Session IV:
Simulation of earthquake repture, wave propagation and standard models for different tectonic settings

2nd ACES (APEC Cooperation for Earthquake Simulation) Workshop in Japan

Spatial Dependence of Acceleration Spectra in Elastodynamic Simulations of Earthquakes: Severely Increased Shaking away from the Epicenter
Bruce Shaw


We examine the radiated waves emitted by events on a model fault. The model produces a complex sequence of events with a wide range of sizes from a frictional instability. The spontaneous events emit a rich spectrum of radiated waves as they rupture through the complex stress field left by previous events. We quantify the radiation by measuring the acceleration spectra, averaging over events of a similar size, and then examine the spatial and magnitude dependence of the average acceleration spectra. For the largest events, we see a striking signal: for a given distance from the fault, as one moves parallel to the fault, away from the epicenter the average spectral acceleration actually Increases. These increases can be as high as a factor of 10 or more. We discuss the physical origin of this effect in the model, and point out the significance for earthquake hazard.

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