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TitleMicroseismicity and Tectonics of Southwest Yukon Territory, Canada, Using a Local Dense Seismic Array
AuthorMeighan, L N; Cassidy, J F; Mazzotti, S; Pavlis, G L
SourceBulletin of the Seismological Society of America vol. 103, no. 6, 2013 p. 3341-3346,
Alt SeriesEarth Sciences Sector, Contribution Series 20130008
PublisherSeismological Society of America
Mediapaper; on-line; digital
File formatpdf
ProvinceYukon; British Columbia
NTS104L; 104M; 114I; 114J; 114O; 114P; 105D; 105E; 115A; 115B; 115C; 115F; 115G; 115H
AreaYukon; British Columbia; Alaska; Canada; United States
Lat/Long WENS-142.0000 -134.0000 63.0000 58.0000
Subjectsgeophysics; tectonics; seismicity; seismic interpretations; tectonic interpretations; tectonic setting; tectonic environments; structural features; faults; Yakutat Block; Duke River Fault; Denali Fault
Illustrationslocation maps; bar graphs
ProgramTargeted Hazard Assessments in Western Canada, Public Safety Geoscience
AbstractThe objective of this paper is to provide a better understanding of the relationship between the microseismicity, active tectonics, and crustal structures in the southwest Yukon Territory, Canada, in order to improve seismic-hazard assessments in this region.We utilize data from a new dense seismic array that was deployed in the southwest Yukon in the summer of 2010. Data from the new seismic array significantly improve the magnitude completeness level in the region from ML 3.0 to 1.0. We analyze 980 events ranging in magnitudes from ML 0.2 to 4.7, at depths from 0 to 35 km. Relocation analysis using the progressive multiple event location shows that seismicity is concentrated in four main areas: (1) Yakutat block northern boundary - Fairweather fault, (2) Duke River fault, (3) southern Denali fault, and (4) a previously unrecognized northeast trending cluster that may highlight a previously unknown active fault. This cluster may contribute to stress and strain transfer inland from the Yakutat block region.
Summary(Plain Language Summary, not published)
Our understanding of earthquake hazards in the southwest Yukon has been limited by a lack of data - specifically, few seismic stations at relatively large distances. With the deployment of a dense array of seismic stations in the vicinity of the Denali Fault in the summer of 2010, we are able to now locate much smaller earthquakes (to M 1) and determine earthquake depths. We located nearly 1000 earthquakes over a 15-month period and were able to determine precise earthquake locations and depths. These new results show a concentration of earthquakes along the Duke River Fault system and have highlighted a narrow NE-trending band of seismicity on a near-vertical structure that was previously unknown. Our new earthquake constraints (and especially focal depths) provide critical new information for modelling GPS data and improving earthquake hazard assessments in this region.