Accession Number : AD0803337

Title :   MAGNITUDE STUDIES CONDUCTED UNDER PROJECTS VT/5054 AND VT/5055.

Descriptive Note : Technical rept.

Corporate Author : GEOTECH GARLAND TX

Personal Author(s) : Swanson, Jack G.

Report Date : 20 JUL 1966

Pagination or Media Count : 34

Abstract : Station magnitude corrections are developed and the possibility of azimuthal dependence of station correction is investigated by means of a statistical model for Blue Mountains Seismological Observatory, Cumberland Plateau Seismological Observatory, Tonto Forest Seismological Observatory, Uinta Basin Seismological Observatory, and Wichita Mountains Seismological Observatory. Azimuthal dependence of station correction is not established at any of the observatories. Refined distance-depth magnitude correction factors are developed for epicentral distances between 20 degrees and 90 degrees for depths between 50 kilometers and 200 kilometers and for distances between 0 degrees and 110 degrees for depths less than 50 kilometers. Existing distance-depth correction factors are found to be too large for distances less than 15 degrees and too small for distances greater than 100 degrees for depths less than 50 kilometers. Station magnitude corrections are also developed from magnitude frequency distributions and are found to agree within 0.06 magnitude unit with station corrections determined from the statistical model. The mean observatory magnitude, computed both as the arithmetic mean of observatory magnitudes and as the logarithm of the arithmetic mean of observatory normalized amplitudes, is compared to the USC+GS magnitude.

Descriptors :   *POSITION FINDING), (*SEISMOLOGICAL STATIONS, SEISMIC WAVES, EPICENTERS, CORRECTIONS, AZIMUTH, NETWORKS, MATHEMATICAL MODELS, SIGNAL-TO-NOISE RATIO, EARTHQUAKES, INTENSITY, ANALYSIS OF VARIANCE, LEAST SQUARES METHOD, GEODESICS.

Subject Categories : Geodesy
      Seismology

Distribution Statement : APPROVED FOR PUBLIC RELEASE