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GEOREF RECORD

Martinez Mountain rock avalanche

C. G. Bock
Martinez Mountain rock avalanche
Reviews in Engineering Geology (1977) 3: 155-168

Abstract

The Martinez Mountain rock avalanche, tentatively dated as early Holocene, comprises approximately 3.8 x 10 (super 8) m (super 3) of granitic gneiss that broke away from the mountainside at elevation 1,926 m and flowed to elevation 49 m. The length of the slide debris is 7.6 km, and the width ranges from 1,070 to 1,370 m. Rock in the area surrounding the slide is closely jointed, with northwest-trending faults cutting under the slide mass. Two dominant sets of high-angle joints intersect at the crown of the slide and are believed to have controlled formation of the broad V-shaped scarp. A third joint set dips down-slope at 15 degrees to 30 degrees , and it locally controlled the basal surface of the slide. Because of the crystalline nature of the rock involved in sliding, water was probably not a significant factor in the triggering mechanism; rather, it is thought that a major seismic event caused the slide. Such seismic triggering is consistent with historic occurrences of massive rockslides and in the seismically active Coachella Valley such an event would provide the energy needed to disaggregate the rock and start it moving. An understanding of the structural geology and probable triggering mechanism provides a basis for comparison with similar geologic terranes and assessment of the potential for catastrophic landsliding that might affect urban developments.


ISSN: 0080-2018
EISSN: 2169-799X
Coden: GAEGA4
Serial Title: Reviews in Engineering Geology
Serial Volume: 3
Serial Info: Landslides
Title: Martinez Mountain rock avalanche
Author(s): Bock, C. G.
Affiliation: Bechtel Assoc. Prof. Corp., Washington, D.C., United States
Pages: 155-168
Published: 1977
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 16
Accession Number: 1978-003016
Categories: Engineering geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. table, sects., geol. sketch maps
N32°30'00" - N33°30'00", W116°00'00" - W115°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 1978
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