ISSN:
1420-9136
Keywords:
Crustal anomalies
;
crustal structure
;
magma bodies
;
Mammoth Lakes
;
pre-S phase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract Observations of several hundredexotic seismic phases (herein defined) recorded in and near Long Valley caldera, California, have been cataloged. I discuss here four classes of such seismograms: (1) seismograms with missing S-waves, (2) seismograms with an unusual pre-S phase seen at the single station SLK northwest of the caldera, (3) seismograms with a strong pre-S phase as seen at a number of stations south of the caldera, and (4) a very large, very slow (〈2 km/sec) post-S phase seen at the single station Benton. For each of these phenomena, it is not yet possible to pin down an unambiguous and unique theoretical explanation. However, for each, I have presented an explanation, summarizing current thinking, which involves nonplanar reflections/refractions within shallow-crustal anomalous zones which can reasonably be supposed to be magma bodies. If these explanations are even partially pertinent, then the investigation of exotic phases near complex regions like Mammoth Lakes and other volcanic areas is potentially a way to bring precise resolving power on the nature and geometry of local crustal anomalies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00879365
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