(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)

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.

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

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.

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

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