Harold Tobin
@haroldtobin.bsky.social
UW prof and director of the Pacific Northwest Seismic Network. WA State Seismologist. All about subduction zones and very messed up rocks.
Tsunami evacuation systems in Kochi City and Kure town, Shikoku Island. The 1946 Nankai Trough earthquake and tsunami swept ashore here, flooding all these areas - only the most recent of many over the past ~1300 years. The vertical evac towers are really impressive.
September 28, 2025 at 7:13 PM
Tsunami evacuation systems in Kochi City and Kure town, Shikoku Island. The 1946 Nankai Trough earthquake and tsunami swept ashore here, flooding all these areas - only the most recent of many over the past ~1300 years. The vertical evac towers are really impressive.
Yokonami melange, a paleo-megathrust, and so, so much chert, near Kure, Shikoku Island, Japan
September 28, 2025 at 7:01 PM
Yokonami melange, a paleo-megathrust, and so, so much chert, near Kure, Shikoku Island, Japan
We spent 15 days up there, and saw no sign of other people. Pretty amazing, when we were in the heart of a well-known national park and less than 70 miles from UW campus! But a hard place to get to: we needed helicopter support to do this work.
September 12, 2025 at 5:30 AM
We spent 15 days up there, and saw no sign of other people. Pretty amazing, when we were in the heart of a well-known national park and less than 70 miles from UW campus! But a hard place to get to: we needed helicopter support to do this work.
We recently spent 2 weeks doing field work in a remote part of Olympic National Park, studying what we think is another part of the 'fossil' subduction plate boundary fault: a paleo-megathrust. The terrain was rugged and challenging, and the rocks were rewarding. Here's a taste. ⚒️
September 12, 2025 at 5:30 AM
We recently spent 2 weeks doing field work in a remote part of Olympic National Park, studying what we think is another part of the 'fossil' subduction plate boundary fault: a paleo-megathrust. The terrain was rugged and challenging, and the rocks were rewarding. Here's a taste. ⚒️
They then could hand off that open ocean tsunami model to coastal inundation models that were pre-computed. Here are some examples from Haleiwa, HI and Crescent City, CA. Looks like they did very well with both timing and amplitude! (5/6)
August 2, 2025 at 5:15 PM
They then could hand off that open ocean tsunami model to coastal inundation models that were pre-computed. Here are some examples from Haleiwa, HI and Crescent City, CA. Looks like they did very well with both timing and amplitude! (5/6)
AS the tsunami passed other DART buoys, they could calibrate and verify the model. This image shows comparison of the model and the observed waves at various DART sites, showing great agreement. (4/6)
August 2, 2025 at 5:15 PM
AS the tsunami passed other DART buoys, they could calibrate and verify the model. This image shows comparison of the model and the observed waves at various DART sites, showing great agreement. (4/6)
Here is their model result for the open-ocean height of the wave (NOT the height at coastlines in shallow water) and how it varied across the Pacific. These were produced well BEFORE the tsunami reached Hawaii. (3/6)
August 2, 2025 at 5:15 PM
Here is their model result for the open-ocean height of the wave (NOT the height at coastlines in shallow water) and how it varied across the Pacific. These were produced well BEFORE the tsunami reached Hawaii. (3/6)
I am glad @evanbush.bsky.social used this quote in this excellent @nbcnews.com story. This is a key message I really wanted to get across in interviews today. Article here: www.nbcnews.com/science/scie...
July 31, 2025 at 3:02 AM
I am glad @evanbush.bsky.social used this quote in this excellent @nbcnews.com story. This is a key message I really wanted to get across in interviews today. Article here: www.nbcnews.com/science/scie...
Wednesday evening, tsunami waves are still sloshing around at Port Angeles, WA ... 18+ hours after they first arrived. Source: @noaa.gov tide gauge website. ⚒️
July 31, 2025 at 2:58 AM
Wednesday evening, tsunami waves are still sloshing around at Port Angeles, WA ... 18+ hours after they first arrived. Source: @noaa.gov tide gauge website. ⚒️
Today's M8.8 (orange circle) and the 1952 M9.0 epicentral locations, separated by only 73 years. I wouldn't have thought that possible! Average recurrence intervals don't tell the full story. ⚒️
July 30, 2025 at 4:35 AM
Today's M8.8 (orange circle) and the 1952 M9.0 epicentral locations, separated by only 73 years. I wouldn't have thought that possible! Average recurrence intervals don't tell the full story. ⚒️
Good news, I guess, but the fact that this is a real story about the government of the United States of America is absolutely bonkers.
June 28, 2025 at 1:51 PM
Good news, I guess, but the fact that this is a real story about the government of the United States of America is absolutely bonkers.
Other work by our group published in Ledeczi et al. (also in @weareseismica.bsky.social ) shows that other, more distal splay faults in the outer wedge are likely to slip with the megathrust instead. Taken together, this means the most likely sources of tsunamigenic slip may need reexamination. 4/4
May 23, 2025 at 8:58 PM
Other work by our group published in Ledeczi et al. (also in @weareseismica.bsky.social ) shows that other, more distal splay faults in the outer wedge are likely to slip with the megathrust instead. Taken together, this means the most likely sources of tsunamigenic slip may need reexamination. 4/4
Here's an interesting fact about Mt. St. Helens: Most of the bulk of the mountain itself was formed in just the last 3000 years – including pretty much all of what was blown away in 1980. The entire volcanic system is only ~275,000 years old. Volcanoes are ephemeral, geologically-speaking. ⚒️
May 19, 2025 at 6:09 AM
Here's an interesting fact about Mt. St. Helens: Most of the bulk of the mountain itself was formed in just the last 3000 years – including pretty much all of what was blown away in 1980. The entire volcanic system is only ~275,000 years old. Volcanoes are ephemeral, geologically-speaking. ⚒️
Today is the anniversary of the Pacific Northwest's worst modern earthquake, the April 13th, 1949 mag 6.7 near Olympia. 8 people died, many were injured, and millions of $$ (in 1940's money) in damage. It was a "slab event" in the subducted plate at ~50 km depth.
April 13, 2025 at 9:29 PM
Today is the anniversary of the Pacific Northwest's worst modern earthquake, the April 13th, 1949 mag 6.7 near Olympia. 8 people died, many were injured, and millions of $$ (in 1940's money) in damage. It was a "slab event" in the subducted plate at ~50 km depth.
In Washington, a Sunday morning wake-up for some in the form of a magnitude 3.7 shallow earthquake at 8:15 am this morning in a fairly remote area between hwy 410 and I-90, east of Enumclaw. [http://www.pnsn.org/event/62080827]
Did You Feel It?: Report it here zpr.io/FxUDGTpFBuQR ⚒️
Did You Feel It?: Report it here zpr.io/FxUDGTpFBuQR ⚒️
April 6, 2025 at 4:37 PM
In Washington, a Sunday morning wake-up for some in the form of a magnitude 3.7 shallow earthquake at 8:15 am this morning in a fairly remote area between hwy 410 and I-90, east of Enumclaw. [http://www.pnsn.org/event/62080827]
Did You Feel It?: Report it here zpr.io/FxUDGTpFBuQR ⚒️
Did You Feel It?: Report it here zpr.io/FxUDGTpFBuQR ⚒️
Flew from Fairbanks to Seattle today.
March 9, 2025 at 7:24 AM
Flew from Fairbanks to Seattle today.
Today marks exactly 20 years since the 2004 magnitude 9.1 great Sumatra earthquake and tsunami, one of the worst disasters of all time. It was the planet's first M9 quake in over 40 years. More than 225,000 lost their lives across 14 different nations, an unprecedented transnational disaster.
December 26, 2024 at 7:50 AM
Today marks exactly 20 years since the 2004 magnitude 9.1 great Sumatra earthquake and tsunami, one of the worst disasters of all time. It was the planet's first M9 quake in over 40 years. More than 225,000 lost their lives across 14 different nations, an unprecedented transnational disaster.
Went to see if our Nankai Trough subduction drilling project was still on display at the Smithsonian Natural History Museum, and it is! Blink and you’ll miss me, but I do enjoy the caption.⚒️
December 14, 2024 at 8:02 PM
Went to see if our Nankai Trough subduction drilling project was still on display at the Smithsonian Natural History Museum, and it is! Blink and you’ll miss me, but I do enjoy the caption.⚒️
I’m very partial to this one.
December 3, 2024 at 5:04 AM
I’m very partial to this one.
Nothing like a relaxed Saturday afternoon in Seattle’s Discovery Park (today has even more gorgeous sunny weather, but I didn’t go anywhere quite as scenic). Olympics looking good with plenty of new snow.
December 1, 2024 at 10:09 PM
Nothing like a relaxed Saturday afternoon in Seattle’s Discovery Park (today has even more gorgeous sunny weather, but I didn’t go anywhere quite as scenic). Olympics looking good with plenty of new snow.
Field work Friday: Here's where I wish I was, contemplating the guts of the Cascadia subduction zone in our field area high up in Olympic National Park. Photo from August 2023. We plan to return next summer! ⚒️
November 23, 2024 at 1:22 AM
Field work Friday: Here's where I wish I was, contemplating the guts of the Cascadia subduction zone in our field area high up in Olympic National Park. Photo from August 2023. We plan to return next summer! ⚒️
It's great to see so many new bluesky folks showing up - scientists, journalists, organizations, and many other great people. I am hoping to be able to drop the other site completely one day soon...
November 15, 2024 at 11:39 PM
It's great to see so many new bluesky folks showing up - scientists, journalists, organizations, and many other great people. I am hoping to be able to drop the other site completely one day soon...
Geology and setting both get 11/10
November 13, 2024 at 5:17 PM
Geology and setting both get 11/10