Dating previously balanced rocks in seismically active parts of California and Nevada

John W. Bell, James N. Brune, Tanzhuo Liu, Marek G Zreda, James C. Yount

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada. In this study we used two independent surface-exposure dating techniques - rock-varnish microlamination and cosmogenic 36Cl dating methodologies - to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down. The results of the exposure dating indicate that all of the precarious rocks are >10.5 ka and that some may be significantly older. At Victorville and Jacumba, California, these results show that the precarious rocks have not been knocked down for at least 10.5 k.y., a conclusion in apparent conflict with some commonly used probabilistic seismic hazard maps. At Yucca Mountain, Nevada, the ages of the precarious rocks are >10.5 to >27.0 ka, providing an independent measure of the minimum time elapsed since faulting occurred on the Solitario Canyon fault.

Original languageEnglish (US)
Pages (from-to)495-498
Number of pages4
JournalGeology
Volume26
Issue number6
DOIs
StatePublished - Jun 1998

Fingerprint

rock varnish
rock
seismic hazard
ground motion
canyon
faulting
earthquake
mountain
methodology
dating
exposure
conflict

ASJC Scopus subject areas

  • Geology

Cite this

Dating previously balanced rocks in seismically active parts of California and Nevada. / Bell, John W.; Brune, James N.; Liu, Tanzhuo; Zreda, Marek G; Yount, James C.

In: Geology, Vol. 26, No. 6, 06.1998, p. 495-498.

Research output: Contribution to journalArticle

Bell, John W. ; Brune, James N. ; Liu, Tanzhuo ; Zreda, Marek G ; Yount, James C. / Dating previously balanced rocks in seismically active parts of California and Nevada. In: Geology. 1998 ; Vol. 26, No. 6. pp. 495-498.
@article{31eba7a2573849868740a5b71527ffe1,
title = "Dating previously balanced rocks in seismically active parts of California and Nevada",
abstract = "Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada. In this study we used two independent surface-exposure dating techniques - rock-varnish microlamination and cosmogenic 36Cl dating methodologies - to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down. The results of the exposure dating indicate that all of the precarious rocks are >10.5 ka and that some may be significantly older. At Victorville and Jacumba, California, these results show that the precarious rocks have not been knocked down for at least 10.5 k.y., a conclusion in apparent conflict with some commonly used probabilistic seismic hazard maps. At Yucca Mountain, Nevada, the ages of the precarious rocks are >10.5 to >27.0 ka, providing an independent measure of the minimum time elapsed since faulting occurred on the Solitario Canyon fault.",
author = "Bell, {John W.} and Brune, {James N.} and Tanzhuo Liu and Zreda, {Marek G} and Yount, {James C.}",
year = "1998",
month = "6",
doi = "10.1130/0091-7613(1998)026<0495:DPBRIS>2.3.CO;2",
language = "English (US)",
volume = "26",
pages = "495--498",
journal = "Geology",
issn = "0091-7613",
publisher = "Geological Society of America",
number = "6",

}

TY - JOUR

T1 - Dating previously balanced rocks in seismically active parts of California and Nevada

AU - Bell, John W.

AU - Brune, James N.

AU - Liu, Tanzhuo

AU - Zreda, Marek G

AU - Yount, James C.

PY - 1998/6

Y1 - 1998/6

N2 - Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada. In this study we used two independent surface-exposure dating techniques - rock-varnish microlamination and cosmogenic 36Cl dating methodologies - to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down. The results of the exposure dating indicate that all of the precarious rocks are >10.5 ka and that some may be significantly older. At Victorville and Jacumba, California, these results show that the precarious rocks have not been knocked down for at least 10.5 k.y., a conclusion in apparent conflict with some commonly used probabilistic seismic hazard maps. At Yucca Mountain, Nevada, the ages of the precarious rocks are >10.5 to >27.0 ka, providing an independent measure of the minimum time elapsed since faulting occurred on the Solitario Canyon fault.

AB - Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada. In this study we used two independent surface-exposure dating techniques - rock-varnish microlamination and cosmogenic 36Cl dating methodologies - to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down. The results of the exposure dating indicate that all of the precarious rocks are >10.5 ka and that some may be significantly older. At Victorville and Jacumba, California, these results show that the precarious rocks have not been knocked down for at least 10.5 k.y., a conclusion in apparent conflict with some commonly used probabilistic seismic hazard maps. At Yucca Mountain, Nevada, the ages of the precarious rocks are >10.5 to >27.0 ka, providing an independent measure of the minimum time elapsed since faulting occurred on the Solitario Canyon fault.

UR - http://www.scopus.com/inward/record.url?scp=84879890695&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84879890695&partnerID=8YFLogxK

U2 - 10.1130/0091-7613(1998)026<0495:DPBRIS>2.3.CO;2

DO - 10.1130/0091-7613(1998)026<0495:DPBRIS>2.3.CO;2

M3 - Article

VL - 26

SP - 495

EP - 498

JO - Geology

JF - Geology

SN - 0091-7613

IS - 6

ER -