California’s new statewide earthquake warning mobile phone app, MyShake, has reached a milestone, issuing its first public alert for a 4.3-magnitude earthquake that struck between the Central Coast and the San Joaquin Valley on Tuesday,media reported. Jennifer Strauss, project manager for the MyShake application, said more than 40 people had received warnings. The app was created by the University of California, Berkeley, and released publicly in October. The app is available on iOS and Android.
There were no reports of injuries or damage due to the weak strength of Tuesday’s quake, which was relatively small and close to the epicenter of the Cholame valley, limited to parts of San Luis Obispo, Monterey, Kings and Kern counties.
The MyShake application relies on seismic information calculated by the U.S. Geological Survey’s main shakeAlert system, which collects seismic ally data from hundreds of terrestrial sensor networks across the West Coast. Seismic early warning systems are able to operate because today’s communication systems are able to issue vibration warnings that travel faster in rocks than seismic waves.
Such systems are particularly effective in strong earthquakes and can provide a few seconds of alarm time. USGS scientist Robert de Groot said the system took 8.7 seconds to raise the alarm in Tuesday’s quake. But these systems often fail to warn people in a timely manner about people close to the epicenter.
Paso Robles is the closest city to the epicenter, about 22 miles southwest. Mayor Jonathan Stornetta said that although the shaking was felt in the city of 32,000 people, it was so mild that no one called the fire department. “I don’t see any damage or impact from the earthquake,” he said. “
The city of Los Angeles has its own version of ShakeAlertLA, an earthquake warning app that was developed by AT?T. It sends warnings to users physically located in Los Angeles County.
When the app did not trigger an alarm before a slight tremor that hit parts of Los Angeles County on July 4 and July 5, there were complaints that a magnitude 6.4 and 7.1 quake struck the Ridgecrest area, about 125 miles from Los Angeles. The earthquake in Los Angeles County was not strong enough to cause widespread damage, but it was long enough and more frightening than usual.
Officials decided to lower the warning threshold for future earthquakes. If a magnitude 4.5 or large earthquake is recorded and the minimum expected shaking at a specific location is weak, or the intensity level is 3 on the “corrected Mercalli strength rating”, the MyShake and ShakeAlertLA applications will be triggered for users in a specific area. In this case, the interior will visibly feel the shaking, which may cause the stopped car to shake slightly, feeling as if the truck was passing, but others may not consider it an earthquake.
The MyShake app raised the alarm Tuesday because the initial reading of the quake was 4.8, higher than its final calculated 4.3.