|Title||Self-contained local broadband seismogeodetic early warning system: Detection and location|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Goldberg D.E, Bock Y|
|Journal||Journal of Geophysical Research-Solid Earth|
|Type of Article||Article|
|Keywords||1-hz gps; accelerometers; algorithm; california; displacement; early warning; earthquake; earthquake detection; hypocenter; motion; picking; records; seismogeodesy|
Earthquake and local tsunami early warning is critical to mitigating adverse impacts of large-magnitude earthquakes. An optimal system must rely on near-source data to maximize warning time. To this end, we have developed a self-contained seismogeodetic early warning system employing an optimal combination of high-frequency information from strong-motion accelerometers and low-frequency information from collocated Global Navigation Satellite Systems (GNSS) instruments to estimate real-time displacements and velocities. Like GNSS, and unlike broadband seismometers, seismogeodetic stations record the full waveform, including static offset, without clipping in the near-field or saturating for large magnitude earthquakes. However, GNSS alone cannot provide a self-contained system and requires an external seismic trigger. Seismogeodetic stations detect Pwave arrivals with the same sensitivity as strong-motion accelerometers and thus provide a stand-alone system. We demonstrate the utility of near-source seismogeodesy for event detection and location with analysis of the 2010 M(w)7.2 El Mayor-Cucapah, Baja, California and 2014 M(w)6.0 Napa, California strike-slip events, and the 2014 M(w)8.2 Iquique, Chile subduction zone earthquake using observatory-grade accelerometers and GPS data. We present lessons from the 2014 M(w)4.0 Piedmont, California and 2016 M(w)5.2 Borrego Springs, California earthquakes, recorded by our seismogeodetic system with Micro-Electro Mechanical System (MEMS) accelerometers and GPS data and reanalyzed retrospectively. We conclude that our self-contained seismogeodetic system is suitable for early warning for earthquakes of significance (>M5) using either observatory-grade or MEMS accelerometers. Finally, we discuss the effect of network design on hypocenter location and suggest the deployment of additional seismogeodetic stations for the western U.S.
We have described the elements of our seismogeodetic earthquake and tsunami early warning system, where the detection and location algorithms initiate higher-order products such as earthquake magnitude scaling, and centroid moment tensor and finite fault slip solutions. These higher-order products can then be used as input to local tsunami prediction and modeling algorithms. The seismogeodetic method allows for a self-contained earthquake early warning system that utilizes the best qualities of seismic and geodetic approaches to earthquake and local tsunami early warning.