WEBVTT 1 00:00:00.773 --> 00:00:03.356 (upbeat music) 2 00:00:05.330 --> 00:00:06.860 line:15% Hi everyone, I'm Mike Poland, 3 00:00:06.860 --> 00:00:09.270 line:15% scientist-in-charge of the Yellowstone Volcano Observatory. 4 00:00:09.270 --> 00:00:12.480 This is the monthly update for October 1st of 2020. 5 00:00:12.480 --> 00:00:13.760 Now, Yellowstone was in the news 6 00:00:13.760 --> 00:00:14.670 during the month of September. 7 00:00:14.670 --> 00:00:16.580 You may have heard there was an earthquake swarm, 8 00:00:16.580 --> 00:00:17.890 centered really around September 10th. 9 00:00:17.890 --> 00:00:20.070 It actually lingered into September 16th. 10 00:00:20.070 --> 00:00:22.740 And before we get into talking about what happened overall 11 00:00:22.740 --> 00:00:25.120 during the month, I wanted to talk about this swarm. 12 00:00:25.120 --> 00:00:27.890 It was a nice little swarm located just south of West Thumb, 13 00:00:27.890 --> 00:00:30.810 south of Yellowstone Lake and North of Mount Sheridan. 14 00:00:30.810 --> 00:00:32.550 Most of it occurred on September 10th. 15 00:00:32.550 --> 00:00:35.406 There were 90 odd earthquakes that occurred that day, 16 00:00:35.406 --> 00:00:37.810 but it lingered on into September 16th. 17 00:00:37.810 --> 00:00:40.490 And overall there were about 125 earthquakes 18 00:00:40.490 --> 00:00:42.270 that occurred in that swarm. 19 00:00:42.270 --> 00:00:43.400 Now that may sound like a lot, 20 00:00:43.400 --> 00:00:45.810 but that's actually par for the course for Yellowstone, 21 00:00:45.810 --> 00:00:47.380 kind of background activity. 22 00:00:47.380 --> 00:00:50.110 Yellowstone has lots and lots of seismic swarms. 23 00:00:50.110 --> 00:00:53.700 There are about 1,5000 to 2,500 earthquakes 24 00:00:53.700 --> 00:00:55.100 every year in Yellowstone. 25 00:00:55.100 --> 00:00:57.970 And about half of these occur as seismic swarms. 26 00:00:57.970 --> 00:00:59.620 This seismicity is related to the fact 27 00:00:59.620 --> 00:01:02.580 that there's faults all over the place in Yellowstone. 28 00:01:02.580 --> 00:01:05.420 This particular swarm here occurred at the intersection 29 00:01:05.420 --> 00:01:08.660 between the caldera, Yellowstone Caldera's bounding faults 30 00:01:08.660 --> 00:01:11.020 and the Mount Sheridan fault zone. 31 00:01:11.020 --> 00:01:12.010 So all of these faults, 32 00:01:12.010 --> 00:01:13.910 plus all of that water moving around the surface, 33 00:01:13.910 --> 00:01:15.840 and the fact that the area is weak overall 34 00:01:15.840 --> 00:01:17.057 because of all the earthquake activity 35 00:01:17.057 --> 00:01:19.280 and magmatic activity over time, 36 00:01:19.280 --> 00:01:21.160 means that earthquake swarms are really common. 37 00:01:21.160 --> 00:01:24.430 These swarms are clusters of earthquakes in time and space. 38 00:01:24.430 --> 00:01:26.470 So rapid-fire sequences of earthquakes, 39 00:01:26.470 --> 00:01:27.930 basically in the same general area. 40 00:01:27.930 --> 00:01:30.010 So they get a lot of notoriety when they happen, 41 00:01:30.010 --> 00:01:32.120 but they happen all the time in Yellowstone. 42 00:01:32.120 --> 00:01:34.150 And really, that's sort of what Yellowstone does. 43 00:01:34.150 --> 00:01:38.040 In fact, in 2017, there was a three month long swarm 44 00:01:38.040 --> 00:01:40.820 that included 2,400 earthquakes. 45 00:01:40.820 --> 00:01:43.270 And one day had 300 of them, 46 00:01:43.270 --> 00:01:46.040 the maximum of which was a magnitude 4.4. 47 00:01:46.040 --> 00:01:47.270 The maximum of this swarm 48 00:01:47.270 --> 00:01:49.670 on September 10th was a magnitude 2.8. 49 00:01:49.670 --> 00:01:51.480 So this is sort of what Yellowstone does. 50 00:01:51.480 --> 00:01:52.660 And these kinds of swarms 51 00:01:52.660 --> 00:01:54.820 happen all the time in Yellowstone. 52 00:01:54.820 --> 00:01:56.580 Okay, let's dive in and talk about 53 00:01:56.580 --> 00:01:58.450 what happened during the month of September. 54 00:01:58.450 --> 00:02:00.480 The University of Utah Seismograph Station, 55 00:02:00.480 --> 00:02:02.640 which is responsible for the operation and maintenance 56 00:02:02.640 --> 00:02:04.340 of the Yellowstone Seismic Network, 57 00:02:04.340 --> 00:02:07.070 recorded 205 earthquakes in the Yellowstone area 58 00:02:07.070 --> 00:02:08.910 during the month of September. 59 00:02:08.910 --> 00:02:11.060 Most of the earthquakes were distributed through the region, 60 00:02:11.060 --> 00:02:12.940 except for that swarm that we just talked about, 61 00:02:12.940 --> 00:02:15.860 of 125 events south of West Thumb 62 00:02:15.860 --> 00:02:17.410 between September 10th and the 16th, 63 00:02:17.410 --> 00:02:18.530 and over 90 of these events 64 00:02:18.530 --> 00:02:20.380 occurred on September 10th alone, 65 00:02:20.380 --> 00:02:23.220 including the largest, a magnitude 2.8. 66 00:02:23.220 --> 00:02:25.290 But this sort of seismicity is very typical 67 00:02:25.290 --> 00:02:26.300 for the Yellowstone region. 68 00:02:26.300 --> 00:02:29.390 So seismicity remains at background levels. 69 00:02:29.390 --> 00:02:31.280 We've seen continued deformation patterns, 70 00:02:31.280 --> 00:02:34.060 that's ground motion patterns, over the past several years 71 00:02:34.060 --> 00:02:36.270 with very little change in the caldera. 72 00:02:36.270 --> 00:02:38.890 This is GPS data vertical deformation 73 00:02:38.890 --> 00:02:40.990 from the White Lake GPS station, 74 00:02:40.990 --> 00:02:42.670 which is on the east side of the caldera, 75 00:02:42.670 --> 00:02:44.620 the Sour Creek Resurgent Dome. 76 00:02:44.620 --> 00:02:46.980 Each one of these points, each one of these circles 77 00:02:46.980 --> 00:02:48.820 is a single day's worth of data. 78 00:02:48.820 --> 00:02:51.100 And this plot spans the last two years. 79 00:02:51.100 --> 00:02:53.210 Downward trends indicates subsidence, 80 00:02:53.210 --> 00:02:55.230 and upward indicates uplift. 81 00:02:55.230 --> 00:02:56.310 So the overall trend 82 00:02:56.310 --> 00:02:57.980 during this two year period is subsidence. 83 00:02:57.980 --> 00:02:59.570 And this dates back to 2015. 84 00:02:59.570 --> 00:03:02.410 Subsidence occurring of a couple of centimeters per year. 85 00:03:02.410 --> 00:03:04.540 That's about an inch per year or so. 86 00:03:04.540 --> 00:03:06.630 And there are small little seasonal changes 87 00:03:06.630 --> 00:03:08.810 that you can see here that happen during the summers. 88 00:03:08.810 --> 00:03:10.890 But overall, that subsidence pattern 89 00:03:10.890 --> 00:03:12.623 has been ongoing since 2015. 90 00:03:13.560 --> 00:03:15.840 The same is true on the western side of the caldera, 91 00:03:15.840 --> 00:03:18.150 where a GPS station near Old Faithful 92 00:03:18.150 --> 00:03:20.690 shows the same pattern, this gradual subsidence 93 00:03:20.690 --> 00:03:22.810 with little seasonal changes here and there, 94 00:03:22.810 --> 00:03:24.920 but gradual substance of a couple of centimeters, 95 00:03:24.920 --> 00:03:26.872 about an inch or so per year. 96 00:03:26.872 --> 00:03:29.480 At Norris, in the Norris Geyser Basin area, 97 00:03:29.480 --> 00:03:31.510 we haven't seen much in the way of deformation 98 00:03:31.510 --> 00:03:33.220 over the past couple of years. 99 00:03:33.220 --> 00:03:38.150 So we have mostly flat from late 2018 to late 2019, 100 00:03:38.150 --> 00:03:39.130 a small subsidence, 101 00:03:39.130 --> 00:03:41.520 and then mostly flat again since early 2020. 102 00:03:41.520 --> 00:03:44.570 So really at Norris, there certainly hasn't been any change 103 00:03:44.570 --> 00:03:46.950 since the beginning of this year. 104 00:03:46.950 --> 00:03:48.640 And finally, turning to Geyser activity. 105 00:03:48.640 --> 00:03:51.250 We had four eruptions of Steamboat Geyser. 106 00:03:51.250 --> 00:03:53.440 This is a plot of the water temperature 107 00:03:53.440 --> 00:03:55.790 for the outflow channel of the geyser. 108 00:03:55.790 --> 00:03:59.240 Anytime you see a spike, that's a major geyser eruption. 109 00:03:59.240 --> 00:04:01.870 These normal oscillations are air temperature, 110 00:04:01.870 --> 00:04:04.050 meaning that there's no water in the channel. 111 00:04:04.050 --> 00:04:06.390 And this sort of jagged lines 112 00:04:06.390 --> 00:04:09.990 are small, minor eruptions of the Geyser. 113 00:04:09.990 --> 00:04:14.261 So each major eruption is preceded by minor activity. 114 00:04:14.261 --> 00:04:16.210 And we had major eruptions on September 1st, 115 00:04:16.210 --> 00:04:18.670 September 9th, September 16th, 116 00:04:18.670 --> 00:04:21.890 and the fourth of the month here on September 26th. 117 00:04:21.890 --> 00:04:23.970 line:15% And of course, we did have Giantess Geyser, 118 00:04:23.970 --> 00:04:25.770 line:15% which erupted for the first time in six years, 119 00:04:25.770 --> 00:04:29.150 line:15% in August erupted again on September 10th. 120 00:04:29.150 --> 00:04:31.170 line:15% So geyser activity in Yellowstone, 121 00:04:31.170 --> 00:04:33.720 line:15% as usual, remain spectacular. 122 00:04:33.720 --> 00:04:34.553 Well that does it for 123 00:04:34.553 --> 00:04:37.030 the Yellowstone Volcano Observatory monthly update. 124 00:04:37.030 --> 00:04:38.340 Remember, if you have any questions 125 00:04:38.340 --> 00:04:40.920 line:15% you can always email us at yvowebteam, 126 00:04:40.920 --> 00:04:43.690 line:15% that's all one word, @usgs.gov. 127 00:04:43.690 --> 00:04:45.310 line:15% Take care, stay healthy, stay safe, 128 00:04:45.310 --> 00:04:47.747 line:15% and we'll see you next month, bye bye. 129 00:04:47.747 --> 00:04:50.330 (upbeat music)