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paulz
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# Posted: 15 Sep 2022 09:36
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Last Tuesday my cell phone, my wife's, my neighbors, all lit up with an alert for an upcoming earthquake. First time that's happened, at least to us. Didn't feel anything, before or after, too far away. Turns out there's this new fangled alert system. Read all about it:
Santa Rosa’s earthquake gave the Bay Area its first real test of the nation’s new ShakeAlert system, and it was a qualified success, warning thousands of residents on Tuesday night with a loud alarm and instructions to seek cover.
“The moment the wave hit the house, my watch and phone went off. It’s a miraculous technology — a definite win,†said Robert Stephens, who was sitting at a table at his home on Sonoma Mountain, about five miles from the quake’s epicenter.
In downtown Sonoma, the alarm sent journalist Sarah Stierch diving under her dining room table for protection. “Very impressed with the alert — it’s my first experience with it,†she wrote on Twitter.
But many residents at greatest risk did not receive an alert until after the shaking started because they were so close to the epicenter. The system gives longer warnings to those who are farther away from the rupture.
After more than a decade in development, the ShakeAlert system is finally a reality for over 50 million West Coast residents. Created by the U.S. Geological Survey, it is 81% complete, with more than 903 buried sensors in California that can mobilize cellphone users who are at risk. When complete, it will have 1,115 sensors and quicker transmission time.
The warnings produced by the ShakeAlert system will be pushed through two delivery systems: a cellphone app called MyShake and the same wireless notification system that issues Amber Alerts, meaning people may receive both notifications.
“The good news is that we’re going in the right direction,†said USGS’s Robert de Groot, the national coordinator of outreach and education for ShakeAlert.
“The ShakeAlert system behaved as we expected it would last night,†he said, “and it shows that we’re continuing to improve earthquake early warning on the West Coast.â€
The system initially overestimated the earthquake’s magnitude, calling it a 4.9; later, the quake was downgraded to a magnitude 4.4. But it identified the site of the quake’s rupture with extreme accuracy, pinpointing the epicenter 2.4 miles north of Santa Rosa.
In some spots, it was overenthusiastic, puncturing the serenity of a seismically uneventful evening. “The alert scared me to death,†wrote Anna Boucher, of San Rafael, who said she did not experience any shaking.
In other places, it worked just as planned. At a youth soccer game in Rohnert Park, “everyone’s phones went off with emergency alert — and then we felt the quake about 20 seconds later,†tweeted Matthew Valkovic. “It was pretty wild!â€
Sometimes it came too late. By the time Santa Rosa resident Kathy McMorrow got the alarm, she and her dog had already felt the temblor and were down the porch stairs. Spectators at the town’s Montgomery High School basketball game heard the alert after the main shock but before the aftershock.
A map showing the range and response time of ShakeAlert an earthquake early warning system to an earthquake that occurred in Santa Rosa on Tuesday, Sept. 13, 2022.Alexa Chipman heard the clamor after the earth finally stood still. “I was like ‘so helpful…I noticed, thanks!’†she joked on Twitter.
While there were few reports of damage or injury, the city has dispatched public works employees to assess possible damage to essential services and city infrastructure.
ShakeAlert’s performance has been a disappointment in some previous earthquakes, especially in rural regions where there are few sensors. While fast, it wasn’t accurate.
But Santa Rosa’s 4.4-magnitude shaker and a 4.3-magnitude aftershock — which struck about two miles northeast of downtown, causing some bottles and other items to topple off store shelves — triggered a near-perfect alert for residents of densely populated communities in Sonoma County, as well as some adjacent towns in Napa, Marin, Contra Costa, Alameda and Mendocino counties, even San Francisco’s Presidio.
At least 20,000 people got the apps’ messages, with more getting notice from FEMA and Google, said de Groot.
UGSG has prioritized high-population areas, especially those located near major faults, in its ‘build up’ strategy. Businesses and public agencies such as BART are already acting on alerts from the system.
Communities on the distant edge of Tuesday’s “shake zone†received an alarm well in advance, up 30 seconds before the shaking.
ShakeAlert relies on cell phones — so residents who weren’t near their phones, or who hadn’t downloaded the app, missed the message.
For the system to send an alert, the earthquake must be recorded as having a magnitude of 4.5 or more. Although the final magnitude was lower, the quake initially registered at 4.9.
Shake Alert does not predict earthquakes, but it detects an earthquake’s initial waves. These waves, which travel quickly, are weaker than the more damaging second set of waves.
When the system’s sensors detect these first waves, it enlists high-speed telemetry to send that ground motion information to processing centers in Seattle, Menlo Park and Pasadena. Within about five seconds, computer algorithms analyze the data to rapidly identify the epicenter and strength of the earthquake and publish a data package, called a ShakeAlert message.
The ShakeAlert message is picked up by government and private partners. FEMA may issue a Wireless Emergency Alert, like an AMBER Alert.
An alert may also be issued by two different apps: the MyShake app, developed by the UC Berkeley, or the QuakeAlertUSA app, a product of Early Warning Labs. Alerts are also delivered though cell phones using Google’s Android Operating System.
The alert buzzes loudly and warns users, with text: “Drop, cover and hold on!â€
It was a much more effective message than what was issued during Santa Rosa’s catastrophic 2017 wildfires, said Stephens, the founder of Best Buy’s Geek Squad.
When alarms sounded during those fires, residents “were walking in circles and did not know what to do, did not know what to pack,†he recalled. “People can’t think during the moment that they’re in crisis.â€
“It was very reassuring to be told, ‘This is what’s happening. This is what you do,’ †he said.
“And the speed at which it came through,†he said, “gives me great confidence in the whole sensor array that they’ve set up.â€
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BRADISH
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# Posted: 15 Sep 2022 11:25
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An interesting story related to this.
I recently met the neighbor directly across the road, and down the hill from me after a few years of crossing paths but never meeting.
Anyway we got talking about things and he mentioned he had one of those earthquake sensors on his property. Both of our cabins straddle an old vacated seismic trail from the 1960's. He said he was outside working one day and a USGS fellow popped out of the woods from no where and started talking to him about it. Apparently they are wicked sensitive. The USGS fellow asked the neighbor - "Yeah, you were here last Thursday around noon too eh?" He was, chopping wood about 100ft away. Anyway they said they might have to move the sensor if he was going to be up there more. Apparently there are thousands of them in the hills where we are at.
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NorthRick
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# Posted: 15 Sep 2022 13:42
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Yeah, I don't know how useful that really is. If you are close to the epicenter of a big one you will know it before the system can send out an alert. If you are much farther away, the affects of the quake are much lower.
Having experienced the 7.1 quake that hit Anchorage in 2018, I can tell you that you don't need a phone alert to tell you to dive under something!
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ICC
Member
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# Posted: 15 Sep 2022 14:30 - Edited by: ICC
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I look at it as a start, a real-life test that will be a learning tool. Nothing is at its best when first released.
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paulz
Member
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# Posted: 15 Sep 2022 14:51
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Quoting: NorthRick If you are close to the epicenter of a big one you will know it before the system can send out an alert.
The irony of being pinned under a pile of rubble and your phone starts pinging away in your pocket.
Agree with ICC though, hopefully it can be made more useful.
When we got the alert Tuesday we weren't sure what was going on, was it still coming, where was it located, should we dive under a table?
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NorthRick
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# Posted: 15 Sep 2022 16:32
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What Paulz posted said the computers crunch the numbers coming from the sensors in about 5 seconds. Which, is pretty darn fast. Let's say it takes a couple of seconds to get the message out across the right cell network. And then, it will take most people a couple of seconds to digest what the heck is going on.
So, say 10 seconds from when the earth ruptures to when you have some understanding of the situation. Again, to me that's amazingly fast. However, according to the google, seismic waves travel at 3.7 miles per second near the surface. In that 10 seconds the earth is now shaking in a 37 mile radius. That's where most of the damage is going to happen and nobody had any forewarning.
On bigger earthquakes, 5 and up in my book, I typically hear them coming a second or two before everything starts to shake. But, to be honest, it's more like a deer in the headlights sort of thing - you stand there wondering how bad is this going to be?
I'll tell you this Paulz, you'll know when you should be diving under a table.
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paulz
Member
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# Posted: 15 Sep 2022 17:38
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As a lifelong California resident I've lived through 60+ years of earthquakes. Last memorable was the 7.1 that hit the Bay Area in '89, co-incidentally just prior to the start of the World Series between Oakland and San Francisco. I was standing in the street out front of my house, just cracking a beer with a neighbor as we got ready to watch the game, a big deal for us Bay Area residents. What I remember most was the telephone poles swaying back and forth, with power lines swinging like giant jump ropes. Then came the usual crashing down of items in the houses. After it calmed down we were again ready to watch the game, unaware of the damage to the stadium, the freeways et all, and unfortunately the lives lost.
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BRADISH
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# Posted: 15 Sep 2022 18:02
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Quoting: NorthRick Having experienced the 7.1 quake that hit Anchorage in 2018, I can tell you that you don't need a phone alert to tell you to dive under something!
We were at breakfast in a building that was probably built in the 60's. When it started I grabbed my wife and drug her outside into the parking lot. My folks came shortly after. I definitely wasn't going to get crushed in that heap of a place had it fallen!
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NorthRick
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# Posted: 15 Sep 2022 18:28
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Quoting: BRADISH We were at breakfast in a building that was probably built in the 60's. When it started I grabbed my wife and drug her outside into the parking lot. My folks came shortly after. I definitely wasn't going to get crushed in that heap of a place had it fallen!
I was in my office. Trying to run down the hall, down the stairs and out the door wasn't a good option once everything really got rocking. So, I dove under my desk and hoped for the best. Fortunately all it had to fend off was a falling ceiling tile.
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KinAlberta
Member
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# Posted: 18 Sep 2022 18:17
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I suppose small earthquake notifications will get more people thinking about their options should a big earthquake occur. Maybe finally reinforcing a risky wall or whatever.
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DaveBell
Moderator
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# Posted: 19 Sep 2022 06:56
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The Virginia quake. I was two stories underground, working for a certain agency, when it hit, I bounded up four flights of stairs, jumped over the guard entrance turn styles and out the door. First one. Scared the crap outta me. Later, the California folks were making fun of us east coasters about our little itty bitty quake. Interestingly, the quake experts said we don't have all the deep faults Cali has. In Cali, the waves will stop/mitigate/absorb at surrounding fault lines. Whereas here they were felt as far north as NY. I wonder since the Cali faults absorb shock waves, do they also reflect shock waves making the events more deadly? I'll never forget that SF bridge pancaking down on cars.
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NorthRick
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# Posted: 19 Sep 2022 13:13
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One thing that is often not reported in news stories is the depth of the earthquake. Where I live, southcentral Alaska, our earthquakes are typically subduction plate earthquakes. The Pacific Plate is being pushed under the North American Plate. When things snap, they tend to be bigger but deeper quakes. 30 miles down, give or take.
I believe California has more slip/strike quakes. This is where two plates are sliding past each other and the quakes can often be much shallower and are felt more.
The Virginia quake was inside a tectonic plate and pretty shallow. I grew up in VA and don't believe I ever felt an earthquake there. We sure get a lot of them up here in AK though.
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