High Frequency S-Wave Scaling to 500 km,
Abstract
A systematic effort at understanding high frequency ground motion of regional S and Lg phases is undertaken to develop stable, transportable methods for regional magnitude scale calibration. Aspects of the study are as follows: (a) an evaluation of the limitations of the coda normalization technique as a robust method of reducing effects of unknown source and site and instrument effects in determining the distance dependence of peak ground motion with distance, (b) the simultaneous determination of source, site and distance function, (c) an evaluation of the relation between the coda Q parameter and the frequency dependent peak motion distance function, (d) empirical determination of the relation between coda excitation and peak motion excitation, and (e) an attempt at modeling observations of peak motions in terms of wave propagation in crustal models, with the corresponding determination of the necessary detail of those models. The results of studying ground motion in the 1 - 16 Hz frequency band in the New Madrid region of the central, and the Southern Great Basin regions of the United States show that significant regionally dependent crustal structure control of the distance dependence occurs in the 0-200 km range. Since this will affect the quantification of source properties from distant observations, one must worry about more than variations in average crustal Q. Crustal and upper mantle structure are also very important. Data processing of other data sets is beginning since the necessary software has been validated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 14, 1995
- Accession Number
- ADP204449
Entities
People
- R. B. Herrmann
Organizations
- Saint Louis University