Observation and inversion of seismo-acoustic waves in a complex arctic ice environment
The propagation of low frequency seismo-acoustic waves in the Arctic Ocean ice canopy is examined through the analysis of hydrophone and geophone data sets collected in 1987 at an ice camp designated PRUDEX in the Beaufort Sea. Study of the geophone time series generated by under-ice explosive deton...
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ftnavalpschool:oai:calhoun.nps.edu:10945/28416 2024-06-09T07:44:05+00:00 Observation and inversion of seismo-acoustic waves in a complex arctic ice environment Miller, Bruce Edward NA Ocean Engineering 1990 98 p.: ill. application/pdf https://hdl.handle.net/10945/28416 en_US eng ocn312746321 https://hdl.handle.net/10945/28416 This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States. Geophone Thesis 1990 ftnavalpschool 2024-05-15T00:26:04Z The propagation of low frequency seismo-acoustic waves in the Arctic Ocean ice canopy is examined through the analysis of hydrophone and geophone data sets collected in 1987 at an ice camp designated PRUDEX in the Beaufort Sea. Study of the geophone time series generated by under-ice explosive detonations reveals not only the expected longitudinal and flexural waves in the ice plate, but also an unexpected horizontally-polarized transverse (SH) wave arriving at a higher amplitude than the other wave types. The travel paths of all three observed wave types are found to be refracted in the horizontal plane along a line coincident with a known ridge separating the ice canopy locally into two distinct half-plates, the first of thin first year ice and the second of thicker multi-year ice. The origin of the SH wave appears to be near the detonation and not associated with the interaction of longitudinal, flexural or waterborne waves with the ridge line. The need to determine the exact location of each detonation from the received time series highlights the dramatic superiority of geophones over hydrophones in this application, as does the ability to detect the anomalous SH waves and the refracted ray paths, neither of which are visible in the hydrophone data. Inversion of the geophone data sets for the low frequency elastic parameters of the ice is conducted initially by treating the ice as a single homogeneous isotropic plate to demonstrate the power of SAFARI numerical modeling in this application. A modified stationary phase approach is then used to extend SAFARI modeling to invert the data sets for the elastic parameters of the tow ice half-plates simultaneously. The compressional/shear bulk wave speeds estimated in the half-plates, 3500/1750 m/s in the multi-year ice and 3000/1590 m/s in the new ice, are comparable to previously obtained values; however, the compressional/shear attenuation values in the tow half-plates, 1.0/2.99 dB/[Lamda] and 1.0/2.67 dB/[Lamda], respectively, are somewhat greater than ... Thesis Arctic Arctic Ocean Beaufort Sea Naval Postgraduate School: Calhoun Arctic Arctic Ocean |
institution |
Open Polar |
collection |
Naval Postgraduate School: Calhoun |
op_collection_id |
ftnavalpschool |
language |
English |
topic |
Geophone |
spellingShingle |
Geophone Miller, Bruce Edward Observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
topic_facet |
Geophone |
description |
The propagation of low frequency seismo-acoustic waves in the Arctic Ocean ice canopy is examined through the analysis of hydrophone and geophone data sets collected in 1987 at an ice camp designated PRUDEX in the Beaufort Sea. Study of the geophone time series generated by under-ice explosive detonations reveals not only the expected longitudinal and flexural waves in the ice plate, but also an unexpected horizontally-polarized transverse (SH) wave arriving at a higher amplitude than the other wave types. The travel paths of all three observed wave types are found to be refracted in the horizontal plane along a line coincident with a known ridge separating the ice canopy locally into two distinct half-plates, the first of thin first year ice and the second of thicker multi-year ice. The origin of the SH wave appears to be near the detonation and not associated with the interaction of longitudinal, flexural or waterborne waves with the ridge line. The need to determine the exact location of each detonation from the received time series highlights the dramatic superiority of geophones over hydrophones in this application, as does the ability to detect the anomalous SH waves and the refracted ray paths, neither of which are visible in the hydrophone data. Inversion of the geophone data sets for the low frequency elastic parameters of the ice is conducted initially by treating the ice as a single homogeneous isotropic plate to demonstrate the power of SAFARI numerical modeling in this application. A modified stationary phase approach is then used to extend SAFARI modeling to invert the data sets for the elastic parameters of the tow ice half-plates simultaneously. The compressional/shear bulk wave speeds estimated in the half-plates, 3500/1750 m/s in the multi-year ice and 3000/1590 m/s in the new ice, are comparable to previously obtained values; however, the compressional/shear attenuation values in the tow half-plates, 1.0/2.99 dB/[Lamda] and 1.0/2.67 dB/[Lamda], respectively, are somewhat greater than ... |
author2 |
NA Ocean Engineering |
format |
Thesis |
author |
Miller, Bruce Edward |
author_facet |
Miller, Bruce Edward |
author_sort |
Miller, Bruce Edward |
title |
Observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
title_short |
Observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
title_full |
Observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
title_fullStr |
Observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
title_full_unstemmed |
Observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
title_sort |
observation and inversion of seismo-acoustic waves in a complex arctic ice environment |
publishDate |
1990 |
url |
https://hdl.handle.net/10945/28416 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Beaufort Sea |
genre_facet |
Arctic Arctic Ocean Beaufort Sea |
op_relation |
ocn312746321 https://hdl.handle.net/10945/28416 |
op_rights |
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States. |
_version_ |
1801372886250815488 |