SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES
207 pages This dissertation details efforts to image the along-strike continuity of major seismic discontinuities in subduction zones using dense (<20 km spacing) arrays of seismometers. The seismic discontinuities were located using receiver-side P-to-S and P-to-P scattered phases from teleseism...
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ftcornelluniv:oai:ecommons.cornell.edu:1813/110805 2023-07-30T04:07:26+02:00 SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES Mann, Michael Everett Abers, Geoffrey Gazel, Esteban McLaskey, Greg Keranen, Kade 2021-12 application/pdf https://hdl.handle.net/1813/110805 http://dissertations.umi.com/cornellgrad:12819 https://doi.org/10.7298/hnw6-dw97 en eng Mann_cornellgrad_0058F_12819 http://dissertations.umi.com/cornellgrad:12819 https://hdl.handle.net/1813/110805 https://doi.org/10.7298/hnw6-dw97 Alaska Cascadia Receiver Function Seismology Subduction Wrangell Volcanic Field dissertation or thesis 2021 ftcornelluniv https://doi.org/10.7298/hnw6-dw97 2023-07-15T18:40:21Z 207 pages This dissertation details efforts to image the along-strike continuity of major seismic discontinuities in subduction zones using dense (<20 km spacing) arrays of seismometers. The seismic discontinuities were located using receiver-side P-to-S and P-to-P scattered phases from teleseismic (30°<epicentral distance<90°, Mw>~5) earthquake P waves. The time series of scattered phases are referred to as “receiver functions” (RFs) though they are slightly different from traditional RFs. Chapter 1 investigates the location and orientation of the subducting Juan de Fuca (JdF) Moho beneath Mount St. Helens (MSH) using RFs from a dense seismometer array that was deployed in a circular area around the volcano. Two-dimensional (2D) migration and three-dimensional (3D) common-conversion point (CCP) stacking imaging methods were used to reveal a continuous JdF slab at 68±2 km beneath MSH, which is the shallowest directly imaged subducting slab beneath an arc volcano in the world. Between 2016 and 2018, we deployed, serviced, and recovered 36 broadband seismometers in a dense array across the road system of southcentral Alaska, which provided the key data for Chapters 2 and 3. RFs from that array and two other dense seismometer deployments across southcentral Alaska were generated using an improved method that accounts for variations in surface geology. 2D migration of the RFs revealed the Yakutat terrane, an oceanic plateau, subducting down to at least 110-km depth on the eastern half of southcentral Alaska. 3D CCP stacking revealed a continuous LVZ atop the Yakutat terrane for over 450 km along strike, at depths <35 km. Chapter 3 describes the use of RF data from Chapter 2 and data from an older dense seismometer array across central Washington, USA, in estimating the thickness and the ratio of P wave velocity to S wave velocity (Vp/Vs) of the LVZ atop the subducting Yakutat terrane in Alaska and the JdF plate in Cascadia. Results show consistent estimates of Vp/Vs that are lower than those of ... Thesis Yakutat Alaska Cornell University: eCommons@Cornell |
institution |
Open Polar |
collection |
Cornell University: eCommons@Cornell |
op_collection_id |
ftcornelluniv |
language |
English |
topic |
Alaska Cascadia Receiver Function Seismology Subduction Wrangell Volcanic Field |
spellingShingle |
Alaska Cascadia Receiver Function Seismology Subduction Wrangell Volcanic Field Mann, Michael Everett SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES |
topic_facet |
Alaska Cascadia Receiver Function Seismology Subduction Wrangell Volcanic Field |
description |
207 pages This dissertation details efforts to image the along-strike continuity of major seismic discontinuities in subduction zones using dense (<20 km spacing) arrays of seismometers. The seismic discontinuities were located using receiver-side P-to-S and P-to-P scattered phases from teleseismic (30°<epicentral distance<90°, Mw>~5) earthquake P waves. The time series of scattered phases are referred to as “receiver functions” (RFs) though they are slightly different from traditional RFs. Chapter 1 investigates the location and orientation of the subducting Juan de Fuca (JdF) Moho beneath Mount St. Helens (MSH) using RFs from a dense seismometer array that was deployed in a circular area around the volcano. Two-dimensional (2D) migration and three-dimensional (3D) common-conversion point (CCP) stacking imaging methods were used to reveal a continuous JdF slab at 68±2 km beneath MSH, which is the shallowest directly imaged subducting slab beneath an arc volcano in the world. Between 2016 and 2018, we deployed, serviced, and recovered 36 broadband seismometers in a dense array across the road system of southcentral Alaska, which provided the key data for Chapters 2 and 3. RFs from that array and two other dense seismometer deployments across southcentral Alaska were generated using an improved method that accounts for variations in surface geology. 2D migration of the RFs revealed the Yakutat terrane, an oceanic plateau, subducting down to at least 110-km depth on the eastern half of southcentral Alaska. 3D CCP stacking revealed a continuous LVZ atop the Yakutat terrane for over 450 km along strike, at depths <35 km. Chapter 3 describes the use of RF data from Chapter 2 and data from an older dense seismometer array across central Washington, USA, in estimating the thickness and the ratio of P wave velocity to S wave velocity (Vp/Vs) of the LVZ atop the subducting Yakutat terrane in Alaska and the JdF plate in Cascadia. Results show consistent estimates of Vp/Vs that are lower than those of ... |
author2 |
Abers, Geoffrey Gazel, Esteban McLaskey, Greg Keranen, Kade |
format |
Thesis |
author |
Mann, Michael Everett |
author_facet |
Mann, Michael Everett |
author_sort |
Mann, Michael Everett |
title |
SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES |
title_short |
SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES |
title_full |
SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES |
title_fullStr |
SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES |
title_full_unstemmed |
SCATTERED WAVE IMAGING OF THE CRUST AND UPPERMOST MANTLE ALONG STRIKE IN THE ALASKA AND CASCADIA SUBDUCTION ZONES |
title_sort |
scattered wave imaging of the crust and uppermost mantle along strike in the alaska and cascadia subduction zones |
publishDate |
2021 |
url |
https://hdl.handle.net/1813/110805 http://dissertations.umi.com/cornellgrad:12819 https://doi.org/10.7298/hnw6-dw97 |
genre |
Yakutat Alaska |
genre_facet |
Yakutat Alaska |
op_relation |
Mann_cornellgrad_0058F_12819 http://dissertations.umi.com/cornellgrad:12819 https://hdl.handle.net/1813/110805 https://doi.org/10.7298/hnw6-dw97 |
op_doi |
https://doi.org/10.7298/hnw6-dw97 |
_version_ |
1772820739825598464 |