{"id":{"repo_id":"central-wash","oai_identifier":"oai:digitalcommons.cwu.edu:etd-1194"},"canonical_url":"https://search.dev.ndltd.org/etd/central-wash/oai:digitalcommons.cwu.edu:etd-1194","repository":{"repo_id":"central-wash","name":"Central Washington University","base_url":"https://digitalcommons.cwu.edu/do/oai/"},"display":{"title":"Field Observations and Modeling of the 1957 Earthquake and Tsunami on the Islands of the Four Mountains, Aleutian Islands, Alaska","abstract":"Due to a lack of research in the Aleutian Islands, a comprehensive history of the Aleutian subduction zone is not developed; however, this study indicates that the Aleutian subduction zone is capable of generating magnitude ~9 earthquakes or larger in addition to trans-Pacific tsunamis. Comparison of simulated runup and observed runup will help to determine the characteristics of rupture in the eastern Aleutians. A recent survey of the tsunami wrackline produced by the 1957 Great Aleutian earthquake (M<sub>w</sub> 8.6) indicates runup up to 17.5 m in the Islands of the Four Mountains (presented here). Combined with other nearfield observations of 22 m on Umnak and 18.5 m on Unalaska (USGS), our measurements establish the 1957 tsunami as a significant tsunami in the 20<sup>th</sup> century. Through modeling this earthquake and tsunami and comparing simulations to nearfield observations, we conclude that the earthquake’s magnitude and amount of eastern slip are both higher than previously estimated. I propose several slip distributions that approximately recreate the observed runup; all of these distributions include high slip in the eastern portion of the aftershock zone, though the location of slip and intensity differ between models. No source model with a M<sub>w</sub> = 8.6 was capable of generating the observed 1957 runup; the event was likely at least M<sub>w </sub>> 8.9. Because nearfield observations are limited to those listed above, and seismic records are inadequate, a more precise solution to the rupture pattern cannot be determined.","abstract_html":"Due to a lack of research in the Aleutian Islands, a comprehensive history of the Aleutian subduction zone is not developed; however, this study indicates that the Aleutian subduction zone is capable of generating magnitude ~9 earthquakes or larger in addition to trans-Pacific tsunamis. Comparison of simulated runup and observed runup will help to determine the characteristics of rupture in the eastern Aleutians. A recent survey of the tsunami wrackline produced by the 1957 Great Aleutian earthquake (M&lt;sub&gt;w&lt;/sub&gt; 8.6) indicates runup up to 17.5 m in the Islands of the Four Mountains (presented here). Combined with other nearfield observations of 22 m on Umnak and 18.5 m on Unalaska (USGS), our measurements establish the 1957 tsunami as a significant tsunami in the 20&lt;sup&gt;th&lt;/sup&gt; century. Through modeling this earthquake and tsunami and comparing simulations to nearfield observations, we conclude that the earthquake’s magnitude and amount of eastern slip are both higher than previously estimated. I propose several slip distributions that approximately recreate the observed runup; all of these distributions include high slip in the eastern portion of the aftershock zone, though the location of slip and intensity differ between models. No source model with a M&lt;sub&gt;w&lt;/sub&gt; = 8.6 was capable of generating the observed 1957 runup; the event was likely at least M&lt;sub&gt;w &lt;/sub&gt;&gt; 8.9. Because nearfield observations are limited to those listed above, and seismic records are inadequate, a more precise solution to the rupture pattern cannot be determined.","abstract_has_math":false,"creators":["Griswold, Frances R."],"institution":null,"degree_name":"Master of Science (MS)","degree_level":null,"degree_discipline":"Geological Sciences","degree_department":null,"school":null,"contributors":["Breanyn MacInnes","David George","Lisa Ely"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-01-01T08:00:00Z","date_published":"2015-01-01T08:00:00Z","updated_at":"2026-07-24T01:36:37Z","subjects":["Tsunami","1957","Aleutians","Alaska","Earth Sciences","Geology","Sedimentology"],"languages":["English"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.cwu.edu/etd/201","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Breanyn MacInnes","David George","Lisa Ely"]},{"key":"dc:creator","label":"Author","values":["Griswold, Frances R."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-08-19T07:00:00Z"]},{"key":"dc:type","label":"Dc Type","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geological Sciences"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Tsunami","1957","Aleutians","Alaska","Earth Sciences","Geology","Sedimentology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.cwu.edu/etd/201"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Due to a lack of research in the Aleutian Islands, a comprehensive history of the Aleutian subduction zone is not developed; however, this study indicates that the Aleutian subduction zone is capable of generating magnitude ~9 earthquakes or larger in addition to trans-Pacific tsunamis. Comparison of simulated runup and observed runup will help to determine the characteristics of rupture in the eastern Aleutians. A recent survey of the tsunami wrackline produced by the 1957 Great Aleutian earthquake (M<sub>w</sub> 8.6) indicates runup up to 17.5 m in the Islands of the Four Mountains (presented here). Combined with other nearfield observations of 22 m on Umnak and 18.5 m on Unalaska (USGS), our measurements establish the 1957 tsunami as a significant tsunami in the 20<sup>th</sup> century. Through modeling this earthquake and tsunami and comparing simulations to nearfield observations, we conclude that the earthquake’s magnitude and amount of eastern slip are both higher than previously estimated. I propose several slip distributions that approximately recreate the observed runup; all of these distributions include high slip in the eastern portion of the aftershock zone, though the location of slip and intensity differ between models. No source model with a M<sub>w</sub> = 8.6 was capable of generating the observed 1957 runup; the event was likely at least M<sub>w </sub>> 8.9. Because nearfield observations are limited to those listed above, and seismic records are inadequate, a more precise solution to the rupture pattern cannot be determined."]},{"key":"dc:title","label":"Title","values":["Field Observations and Modeling of the 1957 Earthquake and Tsunami on the Islands of the Four Mountains, Aleutian Islands, Alaska"]}]}],"canonical_facts":{"dc:contributor":["Breanyn MacInnes","David George","Lisa Ely"],"dc:creator":["Griswold, Frances R."],"dc:date.available":["2016-08-19T07:00:00Z"],"dc:description.abstract":["Due to a lack of research in the Aleutian Islands, a comprehensive history of the Aleutian subduction zone is not developed; however, this study indicates that the Aleutian subduction zone is capable of generating magnitude ~9 earthquakes or larger in addition to trans-Pacific tsunamis. Comparison of simulated runup and observed runup will help to determine the characteristics of rupture in the eastern Aleutians. A recent survey of the tsunami wrackline produced by the 1957 Great Aleutian earthquake (M<sub>w</sub> 8.6) indicates runup up to 17.5 m in the Islands of the Four Mountains (presented here). Combined with other nearfield observations of 22 m on Umnak and 18.5 m on Unalaska (USGS), our measurements establish the 1957 tsunami as a significant tsunami in the 20<sup>th</sup> century. Through modeling this earthquake and tsunami and comparing simulations to nearfield observations, we conclude that the earthquake’s magnitude and amount of eastern slip are both higher than previously estimated. I propose several slip distributions that approximately recreate the observed runup; all of these distributions include high slip in the eastern portion of the aftershock zone, though the location of slip and intensity differ between models. No source model with a M<sub>w</sub> = 8.6 was capable of generating the observed 1957 runup; the event was likely at least M<sub>w </sub>> 8.9. Because nearfield observations are limited to those listed above, and seismic records are inadequate, a more precise solution to the rupture pattern cannot be determined."],"dc:identifier":["https://digitalcommons.cwu.edu/etd/201"],"dc:language":["English"],"dc:subject":["Tsunami","1957","Aleutians","Alaska","Earth Sciences","Geology","Sedimentology"],"dc:title":["Field Observations and Modeling of the 1957 Earthquake and Tsunami on the Islands of the Four Mountains, Aleutian Islands, Alaska"],"dc:type":["Text"],"thesis:degree_discipline":["Geological Sciences"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T01:36:37Z"}