Researchers at the University of Alaska Fairbanks are exploring ways to enhance earthquake early warning systems in Alaska to provide more effective alerts during seismic events.
The study, conducted by Alexander Fozkos and Michael West, reveals that increasing the number and optimizing the placement of seismic stations across the state could add critical seconds—between 5 to 15—to the existing warning times.
Alaska, which experiences tens of thousands of earthquakes annually, is known for some of the world’s largest and most destructive seismic events.
The findings, published in the Bulletin of the Seismological Society of America, aim to build a framework for expanding the U.S. ShakeAlert earthquake early warning system.
Currently, ShakeAlert operates in California, Oregon, and Washington State, but the new research seeks to adapt similar methodologies to the unique seismic conditions present in Alaska.
Fozkos explained, “There were a lot of studies before EEW was widely available on the West Coast, where people were looking at different scenarios. So we wanted a similar kind of science up here with numbers that are Alaska specific.”
The study analyzed various earthquake scenarios to estimate potential warning times for different magnitudes and fault types across the state.
For instance, in southcentral and southeast coastal Alaska, researchers estimated potential warning times ranging from 10 to 120 seconds for magnitude 8.3 earthquake scenarios.
In contrast, for magnitude 7.3 scenarios involving crustal faults in interior and southcentral regions of Alaska, the estimated warning times varied from 0 to 44 seconds.
Additionally, for magnitude 7.8 earthquake scenarios along the subducting slab beneath Alaska, estimated warning times ranged from 0 to 73 seconds.
Fozkos expressed surprise at the findings, particularly concerning the shallow crustal events. “I was expecting decent warning times along the coast and for most of the subduction zone events,” he noted, “but I was not expecting decent warning times for the shallow crustal events.”
The scenarios analyzed in the study considered various factors, including earthquake magnitude, depth, location, and fault style, all of which impact the resulting warning times.
The researchers’ models calculated how many seconds after an earthquake’s origin a quake could be detected and when an alert could be issued, detailing both minimum and maximum warning times for specific locations.
Warning times were defined as the difference between the alert’s issuance and the arrival time of peak ground motion at a given location.
This measurement approach differs from more common definitions in earthquake early warning systems that connect warning time to the arrival of the initial S-wave, or shear wave, from an earthquake.
The researchers opted for peak ground motion to potentially provide a more relevant context for how individuals will respond during an earthquake since strong shaking can occur even after the initial S-wave.
However, the research does not address the actual time required to disseminate alerts from their source to the public.
Fozkos remarked on the challenges that could present obstacles to timely alerts, stating, “The potential lag time in transmitting data and sharing an alert with the public could be a big challenge for Alaska, but I don’t think it’s going to be insurmountable.”
The research team also acknowledged the difficulties posed by Alaska’s severe winters and the remote locations of some seismic stations, which could challenge the reliability of an early warning system.
“There is definitely a need for adding stations to cover redundancy for remote stations,” Fozkos said, underscoring the importance of ensuring that monitoring capabilities remain intact.
Additionally, he highlighted the potential benefits of implementing ocean-bottom seismometers (OBS) and enhancing earthquake detection through distributed acoustic sensing (DAS).
“Coupled with the fact that some of our biggest earthquakes are going to be offshore, tsunamigenic threats, I think OBS and DAS are probably big targets for the future,” he concluded.
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