Seismic Source Functions and Attenuation from Local and Teleseismic Observations of the NTS Events JORUM and HANDLEY
Abstract
This technical report discusses the determination of an accurate source description for Jorum and the results are extended to the teleseismic observations of Handley. The basic data set used to model the source are the strong motion accelerograms collected by Peppin (1964) at a distance of 8 kilometers from the test. At this distance the initial seismic energy represents diving rays and the observations are suitable for comparison with more distant regional and teleseismic observations. Using a modified Von Seggern and Blandford (1972) source representation, and including near-field terms, it has been possible to obtain a source function which not only acurately models the close-in records but alo matches teleseismic observations. After defining the near-field explosion source description, a t* for teleseismic observations is calculated. For WWSSN short and long period observations of these events, we obtain an average t* of about 1.3 for compressional waves with a scatter of about plus or minus 0.2. There are systematic azimuthal trends in the observed t* values which are not strongly correlated with the Silent Canyon caldera but may be correlated with upper mantle structure northeast of NTS. These data do not rule out systematic receiver function bias as the cause of the amplitude variations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 08, 1979
- Accession Number
- ADA072433
Entities
People
- David M. Hadley