The first major earthquakes hit Southern California since the launch of an early warning app for people who live in Los Angeles. Robert de Groot of the USGS explains what went as planned and where there is room for improvement.
In the wake of two major earthquakes to shake the LA area in 48 hours, the threshold for notifications has been lowered. There is also an app update available that adds better functionality for the app. So go update your app to see it!
Here is a lightly edited transcript of our conversation:
What have the past 72 hours been like for you?
It’s been pretty incredible. We’ve had this sequence of a magnitude 6. 4. on July 4th and magnitude 7.1 last night plus many thousands of aftershocks. So it’s been a very interesting time for us and in my particular role. I work with the earthquake early warning program for for USGS. And so that’s been another interesting piece of the entire operation for us.
Tell me about the Early Warning System and the new ShakeAlertLA app
The ShakeAlert earthquake early warning system is being implemented in California, Oregon and Washington.
And so the USGS is role in this whole process is to actually detect the ground motion out in the field to move that information to a processing center and make these Shake alerts, the information about the event available for delivery. And so the piece that most people are asking about now is the city of Los Angeles has recently released shakealert LA and app where they deliver Shake alerts to the residents of Los Angeles County.
Explain the relationship between ShakeAlertLA and the USGS
So the USGS is the source of the shake alerts and what we do is we issue them and everybody that is connected to us delivers them on our behalf.
So we basically produce the information and then we hand it off to people to deliver. The city of Los Angeles shake or tell a app is one of those ways that we get the message out to people
I was surprised that I did not get an alert for the first earthquake and then for the second one, I didn’t get it. What happened in this scenario?
So part of the information that we make available for delivery is an estimation of how much the ground is going to shake and it turns out with Both earthquakes the initial information that we sent out the estimates gave the shaking level in Los Angeles County. It was below a certain level. It was below a certain threshold where the ShakeAlertLA app would not have passed along that information to the residents of LA County.
It’s more about what the settings are for ShakeAlertLA and when they deliver the message that we produce so we produce the messages. They just didn’t deliver it and that’s not at the fault of the of the city of Los Angeles. It was an agreed-upon threshold to deliver those messages
Mainly because if you had a lower threshold, you might get these messages all time?
That’s right. So there’s that delicate balance between sending messages and for us the basic idea is to only deliver messages to people who may experience potentially damaging shaking and what we mean by that is stuff starts falling off shelves or walls or the shaking is where people can’t stand that’s where we want people to really know in many cases if you just feel an event, you’ll be getting a lot of those types of messages, so we want to make sure that we’re not over alerting people
And in this instance, there wasn’t really damaging shaking. It was more of a feeling of shaking and that is the delineation?
Yes in the County of Los Angeles the initial estimation of shaking in Los Angeles County was below that potentially damaging shaking level. We’ve been doing some modeling on that ever since last night and it’s likely that there could have been in Los Angeles County. So we’re looking into this and trying to figure out a way to basically strike that happy balance
But the threshold was lowered in the wake of these recent quakes, right?
Yeah, so what’s really important to to really mention is that the ShakeAlertLA app is is is managed and developed by the city of Los Angeles and we’re providing them a lot of advice and my understanding of what they did last night is that on the ShakeAlertLA app. There’s a feature where you can look at recent earthquakes and what they did was is they moved the recent earthquakes that you see on the screen from a magnitude 4 to magnitude 3 so there would be more events shown on those Maps.
How much of a heads-up should we expect from the early warning?
So the ShakeAlert earthquake early warning system should be able to provide people with seconds to tens of seconds of warning before shaking arrives at their location. And what we’re telling people is that if you feel shaking don’t wait for the alert drop cover and hold on the opposite also is important that if you get the alert don’t wait for the shaking drop cover and hold on.
So it’s either the shaking or the alert that will tell you to take that action.
Are there any limitations of this system at this point like can it get better in the future?
It’s absolutely getting better all the time. And I think this is why working with the City of LA is so critical because there is the sort of technical infrastructure part of it that the USGS is improving all the time, but then there’s also the delivery side.
We’re trying as much as possible to reduce the times between when we make the alert available for delivery. And when that message is actually, you know ends up in someone’s hands in there on their phone or wherever else.
What about people outside LA County?
The app actually works for all residents of Los Angeles County, so even though the City of LA is producing the app everyone in LA county would potentially receive a shake alert and there are other parallel programs that are being put together projects for building apps, but those are still in testing mode. It’s really the City of LA that has taken things to this place where they’re actually sending out alerts to people in, LA County.
Are there any other resources you recommend in general? Are the other Earthquake apps any good?
Most of the apps that you’ll see online are the apps that subscribe to the same information from the USGS about events that have already happened what distinguishes shakealert from all the other types of programs that are out there is that we are providing.
Sometime potentially some time before shaking arrives at your location. So there there really isn’t anything other than ShakeAlertLA that’s out there that’s operating in this capacity in LA county. Now, there are a few other apps that are are being developed. There’s one called Quake alert. Which is being developed by a company called early warning Labs, which is based in Santa Monica.
But that’s also in testing mode. That’s really pretty much it if people want to keep updated with the shakealert earthquake early warning system. We recommend they follow our Twitter feed at and the address is at USGS_ShakeAlert.
Anything else we should know?
This is the largest shaking that we felt in this region in about 20 years. And so we’re learning a lot from this earthquake. So there’s a lot to learn about earthquakes from these events. But what’s also critical to is that this is a way that we’re going to learn how to improve the earthquake early warning system mean it’s one thing to do simulated earthquakes, it’s one thing to do modeling, but to actually have the real earthquakes have the real events and see what they do. It’ll give us that insight we need to. An even better system, so people should not be alarmed at the fact that things happened the way they did this time. This is actually a stepping stone to a much better ShakeAlert system.