NEHRP Clearinghouse

hypoDD: A Program to Comput Double-Difference Hypocenter Locations (hypoDD Version 1.0 - 03/2001).
Waldhauser, F.
January 2001, 30 p.
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HypoDD is a Fortran computer program package for relocating earthquakes with the double-difference algorithm of Waldhauser and Ellsworth (2000). This document provides a brief introduction into how to run and use the programs ph2dt and hypoDD to compute double-difference (DD) hypocenter locations. It gives a short overview of the DD technique, discusses the data preprocessing using ph2dt, and leads through the earthquake relocation process using hypoDD. The appendices include the reference manuals for the two programs and a short description of auxiliary programs and example data. Some minor subroutines are presently in the c language, and future releases will be in c. Earthquake location algorithms are usually based on some form of Geigers method, the linearization of the travel time equation in a first order Taylor series that relates the difference between the observed and predicted travel time to unknown adjustments in the hypocentral coordinates through the partial derivatives of travel time with respect to the unknowns.
Data weighting; Error assessments; Output files; HypoDD; Double-difference algorithms; Utility programs; Earthquakes; Input files; Installation; Hypocenter locations; Epicenters; Syntax; Algorithms; Fortran computer program packages; Earthquake relocation; Data selection; Event clustering