Earthquake System Science: Potential for Seismic Risk Reduction

Abstract

Abstract. Earthquakes in megacities such as Tehran and Los Angeles pose huge risks that could jeopardize national prosperity and social welfare. Quantifying urban seismic risk is a di cult problem because it requires detailed knowledge of the natural and the built environments, as well as an understanding of both earthquake and human behaviors. Risk assessments can be improved through international collaborations that combine the expertise of earthquake scientists and engineers. The most e ective strategies are seismic safety engineering, enforced through stringent building codes and disaster preparations informed by realistic scenarios of large earthquake cascades. These strategies rely on the ability to forecast earthquakes and their e ects and to monitor earthquake cascades in near real time. The practical problems of risk reduction are, thus, coupled to the basic problems of earthquake system science: the interseismic dynamics of fault systems and the coseismic dynamics of fault rupture and groundmotion excitation. In the United States, the Southern California Earthquake Center (SCEC) coordinates an extensive research program in earthquake system science, which includes major e orts to improve time-dependent earthquake rupture forecasts through better understanding of earthquake predictability and to develop attenuation relationships that correctly model the physics of seismic wave propagation. Earthquake system science relies on the premise that detailed studies of fault systems in di erent regions can be synthesized into a generic understanding of earthquake phenomena. Achieving such a synthesis will depend on international partnerships that facilitate the development and comparison of well-calibrated regional models, and it will require the deployment of a cyberinfrastructure that can facilitate the creation and ow of information required to predict earthquake behavior. In the not-too-distant future, we will be able to incorporate much more physics into seismic hazard and risk analysis through physics-based, system-level simulations.