This is the monthly volcano report for October 2019. If you already know what this usual intro says, please click the title of this post or “read more” to continue. The reported earthquake counts are taken directly from the U.S.G.S. and are only earthquakes reported, not earthquakes recorded. Regarding earthquake counts, it is likely that the reported earthquake total for a given location and time period, mostly during earthquake swarms, is lower than the actual count of earthquakes, in certain cases sometimes drastically lower. Remember, most earthquake swarms at volcanoes do not lead to eruptions. However, almost every eruption is preceded by some type of earthquake swarming and surface deformation. Therefore, swarms and deformation should always be monitored closely regardless of where you think the activity is headed.
The volcanoes I will be doing monthly updates on are Yellowstone Caldera in Wyoming, Long Valley Caldera in California, Newberry Caldera and Mt. Hood in Oregon, Mt. Rainier and Mt. St. Helens in Washington state, and Mt. Shasta and Lassen Peak in California. In this update, we will look at reported seismicity counts. If you wish to see recent deformation for Yellowstone or Long Valley, please head to the “Deformation Updates” page which is updated every 2 months or so.
The time period of the reported seismicity counts for this update, derived from the USGS earthquake catalog, is from 00:00UTC October 1, 2019 through 23:59UTC October 31, 2019 and magnitudes are always going to be -1.0 and above so you will see every single earthquake that was reported for this time period. The smallest earthquake ever recorded was a M-1.0 and the largest earthquake ever recorded was a M9.5. Also, the coordinate box I use for each volcano is exactly the same every month, so you always see the activity that occurred in the same area every month. Regarding the 3-plot seismic images I generate for the largest events, I will always try my best to use the closest seismic station to any given event. I will also add the link to the USGS EQ map showing the locations of reported seismicity for the location and time period in question.
Volcanoes of interest this month are Yellowstone and Mt. Rainier. However, this is one of the calmest months I have seen for a while for volcanoes here in the United States, especially for the Cascade Range volcanoes.
During the month of October 2019, Yellowstone Caldera experienced 195 reported earthquake events. This number is higher than the previous month's total of 72 reported earthquakes. October's total is likely smaller than the actual count of earthquakes especially since the October 26-28 earthquake swarm NW of the Norris Geyser Basin near Holmes Hill.
As seen below, there was an energetic swarm on those dates. It was a rapid-fire swarm and could be indicative of hydrothermal fluid migration which does happen from time to time since Yellowstone has an extremely immense hydrothermal-magmatic system.
86 events were reported for this swarm so almost half of this month's total was due to the October 26-28 swarm. Other than this swarm, this was a typical month for Yellowstone Caldera.
The largest earthquake to strike Yellowstone National Park within the month of October 2019 was a M2.9 event at 8.3km in depth on Oct. 16, 2019 at 17:08UTC. It struck just a few miles to the NNE of Canyon Junction, to the NE of Norris. The plots shown below are of this event:
Steamboat Geyser, the largest active geyser in the world located within the Norris Geyser Basin, erupted a total of 5 times during October 2019. Steamboat Geyser remains active and appears to still be erupting on a near-weekly schedule. The video below is the stream of the last eruption of 2019 which was the 42nd eruption of 2019 (the 74th eruption since the early-2018 reactivation).
Long Valley Caldera
Long Valley Caldera saw a total of 604 reported earthquake events for October 2019. This is much lower than the high total of 1,115 earthquakes in September. September saw a fairly intense period of seismicity that occurred in multiple episodes during the whole month. This can be seen in my blog post about that seismicity if you click HERE.
October's seismicity was concentrated around the epicenter of the September swarming, south of the caldera rim, and to the SE near Bishop, CA.
The largest event of the month was a M3.3 at 8.2km in depth on Oct. 26, 2019 at 19:39UTC. It struck SE of the caldera near Bishop, CA and 42 people submitted a report to USGS that they felt this event. Plots below are of this event:
The largest event to strike within the caldera itself was a M2.6 at 5.3km in depth on Oct. 9, 2019 at 07:57UTC. It struck near the epicenter of the September swarming and USGS received 2 felt reports for this event. Plots below are of this earthquake:
Newberry Caldera in Oregon saw no reported events of any magnitude. Check back next month.
Mt. Rainier experienced 24 reported earthquake events for the month of October 2019. This is just barely lower than last month's total of 27 earthquakes. However, 11 of the reported events for October occurred during a small swarm on October 29 which struck directly under the volcano edifice.
The largest event for October was a M2.1 at 0.9km in depth on October 29, 2019 at 08:57UTC. It struck directly under the volcano as part of the minor October 29 swarm. Plots below are of this event:
Mt. St. Helens
Just FYI, I visited Mt. St. Helens 3 times recently and the past 2 times I visited the dome was steaming. It was a pretty cool sight, so please CLICK HERE to see a video of Mt. St. Helens slightly steaming on Sept. 12, 2019.
Mt. St. Helens saw a total of 18 reported earthquake events for October 2019. This is lower than last month's total of 25 earthquakes. The largest event for October was a M0.7 at 0.3km in depth on October 25, 2019 at 11:15UTC. It struck directly beneath the volcano edifice. Plots below are of this event:
Mt. Hood in Oregon surprisingly saw 0 reported earthquake events for October 2019. Mt. Hood has been extremely quiet following the intense July 2019 earthquake swarm. CLICK HERE for information on that swarm.
Mt. Shasta in California surprisingly saw 0 reported earthquake events. Shasta has been suspiciously quiet after the September 2019 earthquake swarm. It was likely the largest swarm at Mt. Shasta in decades. CLICK HERE for information about that swarm.
Lassen Volcanic Center
Lassen Volcanic Center experienced 19 reported earthquake events for the month of October 2019. This is higher than last month's total of 10 reported earthquakes. The largest event was a M1.4 at 3.2km in depth on Oct. 23, 2019 at 04:47UTC. It struck under Lassen and the plots below are of this event:
I used to create monthly volcano updates as videos for my YouTube channel and my website. However, that took far too much time and I have had to discontinue those updates. That being said, I will now do monthly volcano updates via this blog here. I will try to get them out as soon as possible. However, if I am very busy, they may be as much as 1-2 weeks late.