Phys.org August 30, 2024
Earthquake precursors are ambiguous, but recent experimental studies suggest that robust warning signs may precede large seismic events in the short (day-to-months) term. An international team of researchers (USA – University of Alaska Fairbanks, Germany) showed that Ridgecrest sequence (California) and Anchorage earthquake (Alaska) were preceded by up to ~3 months of tectonic unrest on regional scales, as evidenced by abnormal low-magnitude seismicity spreading over the ~15-25% of Southern California and Southcentral Alaska. This precursory unrest had been discovered with an algorithm that integrates an innovative random forest machine learning approach and statistical features built from earthquake catalogs. Supported by finite element solid mechanics models, they proposed that precursory, abnormal, low-magnitude seismicity occurred if the pore fluid pressure within large fault segments escalated significantly as they approached failure, which would lead to major uneven changes in the regional stress field. According to the researchers their findings and method may open new perspectives for surveillance agencies to anticipate when a region approaches an earthquake of great magnitude weeks to months before it occurs… read more. Open Access TECHNICAL ARTICLE
Temporal evolution of the probability of unrest… Credit: Nature Communications volume 15, Article number: 7429, 28 August 2024Â