Bulletin of the Seismological Society of America
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Bulletin of the Seismological Society of America; February 1991; v. 81; no. 1; p. 139-161
© 1991 Seismological Society of America
This Article
Right arrow Full Text (PDF)
Right arrow References
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by MCCALPIN, J.
Right arrow Articles by FORMAN, S. L.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Late Quaternary faulting and thermoluminescence dating of the East Cache fault zone, north-central Utah

JAMES MCCALPIN and S. L. FORMAN

DEPARTMENT OF GEOLOGY UTAH STATE UNIVERSITY, LOGAN, UTAH 84322-4505
CENTER FOR GEOCHRONOLOGICAL RESEARCH INSTAAR UNIVERSITY OF COLORADO, BOULDER, COLORADO 80309-0450

Abstract

The East Cache fault zone (ECFZ), the southernmost of five en-echelon Quaternary normal faults between the Wasatch and Teton faults, displays evidence of two large paleoearthquakes in the last 15,000 years (15 ka). Stratigraphic data from a trench on the central segment of the ECFZ are augmented with one radiocarbon date, the regional radiocarbon chronology, and 14 thermoluminescence (TL) age estimates. Of the 14 TL analyses performed by Alpha Analytic Inc., only 8 satisfied our criteria for statistical acceptability (< 20 per cent coefficient of variation, < 50 per cent extrapolation to residual TL level). The TL age estimates broadly bracket the earlier faulting event at between 8.7 ± 1.0 and 17.4 ± 3.0 ka, and the later event at between 2.5 ± 0.5 and 8.7 ± 1.0 ka. One radiocarbon age further constrains the earlier event to be younger than 15,540 ± 130 yr BP. Correlation of local Quaternary deposits to the regional radiocarbon chronology provides indirect, but more tightly limiting, age constraints of ca. 4 to ca. 7 ka for the later event, and ca. 13 ka to 15,540 ± 130 yr BP for the earlier event. Both events had small vertical displacements at the trench site (0.8 to 1.8 m), but the cumulative net vertical tectonic displacement elsewhere is up to 4.2 m, suggestive of Ms 6.9 to 7.1 paleoearthquakes. Single-event displacements and the extent of fault scarps suggest that these two paleoearthquake ruptures were probably limited to the 20-km-long central segment of the East Cache fault zone near Logan, Utah. The elapsed time since the most recent event on the central segment (ca. 4 to ca. 7 ka) is somewhat less than the estimated recurrence interval between the latest two paleoearthquake (8.6 ± 3.0 ka). However, comparison of only a single poorly constrained recurrence interval with the elapsed time does not result in a confident assessment of future earthquake potential.




This article has been cited by other articles:


Home page
 Bulletin of the Seismological Society of AmericaHome page
D. B. Mason
Earthquake magnitude potential of the Intermountain Seismic Belt, USA, from surface-parameter scaling of late Quaternary faults
Bulletin of the Seismological Society of America, October 1, 1996; 86(5): 1487 - 1506.
[Abstract] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1991 by the Seismological Society of America.