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Institute of Earthquake Science, China Earthquake Administration, Beijing, China
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- PublicationRestrictedGEMS: the opportunity for stress-forecasting all damaging earthquakes worldwide(2006-09-28T11:48:26Z)
; ; ; ; ; ; ; ;Crampin, S.; School of GeoSciences, University of Edinburgh, Edinburgh, Scotland UK; also at Edinburgh Anisotropy Project, British Geological Survey, Edinburgh, Scotland UK ;Zatsepin, S. V.; School of GeoSciences, University of Edinburgh, Edinburgh, Scotland UK ;Browitt, C. W. A.; School of GeoSciences, University of Edinburgh, Edinburgh, Scotland UK ;Keilis-Borok, V. I.; International Institute of Earthquake Prediction and Mathematical Geophysics, Russian Academy of Sciences, Moscow, Russia; also at Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California USA ;Suyehiro, K.; JAMSTEC, Yokosuka, Japan ;Gao, Y.; Institute of Earthquake Science, China Earthquake Administration, Beijing, China ;Walter, L.; Geospace Engineering Research International, Texas, USA; ; ; ; ; ; A new understanding of rock deformation allows the accumulation of stress before earthquakes to be monitored by using shear-wave splitting to assess stress-induced changes to microcrack geometry. Using swarms of small earthquakes as the source of shear-waves, such stress accumulations have been recognised with hindsight before some fifteen earthquakes worldwide. On one occasion the time, magnitude, and fault-break of an M 5 earthquake was successfully stress-forecast in a comparatively narrow magnitude/time window. However, suitable swarms of small earthquakes are very uncommon, and routine forecasting requires measurements of controlled-source observations at bore-hole Stress-Monitoring Sites (SMSs). A prototype SMS confirmed that both science and technology are effective for monitoring stress changes before earthquakes, and the sensitivity is such that a network of SMSs, on a 400 km-grid, say, could stress-forecast all M ≥ 5 earthquakes, that is all damaging earthquakes, within the grid. This paper suggests that a Global Earthquake Monitoring System (GEMS) could forecast all damaging earthquakes in both developing and developed countries worldwide.173 11 - PublicationOpen AccessSeismic anisotropy and shear-wave splitting: Achievements and perspectives: forewordThis special issue of Annals of Geophysics “Seismic anisotropy and shear-wave splitting: Achievements and perspectives” originates from a session (S10) of the 37th General assembly of the European Seismological commission ESC 2021 Conference which was planned to take place on 21 September 2021, in Corfu Greece, but due to the Covid19 pandemic was Virtual. The main theme of the session and of this special issue was the crucial role of seismic anisotropy in investigating the Earth’s interior from the upper crust to the inner core. Shear-wave splitting, one of the most effective ways to study seismic anisotropy, can identify the properties and the geodynamics of the upper mantle, and identify the presence of fluid-saturated microcracks, oriented according to the stress regime, in the upper crust. Azimuthal anisotropy and radial anisotropy can be assessed from earthquake or ambient noise recordings to detect the seismic layered features and to rebuild the 3D seismic structure
256 138 - PublicationRestrictedA few earthquake conundrums resolved(2013-01-30)
; ; ; ;Crampin, S.; British Geological Survey, Edinburgh, Scotland, UK ;Gao, Y.; Institute of Earthquake Science, China Earthquake Administration, Beijing, China ;De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; Several fundamental questions (conundrums) about earthquakes and rocks are inexplicable in terms of conventional sub-critical geophysics. These questions have become so familiar that they are now generally accepted as the way earthquakes and rocks behave and are not recognised as presenting conceptual difficulties. These conundrums are resolved by a new understanding of fluid-rock deformation, where fluid-saturated microcracks in almost all rocks are so closely-spaced they verge on failure and hence are highly-compliant critical-systems which impose a range of new properties on conventional sub-critical geophysics. This new understanding of fluid-rock deformation, this New Geophysics, allows earthquakes to be stress-forecast, and has implications and applications to many solid Earth developments.319 34