The Southern California Earthquake Center, Phase 4 (SCEC4): Tracking Earthquake Cascades

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This cooperative agreement funds the Southern California Earthquake Center (SCEC) for the 5-year period from 1 Feb 2012 to 31 Jan 2017 (SCEC4). The Center is a large consortium of institutions with a national, and increasingly worldwide, distribution that coordinates basic research in earthquake science using Southern California as its principal natural laboratory. The region is data-rich and, with an urbanized population exceeding 20 million, comprises the lion's share of national earthquake risk. SCEC's theme of earthquake system science emphasizes the connections between information gathering by sensor networks, fieldwork, and laboratory experiments; knowledge formulation through physics-based, system-level modeling; improved understanding of seismic hazard; and actions to reduce earthquake risk and promote community resilience. Earthquakes emerge from complex, multiscale interactions within active fault systems that cascade as chaotic chain reactions through the natural and built environments. The current 5-year research program is developing the geoscience required to track earthquake cascades through time-dependent seismic hazard analysis, and it is moving this science forward through highly integrated collaborations that are coordinated across scientific disciplines and research institutions and enabled by high-performance computing and advanced information technology. The collaborations are focused on six fundamental problems of earthquake physics: (a) Stress transfer from plate motion to crustal faults: long-term fault slip rates. (b) Stress-mediated fault interactions and earthquake clustering: evaluation of mechanisms. (c) Evolution of fault resistance during seismic slip: scale-appropriate laws for rupture modeling. (d) Structure and evolution of fault zones and systems: relation to earthquake physics. (e) Causes and effects of transient deformations: slow slip events and tectonic tremor. (f) Seismic wave generation and scattering: prediction of strong ground motions. These problems are interrelated and require an interdisciplinary, multi-institutional approach. The SCEC4 interdisciplinary research initiatives include special fault study areas, which are distributed throughout Southern California; the development of a community geodetic model for Southern California, which combines GPS and InSAR data; and a community stress model, which is a new platform for integrating the various constraints on earthquake-producing stresses.The Center is translating basic research into practical products for reducing risk and improving community resilience. The SCEC4 program aims to transform long-term seismic hazard analysis into a physics-based science. It is helping the USGS and other responsible government agencies develop operational earthquake forecasting into a capability that can provide authoritative information about the time dependence of seismic hazards to help communities prepare for potentially destructive earthquakes. It is providing the science to enable earthquake early warning -- advanced notification that an earthquake is underway and predictions of when strong shaking will arrive at more distant sites -- and to improve the delivery of post-event information about strong ground motions and secondary hazards.SCEC's Communication, Education and Outreach program is built around the theme of creating an earthquake and tsunami resilient California. Through ShakeOut exercises, it is preparing individuals and organizations to respond to changing seismic hazards and introducing them to the new technologies of operational earthquake forecasting and earthquake early warning. It is educating people of all ages -- in California, across the country, and internationally -- about earthquakes, and motivating them to become prepared. A K-14 earthquake education initiative seeks to improve earth science education and school earthquake safety. SCEC's experiential learning and career advancement program provides a diverse cross-section of students and early-career scientists with research opportunities and networking to encourage and sustain careers in science and engineering.