WEBVTT 00:00:04.820 --> 00:00:10.530 Thank you so much to the Whidbey Reads program for inviting me to speak today. 00:00:10.530 --> 00:00:12.405 My name's Rebecca Kramer. 00:00:12.405 --> 00:00:15.945 I'm an operational geophysicist at CVO, 00:00:15.945 --> 00:00:18.195 the Cascades Volcano Observatory. 00:00:18.195 --> 00:00:22.400 Some of you may have joined for talks in previous weeks from my colleagues. 00:00:22.400 --> 00:00:27.575 They discussed geology, hazard mapping, 00:00:27.575 --> 00:00:30.020 and some of the important lessons that we learned 00:00:30.020 --> 00:00:33.040 from the 1980 eruption of Mount St. Helens. 00:00:33.040 --> 00:00:37.100 All the things that they talked about really inform what I do, 00:00:37.100 --> 00:00:38.975 which is to plan, install, 00:00:38.975 --> 00:00:43.550 and maintain monitoring stations on the volcanoes in Oregon and Washington. 00:00:45.230 --> 00:00:48.260 One of the most important factors when monitoring 00:00:48.260 --> 00:00:51.110 a volcano is having enough equipment in lots 00:00:51.110 --> 00:00:56.495 of places on and around all of the areas where an eruption is likely to occur. 00:00:56.495 --> 00:01:01.130 We tend to think of volcanoes as erupting from their summit craters, 00:01:01.130 --> 00:01:02.860 but that's not always what happens, 00:01:02.860 --> 00:01:05.780 and there are things happening underground that are important, 00:01:05.780 --> 00:01:10.295 but they can occur kilometers away from where the eruption actually occurs. 00:01:10.295 --> 00:01:12.710 When I speak of a station throughout this talk, 00:01:12.710 --> 00:01:16.820 I'm referring to scientific equipment that's at a location with infrastructure and 00:01:16.820 --> 00:01:21.775 power and often real-time data transmission or telemetry. 00:01:21.775 --> 00:01:24.650 The map you're looking at right now focuses on 00:01:24.650 --> 00:01:27.305 deformation monitoring at Mount St. Helens. 00:01:27.305 --> 00:01:29.900 One thing it doesn't show you is that there are actually 00:01:29.900 --> 00:01:32.990 many more seismic stations around the volcano. 00:01:32.990 --> 00:01:35.660 They're actually operated by our partners at 00:01:35.660 --> 00:01:39.125 the Pacific Northwest Seismic Network at the UW. 00:01:39.125 --> 00:01:42.260 Some of the deformation monitoring stations on here 00:01:42.260 --> 00:01:45.035 are actually maintained by the consortium UNAVCO. 00:01:45.035 --> 00:01:47.710 Some of them are only surveyed periodically. 00:01:47.710 --> 00:01:50.780 Another thing on this map I want to point out, 00:01:50.780 --> 00:01:53.120 the star in the center is a gas monitoring station 00:01:53.120 --> 00:01:55.980 in the crater, which we'll visit later. 00:01:58.820 --> 00:02:02.800 Let's visit one of our stations in the Mount Helen's crater. 00:02:02.800 --> 00:02:08.255 Our stations are powered by high-capacity batteries that are charged with solar panels. 00:02:08.255 --> 00:02:14.240 That's still the best bang for our buck in terms of power availability and reliability. 00:02:14.240 --> 00:02:16.670 This does present challenges for us in 00:02:16.670 --> 00:02:20.000 the Pacific Northwest with our cloudy and wintry weather. 00:02:20.000 --> 00:02:24.200 So we always have to factor that into engineering our stations. 00:02:24.200 --> 00:02:28.220 This is my favorite photo to emphasize how brutal our weather can 00:02:28.220 --> 00:02:31.955 be. In addition to the rain and the snow and the clouds, 00:02:31.955 --> 00:02:36.965 we even have to deal with fun things like rime ice at some of our stations. 00:02:36.965 --> 00:02:40.925 Some stations are certainly more reliable than others during the winter, 00:02:40.925 --> 00:02:43.190 but our networks are dense enough that we can 00:02:43.190 --> 00:02:47.280 continue to monitor volcanoes with a few stations offline. 00:02:48.560 --> 00:02:51.760 This is a similar map of Mount Rainier. 00:02:51.760 --> 00:02:53.630 The green triangles are 00:02:53.630 --> 00:02:58.415 the deformation survey sites I was talking about that we only visit periodically. 00:02:58.415 --> 00:03:03.475 It's very challenging to operate stations year round at Mount Rainier. 00:03:03.475 --> 00:03:05.330 Again, I want to emphasize, 00:03:05.330 --> 00:03:07.925 there are a number of seismic stations not shown on this map 00:03:07.925 --> 00:03:12.995 operated by the Pacific Northwest Seismic Network that we actually help maintain. 00:03:12.995 --> 00:03:15.875 Here's an example of some infrastructure at 00:03:15.875 --> 00:03:19.850 Observation Rock and one of my colleagues from the PNSN, 00:03:19.850 --> 00:03:23.780 and a photo of a GPS monitoring antenna at Camp Muir. 00:03:23.780 --> 00:03:27.440 If you've ever climbed one of those primary routes, 00:03:27.440 --> 00:03:30.895 you may have walked right past our antenna. 00:03:30.895 --> 00:03:35.450 The bottom line with volcano monitoring is that we go from a volcano at 00:03:35.450 --> 00:03:40.220 rest to a condition of unrest and possibly an eruption, 00:03:40.220 --> 00:03:45.660 and we want to be able to forecast how we go from point A to point B. 00:03:46.760 --> 00:03:50.410 We're constantly asking and trying to answer a series of 00:03:50.410 --> 00:03:54.370 seemingly simple questions about the volcanoes in the Cascades. 00:03:54.370 --> 00:03:59.350 Of course, getting those answers is actually pretty challenging and the idea 00:03:59.350 --> 00:04:01.300 is to form a conceptual model which is 00:04:01.300 --> 00:04:04.345 something that Heather discussed in her talk a few weeks ago. 00:04:04.345 --> 00:04:07.060 The important idea here is that we're not trying to 00:04:07.060 --> 00:04:09.830 get a perfect photograph of what's happening underground, 00:04:09.830 --> 00:04:14.590 but we're trying to visualize and describe the structures and the processes that are 00:04:14.590 --> 00:04:17.260 occurring so that we can provide a better estimate of 00:04:17.260 --> 00:04:20.870 what might happen when a volcano changes behavior. 00:04:20.870 --> 00:04:24.565 Getting the answers to the questions that we're asking 00:04:24.565 --> 00:04:28.600 about what's going on beneath the surface is not so straightforward. 00:04:28.600 --> 00:04:31.610 The good news is that volcanoes usually change 00:04:31.610 --> 00:04:34.985 behavior in ways that are detectable before they erupt. 00:04:34.985 --> 00:04:38.620 But every volcano and every eruption behaves differently. 00:04:38.620 --> 00:04:41.690 The tools and techniques that help forecast an eruption in 00:04:41.690 --> 00:04:46.415 one situation may differ from the ones that are most useful in another time and place. 00:04:46.415 --> 00:04:48.365 I'm going to mostly focus on 00:04:48.365 --> 00:04:52.070 the three main monitoring techniques we use which are seismology, 00:04:52.070 --> 00:04:55.650 gas geochemistry, and geodesy. 00:04:55.870 --> 00:05:00.590 I'm going to make sure that my audio should be 00:05:00.590 --> 00:05:04.385 shared. So that you don't have to listen to me the whole time, 00:05:04.385 --> 00:05:08.030 I'm going to rely on some of my colleagues to 00:05:08.030 --> 00:05:12.710 introduce these monitoring techniques beginning with volcano seismology. 00:05:12.710 --> 00:05:18.630 All of the videos and animations in this presentation are publicly available on the web. 00:05:23.140 --> 00:05:28.280 Most earthquakes associated with young volcanoes are related to the movement of magma 00:05:28.280 --> 00:05:33.200 deep beneath the volcano and may indicate that a quiet volcano is becoming active. 00:05:33.200 --> 00:05:36.050 Although large eruptions are often preceded by 00:05:36.050 --> 00:05:39.500 several significant earthquakes and many small rock-breaking quakes 00:05:39.500 --> 00:05:41.750 there's also the continuous release of 00:05:41.750 --> 00:05:46.105 seismic energy associated with the underground movement of magma. 00:05:46.105 --> 00:05:50.360 Volcanic tremor is a seismic vibration caused by the pulsing of 00:05:50.360 --> 00:05:54.745 pressurized magma and gas and can last for minutes or days. 00:05:54.745 --> 00:05:57.650 The seismogram is of longer duration and more 00:05:57.650 --> 00:06:02.130 continuous than rock-breaking earthquakes of the same amplitude. 00:06:02.900 --> 00:06:08.450 Earthquake swarms recorded by seismometers and the ground deformation monitored by 00:06:08.450 --> 00:06:10.940 tiltmeters helps scientists determine 00:06:10.940 --> 00:06:14.869 the location and depth of moving magma beneath the volcano, 00:06:14.869 --> 00:06:20.100 which in turn gives scientists information to issue hazard warnings. 00:06:28.100 --> 00:06:34.370 Volcano seismology is extremely important because there is almost always a change in 00:06:34.370 --> 00:06:40.255 the number or location or types of earthquakes in the time leading up to an eruption. 00:06:40.255 --> 00:06:45.620 The top image here is showing how the combined size of all the earthquakes happening 00:06:45.620 --> 00:06:51.230 around Mount St. Helens increased dramatically before an eruption in the 1980s. 00:06:51.230 --> 00:06:53.480 The bottom image is showing 00:06:53.480 --> 00:06:58.610 the same information for a few weeks in September and October in 2004. 00:06:58.610 --> 00:07:02.840 The first explosion of that eruption was on October 1st. 00:07:02.840 --> 00:07:05.875 You can see how the seismicity increased, 00:07:05.875 --> 00:07:07.480 and then the explosion occurred, 00:07:07.480 --> 00:07:12.570 and then the seismicity dropped dramatically before jumping back up again. 00:07:16.250 --> 00:07:20.930 A really important fact that Heather mentioned that's worth restating is 00:07:20.930 --> 00:07:25.115 that most of the time when activity at a volcano increases, 00:07:25.115 --> 00:07:27.549 it means there are changes happening underground, 00:07:27.549 --> 00:07:31.910 but most of the time these changes don't lead to an eruption. 00:07:31.910 --> 00:07:36.140 A combination of the geologic knowledge and widespread monitoring networks is what 00:07:36.140 --> 00:07:40.835 helps us improve our forecasts of what may happen if there's unrest. 00:07:40.835 --> 00:07:45.800 The most important vocabulary word in volcano seismology is wave. 00:07:45.800 --> 00:07:48.565 Sometimes it's helpful to get back to basics. 00:07:48.565 --> 00:07:52.270 Seismic waves are energy waves that travel underground. 00:07:52.270 --> 00:07:55.270 When a seismic wave shakes a seismometer, 00:07:55.270 --> 00:07:58.375 which is the instrument we use to detect the ground shaking, 00:07:58.375 --> 00:08:01.640 we can identify lots of interesting parameters. 00:08:01.640 --> 00:08:05.890 The parameters look really different when they get to our instruments than they did at 00:08:05.890 --> 00:08:10.225 the source because of all the stuff they have to travel through. 00:08:10.225 --> 00:08:14.530 These waves contain information not just about the original earthquake, 00:08:14.530 --> 00:08:17.020 but about the layers of the earth that they traveled through. 00:08:17.020 --> 00:08:20.260 A couple of things that we look at. 00:08:20.260 --> 00:08:23.560 The amplitude of a seismic wave can tell us something about 00:08:23.560 --> 00:08:27.445 how big the earthquake was or maybe how close it was. 00:08:27.445 --> 00:08:31.375 The wavelength is literally how long the wave is. 00:08:31.375 --> 00:08:35.630 Another way to think about this is frequency. 00:08:36.330 --> 00:08:41.695 A typical seismic signal looks much messier than this example. 00:08:41.695 --> 00:08:46.290 Let's go to our local slideshow volcano, 00:08:46.290 --> 00:08:50.840 which is not exactly to-scale or representative of real life 00:08:50.840 --> 00:08:58.370 but let's think about how ripples reverberate when you drop a rock in a pond. 00:08:58.370 --> 00:09:00.430 If an earthquake occurs, 00:09:00.430 --> 00:09:03.760 the seismic waves travel outward in every direction. 00:09:03.760 --> 00:09:07.450 As they travel, they change speed and they 00:09:07.450 --> 00:09:10.720 change frequency as they pass through the different layers of the earth. 00:09:10.720 --> 00:09:15.425 So the amplitude and the frequency of those waves gets affected. 00:09:15.425 --> 00:09:20.510 Some types of seismic waves namely the pressure waves or P waves, 00:09:20.510 --> 00:09:25.175 travel faster than the surface waves or the S waves. 00:09:25.175 --> 00:09:30.530 The path from an earthquake to a seismic station is really complex. 00:09:30.530 --> 00:09:33.865 For example, only P waves can travel through liquids, 00:09:33.865 --> 00:09:37.400 and we can use the velocity difference between the P waves and 00:09:37.400 --> 00:09:42.380 the S waves to do some really cool creative things that I'll talk about momentarily. 00:09:42.380 --> 00:09:47.185 Anything that causes the ground to shake creates seismic waves. 00:09:47.185 --> 00:09:49.860 This can include explosions, 00:09:49.860 --> 00:09:53.925 faults moving, tides, even people walking. 00:09:53.925 --> 00:09:56.720 Our seismic instruments are really sensitive so 00:09:56.720 --> 00:10:00.130 they can pick up any of these disturbances if they're close enough. 00:10:00.130 --> 00:10:04.800 I have a couple of these examples from Mount St. Helens. 00:10:43.530 --> 00:10:47.680 Seismologists are able to pick out these different signals 00:10:47.680 --> 00:10:51.510 and identify which ones are relevant and which ones aren't. 00:10:51.510 --> 00:10:53.280 In addition to earthquakes, 00:10:53.280 --> 00:10:56.685 we can detect processes that are happening above the surface, 00:10:56.685 --> 00:10:59.400 like the rockfall that you just saw. 00:10:59.400 --> 00:11:04.060 We can also detect earthquakes that happen on the other side of the earth. 00:11:04.200 --> 00:11:07.420 For example, an earthquake happening in Chile takes 00:11:07.420 --> 00:11:10.690 a little bit of time to reach our stations at Mount St. Helens, 00:11:10.690 --> 00:11:13.070 but we can detect that. 00:11:26.700 --> 00:11:30.640 Seismometers, which are the tools that we use to detect earthquakes, 00:11:30.640 --> 00:11:32.875 have changed a lot over the decades. 00:11:32.875 --> 00:11:37.900 On the top left is an old smoke drum seismograph where basically you have a pen hanging 00:11:37.900 --> 00:11:42.640 like a pendulum and it scratches a piece of paper covered in soot. 00:11:42.640 --> 00:11:43.810 As of a few decades ago, 00:11:43.810 --> 00:11:46.960 we had the slightly more advanced pen and paper system. 00:11:46.960 --> 00:11:48.400 But in recent decades, 00:11:48.400 --> 00:11:50.530 seismometers have all gone digital. 00:11:50.530 --> 00:11:52.510 In the very basic sense, 00:11:52.510 --> 00:11:55.780 a free-moving magnet inside of a coil gets 00:11:55.780 --> 00:12:00.805 shaken around and creates an electric signal that we can digitize. 00:12:00.805 --> 00:12:05.350 These advances are really important because we can start to see signals from 00:12:05.350 --> 00:12:09.820 much smaller earthquakes and much larger earthquakes than we used to be able to. 00:12:09.820 --> 00:12:13.660 We can also use software to more efficiently and completely 00:12:13.660 --> 00:12:18.140 identify and characterize all the earthquakes happening under volcanoes. 00:12:18.360 --> 00:12:23.215 One thing that hasn't changed is that seismometers work best when they're underground. 00:12:23.215 --> 00:12:25.960 They're sensitive even to daily temperature changes. 00:12:25.960 --> 00:12:28.825 The deeper we can place them the better. 00:12:28.825 --> 00:12:32.050 In my job, we spend a lot of time digging holes. 00:12:32.050 --> 00:12:45.955 Some are not very small. 00:12:45.955 --> 00:12:49.585 We're also trying to tell the difference between lots of different kinds of earthquakes. 00:12:49.585 --> 00:12:53.215 You can see visually that each of these earthquakes is different. 00:12:53.215 --> 00:12:57.220 Those differences tell us something about the cause of each event. 00:12:57.220 --> 00:12:59.350 Some of them like the one on the top, 00:12:59.350 --> 00:13:03.505 result from normal tectonic stress or basically rocks breaking. 00:13:03.505 --> 00:13:06.070 Some of the ones at the bottom are caused by 00:13:06.070 --> 00:13:10.400 resonance as magma travels through cracks underground. 00:13:10.560 --> 00:13:14.455 There are some really cool things we can do with volcanic earthquakes. 00:13:14.455 --> 00:13:18.685 Using multiple stations, we can figure out where the earthquakes originated. 00:13:18.685 --> 00:13:21.070 It's important to have seismic stations 00:13:21.070 --> 00:13:24.775 surrounding earthquake locations to get good precision. 00:13:24.775 --> 00:13:28.600 It's also important to have seismometers high on the edifice 00:13:28.600 --> 00:13:32.710 at a volcano so that you can locate shallow earthquakes. 00:13:32.710 --> 00:13:34.870 We can also determine, for example, 00:13:34.870 --> 00:13:36.340 how a fault moves in an earthquake, 00:13:36.340 --> 00:13:40.180 which tells us something about the stress state under a volcano. 00:13:40.180 --> 00:13:46.270 We can do some relatively simple statistics to see if anything has changed over time. 00:13:46.270 --> 00:13:49.105 For example, volcano seismologists 00:13:49.105 --> 00:13:53.050 calculate what's called a b-value and you don't need to know what that stands for. 00:13:53.050 --> 00:13:55.330 Bottom line is that over time, 00:13:55.330 --> 00:13:59.815 there are a lot more small earthquakes happening than large earthquakes. 00:13:59.815 --> 00:14:04.870 If we see a change in the relative number of different sizes of earthquakes, 00:14:04.870 --> 00:14:07.550 then that may get our attention. 00:14:08.640 --> 00:14:14.080 If our resident seismologist could put seismic stations everywhere, he would. 00:14:14.080 --> 00:14:15.789 It's not really practical, 00:14:15.789 --> 00:14:20.410 but sometimes we do have opportunities to do just that over the short term. 00:14:20.410 --> 00:14:24.430 The project iMUSH or Imaging Magma Under St. Helens, 00:14:24.430 --> 00:14:26.725 was a really cool collaborative project. 00:14:26.725 --> 00:14:29.650 It involved multiple universities, the USGS, 00:14:29.650 --> 00:14:32.995 the Forest Service, and the National Science Foundation. 00:14:32.995 --> 00:14:37.150 In addition to having 70 temporary seismic stations, 00:14:37.150 --> 00:14:42.295 the program created its own earthquakes in the form of small controlled explosions. 00:14:42.295 --> 00:14:45.220 They knew the exact location and size and 00:14:45.220 --> 00:14:48.520 frequency of the ground shaking that they caused. 00:14:48.520 --> 00:14:52.060 By recording the seismic waves at all those seismic stations, 00:14:52.060 --> 00:14:54.595 they were basically able to take an MRI 00:14:54.595 --> 00:14:58.225 of the subsurface under and around Mount St. Helens. 00:14:58.225 --> 00:15:03.490 We look at these images in terms of seismic wave velocity. 00:15:03.490 --> 00:15:06.850 The changing speeds that the seismic waves travel at 00:15:06.850 --> 00:15:10.465 underground are related to the subsurface geology. 00:15:10.465 --> 00:15:12.340 We can get an idea, 00:15:12.340 --> 00:15:16.585 for example, of where magma is stored. 00:15:16.585 --> 00:15:23.830 We had way more sensitive instruments before the 2004 eruption than we did in 1980 00:15:23.830 --> 00:15:26.740 but there wasn't an uptick in seismic activity in 00:15:26.740 --> 00:15:30.970 2004 until just a few days before the first explosion. 00:15:30.970 --> 00:15:36.025 Part of the reason was that this was a very different type of eruption from 1980; 00:15:36.025 --> 00:15:37.750 it was contained in the crater, 00:15:37.750 --> 00:15:41.035 it tapped a very shallow magma source, 00:15:41.035 --> 00:15:43.435 and there were fewer volcanic gases. 00:15:43.435 --> 00:15:45.760 There was less strain happening underground, 00:15:45.760 --> 00:15:49.585 fewer earthquakes, and the eruption was less explosive. 00:15:49.585 --> 00:15:55.020 This is showing the earthquakes and seismicity and 00:15:55.020 --> 00:16:00.065 the different types of volcanic earthquakes from September 23rd through 26th. 00:16:00.065 --> 00:16:05.005 Again, just about a week before the first explosion on October 1st. 00:16:05.005 --> 00:16:08.230 Studying the seismic signals prior to and 00:16:08.230 --> 00:16:11.020 during the eruption is a key component of what we do. 00:16:11.020 --> 00:16:13.870 We need to know what the background earthquakes look like, 00:16:13.870 --> 00:16:16.480 to know if there's a change in the behavior. 00:16:16.480 --> 00:16:20.125 There's plenty of background activity at Cascade volcanoes, 00:16:20.125 --> 00:16:23.215 and mostly they're related to tectonic forces. 00:16:23.215 --> 00:16:27.025 We see recurring patterns of earthquakes beneath Mount St. Helens, 00:16:27.025 --> 00:16:29.290 Mount Rainier, Mount Hood, 00:16:29.290 --> 00:16:33.530 and even Newberry, and Crater Lake occasionally in southern Oregon. 00:16:33.900 --> 00:16:38.199 There are multiple hazards associated with eruptions. 00:16:38.199 --> 00:16:41.200 Joe's talk covered a number of them when he described 00:16:41.200 --> 00:16:47.140 hazard maps. And our sensitive seismometers can pick up more than just earthquakes. 00:16:47.140 --> 00:16:50.245 I showed the example of rockfall, 00:16:50.245 --> 00:16:55.300 but we can also detect what's called a lahar. 00:16:55.300 --> 00:16:58.300 An important project we're working at CVO is 00:16:58.300 --> 00:17:01.825 expanding our lahar detection ability at Mount Rainier. 00:17:01.825 --> 00:17:04.585 The word comes from the Javanese language, 00:17:04.585 --> 00:17:08.785 and it describes mudflows and debris flows that originate on volcanoes. 00:17:08.785 --> 00:17:10.720 Cascade volcanoes are steep, 00:17:10.720 --> 00:17:13.750 they have lots of unstable material and lots of groundwater and 00:17:13.750 --> 00:17:17.620 surface water that's available to trigger those mudflows. 00:17:17.620 --> 00:17:21.850 Lahars usually occur when there is an eruption which displaces 00:17:21.850 --> 00:17:26.200 lots of material and rapidly melts the snow and the glaciers. 00:17:26.200 --> 00:17:30.370 The mudflows typically travel down existing channels or 00:17:30.370 --> 00:17:35.515 drainages as Joe described when he discussed hazard maps. 00:17:35.515 --> 00:17:37.915 Lahars are extremely destructive. 00:17:37.915 --> 00:17:42.710 They're one of the most deadly and far-reaching volcanic hazards. 00:17:43.650 --> 00:17:46.120 In recent years we've been adding 00:17:46.120 --> 00:17:49.945 seismic monitoring stations along the Puyallup and Carbon River drainages 00:17:49.945 --> 00:17:52.780 on the west side of Mount Rainier as part of an upgrade 00:17:52.780 --> 00:17:56.080 to an old system for detecting lahars. 00:17:56.080 --> 00:17:59.530 Downstream communities, such as Orting are actually built on 00:17:59.530 --> 00:18:03.445 old deposits from lahars that originated on Mount Rainier. 00:18:03.445 --> 00:18:08.470 In this figure, you're seeing seismic waves and their energy at different frequencies at 00:18:08.470 --> 00:18:11.185 seven different monitoring stations 00:18:11.185 --> 00:18:13.990 in Mount Rainier National Park and along the Puyallup River. 00:18:13.990 --> 00:18:16.150 There was a small debris flow in 00:18:16.150 --> 00:18:19.750 the Mowich drainage and it was clearly picked up by our sensors. 00:18:19.750 --> 00:18:23.440 These little events will give us practice with signals that are 00:18:23.440 --> 00:18:28.270 similar to what we may see for a larger, more dangerous event. 00:18:28.270 --> 00:18:30.505 This image is a couple of years old. 00:18:30.505 --> 00:18:36.085 There are actually a few more sites now where we have seismic monitoring stations. 00:18:36.085 --> 00:18:39.115 You can see we have stations in the park, 00:18:39.115 --> 00:18:42.520 as well as a series of stations tracking along the Puyallup River, 00:18:42.520 --> 00:18:45.640 we've added a few more there and at the Carbon in recent years, 00:18:45.640 --> 00:18:49.420 and we're working on adding more monitoring on additional drainages, 00:18:49.420 --> 00:18:52.940 including the Kautz, the Nisqually, and White River. 00:18:53.550 --> 00:18:56.920 If seismicity is a volcano's heartbeat, 00:18:56.920 --> 00:19:03.530 then gas emissions are like it's breathing or other bodily functions, if you like. 00:19:08.550 --> 00:19:12.189 When the magma is very deep beneath the volcano, 00:19:12.189 --> 00:19:14.185 it has a lot of gas dissolved in it, 00:19:14.185 --> 00:19:17.890 but when that magma starts to rise towards the surface, 00:19:17.890 --> 00:19:20.320 the gases will come out of the magma. 00:19:20.320 --> 00:19:22.145 If this happens very quickly, 00:19:22.145 --> 00:19:25.725 then the volcano might erupt explosively. 00:19:25.725 --> 00:19:28.260 At volcanoes like Mount St. Helens, 00:19:28.260 --> 00:19:33.625 it's important to monitor the gases on a routine basis because, 00:19:33.625 --> 00:19:38.605 at any time, there could be another injection of gas-rich magma from below, 00:19:38.605 --> 00:19:44.120 which might cause the volcano to enter another eruptive phase. 00:19:46.110 --> 00:19:49.870 Volcanic gases are really interesting to us. 00:19:49.870 --> 00:19:52.300 They're the driving force behind eruptions. 00:19:52.300 --> 00:19:56.200 It's ultimately these gases that cause the volcanic tremor and 00:19:56.200 --> 00:20:00.795 the surface deformation that we see using other monitoring techniques. 00:20:00.795 --> 00:20:04.470 The gas composition is also interesting because it points straight to 00:20:04.470 --> 00:20:08.710 the geology and geochemistry of the magma system. 00:20:15.030 --> 00:20:18.520 Two important things that I will focus on are 00:20:18.520 --> 00:20:22.240 the types of gases and how quickly they come out of the ground. 00:20:22.240 --> 00:20:25.360 The bottom line is that molten material is 00:20:25.360 --> 00:20:28.990 generated in the mantle under high pressures and temperatures. 00:20:28.990 --> 00:20:31.435 As this material moves toward the surface, 00:20:31.435 --> 00:20:33.625 the pressure and temperature changes. 00:20:33.625 --> 00:20:36.730 As this happens, gases that were dissolved in 00:20:36.730 --> 00:20:41.080 the magma start to come out of the liquid and into their vapor phase. 00:20:41.080 --> 00:20:44.110 This is just like the release of CO2 gas when you 00:20:44.110 --> 00:20:48.460 suddenly opened a soda bottle and lower the pressure inside of it. 00:20:48.460 --> 00:20:51.850 Different gases come out at different depths and temperatures. 00:20:51.850 --> 00:20:55.615 For example, CO2 comes out much deeper than SO2. 00:20:55.615 --> 00:20:58.810 Water starts to vaporize out of magma at 00:20:58.810 --> 00:21:02.470 about a kilometer below the surface, so very shallow. 00:21:02.470 --> 00:21:04.330 Water is important, it's 00:21:04.330 --> 00:21:09.289 the most important volcanic gas because it's what will really drive an eruption. 00:21:09.289 --> 00:21:12.380 This is a photo of one of my colleagues with a group 00:21:12.380 --> 00:21:15.335 from the Indonesian equivalent of the USGS, 00:21:15.335 --> 00:21:20.150 standing in front of a gas monitoring station that they installed at Timbang Crater. 00:21:20.150 --> 00:21:25.140 The area is a critical agricultural center for the island of Java. 00:21:25.150 --> 00:21:29.070 At Timbang Crater, we don't see a lot of eruptions there, 00:21:29.070 --> 00:21:30.650 we see steam explosions. 00:21:30.650 --> 00:21:33.140 But more importantly, there are 00:21:33.140 --> 00:21:39.060 toxic carbon dioxide plumes basically that come out of the crater. 00:21:39.060 --> 00:21:41.210 Because it's denser than air, 00:21:41.210 --> 00:21:43.910 the carbon dioxide flows downhill. 00:21:43.910 --> 00:21:47.840 This region has seen fatalities from this phenomenon in the past. 00:21:47.840 --> 00:21:53.295 Basically, the CO2 comes out of the ground and then pools in these low-lying areas. 00:21:53.295 --> 00:21:56.030 You can see on the right the percentage of 00:21:56.030 --> 00:21:59.955 CO2 detected over a few months at the station. 00:21:59.955 --> 00:22:02.370 At four percent CO2, 00:22:02.370 --> 00:22:05.525 you are considered an immediate danger by OSHA, 00:22:05.525 --> 00:22:10.205 thirty minutes at five percent will lead to feeling intoxicated. 00:22:10.205 --> 00:22:15.175 A few minutes at 7-10 percent CO2 leads to unconsciousness, 00:22:15.175 --> 00:22:18.140 and at around 14 percent, 00:22:18.140 --> 00:22:21.480 you're pretty much at instantaneous lights out. 00:22:22.500 --> 00:22:26.035 What gases does a volcano produce? 00:22:26.035 --> 00:22:27.835 We've gone over CO2 a little bit, 00:22:27.835 --> 00:22:29.710 I mentioned a couple others. 00:22:29.710 --> 00:22:33.760 Carbon dioxide separates from magma at great depths. 00:22:33.760 --> 00:22:38.695 Sulfur dioxide exsolves or comes out of the magma at shallower depths, 00:22:38.695 --> 00:22:42.025 it might tell us that magma is closer to the surface. 00:22:42.025 --> 00:22:46.795 Hydrogen sulfide comes from magmatic gases interacting with groundwater. 00:22:46.795 --> 00:22:48.955 It smells like rotten eggs. 00:22:48.955 --> 00:22:53.170 You may have smelled hydrogen sulfide 00:22:53.170 --> 00:22:57.100 if you've visited hot springs or been to Yellowstone National Park. 00:22:57.100 --> 00:23:01.225 Hydrogen chloride and hydrogen fluoride are halides, 00:23:01.225 --> 00:23:04.675 and they also indicate magma near the surface, 00:23:04.675 --> 00:23:07.345 but they dissolve really easily in water. 00:23:07.345 --> 00:23:09.790 They can actually lead to acid rain and 00:23:09.790 --> 00:23:13.465 other negative health effects if people are exposed to them. 00:23:13.465 --> 00:23:17.320 Finally, water. Water is really tricky to measure. 00:23:17.320 --> 00:23:18.594 It likes to condense, 00:23:18.594 --> 00:23:21.835 it gets emitted in places that are really tough to access, 00:23:21.835 --> 00:23:24.310 but water and carbon dioxide are 00:23:24.310 --> 00:23:29.725 really important barometers for how eruptible a magma is. 00:23:29.725 --> 00:23:32.360 They're just really hard to measure. 00:23:33.150 --> 00:23:36.220 CO2 becomes a vapor at great depths. 00:23:36.220 --> 00:23:37.825 It's colorless and odorless, 00:23:37.825 --> 00:23:39.730 and as we talked about, 00:23:39.730 --> 00:23:44.815 it can be hazardous and it kills trees and vegetation. 00:23:44.815 --> 00:23:50.065 Sulfur dioxide or SO2 comes out at shallower depths. 00:23:50.065 --> 00:23:52.780 It's colorless, but it has this pungent, 00:23:52.780 --> 00:23:55.630 acidic odor and it really irritates your mucus membranes, 00:23:55.630 --> 00:23:57.940 your eyes, and your nose and throat. 00:23:57.940 --> 00:24:00.715 Hydrogen sulfide, or H2S, 00:24:00.715 --> 00:24:03.550 again, is caused by sulfur interacting with water. 00:24:03.550 --> 00:24:05.634 It's colorless and it's flammable, 00:24:05.634 --> 00:24:07.495 and it smells like rotten eggs. 00:24:07.495 --> 00:24:10.630 Actually your nose is much better at 00:24:10.630 --> 00:24:14.965 detecting H2S than any gas monitoring instrument at low levels 00:24:14.965 --> 00:24:17.830 but at toxic levels, 00:24:17.830 --> 00:24:20.095 it actually becomes odorless. 00:24:20.095 --> 00:24:24.445 Gas geochemists try to do creative things. 00:24:24.445 --> 00:24:26.950 They try to relate how much gas is coming out 00:24:26.950 --> 00:24:29.635 of a volcano to how much material has erupted. 00:24:29.635 --> 00:24:33.460 The approach works okay in places like Hawai'i because sulfur 00:24:33.460 --> 00:24:37.540 is easy to detect and it dissolves easily in basalt. 00:24:37.540 --> 00:24:40.555 In the 1980s in Alaska, 00:24:40.555 --> 00:24:42.790 there seemed to be a correlation between 00:24:42.790 --> 00:24:48.460 gas emission rates and the likelihood of an eruption from some volcanoes, 00:24:48.460 --> 00:24:50.560 but this was purely empirical. 00:24:50.560 --> 00:24:52.675 Every volcanic system is different, 00:24:52.675 --> 00:24:55.090 and even a dramatic change in gas emissions 00:24:55.090 --> 00:24:58.370 does not necessarily mean an eruption is imminent. 00:24:58.770 --> 00:25:01.885 How do we sniff gas? 00:25:01.885 --> 00:25:05.635 The misspelling is intentional and you'll see why as soon. 00:25:05.635 --> 00:25:11.455 We either directly sample the gas or we detect it remotely. 00:25:11.455 --> 00:25:15.115 Direct sampling tells us what kinds of gases are present, 00:25:15.115 --> 00:25:19.000 and remote sensing tells us how fast the gas is coming out. 00:25:19.000 --> 00:25:22.750 One is like checking to see if a stove burner is hot by touching it, 00:25:22.750 --> 00:25:26.390 and the other one is holding up a thermal camera to check. 00:25:26.850 --> 00:25:31.060 Direct gas sampling has been around for over 100 years. 00:25:31.060 --> 00:25:35.575 If you see this font on a USGS publication then you know it's more than a few years old. 00:25:35.575 --> 00:25:39.250 The gas is collected in glass bottles. 00:25:39.250 --> 00:25:41.095 They have to be sealed, 00:25:41.095 --> 00:25:43.495 they have to be shipped to a lab and analyzed. 00:25:43.495 --> 00:25:45.685 It's tricky to collect the samples, 00:25:45.685 --> 00:25:47.305 it's tricky to transport them, 00:25:47.305 --> 00:25:49.780 and it takes awhile to get results. 00:25:49.780 --> 00:25:55.945 USGS scientists developed a gas sampling lab that can operate as its own station. 00:25:55.945 --> 00:25:58.135 The equipment is called MultiGAS, 00:25:58.135 --> 00:26:01.389 and it includes optical and electrochemical sensors. 00:26:01.389 --> 00:26:03.700 It was designed and built in-house by 00:26:03.700 --> 00:26:07.270 the Volcano Disaster Assistance Program and the USGS, 00:26:07.270 --> 00:26:11.875 and it solves the problem of needing to hike around with gas flasks everywhere, 00:26:11.875 --> 00:26:14.680 and it runs every day of the year. 00:26:14.680 --> 00:26:18.490 Our other method of detecting volcanic gases is to use 00:26:18.490 --> 00:26:21.475 remote sensing to see what the flux is. 00:26:21.475 --> 00:26:24.430 In other words, the rate of gas emissions. 00:26:24.430 --> 00:26:28.495 We have a remote sensing instrument called a DOAS scanner. 00:26:28.495 --> 00:26:33.534 It has a camera that captures light from the sun coming through the atmosphere. 00:26:33.534 --> 00:26:37.840 Volcanic gases cause different wavelengths of light to reflect 00:26:37.840 --> 00:26:42.190 and refract in predictable ways that we can measure. 00:26:42.190 --> 00:26:46.240 If you think about how the atmosphere filters out blue light at low angles 00:26:46.240 --> 00:26:50.590 and causes the sunset to be red and orange, it's like that. 00:26:50.590 --> 00:26:54.519 The DOAS station is actually pretty complex, 00:26:54.519 --> 00:26:55.780 but above the surface, 00:26:55.780 --> 00:26:58.100 it just looks like a little camera. 00:26:58.560 --> 00:27:01.720 We put our gas monitoring instruments at 00:27:01.720 --> 00:27:05.485 different places on the volcano depending on their purpose. 00:27:05.485 --> 00:27:09.880 MultiGAS is meant to tell us the types of gases coming out at the source, 00:27:09.880 --> 00:27:12.815 so it needs to be right in the gas plume. 00:27:12.815 --> 00:27:17.280 DOAS or spectrometers need to be outside the plume so 00:27:17.280 --> 00:27:22.330 that they can scan a wide area and see how fast the gas is coming out. 00:27:23.130 --> 00:27:28.915 Using these two methods in combination helps us see if there are changes in a system. 00:27:28.915 --> 00:27:31.510 Again, changes don't mean an eruption is eminent. 00:27:31.510 --> 00:27:38.120 Even external factors like seasonal groundwater changes can affect the gases we detect. 00:27:38.250 --> 00:27:45.655 The USGS has done campaign style MultiGAS measurements at multiple Cascade volcanoes. 00:27:45.655 --> 00:27:50.095 The bottom line is that there isn't much gas. 00:27:50.095 --> 00:27:56.185 There are signals consistent with magma cooling at Mount Hood and Lassen and Mount Baker. 00:27:56.185 --> 00:28:00.280 Most of the gases seen are typical for hydrothermal areas. 00:28:00.280 --> 00:28:02.500 In some isolated instances, 00:28:02.500 --> 00:28:04.900 the gases do create their own hazard. 00:28:04.900 --> 00:28:09.310 Mammoth Mountain has seen low lying areas with CO2 build-up. 00:28:09.310 --> 00:28:11.275 That's in northern California. 00:28:11.275 --> 00:28:13.960 You sometimes hear stories of climbers needing to be 00:28:13.960 --> 00:28:16.795 rescued from caves or holes high on Mount Hood, 00:28:16.795 --> 00:28:20.515 and they report experiencing headaches, shortness of breath, 00:28:20.515 --> 00:28:25.225 and nausea, which is consistent with exposure to hydrogen sulfide. 00:28:25.225 --> 00:28:30.370 We have one permanent MultiGAS station in the Cascades on the new dome at 00:28:30.370 --> 00:28:34.495 Mount St. Helens, and that station is named SNIF, S-N-I-F. 00:28:34.495 --> 00:28:38.290 Here's a selfie of me helping service the station a few years ago, 00:28:38.290 --> 00:28:40.610 wearing my safety gear. 00:28:41.940 --> 00:28:46.340 There's too little gas to be detectable, much less hazardous. 00:28:46.980 --> 00:28:49.825 This is what the inside of a gas station looks like, 00:28:49.825 --> 00:28:52.765 mostly batteries and gas canisters. 00:28:52.765 --> 00:28:55.270 I'm going to let my colleague, Peter, 00:28:55.270 --> 00:28:58.550 tell you a little bit more about monitoring at SNIF. 00:29:32.640 --> 00:29:37.435 Here we are at Mount St. Helens, in the crater. 00:29:37.435 --> 00:29:41.395 This is the Mount St. Helens SNIF site. 00:29:41.395 --> 00:29:47.515 This is a gas monitoring site that was put in at the end of August 2014, 00:29:47.515 --> 00:29:53.485 and its purpose is to monitor gas plumes within Mount St. Helens. 00:29:53.485 --> 00:29:56.785 This plume here contains mostly water vapor, 00:29:56.785 --> 00:29:58.390 but also contains carbon dioxide, 00:29:58.390 --> 00:30:02.155 sulfur dioxide, and a really trace amount of hydrogen sulfide. 00:30:02.155 --> 00:30:06.580 Its composition is consistent with a very shallow, hot, 00:30:06.580 --> 00:30:09.940 oxidized melt, and so it's 00:30:09.940 --> 00:30:14.365 a magmatic gas essentially that's being emitted to the atmosphere. 00:30:14.365 --> 00:30:21.175 It has a very low carbon-sulfur ratio which is consistent with low pressure degassing. 00:30:21.175 --> 00:30:23.500 It's mainly sulfur dioxide, 00:30:23.500 --> 00:30:24.910 very little hydrogen sulfide, 00:30:24.910 --> 00:30:28.840 which is also consistent with high temperature, low pressure degassing. 00:30:28.840 --> 00:30:32.800 This is the only place in the Cascades where we presently get sulfur dioxide degassing. 00:30:32.800 --> 00:30:37.090 Everywhere else there's hydrothermal systems that are 00:30:37.090 --> 00:30:39.865 in-between the point where the gas 00:30:39.865 --> 00:30:42.910 separates from the magma and then makes its way to the surface. 00:30:42.910 --> 00:30:47.950 It interacts with hydrothermal fluids and rocks and water and it's during that process, 00:30:47.950 --> 00:30:50.455 any sulfur dioxide that's degassed, 00:30:50.455 --> 00:30:54.370 gets converted into hydrogen sulfide and other species. 00:30:54.370 --> 00:30:56.890 It's not actually emitted to the atmosphere. 00:30:56.890 --> 00:31:00.430 This station, which you can see in front of you, 00:31:00.430 --> 00:31:03.895 is actually a station to monitor just those four gases, 00:31:03.895 --> 00:31:05.770 water vapor, carbon dioxide, 00:31:05.770 --> 00:31:08.480 sulfur dioxide, and hydrogen sulfide. 00:31:12.230 --> 00:31:15.150 What do we learn from SNIF? 00:31:15.150 --> 00:31:19.230 There's not a lot of gas at Mount St. Helens between eruptions. 00:31:19.230 --> 00:31:22.335 Why? We don't know yet. 00:31:22.335 --> 00:31:27.675 In fact, most of the gases emitted are at levels that are too low to be detected, 00:31:27.675 --> 00:31:32.400 especially as we get further and further away from the 2004-2008 eruption. 00:31:32.400 --> 00:31:38.285 We did have a little blip in background levels in 2017 that went quickly back to normal. 00:31:38.285 --> 00:31:40.540 The cause isn't fully understood. 00:31:40.540 --> 00:31:45.745 The plots on the right side of this image just show calibration information. 00:31:45.745 --> 00:31:48.775 There are gas cylinders at SNIF 00:31:48.775 --> 00:31:53.065 that contain known concentrations of these gases for comparison. 00:31:53.065 --> 00:31:57.200 The cylinders have to be changed out every two years or so. 00:32:00.480 --> 00:32:05.110 I'm going to wrap this up with my favorite suite 00:32:05.110 --> 00:32:09.100 of monitoring tools which are used to detect ground deformation. 00:32:09.100 --> 00:32:12.680 Here's an introduction by my friend DZ. 00:32:13.980 --> 00:32:17.110 One of the things moving magma tends to 00:32:17.110 --> 00:32:19.975 do is it tends to deform the surface of the earth. 00:32:19.975 --> 00:32:24.940 It tends to cause the surface to bulge upward or to spread apart. 00:32:24.940 --> 00:32:28.270 One of the instruments we use to measure deformation is a tiltmeter. 00:32:28.270 --> 00:32:32.980 A tiltmeter measures very subtle changes in the surface of 00:32:32.980 --> 00:32:39.025 the earth as magma accumulates beneath the station or moves upward, for example. 00:32:39.025 --> 00:32:43.705 Another instrument we use is the Global Positioning System or GPS. 00:32:43.705 --> 00:32:45.895 We put several of them out on the volcano, 00:32:45.895 --> 00:32:49.570 we record signals from satellites orbiting above the earth, 00:32:49.570 --> 00:32:53.740 and we look for movement of one of the stations with respect to the other. 00:32:53.740 --> 00:32:55.180 As the ground deforms, 00:32:55.180 --> 00:32:56.635 the volcano changes its shape, 00:32:56.635 --> 00:32:58.540 those stations move, and that 00:32:58.540 --> 00:33:01.970 tells us something about what's going on beneath the surface. 00:33:10.070 --> 00:33:13.799 As things change below the surface of a volcano, 00:33:13.799 --> 00:33:15.875 we may or may not see earthquakes, 00:33:15.875 --> 00:33:18.670 we may or may not see a change in volcanic gases, 00:33:18.670 --> 00:33:22.045 and we may or may not see the ground surface move. 00:33:22.045 --> 00:33:25.270 Usually these movements are so 00:33:25.270 --> 00:33:29.365 small that there are very few ways that we can detect them. 00:33:29.365 --> 00:33:32.815 But if we do detect motion at multiple locations, 00:33:32.815 --> 00:33:37.449 we can actually use the data to create a model for what's happening underground. 00:33:37.449 --> 00:33:40.795 For example, if there's a magma intrusion 00:33:40.795 --> 00:33:44.320 and it causes ground swelling and we have enough stations, 00:33:44.320 --> 00:33:47.200 we can start to figure out the approximate volume 00:33:47.200 --> 00:33:50.900 and the shape and the depth of that intrusion. 00:33:52.170 --> 00:33:57.955 One instance of very dramatic ground deformation that we could see with our eyes, 00:33:57.955 --> 00:34:02.500 was the bulge that grew on the north side of St. Helens in 1980. 00:34:02.500 --> 00:34:04.900 It was identified in March of that year, 00:34:04.900 --> 00:34:08.390 and this was pre-GPS. 00:34:09.390 --> 00:34:13.780 Back then, scientists used instruments where they bounced the laser beams off of 00:34:13.780 --> 00:34:18.085 reflectors that were on the mountain and that's how they could see ground movement. 00:34:18.085 --> 00:34:22.360 They could determine if the reflectors were moving towards them or away from them. 00:34:22.360 --> 00:34:28.675 The obvious over-steepening and swelling of the volcano is really what 00:34:28.675 --> 00:34:31.570 primed it for that catastrophic landslide and 00:34:31.570 --> 00:34:35.035 the lateral blast that destroyed so much of the area. 00:34:35.035 --> 00:34:38.455 But because the hazard was identified in advance, 00:34:38.455 --> 00:34:40.360 the area was at least kept closed to 00:34:40.360 --> 00:34:44.930 the general public despite really high demand for access. 00:34:45.170 --> 00:34:50.520 I'm going to use the term GPS to describe our modern deformation monitoring stations. 00:34:50.520 --> 00:34:52.830 But if you want to impress your friends at dinner parties, 00:34:52.830 --> 00:34:55.320 the correct terminology is now GNSS, 00:34:55.320 --> 00:34:58.550 which stands for Global Navigation Satellite System. 00:34:58.550 --> 00:35:02.335 It includes GPS, which is operated by the United States, 00:35:02.335 --> 00:35:07.340 but it also incorporates satellite systems launched by other countries. 00:35:08.130 --> 00:35:12.010 The funny-looking antenna and tripod are basically 00:35:12.010 --> 00:35:16.090 super advanced versions of the GPS antenna in your cell phone. 00:35:16.090 --> 00:35:21.325 Satellites flying above the earth at 20,000 kilometers altitude, 00:35:21.325 --> 00:35:24.430 at a speed of about 14,000 kilometers an 00:35:24.430 --> 00:35:29.690 hour emit signals that are picked up by our antennas. 00:35:29.790 --> 00:35:33.745 GPS satellites have really accurate clocks, 00:35:33.745 --> 00:35:35.890 so we know what time the signal was sent, 00:35:35.890 --> 00:35:38.665 and then we can see how long the signal takes to reach us 00:35:38.665 --> 00:35:42.500 and determine the distance the signal traveled. 00:35:45.030 --> 00:35:50.050 If you record signals from multiple satellites with known orbits, 00:35:50.050 --> 00:35:53.260 you can start to triangulate your own position. 00:35:53.260 --> 00:35:55.345 Then if you move, 00:35:55.345 --> 00:35:57.820 you'll calculate a new position. 00:35:57.820 --> 00:36:00.025 Your phone does an okay job of this. 00:36:00.025 --> 00:36:02.560 It gets you down to tens of meters of accuracy. 00:36:02.560 --> 00:36:06.655 A little handheld GPS unit will get you a few meters. 00:36:06.655 --> 00:36:08.395 But that's not good enough for us. 00:36:08.395 --> 00:36:13.840 A large magma intrusion can cause the earth's surface to deform less than a centimeter, 00:36:13.840 --> 00:36:17.830 so that's why we need such ridiculous looking antennas. 00:36:17.830 --> 00:36:22.435 Our advanced equipment can deal with issues like effects from the atmosphere. 00:36:22.435 --> 00:36:27.895 Our equipment can filter out phantom GPS signals that bounce off the ground surface. 00:36:27.895 --> 00:36:30.595 The antennas do have to be secured to the ground by 00:36:30.595 --> 00:36:36.040 an extremely stable structure that ideally won't bend too much in the wind or snow, 00:36:36.040 --> 00:36:39.380 or even respond to big temperature changes. 00:36:39.570 --> 00:36:43.810 Picking up these tiny signals is made even more challenging 00:36:43.810 --> 00:36:47.890 because the ground beneath our feet is always moving even if we can't feel it. 00:36:47.890 --> 00:36:51.220 Big earthquakes cause big ground motions. 00:36:51.220 --> 00:36:54.250 Tectonic plates are always shifting and rotating. 00:36:54.250 --> 00:36:58.914 On the left, you see arrows and those are pointing in the direction of movement 00:36:58.914 --> 00:37:03.715 of hundreds of these GPS stations that are installed throughout Washington and Oregon. 00:37:03.715 --> 00:37:07.090 Most of them are operated by UNAVCO and 00:37:07.090 --> 00:37:11.215 the arrows may represent just a few centimeters of movement over many years. 00:37:11.215 --> 00:37:15.370 But you can see that the whole region is shifting and rotating. 00:37:15.370 --> 00:37:18.220 We also have really interesting very deep, 00:37:18.220 --> 00:37:21.430 slow earthquakes that happen in the Pacific Northwest. 00:37:21.430 --> 00:37:23.620 They're too slow to feel, 00:37:23.620 --> 00:37:26.380 but they do cause GPS stations to move. 00:37:26.380 --> 00:37:29.065 This is known as episodic tremor and slip. 00:37:29.065 --> 00:37:32.815 It's not related to our volcanoes directly, 00:37:32.815 --> 00:37:34.360 but we have to be aware of 00:37:34.360 --> 00:37:38.065 all these ground movements so that we can subtract them from our data, 00:37:38.065 --> 00:37:42.710 so that the only movement we see is caused by volcanic processes. 00:37:42.810 --> 00:37:48.265 We did see ground movement during and after the 2004 Mount St. Helens eruption. 00:37:48.265 --> 00:37:49.810 When the eruption began, 00:37:49.810 --> 00:37:53.590 there was a GPS station at Johnston Ridge Observatory to the north. 00:37:53.590 --> 00:37:55.390 When the eruption started, 00:37:55.390 --> 00:37:58.510 the GPS began moving to the south and down, 00:37:58.510 --> 00:38:01.720 so basically toward the volcano. 00:38:01.720 --> 00:38:07.165 This was happening as the eruption drained material from the reservoir underground. 00:38:07.165 --> 00:38:10.040 It's like deflating a balloon. 00:38:10.080 --> 00:38:12.940 Ever since the eruption, 00:38:12.940 --> 00:38:18.160 the domes from the 1980s and early 2000s have been cooling and contracting. 00:38:18.160 --> 00:38:22.765 The station in the bottom figure was located on the 1980s dome. 00:38:22.765 --> 00:38:25.900 Sadly, the station was destroyed by snow a few years ago. 00:38:25.900 --> 00:38:28.720 But it showed a steady trend moving down to 00:38:28.720 --> 00:38:33.040 the east as the domes cooled over the span of decades. 00:38:33.040 --> 00:38:37.240 Another method for seeing the ground move is using tiltmeters. 00:38:37.240 --> 00:38:41.305 They're basically really sensitive bubble levels put in boreholes in the ground, 00:38:41.305 --> 00:38:45.520 and if the ground tilts, the bubble goes off level and we see the signal. 00:38:45.520 --> 00:38:49.465 They're wonderfully sensitive, but they can't handle really big movements. 00:38:49.465 --> 00:38:51.835 They're also very difficult to install. 00:38:51.835 --> 00:38:54.860 We have to drill at least 10 feet underground. 00:38:55.470 --> 00:38:58.720 There were a lot of interesting tiltmeters signals on Mount St. 00:38:58.720 --> 00:39:01.960 Helens during the 2004-2008 eruption. 00:39:01.960 --> 00:39:04.990 During a period of dome growth in the crater, 00:39:04.990 --> 00:39:09.820 there were these pulses of motion that would last a few hours where the surface would 00:39:09.820 --> 00:39:15.880 inflate a tiny amount very quickly and then deflate very gradually. 00:39:15.880 --> 00:39:18.730 The tiltmeters in the crater would move away from 00:39:18.730 --> 00:39:22.460 the eruption vent and then move back closer together. 00:39:23.910 --> 00:39:28.675 Another method that we use for monitoring ground deformation is called InSAR 00:39:28.675 --> 00:39:33.040 or Interferometric Synthetic Aperture Radar. 00:39:33.040 --> 00:39:35.275 Say that 10 times fast. 00:39:35.275 --> 00:39:39.865 Just like the reflection measurements in the 1980s, 00:39:39.865 --> 00:39:43.000 they're satellites transmitting electromagnetic waves that 00:39:43.000 --> 00:39:46.900 measure the signals that are reflected back to them from the ground. 00:39:46.900 --> 00:39:50.710 They do the same thing over and over as they pass over an area, 00:39:50.710 --> 00:39:55.135 and we can compare before and after images to see changes. 00:39:55.135 --> 00:39:59.500 In recent years, satellite imagery is becoming more available than ever. 00:39:59.500 --> 00:40:02.290 It can show us deformation over 00:40:02.290 --> 00:40:06.760 really wide areas and in places where we don't have monitoring stations. 00:40:06.760 --> 00:40:10.420 These satellite methods do have limitations. 00:40:10.420 --> 00:40:15.520 The types of electromagnetic waves they use don't travel well through trees. 00:40:15.520 --> 00:40:17.665 They don't reflect well off snow. 00:40:17.665 --> 00:40:20.920 We have a lot of trees and snow in the Cascades. 00:40:20.920 --> 00:40:24.685 The satellites only pass by about once every two weeks, 00:40:24.685 --> 00:40:27.985 which during an eruption is a very long time to wait. 00:40:27.985 --> 00:40:35.770 The method also isn't as sensitive to tiny movements as our GPS or tilt instruments. 00:40:35.770 --> 00:40:37.720 Let's put this all together. 00:40:37.720 --> 00:40:43.120 A perfect volcanic eruption at a perfectly well-behaved volcano is 00:40:43.120 --> 00:40:45.850 preceded by earthquakes that show us that magma is 00:40:45.850 --> 00:40:49.300 moving and we can track those earthquakes underground. 00:40:49.300 --> 00:40:55.120 We maybe see CO2 gas coming out and 00:40:55.120 --> 00:41:01.420 then H2S and then SO2 and water comes in a predictable way. 00:41:01.420 --> 00:41:04.150 That's rarely the reality. 00:41:04.150 --> 00:41:09.260 Volcanoes are really complex and every system and eruption is unique. 00:41:10.740 --> 00:41:13.510 Because of this inherent complexity, 00:41:13.510 --> 00:41:18.325 we have to use lots of different tools above and beyond what I've discussed here. 00:41:18.325 --> 00:41:20.710 For example, infrasound uses 00:41:20.710 --> 00:41:24.054 special microphones to detect pressure waves in the atmosphere. 00:41:24.054 --> 00:41:29.035 They can be caused by explosions or by big lahars traveling down a drainage. 00:41:29.035 --> 00:41:35.200 Gravity changes tell us if the mass of the earth below us has changed or moved. 00:41:35.200 --> 00:41:40.225 Yes, gravity is different at every point on earth and it can change. 00:41:40.225 --> 00:41:46.090 Monitoring stream temperatures and chemistry can be important diagnostic tools. 00:41:46.090 --> 00:41:50.740 It's also important to track stream levels and sediment loads 00:41:50.740 --> 00:41:55.855 to assess flooding hazards even when there's no volcanic unrest. 00:41:55.855 --> 00:41:58.720 Thermal imagery has been very beneficial during 00:41:58.720 --> 00:42:02.635 Kīlauea's erupted activity since the 1980s in Hawai'i. 00:42:02.635 --> 00:42:05.770 Finally, lightning detection is playing 00:42:05.770 --> 00:42:09.310 an increasingly important role in volcano monitoring. 00:42:09.310 --> 00:42:11.215 Volcanic lightning is real. 00:42:11.215 --> 00:42:14.320 It's hands down the coolest natural phenomenon. 00:42:14.320 --> 00:42:17.030 You can try to argue that if you want. 00:42:17.310 --> 00:42:21.025 Lightning can be detected using sensors that 00:42:21.025 --> 00:42:24.505 are thousands of miles away spread around the globe. 00:42:24.505 --> 00:42:27.595 This can help identify eruptions that are occurring 00:42:27.595 --> 00:42:31.165 at remote volcanoes that don't have any monitoring equipment. 00:42:31.165 --> 00:42:35.150 That has really important implications for air travel. 00:42:35.400 --> 00:42:37.945 Even with all this information, 00:42:37.945 --> 00:42:43.105 we can't predict exactly when or how a volcano will erupt. 00:42:43.105 --> 00:42:45.115 We can track changes carefully. 00:42:45.115 --> 00:42:49.195 We can estimate how likely different events are to occur, 00:42:49.195 --> 00:42:54.070 and we provide the best possible information to officials and the public. 00:42:54.070 --> 00:42:58.180 But typically, a volcano at rest tends to stay at rest. 00:42:58.180 --> 00:43:00.800 Just like me early in the morning. 00:43:00.810 --> 00:43:05.185 It's really important to have multiple tools to monitor volcanoes. 00:43:05.185 --> 00:43:06.940 They all behave differently. 00:43:06.940 --> 00:43:10.510 There are examples of eruptions where the ground deformed, 00:43:10.510 --> 00:43:12.925 but there weren't a ton of earthquakes. 00:43:12.925 --> 00:43:16.300 There are examples where earthquakes increased dramatically, 00:43:16.300 --> 00:43:20.390 but there wasn't a noticeable change in gas before an eruption. 00:43:20.460 --> 00:43:26.740 We use the information provided by geologists to help plan our monitoring networks, 00:43:26.740 --> 00:43:31.000 including the locations of our stations and the types of equipment that we install. 00:43:31.000 --> 00:43:36.400 We recently added seismic and GPS stations higher on the edifice at Mount Hood. 00:43:36.400 --> 00:43:39.670 We're planning on adding MultiGAS there later. 00:43:39.670 --> 00:43:43.750 Our lahar monitoring network at Mount Rainier is ever expanding, 00:43:43.750 --> 00:43:47.875 and we're adding improved lahar detection capabilities at Mount St. Helens. 00:43:47.875 --> 00:43:51.760 We'll also be installing a scanning DOAS gas instrument 00:43:51.760 --> 00:43:53.215 at Mount St. Helens this summer, 00:43:53.215 --> 00:43:57.020 and we're working to add stations around Glacier Peak. 00:43:59.220 --> 00:44:02.500 What is our most important monitoring tool? 00:44:02.500 --> 00:44:05.695 I would argue that our most important tool is our eyes. 00:44:05.695 --> 00:44:09.040 What we see helps us identify how volcanoes behaved in 00:44:09.040 --> 00:44:12.850 the past and what hazards they may present in the future. 00:44:12.850 --> 00:44:17.320 Geologists see the deposits from past eruptions and from lahars. 00:44:17.320 --> 00:44:19.450 People like the park ranger on the left here, 00:44:19.450 --> 00:44:22.430 have witnessed small debris flows at Mount Rainier. 00:44:22.430 --> 00:44:25.650 The eyewitness accounts and photos from the Mount St. 00:44:25.650 --> 00:44:28.620 Helens 1980 eruption helped document 00:44:28.620 --> 00:44:31.215 a landslide and lateral eruption that were 00:44:31.215 --> 00:44:35.350 completely unheard of in the world of volcano science. 00:44:35.610 --> 00:44:39.550 On that note, one technology that's really 00:44:39.550 --> 00:44:43.630 expanded our abilities in recent years is unmanned aerial systems. 00:44:43.630 --> 00:44:47.350 A small group of amazing people worked for many years to 00:44:47.350 --> 00:44:51.850 add UAS capabilities to our toolbox. 00:44:51.850 --> 00:44:55.570 The program was scaled really rapidly during 00:44:55.570 --> 00:45:01.434 the Kīlauea 2018 eruption response and that eruption had everything; 00:45:01.434 --> 00:45:04.645 earthquakes, ground deformation, gas emissions. 00:45:04.645 --> 00:45:10.645 But it was also an exciting opportunity to explore and test new monitoring techniques. 00:45:10.645 --> 00:45:15.010 None of the techniques really capture the impressive nature of an eruption, 00:45:15.010 --> 00:45:17.050 quite like the photos and videos. 00:45:17.050 --> 00:45:21.804 So please enjoy some of this drone footage from the 2018 response. 00:45:21.804 --> 00:45:23.920 Thank you so much for your time and attention and 00:45:23.920 --> 00:45:27.020 I would be happy to answer any questions.