3D Fault Information Improves Alert Accuracy for Earthquake Early Warning
upstart writes:
3D fault information improves alert accuracy for earthquake early warning:
The benefits of 3D fault models vary depending on the fault style (a strike slip versus a reverse fault, for instance), whether the event is a subduction or crustal earthquake, and the level of shaking that triggers the alert, according to Jessica Murray and colleagues at the U.S. Geological Survey.
They suggest 3D models would be an improvement over 2D models for an alert threshold of MMI 4.5, meaning that the alert would be triggered for shaking exceeding the "light" intensity category, where most people indoors would feel some shaking. In their study, 3D models also substantially improved alert accuracy for all subduction zone earthquakes at MMI 4.5 and MMI 2.5 (weak motion felt only by a few people) thresholds.
The study's findings could be useful for earthquake early warning systems like the U.S. West Coast's ShakeAlert, the researchers note in the Bulletin of the Seismological Society of America.
For now, ShakeAlert's algorithms use seismic data to characterize an earthquake source as a point or line. But researchers are already looking at ways to incorporate 3D source information, gleaned from fault displacement data collected by Global Navigation Satellite Systems (GNSS), into ShakeAlert.
"The expectation has been that such information would improve alerting because it would offer a better characterization of large earthquake sources compared to a point source," Murray explained. "This assumption has not been explored in terms of how a more realistic source characterization would translate to ground motion estimates, so that is one thing we set out to do."
Journal Reference:
Jessica R. Murray, Eric M. Thompson, Annemarie S. Baltay, et al. The Impact of 3D FiniteFault Information on GroundMotion Forecasting for Earthquake Early Warning, Bulletin of the Seismological Society of America (DOI: 10.1785/0120210162)
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