Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952
Benioff's suggestion that the 58-min period sinusoidal oscillation found on a Pasadena strain seismogram after the Kamchatka earthquake of November 4, 1952 may represent the earth's gravest normal mode is re-examined in terms of a slow large-scale post-seismic deformation. The mechanism an...
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ftcaltechauth:oai:authors.library.caltech.edu:54918 2023-05-15T16:58:51+02:00 Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 Kanamori, Hiroo 1976-01 https://authors.library.caltech.edu/54918/ https://resolver.caltech.edu/CaltechAUTHORS:20150218-074620986 unknown Elsevier Kanamori, Hiroo (1976) Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952. Physics of the Earth and Planetary Interiors, 11 (3). pp. 216-226. ISSN 0031-9201. doi:10.1016/0031-9201(76)90066-2. https://resolver.caltech.edu/CaltechAUTHORS:20150218-074620986 <https://resolver.caltech.edu/CaltechAUTHORS:20150218-074620986> Article PeerReviewed 1976 ftcaltechauth https://doi.org/10.1016/0031-9201(76)90066-2 2021-11-11T19:02:49Z Benioff's suggestion that the 58-min period sinusoidal oscillation found on a Pasadena strain seismogram after the Kamchatka earthquake of November 4, 1952 may represent the earth's gravest normal mode is re-examined in terms of a slow large-scale post-seismic deformation. The mechanism and the seismic moment of the main shock of the Kamchatka earthquake are determined by using the amplitude and the initial phase of G_2 and R_2 recorded at Pasadena and R_6 recorded at Palisades. By constraining the dip angle and the strike of the fault at 30° (towards NW) and N34°E, respectively, on the basis of the geometry of the Benioff zone, the slip angle is determined as 110° which represents 74% thrust and 26% right-lateral faulting. The direction of the slip angle agrees with the slip direction of the Pacific plate. A seismic moment of 3.5 · 10^(29) dyn cm is obtained. If a fault area of 650 · 200 km^2 is assumed, an average dislocation of 5 m is obtained. Spectral analyses of the Pasadena strain records show that the 58-min sinusoidal oscillation in fact consists of a spectral peak near 54 min which is very close to the _0S_2 mode and other high-frequency peaks which can be correlated to the earth's normal modes. The records from two independent recording galvanometers correlate with each other very well, indicating that the recorded oscillation represents a real strain and not instrumental noise. The phase relation between the NS and EW components is consistent with the strain field associated with _0S_2 mode. Although these results provide positive evidence for a slow post-seismic deformation, the cause of the abrupt termination of the oscillation and the excitation mechanism remain unresolved. Article in Journal/Newspaper Kamchatka Caltech Authors (California Institute of Technology) Pacific Palisades ENVELOPE(159.167,159.167,-82.833,-82.833) Physics of the Earth and Planetary Interiors 11 3 216 226 |
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Caltech Authors (California Institute of Technology) |
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description |
Benioff's suggestion that the 58-min period sinusoidal oscillation found on a Pasadena strain seismogram after the Kamchatka earthquake of November 4, 1952 may represent the earth's gravest normal mode is re-examined in terms of a slow large-scale post-seismic deformation. The mechanism and the seismic moment of the main shock of the Kamchatka earthquake are determined by using the amplitude and the initial phase of G_2 and R_2 recorded at Pasadena and R_6 recorded at Palisades. By constraining the dip angle and the strike of the fault at 30° (towards NW) and N34°E, respectively, on the basis of the geometry of the Benioff zone, the slip angle is determined as 110° which represents 74% thrust and 26% right-lateral faulting. The direction of the slip angle agrees with the slip direction of the Pacific plate. A seismic moment of 3.5 · 10^(29) dyn cm is obtained. If a fault area of 650 · 200 km^2 is assumed, an average dislocation of 5 m is obtained. Spectral analyses of the Pasadena strain records show that the 58-min sinusoidal oscillation in fact consists of a spectral peak near 54 min which is very close to the _0S_2 mode and other high-frequency peaks which can be correlated to the earth's normal modes. The records from two independent recording galvanometers correlate with each other very well, indicating that the recorded oscillation represents a real strain and not instrumental noise. The phase relation between the NS and EW components is consistent with the strain field associated with _0S_2 mode. Although these results provide positive evidence for a slow post-seismic deformation, the cause of the abrupt termination of the oscillation and the excitation mechanism remain unresolved. |
format |
Article in Journal/Newspaper |
author |
Kanamori, Hiroo |
spellingShingle |
Kanamori, Hiroo Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 |
author_facet |
Kanamori, Hiroo |
author_sort |
Kanamori, Hiroo |
title |
Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 |
title_short |
Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 |
title_full |
Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 |
title_fullStr |
Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 |
title_full_unstemmed |
Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952 |
title_sort |
re-examination of the earth's free oscillations excited by the kamchatka earthquake of november 4, 1952 |
publisher |
Elsevier |
publishDate |
1976 |
url |
https://authors.library.caltech.edu/54918/ https://resolver.caltech.edu/CaltechAUTHORS:20150218-074620986 |
long_lat |
ENVELOPE(159.167,159.167,-82.833,-82.833) |
geographic |
Pacific Palisades |
geographic_facet |
Pacific Palisades |
genre |
Kamchatka |
genre_facet |
Kamchatka |
op_relation |
Kanamori, Hiroo (1976) Re-examination of the earth's free oscillations excited by the Kamchatka earthquake of November 4, 1952. Physics of the Earth and Planetary Interiors, 11 (3). pp. 216-226. ISSN 0031-9201. doi:10.1016/0031-9201(76)90066-2. https://resolver.caltech.edu/CaltechAUTHORS:20150218-074620986 <https://resolver.caltech.edu/CaltechAUTHORS:20150218-074620986> |
op_doi |
https://doi.org/10.1016/0031-9201(76)90066-2 |
container_title |
Physics of the Earth and Planetary Interiors |
container_volume |
11 |
container_issue |
3 |
container_start_page |
216 |
op_container_end_page |
226 |
_version_ |
1766050963429261312 |