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Hypocentral parameters; dipping interfaces; sequential unconstrained optimization; penalty function approach; earthquakes

The paper describes an algorithm for estimating the hypocentral coordinates and origin time of local earthquakes when the wave speed model to be employed is a layered one with dipping interfaces. A constrained least-squared error problem has been solved using the penalty function approach, in conjunction with the sequential unconstrained optimization technique of Fiacco and McCormick. Joint confidence intervals for the computed parameters are estimated using the approach of Bard for nonlinear problems. These results show that when a hypocentre lies outside the array of recording stations and head waves from a dipping interface are involved, then its inclination must be taken into account for dip angles exceeding 5°.

Irene Sarkar¹ R Chander¹ K N Khattri¹ V K Gaur^{1 2}

1. Department of Earth Sciences, University of Roorkee, Roorkee - 247 667, India
2. National Geophysical Research Institute, Hyderabad - 500 007, India

Published

December 1987

Manuscript received

7 November 1986

Manuscript revised

14 December 1987