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High-resolution seismic profiling reveals faulting associated with the 1934 Ms 6.6 Hansel Valley earthquake (Utah, USA)

Pier Paolo G. Bruno, Christopher B. DuRoss and Sotirios Kokkalas
High-resolution seismic profiling reveals faulting associated with the 1934 Ms 6.6 Hansel Valley earthquake (Utah, USA)
Geological Society of America Bulletin (May 2017) 129 (9-10): 1227-1240

Abstract

The 1934 Ms 6.6 Hansel Valley, Utah, earthquake produced an 8-km-long by 3-km-wide zone of north-south-trending surface deformation in an extensional basin within the easternmost Basin and Range Province. Less than 0.5 m of purely vertical displacement was measured at the surface, although seismologic data suggest mostly strike-slip faulting at depth. Characterization of the origin and kinematics of faulting in the Hansel Valley earthquake is important to understand how complex fault ruptures accommodate regions of continental extension and transtension. Here, we address three questions: (1) How does the 1934 surface rupture compare with faults in the subsurface? (2) Are the 1934 fault scarps tectonic or secondary features? (3) Did the 1934 earthquake have components of both strike-slip and dip-slip motion? To address these questions, we acquired a 6.6-km-long, high-resolution seismic profile across Hansel Valley, including the 1934 ruptures. We observed numerous east- and west-dipping normal faults that dip 40 degrees -70 degrees and offset late Quaternary strata from within a few tens of meters of the surface down to a depth of approximately 1 km. Spatial correspondence between the 1934 surface ruptures and subsurface faults suggests that ruptures associated with the earthquake are of tectonic origin. Our data clearly show complex basin faulting that is most consistent with transtensional tectonics. Although the kinematics of the 1934 earthquake remain underconstrained, we interpret the disagreement between surface (normal) and subsurface (strike-slip) kinematics as due to slip partitioning during fault propagation and to the effect of preexisting structural complexities. We infer that the 1934 earthquake occurred along an approximately 3-km wide, off-fault damage zone characterized by distributed deformation along small-displacement faults that may be alternatively activated during different earthquake episodes.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 129
Serial Issue: 9-10
Title: High-resolution seismic profiling reveals faulting associated with the 1934 Ms 6.6 Hansel Valley earthquake (Utah, USA)
Affiliation: Khalifa University of Science and Technology, Petroleum Institute, United Arab Emirates
Pages: 1227-1240
Published: 20170516
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 53
Accession Number: 2017-075979
Categories: SeismologyStructural geologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 2 tables, geol. sketch maps
N41°00'00" - N42°00'00", W114°04'60" - W111°52'60"
Secondary Affiliation: Utah Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201740
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