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Earthquake Early Warning for California

Earthquake Early Warning (EEW) is a method of rapidly identifying an earthquake in progress and transmitting alerts to nearby population centers before damaging ground shaking arrives.

The first few seconds of the initial P-wave arrivals at one or more stations are used to detect the event. A warning of imminent shaking can be used to activate automatic safety measures, such as slowing down trains, isolating sensitive factory equipment, or opening elevator doors. We envision the alerts will be sent directly to the public via cell phone, computer, television, or radio. The Berkeley Seismological Laboratory, together with its project partners, is collaborating to build a single, integrated, end-to-end system for testing Earthquake Early Warning in California.



Satellite map showing potential tremorscope station locations.
With a grant from the Moore Foundation, the BSL is installing TremorScope: four borehole and four surface stations positioned to record deep tremor along the San Andreas Fault in central California. Recently discovered tremors (gold stars) and the location of the proposed stations, whose instrumentation will be used to study the behavior of faulting in the deep crust.

Until recently, active fault zones were thought to deform via seismic earthquake slip in the upper, brittle section of the crust, and by steady, aseismic shear below. However, in the last few years, this view has been shaken by seismological observations of seismic tremor deep in the roots of active fault zones. First recognized on subduction zones in Japan and the Pacific Northwest, active tremor has also been found along a short section of the southeast San Andreas near Parkfield, CA—one of the most densely monitored fault segments in the world. This deep zone of activity is located right below the nucleation zone of the great 1857 Fort Tejon earthquake.


Map showing plate boundaries surrounding the Mendocino Triple Junction offshore of Northern California, dots for earthquake locations, beachball-like mechanism diagrams, and an evenly-spaced grid of plus signs. Four seismic stations are labeled.
For large earthquakes that may generate tsunamis, it is important to determine the size and type of faulting of the event rapidly. The BSL has developed a method to continuously scan an offshore region for earthquakes, and quickly determine their size and mechanism.

Improving Tsunami Warning

North of Cape Mendocino, CA lies the Cascadia Subduction Zone, capable of generating megaquakes far larger than the magnitude 8s possible on the San Andreas Fault and helping to make the coast of Northern California the most tsunami-prone area of the continental US. Initial early warnings for tsunamis are, more often than not, issued before the mechanism—thrust, strike-slip, or normal—of the potentially tsunamogenic earthquake is known. Since earthquake-induced tsunamis arise most often from the ocean bottom's response to a thrust (i.e., subduction) event, rapid determination of the mechanism is an important improvement upon the standard processing systems. Read more...



More research from the Berkeley Seismo Lab

The Global Seismology Research Group at UC Berkeley is a part of the Department of Earth and Planetary Science and our research focuses on structure and dynamics of the deep earth, from the crust to the inner core. We tackle theoretical wave propagation problems in complex 3D media, including forward modeling and tomographic inversion for elastic as well as anelastic structure. In order to better understand the chemical and thermal state of the mantle and the processes operating therein, we seek to apply the latest findings of the mineral physics community within the context of our seismic probing. We also study earthquake source mechanisms and scaling laws, as well as global seismic moment release and its relation to plate tectonics. One of our recent research directions concerns the Earth's "hum" and the insights it brings to ocean/atmosphere/solid earth interactions.

The Active Tectonics research group is part of the Department of Earth and Planetary Science and our research focuses on problems relating to fault zone processes and crustal deformation. We rely on geodetic measurements using GPS and InSAR, investigations of seismicity, examination of tectonic landscapes, and field mapping of geologic structures. Such observations can be used to constrain models of the first-order mechanics of an actively deforming region, such as the San Andreas fault system, the Sumatra-Andaman subduction zone, volcano deformation on the Big Island of Hawaii, or the India-Eurasia collision zone. Many of our efforts are focused on elucidating the various components of the earthquake cycle and related rheological properties of lithospheric materials. We also consider repeating micro-earthquakes and deeply seated non-volcanic tremors to improve our understanding of the behavior of shallow and deep fault zones, respectively. Our approach is interdisciplinary, integrating geodetic, geomorphic, geologic, and seismological observations along with theoretical modeling.

Richard Allen's research group is involved in many different areas of research. The Earth Imaging group uses a wide variety of seismological techniques to image 3D Earth structure in an effort to understand the dynamic processes responsible for deformation, volcanism and earthquakes at the Earth's surface. The Realtime Seismology group is interested in all aspects of rapid geophysical data characterization. The desire for realtime information is motivated by hazard mitigation objectives, and the development of such techniques drives fundamental research into earthquake source processes.

The more than 30 research studies in our latest Annual Report reflect the diverse research interests of our faculty, researchers, post-docs, and gradutate students.