CRUSTAL STUDIES. CONTINUATION OF BASIC RESEARCH IN CRUSTAL STUDIES
TEXAS INSTRUMENTS INC DALLAS SCIENCE SERVICE DIV
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Crustal models were constructed for TFO in Arizona and LASA in Montana. A long period event recorded at TFO with epicenter in Southern California was time partitioned and Rayleigh wave dispersion in the frequency range of 0.025 to 0.175 was derived. By use of these data, the adequacy of the TFO model crust was substantiated at low frequencies by a direct comparison of theoretical and experimental dispersion curves. The mode separation studies include the design and application of mode separation processors to separate the M21 mode from the Rayleigh mode in the frequency range 0.0 to 0.25 cps by use of field data. An analog model having a crustal layer with an abrupt thickness change 3 cm to 5 cm was used for scattering studies. The source was located on the surface of the model. The dominant leaking mode of propagation in the thin end of the model is PL22. Theory predicts that this energy is primarily scattered into the leaking mode PL23 in the 5-cm end. There is also some evidence of wave propagation which is not readily explained in terms of modes. Filtering techniques were used to analyze energy scattered by small surface irregularities. The primary scattered energy is a reflection of a portion of the incident Rayleigh wave.
- Geology, Geochemistry and Mineralogy
- Seismic Detection and Detectors