A new study has found that for a wide range of earthquake scenarios in Alaska, an earthquake early warning (EEW) system could provide at least 10 seconds of advance notice before hazardous shaking begins enough time for people to take cover, halt surgeries, or slow trains.
Researchers Alexander Fozkos and Michael West from the University of Alaska Fairbanks say that increasing the number and improving the spacing of seismic stations could extend warning times by an additional 5 to 15 seconds. Alaska, which experiences tens of thousands of earthquakes each year and has seen some of the world’s largest quakes, currently has no public EEW system in place.
Their findings, published in the Bulletin of the Seismological Society of America, could help expand the U.S. ShakeAlert network, now active only in California, Oregon, and Washington.
For magnitude 8.3 earthquakes along known coastal faults, the study projects warning times ranging from 10 to 120 seconds. Interior and southcentral crustal quakes of magnitude 7.3 could allow anywhere from zero to 44 seconds, while deep subduction quakes of magnitude 7.8 might yield zero to 73 seconds.
One surprise for the team was the potential for usable warning times even in shallow crustal events, despite the lower density of seismic stations inland.
The researchers calculated warning time based on when peak ground motion not the initial S-wave would arrive, believing this is more relevant to public safety. They did not factor in the time needed to transmit alerts to devices, a potential challenge in Alaska’s remote and harsh environments.
Fozkos says the state will need more seismic stations, redundancy for remote areas, and possibly ocean-bottom seismometers and distributed acoustic sensing to detect offshore quakes that could trigger tsunamis.
“Some of our biggest threats are going to come from offshore,” he said. “The more sensors we have in place, the better our chances of getting life-saving warnings out in time.”