Surface Displacement Measurement from Remote Sensing Images

7Remote Sensing of the Earthquake Deformation Cycle

Mathilde MARCHANDON¹, Tim J.WRIGHT² and James HOLLINGSWORTH¹

¹ISTerre, Grenoble, France

²COMET, University of Leeds, UK

7.1. Introduction

Our most basic understanding of the earthquake deformation cycle comes from the theory of the elastic rebound elaborated by Reid (1910) after the 1906 San Francisco earthquake. As tectonic plates slowly move, elastic strain is accumulated on faults. When the accumulated strain is large enough to overcome the fault strength, all the strain is suddenly released by a sudden slip on the fault, producing an earthquake. Fault slip induces displacements at the ground surface that can be measured and used to better understand earthquake processes. Displacements can also be measured during the long “inter-seismic” buildup to earthquakes and the rapid “post-seismic” transients that follow many earthquakes.

Before the advent of space-based geodesy, surface displacement measurements could only be made at sparse locations and only in regions where a surveyed network was in place before the earthquake. Thirty years ago, the development of the interferometric synthetic aperture radar (InSAR) technique revolutionized our ability to measure the surface displacement fields of earthquakes. By comparing the phase of RADAR satellite images, InSAR can precisely measure the surface displacements of earthquakes with nearly complete spatial continuity. Since its first application for measuring the coseismic displacements ...