Open-File Report 2015-1028
AbstractWe present a two-dimensional system of generalized coordinates for use with geometrically complex fault ruptures that are neither straight nor continuous. The coordinates are a generalization of the conventional strike-normal and strike-parallel coordinates of a single straight fault. The presented conventions and formulations are applicable to a single curved trace, as well as multiple traces representing the rupture of branching faults or noncontiguous faults. An early application of our generalized system is in the second round of the Next Generation of Ground-Motion Attenuation Model project for the Western United States (NGA-West2), where they were used in the characterization of the hanging-wall effects. We further improve the NGA-West2 strike-parallel formulation for multiple rupture traces with a more intuitive definition of the nominal strike direction. We also derive an analytical expression for the gradient of the generalized strike-normal coordinate. The direction of this gradient may be used as the strike-normal direction in the study of polarization effects on ground motions. |
First posted February 10, 2015 For more information concerning the research in this report, contact: Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge. More information about viewing, downloading, and printing report files can be found here. |
Spudich, Paul and Chiou, Brian, 2015, Strike-parallel and strike-normal coordinate system around geometrically complicated rupture traces—Use by NGA-West2 and further improvements: U.S. Geological Survey Open-File Report 2015-1028, 20 p., https://dx.doi.org/10.3133/ofr20151028.
ISSN 2331-1258 (online)
Abstract
Introduction
Generalized Coordinate System for a Single Rupture Trace
Generalized Coordinate System for Multiple Rupture Traces
Strike-Normal Direction Defined by ∇T
Examples
Data and Resources
Acknowledgments
References