On‐Site Early Warning and Rapid Damage Forecasting Using Single Stations: Outcomes from the REAKT Project

Abstract

Earthquake early warning systems (EEWS) in their various forms are recognized as potentially valuable tools for mitigating against the risk associated with earthquakes (see Allen, 2013; Wenzel and Zschau, 2014). For example, operational systems currently exist in Japan (Horiuchi et al. , 2005; Kamigaichi et al. , 2009), Taiwan (Wu and Zhao, 2006; Wu, Chen, et al. , 2013), and Mexico (Espinosa‐Aranda et al. , 2009), while there are others nearing operational status, under development, or are being strongly considered in regions such as Italy (Satriano et al. , 2011), Turkey (Alcik et al. , 2009; Wenzel et al. , 2014), California (Bose et al. , 2009), Romania (Bose et al. , 2007), Israel (Allen et al. , 2012), and Spain (Carranza et al. , 2013). However, EEWS are not only valuable for the mainshock, but also for the period after a disastrous earthquake when there is the possibility of reducing losses due to aftershocks if early warning/rapid response systems can be rapidly deployed in the field. In such cases, the deployed instruments could serve a number of functions, such as 1. implementing a threshold‐based on‐site early warning system (OSEWS) for infrastructure; 2. monitoring the structural response, and its changes, of buildings and infrastructure in real time during the aftershock sequence; 3. allowing the assessment of the expected damage to nearby structures soon after an aftershock’s occurrence; 4. allowing the overall expected damage to a target structure during the aftershock sequence to be estimated; and 5. validating damage forecasts determined by probabilistic approaches (or others) and updating the fragility curves based on recorded ground motion. A recent important development in this direction is the Community Seismic Network approach and the Quake‐Catcher Network in California, U.S.A., based on the installation by community volunteers of low‐cost accelerometers in houses and buildings (Clayton et al. , 2011; Kohler et al. , 2013). Within the …