The science behind the back-to-back earthquakes that struck northern Venezuela : NPR

MICHEL MARTIN, HOST:

We wanted to spend a few minutes on the science behind those earthquakes in Venezuela. So we’ve called earthquake scientist Judith Hubbard. She’s a visiting professor with Cornell University. Good morning, Professor. Thanks so much for joining us.

JUDITH HUBBARD: Good morning, Michel.

MARTIN: So the U.S. Geological Survey, as John just told us, is telling us that these were two earthquakes, measuring them as magnitude 7.2 and 7.5 within a minute of each other. Now, this may seem like hair-splitting, given the loss of life that we’re already seeing. But are you convinced that this is two large back-to-back quakes? And if so, how common is something like this?

HUBBARD: So back-to-back earthquakes can occur. They’re certainly in the geological record – they’ve happened within the last decade. I don’t know for sure that I would call this two earthquakes. I think we’re going to need to see more science come out. A magnitude 7.2 earthquake, like the first one, would take about 30 or 40 seconds to finish. So whether you define a break between that one and the next one is a little unclear to me. I think for people in the area, they would have felt this as one very large earthquake. That’s what I’m seeing from people’s reports.

MARTIN: And what do we expect in terms of aftershocks?

HUBBARD: Well, we know that large earthquakes produce quite a lot of aftershocks. There’s an aftershock forecast from the USGS right now. Typically, we would see, you know, at least one aftershock of about magnitude 6.5, but there is a chance that there could be larger aftershocks, including possibly, although the probability is quite low, of earthquakes even larger than the magnitude 7.5 in the coming days to months.

MARTIN: Wow. So based on the data that you’ve studied and you’re familiar with, what are we looking at in terms of loss of life and property damage because of this?

HUBBARD: One of the things that you have to know about an earthquake this big is that you see it on a map as a point. This is not a point. It was an earthquake that ruptured a fault that’s probably 100, 150 kilometers long. And what that means is there’s a lot of people who live quite close to that fault, which probably is just north of the coast. The – last night, it was a little unclear what the rupture looked like. This morning, we’re seeing models that show a rupture that starts west of Caracas and moves east towards Caracas, getting quite close. So it seems like there’s a lot of areas in that high-intensity shaking zone.

MARTIN: So as we’ve been reporting that this is – whether this is one event or two events, we’re reporting that this is one of the most serious in Venezuela’s history. Is this region particularly vulnerable to earthquakes, and if so, why?

HUBBARD: Yes, this is actually a plate boundary, and it’s right between the South American plate and the Caribbean plate. The Caribbean plate’s moving about 20 millimeters east every year, which may sound like a small amount, just 2 centimeters. It’s about an inch, but it adds up. And that movement is accommodated irregularly as earthquakes. The fault’s going to build up the strain and then they slip all at once. So this earthquake would have released a lot of that strain. We don’t yet know how much slip occurred in it, but I would guess a few meters. What that means is that if you saw the fault line, you’d see things actually move, you know, offset by a few meters from before the earthquake to afterwards.

MARTIN: OK. Now, forgive me if this is a dumb question, OK? But there was also a magnitude 7.2 earthquake off the coast of northern Japan about half an hour after the Venezuela quakes. Is it possible that the two were related?

HUBBARD: You know, usually, I would say it’s impossible that one magnitude 7 in one part of the country can’t possibly be related to a magnitude 7 on the other side of the world. I still think it’s very unlikely, but the reality is that the shaking waves from the earthquake in Venezuela would have reached Japan before the second earthquake there started. So it is technically possible, and there is a term for that. It’s called dynamic triggering. That being said, I think it’s very unlikely because the area that produced this about magnitude 7 earthquake in Japan had a magnitude 7.5 just last December, so it’s still in the aftershock period.

MARTIN: And earlier in the day, Wednesday, a 5.6 earthquake hit Northern California. So how often do we see days with this kind of seismic activity?

HUBBARD: This is high seismic activity, obviously, because there was a magnitude 7.5 in Venezuela. But we’re – you have to think about why you’re paying attention to these earthquakes. If there had been that earthquake in Japan or especially that earthquake in California on a regular day, nobody would have really blinked. And if the earthquake in California had occurred somewhere else, nobody would have blinked. There’s magnitude 5.6s all the time. So it’s high, but that’s mostly because of the large earthquake in Venezuela.

MARTIN: And because there are people there and because there are people there because…

HUBBARD: And because there’s people. That’s right. A lot of earthquakes go totally unnoticed because they happen in the middle of the ocean or in a desert area with no people. But obviously, that’s not the case here.

MARTIN: Thanks so much for this. That’s Judith Hubbard, visiting professor at Cornell and co-creator and writer for the Earthquake Insights Substack. Professor Hubbard, thanks so much.

HUBBARD: Thanks very much.

(SOUNDBITE OF MUSIC)

Copyright © 2026 NPR. All rights reserved. Visit our website terms of use and permissions pages at www.npr.org for further information.

Accuracy and availability of NPR transcripts may vary. Transcript text may be revised to correct errors or match updates to audio. Audio on npr.org may be edited after its original broadcast or publication. The authoritative record of NPR’s programming is the audio record.