Accession Number:

ADA193563

Title:

Body and Surface Wave Modeling of Observed Seismic Events Part 1.

Descriptive Note:

Semiannual technical rept. no. 2,

Corporate Author:

CALIFORNIA INST OF TECH PASADENA SEISMOLOGICAL LAB

Report Date:

1987-05-11

Pagination or Media Count:

162.0

Abstract:

The main topics are 1 the effects of lateral structure, in particular, complicated sedimentary basins on the propagation and amplication of seismic strong motion and 2 the effects of ocean continent transition zones on L sub g waves. 1 2-D finite difference techniques are used to model the seismic strong motions observed for the 1971 San Fernando earthquake. The finite difference seismograms show strong effects due to lateral variation in sediment thickness in the San Fernando valley and the Los Angeles basin. Using basin structure derived mostly from well logs and teleseismically determined source parameters, two dimensional SH and P-SV finite difference calculations reproduce the amplitude and duration of the strong motion velocities recorded across the Los Angeles and San Fernando basins for the period range 2-10 secs. The edges of basins nearest the seismic source show ground motion amplification up to a factor of three over the case without the basin, and tend to convert direct shear waves into Love and Rayleigh waves that travel within the basin. 2 The methods for Representation Theorem coupling of finite element or finite difference calculations and propagator matrix method calculations to produce a hybrid method for propagation of SH mode sum seismograms across paths that contain regions of non plane-layered structure are explained and developed.

Subject Categories:

  • Seismology
  • Geology, Geochemistry and Mineralogy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE