Science for Earthquake Risk Reduction
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components in studies of earthquake-prone regions. These studies provide information on the localization of stresses and their changes, which can be used then in hazard assessment. Earthquake simulations can complement the knowledge on tectonic stress release at the faults, which have not been ruptured in the past or if the information on historical earthquakes have not been recorded. Because historical data on seismicity are usually incomplete and instrumental observations cover a short time interval compared to the duration of the tectonic processes responsible for earthquakes, studies of seismic hazard based only on historical and instrumental observations are lacking the information on large earthquake occurrences. Numerical modelling of seismic processes allows to generate synthetic earthquake catalogues covering long time intervals and provides a basis for reliable estimates of the parameters of the earthquake occurrences (e.g. Soloviev and Ismail-Zadeh, 2003; Rundle et al., 2006; Ismail-Zadeh et al., 2018). Results of the modelling can then be used in assessments of seismic hazard (e.g., Sokolov and Ismail-Zadeh, 2015, 2016). Seismic hazard assessments provide an information on strong ground motions due to potential earthquakes combining the knowledge on seismological, tectonic, geomorphological, and geological features and modelling results. Although a seismic hazard assessment identifies a spatial distribution of strong ground motions and predicts the exceedance of a certain level of ground motions for a certain period of time with a prescribed probability, it does not answer an important questions required for disaster risk management: when does a big earthquake occur? Earthquake forecasting tries to answer the question, although opinions on the possibilities of forecasts range from the statement that earthquake prediction is intrinsically impossible (Geller et al., 1997) to the statement that prediction is possible, but difficult (e.g., Knopoff, 1999; Keilis-Borok et al., 2001). Earthquake forecasting based on monitoring of precursors (e.g. a ground elevation, water level in boreholes, radon emission, electromagnetic field issues, and animal behaviour) issues an alarm at the time of the abnormal behaviour of the precursors. Alarm-based earthquake prediction methods have been developed for the last several decades. For example, the intermediate-term earthquake prediction method (M8 algorithm; Keilis-Borok and Kossobokov, 1990; Ismail-Zadeh and Kossobokov, 2020) aims to forecast large (magnitude 8 and greater) earthquakes by monitoring and analysis of several parameters of the seismic activity in a region. Another type of earthquake prediction is based on calculating the probabilities of target events within future space-time domains, e.g., the shortterm earthquake probability (STEP) method that uses aftershock statistics to make hourly revisions of the probabilities of strong ground motion (Gerstenberger et al., 2005).
DOI: 10.1007/s12594-020-1540-y
Although earthquake prediction methods are improvin
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