Patrick Lynett

Another huge landslide and tsunami in coastal Alaska yesterday morning. Still a bit of a puzzle, but working with the @AKearthquake source location, the timing of waves from eyewitnesses on Harvest Island and in Endicott Arm, and the @NOAA Juneau tide gage recording, it appears that a massive slide occurred ~5 km east of the end of Tracy Arm. With this info guiding simulations, a plausible/likely scenario (there are others!) is that the slide ran down Sawyer Glacier, impacted into the water at the end of Tracy Arm, and displaced somewhere between 100-200 million cubic meters of water. A simulation with this info matches eyewitness tsunami observations and the tide gauge, shown below. Animation here as well. If this source pans out (the slide location is still uncertain – need satellite imagery to confirm), there were likely *very* large waves within ~5 km of the slide-water impact location at the end of Tracy Arm.

@AKearthquake Tsunami signal on the Juneau tide gage. Likely a large wave at generation...

We received reports this morning from the Endicott Arm area of Southeast Alaska of a local tsunami that rolled through the area just after 5:30 AM. Seismic signals large enough to be seen widely across southern Alaska confirm a significant landslide in the region at about same time. We are working with other agencies and colleagues to understand the full sequence of events, but at this point, all evidence suggests that this set of 1-foot high waves was set in motion by a landslide of several tens of millions of cubic meters of rock striking the water. We are working to confirm the exact location. Learn more about our landslide monitoring efforts here: earthquake.alaska.edu/what-it-takes-…

Happened to be in Corvallis for a meeting, decided to drive down to Crescent City to document the tsunami in the harbor. Made it there just before midnight last night and stayed into the morning. Many surges like that shown in the video below, which was taken a bit before 7 AM.

Hey @tsunamichile, @igna_sepulveda - have you looked into this source at all? It’s a curious one. From our quick modeling, looks like there needs to be ~ 5 km patch of ~2 m of subsidence right offshore of Esmeraldas, in order to get a 1 m amp negative wave with half-period of about 5 minutes, arriving 1 minute after the earthquake. There is no plausible landslide source I can come up with to match these observational constraints.

Local Tsunami (very likely) Triggered by Delta Failure During the Mw 6.3 2025 Esmeraldas (Ecuador) Earthquake con @igna_sepulveda

@PavewayIV @patton_cascadia behavior. In years when large waves pummel beaches repeatedly, there is little recovery, just repeated erosion of eroded beaches. In severe years, dune systems can be nearly erased, and recovery of a dune system can take a very long time (years).

@PavewayIV @patton_cascadia Not unless you can figure out a way to turn corn into sand! Beaches are very dynamic, especially during the stormy (winter) season. Beaches erode during the winter and accrete (recover) during the rest of the year, in terms of average behavior. Erosion is a much faster...

Spent the past couple days surveying beach impacts in socal from last weeks swells. Lots of erosion, with the beaches near Ventura Harbor hit the worst. Some dune erosion and 2+ m scarps. Hopefully some breaks in waves to give time to recover. #cawx #waves

@CatalanPato @Mo_Heidarzadeh Well, I would say mostly yes. The shoreline is fairly straight, at least relative to the length of the 15 min wave. But maybe I need to do a real analysis here…

@Mo_Heidarzadeh @lynett_patrick Is it really that open (the shelf that is)?

busy few days... For the wave nerds, check out the tide gage in Santa Barbara Harbor last Thurs afternoon during the first swell. 1+m crest-to-trough harbor sloshing at low tide. Similar wave height as the Hunga Tonga tsunami of 2022. Likely the... #cawx #waves #SantaBarbara

@Mo_Heidarzadeh @CatalanPato Well, to first guess, the grave mode period would be 4*L / sqrt(g*h), which for a average depth of 3m , gives a mode of ~5 min, no? The interesting part is why does the open shelf seem to resonate so strongly at 15 minutes, but the harbor not at five.

@lynett_patrick @CatalanPato Yes, a max fundamental period of a 400-m harbour would be 30 seconds or less

@CatalanPato There was no weather to speak of that day, so the mode very likely was excited through IG. Kind of amazing

@lynett_patrick Did the incoming swell had some IG content (bound?) that matched the harbor fundamental? Or what other down shifting process is at play? (Do I qualify as a wave nerd?)

... very long period (and large height) swell matched a resonant period of the harbor at low tide, and the ringing was strong.

Significant tsunami waves appear to be incoming (peak to peak waveheight of 1.5 m) at Toyama sea level station due to M7.5 earthquake near west coast of Japan

#HermosaBeach 83'. One of the reasons the City now builds a winter berm in front of the plaza.

@Mo_Heidarzadeh Yes, for sure. This is the classic setup for wave driven coastal flooding here. King tides this time of year, and now is when the large W/NW swells and storms come. Heads up for our Sat morning (in about 18 hours) - looks like a slightly bigger swell for socal at high tide.

@lynett_patrick Hi @lynett_patrick, thanks for adding this local observation- looking at the tide cycle, it appears the high waves came just at the high spring tide - unlucky combination!

This sudden flooding in Southern #California yesterday most likely was a #meteo_tsunami. It is important to note that #Ventura has already experienced a few #meteo_tsunamis in the past #Tsunami #USA

To celebrate #TsunamiDay, visitors at @UN headquarters in NY experienced a unique 3-min virtual reality tsunami drill to learn vital information on how to stay safe during a tsunami. 👉 ow.ly/Rn8350Q5ojR #GetToHighGround

Join us at the @UN General Assembly building today in New York for a unique experience! Learn about tsunami preparedness with a 3-min virtual reality drill. Learn crucial safety measures! @MofaJapan_en @JapanMissionUN #TsunamiDay