Modeling regional seismic waves. Final report, 24 Mar 89-31 Jul 91
This study can be divided into three main topics: modeling regional broad-band seismograms from the Imperial Valley to Pasadena, Determining surface wave magnitudes for NTS events using regional data, and waveform modeling to determine depth of earthquakes in Tibet leading to new origin times and a better estimation of P(sub n) and S(sub n) velocities. In section 1, broad-band wave propagation along a corridor from Imperial Valley to Pasadena, California is addressed. The path consists of 50 km of slow basin structure with a shallow moho followed by 250 km of relatively normal Southern California structure approaching Pasadena. In section 2, surface wave magnitudes for 112 Nevada Test Site (NTS) explosions from a data set of regional long-period seismograms from North American stations are calculated. In order to utilize the newer regional stations (Delta < 25 deg), a new method for determining M(sub s) has been developed which employs synthetic seismograms to establish a relationship between the amplitude of the regional Airy phase, or Rayleigh pulse, of the data and an associated surface wave magnitude, based on conventional M(sub s) determinations, calculated from a synthetic seismogram propagated to 40 deg. In section 3, a note on the relocation of the Tibetan earthquake is presented. Present ISC locations for earthquakes beneath Tibet indicates a random distribution of events down to a depth of about 50 km. A detained investigation of the Tibetan earthquakes, with magnitudes greater than 5.5 from 1964 to 1986, yields a distinctly different picture.
- Research Organization:
- California Inst. of Tech., Pasadena, CA (United States). Seismological Lab.
- OSTI ID:
- 5643404
- Report Number(s):
- AD-A-246894/0/XAB; CNN: F19628-89-K-0028
- Country of Publication:
- United States
- Language:
- English
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58 GEOSCIENCES
580000 -- Geosciences
ASIA
CALIFORNIA
DEPTH
DETECTION
DEVELOPED COUNTRIES
DIMENSIONS
EARTHQUAKES
EXPLOSIONS
FEDERAL REGION IX
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
NATIONAL ORGANIZATIONS
NEVADA
NEVADA TEST SITE
NORTH AMERICA
NUCLEAR EXPLOSIONS
RAYLEIGH WAVES
SEISMIC ARRAYS
SEISMIC DETECTION
SEISMIC DETECTORS
SEISMIC EVENTS
SEISMIC SURFACE WAVES
SEISMIC WAVES
SEISMICITY
SEISMOGRAPHS
SEISMOLOGY
TIBET
US DOE
US ORGANIZATIONS
USA
WAVE FORMS
WAVE PROPAGATION