A study of amplitude variations and m sub b bias at lasa subarrays. Technical report
LASA subarray amplitude anomalies are investigated using 395 medium-sized events, distributed in ten azimuthally divided sectors. Although LASA magnitudes, when averaged over all azimuths, are only slightly biased relative to NEIS magnitudes, the amount of bias varies with azimuth and subarray, suggesting that a simple station correction for m sub b bias is not adequate. In addition, fluctuations among LASA subarrays are about 0.15 in standard deviation, even when these magnitudes are calibrated in sectors. Details of such fluctuations are explained in part by local crustal and upper-mantle heterogeneities under LASA. The amplitude anomalies are linearly related to the amount of travel-time anomalies in each sector, implying that both effects are due to crustal focussing.
- Research Organization:
- Teledyne Geotech, Alexandria, VA (USA). Seismic Data Lab.
- OSTI ID:
- 5974758
- Report Number(s):
- AD-A-065319
- Country of Publication:
- United States
- Language:
- English
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ATTENUATION
DATA ACQUISITION
DETECTION
EXPLOSIONS
MEASURING INSTRUMENTS
SCATTERING
SEISMIC ARRAYS
SEISMIC DETECTION
SEISMIC WAVES
UNDERGROUND EXPLOSIONS
VARIATIONS