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 […]
Tag Archives: Geophysics
Predicting avalanches: Fracture characteristics of anticracks in highly porous materials
Phys.org September 2, 2024 When porous materials are subjected to compressive loads, localized failure chains or anticracks, can occur and cause large-scale structural failure. The resistance to anticrack growth is governed by fracture toughness. To understand more about the mixed-mode fracture toughness for highly porous materials subjected to shear and compression, an international team of researchers (Germany, Switzerland) designed fracture mechanical field experiments tailored for weak layers in a natural snowpack. Using a mechanical model for interpretation, they calculated the fracture toughness for anticrack growth for the full range of mode interactions, from pure shear to pure collapse. The measurements […]
California Quakes Mysteriously Preceded by Shifts in Earth’s Magnetic Field
Science Alert October 10, 2022 Magnetic field changes as earthquake precursors have been the subject of numerous studies and some controversy. Infrequent large earthquakes and sparse magnetometer coverage along fault zones complicate statistical analysis. A team of researchers in the US (Google Research, industry) analyzed ground-based magnetic time-series measurements before 19 earthquakes in California drawing from over 330,000 site-days of measurement spanning a decade. They applied a pre-specified statistical analysis with two key ideas – combining signals from nearby sites via spectral cross-power, and then looking for large spikes in frequency domain 0.016–25 Hz. They used the machine learning concept […]
The Mysterious Anomaly Weakening Earth’s Magnetic Field Seems to Be Splitting
Science Alert May 26, 2020 New satellite data from ESA reveal that the South Atlantic Anomaly is a vast expanse of reduced magnetic intensity in Earth’s magnetic field, extending all the way from South America to southwest Africa. Since our planet’s magnetic field acts as a kind of shield – protecting Earth from solar winds and cosmic radiation, in addition to determining the location of the magnetic poles – any reduction in its strength is an important event we need to monitor closely, as these changes could ultimately have significant implications for our planet. The ESA notes that the most […]