Data Transfer File Formats for Earthquake Simulators

Abstract

Online Material: Specifications for the standard earthquake simulator input and output files. An earthquake simulator is a computer program that simulates a long sequence of earthquakes, which may range from tens of thousands of years up to millions of years. Different simulator codes have different input requirements, but in general the inputs to a simulator program include the fault system geometry, fault slip rates, rake angles, friction parameters, initial stress state, and elastic parameters. The output from a simulator program is a list of events, each of which is characterized by time, location, magnitude, rupture area, mean slip, stress change, and, optionally, a map that shows the distribution of slip over the fault surface. It is challenging to demonstrate that an earthquake simulator program is reliable, in the sense that it produces a simulated history whose statistical properties are similar to the properties of real earthquake sequences. The Southern California Earthquake Center (SCEC) Earthquake Simulator Comparison Project addresses this challenge by comparing the results from five different earthquake simulators with each other and, to the extent possible, with what is known about real earthquakes (Tullis et al. , 2012a). The five simulators are independently developed, so agreement among the simulators can provide some confidence in their reliability. To carry out the comparison, it is necessary for each simulator code to receive precisely the same inputs. It is also necessary for each simulator code to generate output in the same format, so that output from all the codes can be analyzed by the same set of statistical tools. We have achieved this by designing standard file formats for transferring data into and out of simulator codes. Although the standard files are formatted as ASCII text and are human‐readable, they are intended primarily for transferring data from one computer program to another. …