气候变化领域集成服务门户(CCPortal): Rapid strain release on the Bear River fault zone, Utah–Wyoming—The impact of preexisting structure on the rupture behavior of a new normal fault

CCPortal

DOI	10.1016/j.tecto.2021.228819
	Rapid strain release on the Bear River fault zone, Utah–Wyoming—The impact of preexisting structure on the rupture behavior of a new normal fault
	Hecker S.; DeLong S.B.; Schwartz D.P.
发表日期	2021
ISSN	00401951
卷号	808
英文摘要	Earthquake clustering (grouping in space and time) is a widely observed mode of strain release in the upper crust, although this behavior on individual faults is a departure from classic elastic rebound theory. In this study, we consider factors responsible for a cluster of earthquakes on the Bear River fault zone (BRF), a recently activated, 44-km-long normal fault on the eastern margin of Basin and Range extension in the Rocky Mountains. The entire surface-rupturing history of the BRF, as gleaned from paleoseismic and geomorphic observations, began only 4500 years ago and consists of at least three large events. Rupture of the BRF is spatially complex and is clearly conditioned by preexisting structure. In particular, where the south end of the fault intersects older thrust faults and upturned strata along the south-dipping flank of the Precambrian basement-cored Uinta arch, the main trace ends abruptly in a set of orthogonal splays that accommodate down-dropping of a large hanging-wall graben against the arch. We hypothesize that the geomechanically strong Uinta arch crustal block impeded the development of the BRF and, over time, enabled a significant accumulation of elastic strain energy, eventually giving rise to a pulse of strain release in the mid- to late Holocene. We surmise that variations in fault strength, both in space and time, is a cause of earthquake clustering on the BRF and on other faults that are structurally and tectonically immature. The first two earthquakes on the BRF occurred during the same period of time as a regional cluster of earthquakes in the Middle Rocky Mountains, suggesting that isolated faults in this slowly extending region interact through widespread changes in stress conditions. © 2021
关键词	Clustering Earthquake Neotectonics Paleoseismology
英文关键词	Arches; Earthquakes; Strain energy; Basin and range; Earthquake clustering; Elastic rebound theory; Elastic strain energy; Mid to late Holocene; Precambrian basement; Regional clusters; Stress condition; Fault slips; earthquake catalogue; earthquake magnitude; earthquake rupture; fault zone; neotectonics; normal fault; paleoseismicity; thrust fault; upper crust; Rocky Mountains; United States; Utah; Wyoming
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207985
作者单位	U.S. Geological Survey, P.O. Box 158, Moffett Field, CA 94035, United States
推荐引用方式 GB/T 7714	Hecker S.,DeLong S.B.,Schwartz D.P.. Rapid strain release on the Bear River fault zone, Utah–Wyoming—The impact of preexisting structure on the rupture behavior of a new normal fault[J],2021,808.
APA	Hecker S.,DeLong S.B.,&Schwartz D.P..(2021).Rapid strain release on the Bear River fault zone, Utah–Wyoming—The impact of preexisting structure on the rupture behavior of a new normal fault.Tectonophysics,808.
MLA	Hecker S.,et al."Rapid strain release on the Bear River fault zone, Utah–Wyoming—The impact of preexisting structure on the rupture behavior of a new normal fault".Tectonophysics 808(2021).