. But the heat flow is 30 to 40 times the average. There’s enough heat that you could turn it into electricity of 5 gigawatts. But basically, it’s related to magma that’s crystallizing, that is, it’s cooling, and it’s also being re-fed of a very small number here, which by the way is about the same number that’s being fed out of Hawaii, .01 cubic kilometers per year.

I have to show this because I was flying in 1984—people have seen my picture—and I was out of gas, I had 20 pounds of fuel left, the National Geographic photographer was out of film, I looked to the right, I was headed for West Yellowstone, I said “Wow, there’s a big forest fire at Norris.” (The crowd laughs.) I got over there and wow, guys, there it is, the eruption of Steamboat Geyser. You can see the eruption; in this case the trees are on the order of 50-70 feet high. It had hot stream jets going to heights of about 500 feet, another 500 feet of hot steam, and finally a mist, and I turned and scooted back.

The point being, it’s the world’s tallest geyser, sending water at least 400 feet high, and steam another 500 to a 1,000 feet, and the reservoir temperature is estimated to be around 300 degrees C. It erupts for, well, for about 20 to 30 minutes, people think. Now, before the last few years, it erupted every five to 10 years, but in the last couple of years, it’s erupted about six times. So the averages are catching up with me.

If I were to calculate the probability of taking this picture, that is the opportunity, it’s one chance in a 100 million. That’s worse than winning the state lottery.

Yellowstone’s heat does things. It cooks the soils or the cretaceous sediments. Here’s Rainbow Hot Spring; here’s upper Pelican Valley, and this is where our actually hydrocarbon-bearing materials are being cooked out of the sediments, not the volcanic rocks, but the edge of the cretaceous system coming in from the Wyoming hydrocarbon belt, if you wish. These materials are well known. There’s about six of these. So it tells you in fact that there are hydrocarbons and there is sufficient heat to act like a natural oil refinery. These things were discovered 100 years ago.

It’s also very active earthquake-wise. This is the Mirror Plateau on the northeast side of Yellowstone. The faults start from here to here, and are on the order of 100 feet. You can see the fault right here. The whole caldera dropped on the right side. There are some little faults coming along here that you can see, and they dropped the center portion, and this is called a graben. And there you are. That’s the top of that fault zone, and that fault zone is probably only a few 10s of thousands of years old. We established a new seismic station right up here on this cliff just two years ago. So we have coverage in this part of the caldera.

There’s also a fault like it on the south end. Here’s Eagle Bay. Eighteen feet since the glaciers receded, so 14,000 years ago until now there’s been roughly six meters. That means you’d have six magnitude seven earthquakes or you would have three more Hebgen Lake earthquakes, yet it’s not active today. Here’s the upside, here’s the downside.

Here’s a map showing through 2002 the seismicity—people have seen this, and we’ve always known about this great swarm of activity. It’s on the east side of the Hebgen Lake Fault, that ruptured right here. That’s where that picture was taken, right there. We got this cloud of earthquakes that come in we think on the edge of caldera one. Then they come in along fracture zones into the caldera, turn south and they parallel theses faults that are buried beneath—here’s the Teton Fault, the Sheridan Fault and the South Arm Fault. These are alignments of earthquakes that are on fault zones that preceded the volcanic system.

Yellowstone is the most seismically active area of the whole interior west, excluding the San Andreas, and it literally has thousands of earthquakes per year or more. We had an earthquake swarm on the northwest side of Yellowstone in 1985. This would be between the Madison Canyon and West Yellowstone. The earthquakes extended along a zone here (on the map) from October through November, and we had literally hundreds of earthquakes per day occurring. You can see the color progression from the youngest down here to the oldest this way. That turns out to be 30 meters a day. Earthquakes are progressing. Moreover, if you go from October clear into December, that’s the same pattern, now you look here on the vertical, they progress from shallowest to deepest. So, there’s something systematic about this.

What that is, we think, are basically fluids that come off the hydrothermal system, they leaked up and charged, that is put additional pressure on existing faults and created this swarm of earthquakes which happens to be right here, and these arrows show how an earthquake or a dike may have occurred.

Now the question is, did the extension of the whole system, and all the arrows here show how the earth’s pulling apart from different methods, let me just say it’s stretching northeast to southwest. Is the stretching causing the earthquakes, or are the earthquakes and the volcanic system causing the stretching. It’s the case of chicken or egg.

Henry (Hank Heasler), we don’t know that yet, but we know the earthquakes and the swarms are related to volcanic systems. If we map the depths of earthquakes, it’s just like taking a thermometer and plugging it into the earth because the depth of earthquakes is constrained by how cold the rock is. If it’s cold, it’s brittle; if it’s hot, it’s plastic. I have contoured here the depths to the zone of about 400 degrees centigrade, and you can see the whole of the caldera has earthquakes that are typically at six kilometers deep, and they underlie the caldera. So we know there’s a layer 400 degrees centigrade at only about four to five kilometers. That’s the conductive heat flux that’s coming off this system. There’s a magma chambers superimposed on them. There’s one here, and one here I’ll show you.

This is what we do. We take seismic data and we create a CAT scan just like you do in the hospital. With 15,000 earthquakes recorded in what’s called tomography we’ve actually imaged what we think is the crystallizing magma body. There’s the map at depth. The shallowest one, the resurgent dome to the south, the biggest, the resurgent dome to the north, and then there’s actually a low-velocity body up to the northwest, which we think is simply fractured rocks with a lot of CO2. But this is the guy that is driving Yellowstone today. Of course, my real long-term question is where did it come from? And by the way here’s that earthquake swarm that occurred in 1985, right at the base of this CO2 system.

In my GS-0 days (crowd laughs), in 1956 I was stationed at Peale Island and this is a picture taken off the veranda of Peale Island looking south toward Grouse Creek, and there was a boat dock there. That boat dock was out of water most of the summer, always was for me. Coming back in 1973 with Ken Dean, a biologist (he’s doing stomach sampling of trout), I was worried about the fact that all these trees were dying. A sinking shoreline inundates the trees. This was the key that says, “Hey guys, Yellowstone Lake is not what we think it is, it’s not static.”

I got these pictures from Bill Romme just a year ago, and I went back and looked at areas around the southeast arm—here’s site one, and these trees had all been inundated and killed by 1983; here’s site 2, this is now an island and it used to be peninsula on the maps (these were taken in the fall); site 3 right here. He tells me there was a bout a half a meter of water or more that inundated these portions of the shoreline that he measured at the time, but he was doing other studies, and really didn’t make a big point of this until he saw my dock and he said, “Hey, here’s something that correlates. I’ve been looking at these same phenomenon from the standpoint of the sunken tree, or the fish being killed near the trees at the shoreline.”

What happens is, if you take a water body here and lift it up on the north end, it’s going to tilt on the south end, and there are the trees that get inundated, something on the northwest side is lifting them up. This northwest side, of course, is essentially the caldera and we are looking at the effect of the bathtub ring.

So in 1975, we knew something was happening, so I received some funding from the USGS, and we went back to all of the old benchmarks in Yellowstone that were established in 1923, and we made leveling surveys. This is one of my PhD students (referring to the photo).

We discovered, this is the figure that we published in Science, we had the whole inner portion of Yellowstone raised 750 millimeters, in other words, 75 centimeters, this whole system had risen with respect to Sylvan Lake, we called that arbitrary zero. Each one of these triangles is a benchmark for the survey. Of course, they’re along the old roads, and across the central plateau.

Almost a meter, and by 1985 it had risen a full meter. There’s not many places anywhere on the Earth that you’ve got something that’s 50 kilometers long, 30 kilometers wide, that’s that big that’s risen that fast. Another turning point in my life.

So were started looking at how we were going to measure how things move. And in a big experiment funded by NSF between 1998 and 2002, we put out an array of GPS instruments. The yellow are what we call campaign—these are GPS instruments that run on benchmarks for two days at a time about every other year, and the red stations are permanent stations that record the GPS data continuously and are sampled and transmitted in real-time. We call this the hotspsot area, and these GPS stations are the ones I am going to show you some data from.

What GPS does is it takes a satellite, a constellation of 25 orbiting systems, we record the data on Earth, and we can recover the location of the point on Earth with respect to the satellite orbits, then we can recalculate the point on the ground, and with the new coordinate systems, we can get to within one millimeter. Now, these are not REI backpack GPS (audience laughs), these are Geodyssey systems that cost $20,000 to $30,000 (in our new Earth Scope program we actually got the price down to $7,000).

So here’s one (pointing to photograph). Up on here is the actually antennae. All it is an antennae that receives signals from a GPS satellite. I go out in the field and I say, “Oh, I’m receiving satellites.” I look up and everyone looks up, you know, looking for these satellites, and of course, they are orbiting the Earth at 22,000 kilometers, kind of invisible.

This is a inbar rod We just stick down into the bedrock, and put a piece of concrete around it to protect it. And then we send the data out using this solar panel and radio. These data record every 30 seconds. We record them in real-time. They go through Washburn on the telephone line down to the mammoth telecom office, and then they normally get passed the firewall, but they don’t now because of the Interior. So we download by the phone lines every night—30-minute phone calls for about seven of them.

We have lots of untrained, scraggly, grizzled operators (audience laughs). These are our campaign systems where we set the instruments up over the tripod over a benchmark. This is Hayden Valley, station KG, and this is down at the South Arm (of Lake Yellowstone). These guys are well trained. And we record them, by the way. If you biologists want to see about your carnivores we can give you the footprints.

Let’s look at what they do. Here’s Mammoth, and we put Mammoth intentionally, it’s outside the caldera. Each one of these points is one day. And this is the vertical. Here’s Mammoth, so starting back in ‘99 what you do is fit a line through all these data, but you can see the caldera is moving upwards, but once you get inside the caldera, here’s White Lake right here, it’s moving down; Hayden Valley’s moving down; Lake Junction is moving down; and Old Faithful is moving down, but not quite so fast. The rates are 7 millimeters per year inside Lake Junction so the whole Yellowstone Lake is actually going down. Hayden Valley is going down a millimeter pre year, it’s not as fast, but look at White Lake—17 millimeters per year. These numbers are about 10 times the average we’d expect. This system is really moving. So here’s the data that I showed you before. We just took these data of the ground expanding, and we calculated the volume in the Earth that would have to expand to create the uplift. If you take the Earth and put a balloon down there and pressurize the balloon, the surface lifts. Here’s the balloon. It goes from the Earth’s surface to 9 kilometers. And you can see that in this projection, looking from the southeast, there’s a branch here and a branch here.

Here’s the contraction. That is between ’87 and ’85 the caldera reversed, and now the caldera is going down. It’s going down at upwards of almost 12 millimeters per year. Look at all the vectors. This is GPS (right graphic), this is leveling (left graphic). You can see that all of the vectors are pointing inwards, so as the ground is going down it sucks the walls in, but the overall motion say from Cooke City to the Snake River Plain is extension. You can see all of the arrows pointing down to the southwest. Everything is pulling away to the southwest because of this whole uplift, but superimposed is this localized anomaly. Here’s the volume (pointing to lower right graph) that had to dilate or compress. Now I haven’t told you what is in this stuff, we think it’s hydrothermal fluids, we don’t think it’s magma. I’ll show you why in a moment.

Here it is ’95 to 2000. Wow, we reversed from subsidence to uplift shown by the red. Now the uplift is over here asymmetrically in the northwest side of Yellowstone. We are still getting stretching to the southeast. The volume is not quite as big on an annual rate, but it still roughly occupies the same location.

Here’s the data through this year (2003). We still see uplift of the caldera but at not quite as high a rate; still extension to the southeast. The actual rate up here is decreasing. I haven’t modeled it yet, so it’s a question mark. I suspect it’s going to look much like the one I just showed. So let me compare this with the seismic imaging.

So here’s a picture of that magma body. Here’s the gas body. Here’s the period 23 through 97. Here’s that expanding volume. Now within the expanding volume are hydrothermal fluids that are pressurized. They’re pushing the walls up and their pushing the surface up because it’s unconstrained. This is the view from the top. There’s the source zone. There’s the magma body beneath it. Here’s a view from the south. And a view from the east. Can you absorb all that?

Here its going down. Same place except now this volume is decompressing. This is where the gas body would be. Here’s the magma system is. These things are all related.
Fluids come off the magma body. They send up hydrothermal fluids and gasses. They get trapped up here in the upper crust. They expand and contract depending on the pressures that hold them in. How tight is the pressure cooker? Here it’s releasing. Is it releasing because we just released the pressure a little bit? We don’t know.

And here it is for the latest period, 2000; again compressing. So Yellowstone really is a living, breathing thing and it’s breathing because it’s got heat and magma in the lower crust, drives up into the uppermost crust. That’s what feeds…There’s Yellowstone’s hot spring systems origins, right there. And they’re changing annually.

Well I said it was living and breathing so here is a plot of earthquakes 2003 into 2004 and I’m plotting them per quarter. Numbers of earthquakes per quarter. Here’s the numbers. And you can get about a thousand or so. The seismograph network ran until 1985. The USGS turned it off. We reopened it and right then we had the biggest swarm in Yellowstone history. In 1985 we recorded literally thousands of earthquakes in a few months. And you can see the earthquakes then decrease, now starting back up again. Here’s the caldera deformation. Uplift in 23 and it turned around right when that swarm occurred. It was going down at 20mm per year, then it turned around and now it’s bifurcated. The southeast side is subsiding and the northwest side is uplifting. So it is not only a living, breathing critter but it’s asymmetric.

Oh gosh, this guy already told me this. You know Jeager. Jeager formed the Hawaii Volcano Observatory. A professor at MIT, in 1925 he quit MIT (1922). On his way to Hawaii, he rode a horse through Yellowstone and made this observation in a memoir. “Anyone who spends summers in a place like Yellowstone comes to know the land to be leaping.” I showed you that. “The mountains are falling all the time…” I showed you that. “by millions of tons” Well there’s lots of rock. “Something underground must be shoving them up. How much is the ground tilting?” 1922 guys. What a perception. Now I showed this to Gayle Norton and to the director of NSF. “The genius who finances and mans the first mountain observatory will found a new science.” And boy, they catch on to that in a hurry.

OK, What about the Back Basin. We need to close this thing. Here’s a little update.

I’m going to give you a little bit of an update from the perspective of our data. You folks who were intimately involved, some of my students with post-docs, Hank Heasler, and other folks, I just wanted to point out that these are the people who helped author the progress report that we did. It was supported by the park service, University of Utah, that is we installed stations in the Back Basin of Norris. Here’s one of our GPS stations that was installed just on the edge of Tantalus Creek. I’m just going to show you a few of our results. I presume that Hank has already enlightened you on the hydrothermal results.

First of all, here’s what a broadband seismograph looks like. We put broadband seismometers at all the points shown in red triangles. It is a recording in a box here, a little solar panel. The seismometer sits under this little water cooler. The temperature, by the way here, was 75 degrees Centigrade. These are about $20,000 instruments that we got from UNAVCO Pool and we’re trying to record earthquakes. We set up a GPS station. The little recording box has a little solar panel and they are all the stations shown in blue. Steamboat Geyser, down the south end of Back Basin and up to Tantalus.

Let me show you the results. So, here are the stations. I’m just showing the GPS (inaudible). We recorded no earthquakes. I can show you some detail of analyzing the earthquake data. What I want to show you is how fast things are moving north-south, east-west, and up or down referenced to a station up at the edge of Norris. I want to point out that the average background motion in Yellowstone is about a couple of tenths of a centimeter per year.

Here’s the station at Porkchop. It’s not doing much. But it’s moving to the east. Here’s the station STSB, that’s Steamboat. Look at this guy. It’s going up at 6.7 inches per year. That’s the ground motion. Now it can’t go on that long, or you’ve got a whole new parking lot out there, or an eruption. Here’s Tantalus. It seems to be going up and so does Dixon. So they seem to be up to the north. And we see motion to the north, in the direction moving actually away from the north.

Let me show you the map. We referenced a station here. That’s our base station up on the Norris Hill. The vertical is red. There’s Norris. Steamboat had a major eruption on October 22, one month after we pulled out the equipment, wouldn’t you know it. But I think we were starting to catch some of the precursory motion. You see that the basin is tilting down to the southeast. It looks like it’s tilting down in response to fluids, very shallow fluids, in this system. This is a marvelous observational way of how we are going to start monitoring hydrothermal systems.

How do they work? Normal winter-spring you recharge the fluids and the water pressure from the surrounding ground water keeps the pressure on the hydrothermal fluids. In the summer, or in a drought like we’ve had the last few yours, we’ve released the pressure because the drought has reduced the water table. That’s releasing the pressure cooker so we are right at the pressure-temperature line where you have liquid. Then if you really get critical, and you take too much away, that is if you take the top off the steam-pot, then you get into a domain where you actually start boiling water. So you get resulting release in pressure from the existing hydrothermal fluid. You start boiling at ground level. Of course, you don’t want to be standing around there. As Hank will tell you, it’s 200 degrees Centigrade. This requires really careful NPS assessment. I think this phenomenon is much more common than we thought.

So my conclusions are: there weren’t any earthquakes but the surface showed strong tilting. The noise from the seismic data (inaudible) shallow water and I think we were able to show we can monitor this system and I think we caught Steamboat in a precursory motion before it erupted.

OK guys, Yellowstone plumes or plums. Plume theory is basically part of plate tectonics. It has been simplistically depicted, really poorly, in the past few years. From the high-resolution imaging I’m going to show you, Yellowstone is shown not to be a vertical plume or a plum.

Plum, I use that term to say, a plum is self contained, it doesn’t have a long stem. Here’s the plume, that’s been depicted as coming from the core-mantle boundary, with magma coming to the surface of the earth and plumbing all the hotspots. Here are the common hotspot systems in the world. You all like to go to Hawaii. Long living volcanism. Iceland, long living volcanism. Here’s the Eiffel Plume. I’m going to show you those, remember them. Yellowstone, here’s other hotspots in oceans, on land, that are now well known. They are not necessarily large systems like Hawaii, Iceland, or Yellowstone, but they are active systems.

So here’s the tradition. They have a core-mantle boundary at 2700 km. This is liquid outer core and the traditional view is fluids go squirting up this little pipe. They get up here and the over-riding plate is moving to the left so it pulls off, (it shears off) the (inaudible) just like I showed you for Yellowstone. That’s a traditional vertical plume.

These are all hypothetical. They are all cartoons. We’ve only been able to get seismic images in the last decade to actually see what this looks like. We put out an array of seismographs between 1998 and 2002. Our stations are in light blue. There are 80 in triangles. Then we took seismographs from Tetons, the Yellowstone array, a little portable array here. We recorded earthquakes from around the world. They sent seismic waves up vertically and we did CAT scans. We did the same physics as an MRI. We did it before they did actually. I’m going to show you what we found.

Here is a picture of a slice through the earth at 90 km deep. So 60 miles down I do a slice. Just take my word, red is hot, blue is cold. Actually we’re mapping seismic velocity in terms of differences between a homogeneous earth so if it’s 0 it means it’s the same velocity as this layer in our model. If it’s blue it’s higher meaning colder and red means hotter. Well here’s Yellowstone. It’s hot and cold on the sides. 150 miles, it’s hot. Look how it’s starting to spread out. 270 miles, it’s gone. It’s over here. 350 miles, it’s totally gone from theYellowstone (inaudible). It’s over here. So here’s a cross section, B-B prime beneath Yellowstone and it squirts over here. C-C prime, down toward Island Park off to the northwest. Right beneath Yellowstone there is no velocity reduction and so people said there was no plume at Yellowstone. They didn’t have the data we did. This is a pretty amazing picture.

Now I did a 3-dimensional picture. I took this body at depth. See this little red thing. That’s the little magma chamber at the surface I showed you. That’s the crustal magma chamber. This is down to 200 km with a 1 ½ % melt. 1% melt goes down to 300-400 km. .75% here is the body to a depth of 400 km. As it’s squirting off to the northwest.

Now, how does the earth work. The earth we know moves to the southeast. This is the surface plate motion these vectors all show. North American moving to the southwest. Here’s the Pacific Plate moving up toward Alaska and the Pacific and this is the San Andreas Fault. But did you know if you go down 300 km that the earth’s mantle is flowing back to the east? Here’s the cross-section right here. Here’s the core-mantle boundary. This is a convection cell. The plate is moving to the left. The cell is moving to the right. So this is the direction of the motion of magma at 100 km. Up here, the surface is solid, moving this way. So they scrape along right here, produce heat, just because of shear collision.

So if you want a hotspot at Yellowstone it has to come from the core-mantle boundary at 125 degrees. Who’s from Oregon. That’s where it has to originate. Deep down at the mantle boundary, it’s at Oregon. Then it comes up, gets caught in the mantle return flow. You see it turning over. So if that’s where it’s going to come from, that’s where it has to start. So there is not a vertical plume at Yellowstone.

So this is where we think it came from. This is at 16 million years. This is the path of the magma off to the northwest and here’s what we imaged. You folks are the first people to see this image, besides two graduate students in post-doc. We just made it. You can judge for yourself.

I am a very skeptical scientist. I posed something entirely different to another PhD student and here is a picture of his image to the northwest, line A, line B. There is nothing beneath Yellowstone but look to the northwest.

And that image looks like this. There’s something down there. So I took the picture from Iceland because Iceland has a reasonably well defined plume. People say they are not sure how deep it goes. Iceland, the island. They know it goes about 400 km down. It’s pretty narrow. You can’t constrain the depth of these rays unless you have a wide piece of land.

Here’s Eiffel. This is beneath the central portion of the whole Rhine Graben of Europe. It’s called the Eiffel Plume. It goes down to 400 km depth. Here’s Yellowstone. This thing goes to about 500 km depth. So if it walks like a duck and sounds like a duck it’s probably a Yellowstone Plume.

We think, however, that it doesn’t go to the core-mantle boundary. Here’s a cross-section through the earth along this line. Here’s Hawaii and you can see this magma beneath Hawaii almost to the core. Not very strong. Here’s Iceland. Look, magma comes off the core-mantle boundary but at Yellowstone it probably stops or is fed at a depth of maybe about 1000 km but it’s bent off to the northwest because that’s where the motion of the material is kept. I think it’s caused by decompression melting, not from the core-mantle boundary.

Let me tell you something. It doesn’t matter to the earth’s surface at Yellowstone where the magma and heat come from. It doesn’t care out here. It’s a huge volcanic system. It’s an active earthquake system. It doesn’t matter if it’s a deep plume source or a shallow decompression source. All the effects remain the same.

Let me finish off with Earth Scope. Earth Scope is a revolution earth science. NSF just funded a 100 university consortium of universities for seismic imaging, GPS, and drilling of the Western United States, treating the active processes of the Western US as a natural plate boundary laboratory. And they gave us $355,000,000 for five years. $290,000,000 for new seismographs, GPS, and a drill hole in the San Andreas and you can see another $100,000,000 for research. This is coming directly as a line item. The congressmen, university, and the Bush administration actively support it.

We are going to put out arrays of GPS units. We are going to put out about 1,000 GPS stations. There is a permanent array known as the backbone shown in light blue. There is going to be a hotspot array at Yellowstone. These are arrays of GPSs so close you can’t see them. There’s going to be about a thousand of them. With this we are going to capture how the ground is moving.

In the next slide we’ll show you where all the seismograph stations are going to be located. We’re going to start out, we’re putting the stations right now because we’re drilling a hole in the San Andreas Fault, just north of Los Angeles. And then next year we’ll put seismograph stations here. Then they’ll be here. And they are transportable. This array will move across the United States over about 10 years. At the end of 10 years we will be able to create images of the earth for the entire US and we’ll see how fast the whole US is moving.

This is what a station looks like. There’s a seismograph buried right here. The GPS receiver just like I’ve shown you. There’s a box with a solar antenna and a radio system. So here’s a combined, collocated GPS-seismic system. We’re going to buy about 3,000 of these guys. When they’re installed, you put this all together, and they’re about $100,000 each.

Here’s the Yellowstone picture. We are going to install in and around the Yellowstone Hotspot an additional 30 stations. We’re going to concentrate on the Yellowstone Plateau and I’ve already had discussions with Frank Walker and John Varley, Tom Olliff and Hank Heasler about this idea. We are going to put in an array perpendicular to the Hebgon Lake Fault Zone to see how fast it is moving and why it is still moving. (inaudible) We’re going to be putting additional stations across the Wasash Fault to see if in fact we might be able to see premonitory motion of the Wasash Fault. So this is a big science initiative put together by universities that work very hard and I want to point out is very integrative. We work amongst a lot of people. It’s not just one geologist or one geophysicist, it’s teams with various backgrounds.

Well, I’m going to stop here because I’m running out of breath, the literal end. Here’s a picture taken of the late Rick Hutchinson. Harley Bents, one of my former PhDs is now the chief seismologist of the National Earthquake Information Center. We were walking from Hot Springs Basin back to the Fern Lake cabin, having had lunch in Hot Springs Basin. He sat down in this nice grass in the shade and I said, “Don’t sit there.” He bent over to get a drink of water and the ph got him and his pants fell apart. Importantly, listen to your professors. Don’t sit in acid waters.

Thank You.

(Applause)

I’ll answer any questions you’d like. We’re running a little bit late but not too bad.

Question: I wonder if you could take a minute to explain why you think it is a shallow plume due to decompression melting..(inaudible).

Answer: Well you saw the depth of it. It’s not deep. It doesn’t look like it goes to the core-mantle boundary. It might later if we got more data but we think it may be cut off at about 600 to 800 km but I’m prepared to do some reprocessing. So how do you get a melt not driven by something down here? People think plumes start at the core-mantle boundary because Jason Morgan said they did in 1972. He just said, “Ah, let’s make a cartoon up”. He didn’t do the physics or the chemistry. If you want one though you can take a material that is already at critical temperature and pressure and if you decompress it of course fluids come out, namely partial melts. You can get 1 to 3 partial melt of depleted basaltic residuum. So that just comes from decompression melting. That’s a natural way to get magma in the earth. There’s magma in lots of places in the earth’s mantle that’s related to decompression melting. Now maybe that plume is going down. I don’t know. No one really knows what plumes look like. We’ve just gotten the first images in the last year of Eiffel, Iceland, and Yellowstone. There was a paper that just came out in Science in December which used some other data, but not nearly as high a resolution, which show plumes beneath Iceland, partial plumes beneath Hawaii and the shallow system beneath Yellowstone. It probably doesn’t go below 1500 km. Our high resolution show the actual body. Why does it do it this way? Good question. We’re trying to put these into chemical models because we have to actually work in the chemistry with the geophysics to understand the actual dynamics of decompression melting. I can’t answer your question because we don’t know the answer yet. I can refer you to some papers.

Question: Do you find decompression melting that doesn’t result in a hotspot?

Answer: That doesn’t result in a hotspot? Oh, I’m sure there must be. But the hotspot … some of it leaks through and eventually creates hotspots are areas of concentrated volcanism. Remember the definition I showed you from 1965, it’s periods of long-lived volcanism. There are hotspots that have to have high temperatures and long-lived volcanism that don’t have to be over plumes. Like in plate boundaries and mid-oceanic ridges. So you don’t have to have the converse.

Question: (inaudible)

Answer: It has a lot to do with it. The Basin Range, not so much to the structure. The Basin Range is the lid and if you open the lid, and it is opening, the Basin Range is stretching at 1.2 cm per year as it has for 17 million years. We’ve doubled the length of the Basin Range. We’ve doubled the distance from Yellowstone to Reno. So if you stretch the surface, you’re releasing the lid pressure. In other words the horizontal compression pressure is relaxing and that gives rise, probably, to the whole Yellowstone system. It’s coupled with the fact that this material is here. If we didn’t have the Basin Range, I doubt we’d see Yellowstone. Remember Yellowstone started at Boise. Now maybe Yellowstone is dead. Maybe we’re at the edge of the intra-plate now (the Basin Range) where all the deformation ends at the Intermountain Seismic Belt. The stable plate, North America, goes all the way to the mid-oceanic ridge, the Mid-Atlantic Ridge and that’s stable. I’m just beginning to wonder, you know, it’s taken a lot of energy to stretch out the Basin Range. Are we going to have enough energy to keep eating into the Rocky Mountains? They’re cold, they refract the heat, and so we may be slowing down this whole progression of volcanism along the Snake River Plain track. We don’t have that answer and probably won’t have it for several thousand years but we know that volcanism is going on and we know there’s earthquakes going on. It’s an active place.

Question: The (inaudible) suggests that there might not be an eruption…

Answer: I’m talking about big eruptions. If you’ve got this mound of just shallow magma, I mean, you certainly could have the Pinatubo-sized eruptions are much more likely. That hasn’t gone away. But the BBC eruption…I can’t answer that. But we may have slowed it down. But we may not too. We know that the Intermountain Seismic Belt, this big belt of earthquakes is a zone of intra-plate stretching. If the stretching keeps up, and there is no reason to think it won’t, we’re going to keep decreasing the pressure on the lid and allowing material to come up. It’s not being forced up. It’s coming up buoyantly because it is low density, high temperature.

Question: Could you go over again why the (inaudible)

(Some missing footage here - tape change.)

Answer: So we surveyed in ‘75, 6, and 7. When we came across from Canyon to Lake, the surveyor we had, had all the original notes in a book. That he had copied from the original surveys of ’23. And I happened to be with him and we came passed LeHardy Rapids. And there was a benchmark, you know where the parking lot is, well in the trees on the north side there’s a benchmark. It’s a concrete block sticking up. And he got there and he said, “Boy, those guys really did a screwy job”. We’re 1 ½ feet higher than they are. They’re off 1 ½ feet. How could those surveyors be off?” Actually, the ground had risen 18” or more. The height of the uplift is a little bit further to the west.

We took the data back home, and being the skeptic that I am, we spent an entire PhD thesis trying to prove that what we saw had nothing to do with the earth. We said it was surveying errors. It was ground water. It was all kinds of things but it didn’t go away. There was uplift of the whole caldera. This was just in historic time. The mapping by the quaternary geologist has shown that the caldera in the north side of the lake area go up and down over tens of thousands of years, certainly since glaciation. We would argue, if you look carefully, that at LeHardy Rapids, where a fault runs through…LeHardy Rapids is a fault zone. (to John Varley - Where we used to take fish. He’s a fisheries biologist. I used to take fish out of those rapids and study them.) There is a fault zone that runs north-south. I remember thinking, “Why are those falls here? That’s a strange place for a falls. The big falls ought to be down at the Grand Canyon and these are not.” There’s a fault zone there. By the way, when you are there and you are looking across, and you say to yourself, “Obviously the fault is up on the east and down on the west” right? That’s why the water goes down. Actually it’s wrong, it goes up on the west and down on the east. But it’s a fracture zone and the whole system is lifted up. It’s the axis of deformation that we map from historic data and it matches what the quaternary geologists have seen in the north side of Yellowstone Lake, looking at the lake sediments. I think it is because these magmatic systems and hydrothermal systems, they breath. They inflate and they deflate. And they inflate and they deflate. Now once in the while they burp and that’s probably when we get the rhyolites. That happens every 19,000 years. We haven’t had one for 70,000 years. That is these post-caldera flows. Are we behind? We probably are. But the bigger thing of course is that when those faults rupture, they produce earthquakes. We will probably see any kind of deformation with our GPS stations and our seismic.

I didn’t answer your question really well because we don’t really know the answer to what the magmatic system is but the resurgent dome at Mallard Lake connected by the Elephant Back Fault Zone to the resurgent domes to the north, Sour Creek. That’s probably a fracture zone and these faults at LeHardy are part of that connecting zone. It’s kind of the plumbing zone between them. And these two domes look like they go up and down together at least historically. So there’s got to be a plumbing connection somehow. Now I think it’s hydrothermal. I don’t think it’s magma because the fluids have to move too fast. You can’t move these domes up and down in synchronicity 75 to 85 because the material has to be very non-viscous; hot water, steam, etc. That’s my theory.

Question: Is there any residual isostatic rebound still happening or are we long beyond.

Answer: No we’re passed any isostatic rebound of the de-glaciation, especially where it’s so hot. This material responds so quickly. You put a load on Yellowstone and, Splat, it sinks. Take the load off and it rises up immediately. No there’s very little chance of that. It produces big forest fires there. Can you imagine what these things would do with forest fires. They would really be happy. (Bob laughs) It’s a very exciting place folks and I appreciate, first of all, all of your professional callings or more importantly your friends. I hope you share the excitement and ideas that we’re starting to find. It’s taken me 30 years to put all this together. It is starting to come together and we’re pretty excited about it.

Thank you.

(Applause)