A Source Model for the 1975 Pocatello Valley Earthquake,
Abstract
A source model is determined for the 1975 Pocatello Valley earthquake by fitting synthetic seismograms to the observations of long and short period P waves. The focal plane is constrained by a focal mechanism solution from P wave first motion observations and by the aftershock locations. The event is characterized by normal faulting on a plane dipping 39 deg to the west with a large left-lateral strike-slip component. Two source models were used for the synthetic seismogram computations. Parameter variations to fit the observations were done with the analytical model of Archambeau and Minster. Two three-dimensional finite difference simulations of earthquake faulting were done on the ILLIAC 4 computer. Comparing the results to the analytical model, we interpret the derived parameters in terms of the physics of faulting. We conclude that variable rupture velocity/variable stress drop effects are required to simultaneously fit the long and short period data. Source directivity effects are important with unilateral rupture toward the free surface being required to fit the data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 28, 1978
- Accession Number
- ADA068568
Entities
People
- J. T. Cherry
- S. M. Day
- T. C. Bache
- T. G. Barker