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

A series of earthquakes, including a preliminary M4.3, shook the San Bernardino area Thursday morning, with shaking felt across SoCal. @drlucyjones.bsky.social explains what it means—watch the full discussion on NBC LA: www.nbclosangeles.com/news/earthqu...

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

An 8.7M earthquake in Russia has prompted a tsunami watch along the entire #California coast. @drlucyjones.bsky.social takes a closer look at the initial temblor and what the watch means in this NBC LA interview: www.youtube.com/watch?v=Uw2E...

@drlucyjones.bsky.social joins KTLA5 to discuss the California coast #tsunami watch following the 8.7M quake in Russia. Watch the full interview: www.youtube.com/watch?v=NuKG...

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.

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/...

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.

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.

A new study outlines the flooding risk from a magnitude 9 quake along the 700-mile Cascadia fault [email protected] explains that while we could still see damage for coastal areas, the fault line is offshore, so the heaviest shaking would be underwater. Watch her full interview on ABC7:

Last week, @drlucyjones.bsky.social gave a lecture at the Newport Beach Public Library, providing insights on earthquake prediction, the importance of resilient structures, and why knowing your neighbors may matter most. Read more on the @latimes.com: www.latimes.com/socal/daily-...

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!

@drlucyjones.bsky.social joined KCAL News today to discuss the recent 5.2-magnitude earthquake in #SanDiego County, noting a relatively large aftershock sequence. In the same interview, she also addressed the overall earthquake activity in #SoCal ▶️: www.youtube.com/watch?v=rFJ1...

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.

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

The USGS produces a nice quantification of the risk of aftershocks. 7% chance of another M5 and less than 1% chance of being followed by a M6.

Today's M5.2 is the largest quake near the Elsinore fault since I came to California in 1983. But there were quite a few M4s along the way. A junior sibling to the San Andreas, the Elsinore is long enough to have given us some bigger events

A 7.7 quake struck Myanmar on Friday, killing over 2,000 people and shaking buildings as far as Bangkok. What caused this quake, and could it happen in the US? @drlucyjones.bsky.social joined ForbesWomen’s Maggie McGrath to answer these questions and more ▶️ www.youtube.com/watch?v=sc-v...

I was proud to be a federal scientist at the USGS for 33 years. "Earth science in the public service" meant I could focus on creating and explaining science for public officials and providing public education, not just educating students at one university. theconversation.com/us-earthquak...

#AirTalk with Larry Mantle celebrates 40 years on air, with leading voices joining to help listeners better understand the many facets of L.A.—from science to politics to history. Hear from guests, including seismologist @drlucyjones.bsky.social in this special episode: laist.com/shows/airtal...

After the fires, the only person I wanted to talk to was @drlucyjones.bsky.social. I was so thrilled to be able to sit down with her for this interview for Dwell. Our conversation about LA's future was, at times, painfully honest — but ultimately very hopeful

Quakes cause shaking at a range of frequencies. The lowest frequencies are controlled by the length of the fault that moves in the quake. A 400km long fault creates longer wave length (lower frequency) waves than a 10km long fault. So all quakes produce hi frequencies but only big quakes have low.

The high rise that collapses in Bangkok would have lower design standards than a building in LA. But notice the very long period (slow) motions in Bangkok. The long period waves travel farther and affect taller buildings, so collapsing a high rise while smaller buildings are ok is to be expected.

This earthquake is similar to what we think happened in 1906 in northern California - that was a M7.7 with 440km rupture length. The strong shaking in Bangkok at ~600km distance is like a quake in San Francisco causing damage in LA. www.youtube.com/watch?v=oRuk...

This is an excellent post, summarizing the scientific data from the Myanmar earthquake. The long fault and close proximity to major cities indicate a high level of damage and we should expect the death toll to rise. But the ongoing civil war near Mandalay suggests we may never know.

This could be devastating. This is strike-slip mechanism on a plate boundary, much like the 1906 quake on the San Andreas. The rupture length is at least 300km. The capital, Yangon, is near the fault, but I can’t yet see if the fault ruptured towards Yangon or away from it

Small quakes do not prevent big quakes. It takes 1000 M3s to relieve the stress of one M5. It does slightly increase the chance of more just because the rate is up. As a seismologist with almost 50 years experience looking at quakes, I am thinking "How interesting. I wonder what will be next?"

The Malibu quakes: There have now been 12 M≥3.0 quakes in approximately the same location north of Malibu since February 2024. In comparison, the previous 25 years had 7 M≥3s in the same location. A couple are clear aftershocks (within a few hours of a larger event), but the others are spread out

Wow! I'm honored that KUSC wanted to include me as a woman making history - in music! I've only got one composition to my name so this is very special. www.kusc.org/articles/wom...

Does climate change have any impact on #LosAngeles earthquakes? @drlucyjones.bsky.social sat down with NBC Los Angeles on Monday, March 10, to discuss recent seismic activity along the #Malibu Coast fault system. Watch the full interview here: www.nbclosangeles.com/on-air/does-...

I was out on a walk during the M4.1 quake. Not much to say about it. Run-of-the-mill for earthquake country. The most interesting thing is that it is the 3rd M4 at essentially the same location over the last 13 months.

A M3.9 in North Hollywood. Too small to definitively assign to any fault, but the closest is the Hollywood fault. Yawn. Nothing much to say about an earthquake in earthquake country. I am in Boston and am heading back to sleep.

It's essentially impossible to definitively assign a small quake (with fault area ~100m) at 8 km depth to a fault we map at the surface. But these look like they could be on the San Andreas itself which is relatively rare. The focal mechanisms align with the fault orientation

After the January 2025 #LAfires burned thousands of homes in Altadena, Pasadena, and the Pacific Palisades, the @caltech.edu Science Exchange asked @drlucyjones.bsky.social to share her insights on how communities recover from natural disasters.

“Emergency management is not just response,” @drlucyjones.bsky.social concluded in that report. “It is developing resilience before, responding efficiently during, and recovering quickly after a disaster.” Explore the full column on @latimes.com: www.latimes.com/california/s...

The California Earthquake Authority gives $3000 grants for seismically retrofitting your home. Registration is open now. See if you qualify at www.californiaresidentialmitigationprogram.com/our-seismic-...

“After a wildfire, the hazard to the public is not over,” said Jeremy Lancaster, California’s state geologist. …The two major hazards after a wildfire are flash flooding and post-fire debris flows.” www.nytimes.com/2025/01/16/c...

In her latest opinion piece for the @latimes.com, @drlucyjones.bsky.social discusses the most important factor in a resilient community. Read it here: www.latimes.com/opinion/stor...

@drlucyjones.bsky.social joined @abc7.bsky.social yesterday to talk about the people who have had to evacuate due to the fast-moving fires and what they’re going through from a mental and emotional perspective: ▶️ www.youtube.com/watch?v=BR2K...

🔴 @drlucyjones.bsky.social is live on NBC LA. Watch here: www.nbclosangeles.com/weather-news...

I'm in Pasadena, smelling the #EatonFire. I activated the group text for a disaster group that planned together last year, checking in, seeing if anyone needs help. One person has been evacuated and needed help. We all felt better for doing something. Helping neighbors is the most powerful response.

It makes us wonder, but probably not. When we look at data for all big earthquakes, we see increased chance of another quake out to about 4 times the length of the fault in the mainshock. The M7 fault length is about 50 km, so increased triggering out to ~200km. The NV quake is >600km away.

Thursday’s quake hit along the intersection of three plates. Learn the science behind the recent 7.0 magnitude earthquake from @drlucyjones.bsky.social as she speaks with Spectrum News 1’s “Inside the Issues” host Amrit Singh: ▶️ spectrumnews1.com/ca/southern-...