Lucy Jones

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(2 of 2) 3. The shallow depth suggests it is at the top part of the subduction zone that moved in the 2011 M9 3/11 disaster. By our standard definitions, this would be classified as aftershocks of 2011.

1. Earthquakes occur in sequences, so this is one sequence that happens to have a lot of both foreshocks and aftershocks. 2. The focal mechanism shows a thrust fault, suggesting this is on the subduction interface. ... (1 of 2)

Lucy Jones: Seismology, ShakeOuts, and String Quartets | Making Los Angeles What do Chinese literature, medieval string instruments, and earthquake drills have in common? In Los Angeles, the answer is Lucy Jones. Often called “L.A.’s earthquake queen” — a nickname she’s not e...

This was a fun interview. It ended up being quite a retrospective on how seismology has changed over the 4 decades I have been in Pasadena. making-l-a.simplecast.com/episodes/luc...

Only the Rialto events are aftershocks to the July 31 M4.3. The Lytle Creek events are near the San Andreas but not necessarily on it. We often see small events around the San Andreas but some analyses suggest they are on small faults not the main surface that will move in the big quakes.

In the last 24 hours, we have seen several M3s in 3 locations. The events near Ontario are at the western end of the Fontana trend. The Lytle Creek events are near the San Andreas & the Rialto events are where the Fontana trend intersects the San Andreas. Last week's M4.3 was at the Rialto location

The New York - Philadelphia - Wilmington urban corridor has felt small earthquakes roughly every 2-3 years. Moderately damaging earthquakes strike somewhere in the urban corridor roughly twice a century. So infrequent but not weird

On the M4.3 on the Fontana trend

Looks like a small swarm in the Fontana trend. This M4.2 had a few foreshcoks including a M3.0. The Fontana trend is a NE-striking lineation of earthquakes under the sediments of the San Bernardino Vslley. We believe it is one of the left-lateral striking faults that are south of the San Gabriels.

I’m seeing lots of questions about whether the rate of great earthquakes is changing or whether climate change affects earthquakes. The answer is no. The long term rate of these big events is about 1/decade. But the distribution is random. The last one was 2011 in Japan

The 7/29/2025 M8.8 looks like a repeat of an earthquake in 1952

In addition to many M7+ earthquakes, this boundary has also hosted half a dozen M8+ earthquakes. Red circles mark the epicenter above the site where fault rupture began, and yellow shows the area on the megathrust fault that ruptured.

Not obviously. Quakes are many kms below the surface so surface impacts rarely make a difference. Water table depletion can reduce the pore pressures (pressure in the water at depth) and that can slightly reduce the risk (just like fracking-related injection increases the pressure causing quakes)

This is normal behavior. We expect most M4.3's to have some aftershocks. Quakes in the Imperial Valley tend to have more aftershocks than other places.

I once had a M2.7 directly under my house that felt so strong I went to work without waiting for a page (in pre-Internet days). It's a good reminder that how strong the shaking feels has much more to do with how close you are to the event. Duration of shaking is better for guessing magnitude.

Even very small quakes can be felt if you are nearby (and a shallow quake is closer to people on the surface). But there is not much to be said about an M2.7 except that it happened
earthquake.usgs.gov/earthquakes/...

YouTube video by Ólafur Waage Icelandic Independence Day #nordic #comedy #denmark #iceland #history #language

Most births in Iceland are in the summer.

www.youtube.com/shorts/oRw8d...

In Dante’s Peak, the volcanologist has to choose between his first chance for sex in 5 years or tracking down a geochemical anomaly and he goes after the anomaly. That’s as realistic as it gets

Both 1974 Earthquake & Dante’s Peak are realistic about the scientists. In Earthquake, the Lab director talking to the Mayor - we are seeing something unusual but we don’t know what it means - felt like our experience after Landers, worried that it might trigger the San Andreas

This study uses "overdue" to mean that time time since the last quake is longer than the average time between earthquakes. But that doesn't mean the next quake is more likely in the near future. The length of intervals between events is very variable even at one location.

This does not mean the big earthquake is more likely. Whatever is making for long intervals is happening now.

It is so cool to see actual fault offset, but I am also struck by how small the shaking is. This is the ultimate "near-field" site, but the shaking is not enough to topple any of the tall vases.

I see it now. I was looking in the foreground and completely missed it. Maybe 2-3 meters?

This doesn't look like fault movement. Notice the crack forms in the concrete but doesn't offset the edges. This looks like shaking compacted the ground under the concrete and caused a crack.

It was incredible. The OcTech singers are amazing and their music helped us metabolize our grief and anger over the fires and the attacks on science. We ended with singalongs and essentially the whole audience joined in. A good night

#FieldPhotoFriday Back from the beach and up into the mountains, sometimes the field techs need to go even higher! Atop an antenna at the peak of a mountain near Lake Arrowhead to be exact! Climbing can be a regular part of the job, they do what it takes to keep the data flowing!

I've partnered with OcTech, Caltech's choral octet, to create Courage To Care: a concert & discussion to process climate angst in a time of historic fires. If you're in SoCal, come build community with us!

Sunday, April 27th, 7:30 PM
Dabney Lounge on the Caltech campus
Tickets: No tickets - free!

Interesting to look at the detailed relocations of the aftershocks to the M5.2. It looks like they are not on the main strand of the Elsinore fault.

I’ve wondered what it would take to notice a quake on a rollercoaster. Would even 1g acceleration be enough?

Earthquake Early Warning requires estimating the magnitude from the first few seconds on just a few stations. It is always very rough but lets us get out something quickly. There is a lot of variation between locations. The final magnitude averages 100+ stations and is always more accurate