Optimal Seismic Network Density for Earthquake Early Warning: A Case Study from California

Earthquake Early Warning Systems (EEWS) rapidly detect the initiation of earthquakes and issue warning alerts of possible forthcoming ground shaking. Currently, public warning systems exist in Japan and Mexico, and the development of other EEWS are ongoing in many other regions of the world including the U.S. West Coast (Allen et al. , 2009). Probing the way business and the public actively use early warning information is a crucial factor in early warning system design (Aktas et al. , 2010; Kuyuk, 2010; Kuyuk et al. , 2008; Nakamura, 1988). During the 2011 M  9 Tohoku‐oki, Japan, earthquake, an earthquake warning was successfully issued although the magnitude was underestimated (Hoshiba et al. , 2011). To determine the usefulness of the alerts, the Japan Meteorological Agency (JMA) conducted a public survey (JMA, 2012). Results from the ∼2000 people who answered the survey indicated that most people want two main pieces of information from an EEW message: the time when strong shaking is expected to begin at their location and the estimated shaking intensity. The survey also showed that although the JMA warnings provide additional information about the earthquake location, magnitude, and depth, people are less interested in this information and more interested in the potential impending dangers the large earthquake might cause at their location.Many factors contribute to the time between the issued earthquake warning and the subsequent ground shaking at a given location. In this paper, we refer to this period as the warning time. The warning‐time duration is dictated by many factors, of which the most important are the proximity of stations to the earthquake epicenter, data telemetry speed, data processing time, and the time needed to disseminate the warning. Once an …