東華大學圖書館 |

Source Processes of Shallow and Deep Earthquakes as Imaged by the Back-Projection Method.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Source Processes of Shallow and Deep Earthquakes as Imaged by the Back-Projection Method./
作者:	Kehoe, Haiyang L.
面頁冊數:	1 online resource (173 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-10, Section: B.
Contained By:	Dissertations Abstracts International84-10B.
標題:	Geophysics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30318435click for full text (PQDT)
ISBN:	9798379416225

Source Processes of Shallow and Deep Earthquakes as Imaged by the Back-Projection Method.
Kehoe, Haiyang L.

Source Processes of Shallow and Deep Earthquakes as Imaged by the Back-Projection Method. - 1 online resource (173 pages)

Source: Dissertations Abstracts International, Volume: 84-10, Section: B.

Thesis (Ph.D.)--The University of Arizona, 2023.

Includes bibliographical references

The physical mechanisms governing earthquakes clarify the dynamic processes at Earth's plate boundaries and inform the evaluation of global seismic hazards. One effective method of interrogating these mechanisms involves imaging earthquake source processes with the backprojection method, which time-reverses seismograms recorded at arrays of seismometers to determine the spatiotemporal evolution of the sources of seismic waves. This method benefits from dense and large aperture arrays and has therefore gained considerable utility with the advent of seismic networks such as the Hi-net array in Japan and the USArray in North America. As instrumentation has improved, so have the techniques enhancing the resolution of backprojection images. Such developments in instrumentation and methodology have discerned increasingly finer scale details of the largest earthquake ruptures and lowered the magnitude threshold required to determine the finite source processes of smaller earthquakes.This dissertation outlines improvements to the back-projection method that image the rupture properties of earthquakes across diverse depth ranges and tectonic environments. First, a novel genetic algorithm-based back-projection technique using data recorded at teleseismic distance windows (30°-90°) images the complex source process of the 2018 Mw 6.9 Hawaiʻi earthquake, revealing the heterogenous frictional properties of the decollement hosting this event and informing hazard estimates of future large magnitude events near Kilauea (Appendix A). Second, the acceleration of the 2017 Mw 7.7 Komandorsky Islands earthquake to supershear speeds across a fault stepover is observed for the first time in nature using a similar backprojection method and regional (0°-35°) seismic data (Appendix B). This type of supershear transition, having only been previously documented by numerical modeling efforts, has significant implications on the evaluation of the elevated seismic hazards associated with supershear earthquakes, particularly in analog tectonic environments near large population centers (e.g., the San Andreas Fault). Third, an image deconvolution back-projection method benefitting from the previously described station selection method at regional distance windows (0°-21°), is used to constrain the rupture properties of 19 Mw > 6 deep-focus (hypocentral depth > 300 km) earthquakes near Izu-Bonin (Appendix C). The location of these events beneath the Hi-net array in Japan resolves each source process in three spatial dimensions and time. We find evidence that rupture direction depends on reported seismic moment and attribute this observation to a change in the prevailing causal mechanism of deep-focus earthquakes at a critical seismic moment, itself a function of the thickness of the metastable olivine wedge within the interior of the subducting Izu-Bonin slab. This study, only made possible by the methodological improvements developed throughout this dissertation, illuminates details of deep-focus earthquakes that have remained enigmatic since their discovery.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798379416225Subjects--Topical Terms:

535228
Geophysics.
Subjects--Index Terms:

Back projectionIndex Terms--Genre/Form:

542853
Electronic books.

Source Processes of Shallow and Deep Earthquakes as Imaged by the Back-Projection Method.
LDR:04477nmm a2200397K 4500 001 2358586
005 20230814100758.5
006 m o d
007 cr mn ---uuuuu
008 241011s2023 xx obm 000 0 eng d
020 $a 9798379416225
035 $a (MiAaPQ)AAI30318435
035 $a AAI30318435
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Kehoe, Haiyang L. $3 3699125
245 1 0 $a Source Processes of Shallow and Deep Earthquakes as Imaged by the Back-Projection Method.
264 0 $c 2023
300 $a 1 online resource (173 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 84-10, Section: B.
500 $a Advisor: Kiser, Eric.
502 $a Thesis (Ph.D.)--The University of Arizona, 2023.
504 $a Includes bibliographical references
520 $a The physical mechanisms governing earthquakes clarify the dynamic processes at Earth's plate boundaries and inform the evaluation of global seismic hazards. One effective method of interrogating these mechanisms involves imaging earthquake source processes with the backprojection method, which time-reverses seismograms recorded at arrays of seismometers to determine the spatiotemporal evolution of the sources of seismic waves. This method benefits from dense and large aperture arrays and has therefore gained considerable utility with the advent of seismic networks such as the Hi-net array in Japan and the USArray in North America. As instrumentation has improved, so have the techniques enhancing the resolution of backprojection images. Such developments in instrumentation and methodology have discerned increasingly finer scale details of the largest earthquake ruptures and lowered the magnitude threshold required to determine the finite source processes of smaller earthquakes.This dissertation outlines improvements to the back-projection method that image the rupture properties of earthquakes across diverse depth ranges and tectonic environments. First, a novel genetic algorithm-based back-projection technique using data recorded at teleseismic distance windows (30°-90°) images the complex source process of the 2018 Mw 6.9 Hawaiʻi earthquake, revealing the heterogenous frictional properties of the decollement hosting this event and informing hazard estimates of future large magnitude events near Kilauea (Appendix A). Second, the acceleration of the 2017 Mw 7.7 Komandorsky Islands earthquake to supershear speeds across a fault stepover is observed for the first time in nature using a similar backprojection method and regional (0°-35°) seismic data (Appendix B). This type of supershear transition, having only been previously documented by numerical modeling efforts, has significant implications on the evaluation of the elevated seismic hazards associated with supershear earthquakes, particularly in analog tectonic environments near large population centers (e.g., the San Andreas Fault). Third, an image deconvolution back-projection method benefitting from the previously described station selection method at regional distance windows (0°-21°), is used to constrain the rupture properties of 19 Mw > 6 deep-focus (hypocentral depth > 300 km) earthquakes near Izu-Bonin (Appendix C). The location of these events beneath the Hi-net array in Japan resolves each source process in three spatial dimensions and time. We find evidence that rupture direction depends on reported seismic moment and attribute this observation to a change in the prevailing causal mechanism of deep-focus earthquakes at a critical seismic moment, itself a function of the thickness of the metastable olivine wedge within the interior of the subducting Izu-Bonin slab. This study, only made possible by the methodological improvements developed throughout this dissertation, illuminates details of deep-focus earthquakes that have remained enigmatic since their discovery.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Geophysics. $3 535228
653 $a Back projection
653 $a Earthquakes
653 $a Natural hazards
653 $a Rupture properties
653 $a Seismology
653 $a Source processes
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0373
690 $a 0467
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a The University of Arizona. $b Geosciences. $3 1019596
773 0 $t Dissertations Abstracts International $g 84-10B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30318435 $z click for full text (PQDT)