Broad belts of shear zones: The common form of surface rupture produced by the 28 June 1992 Landers, California, earthquake Metadata
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- Main Title Broad belts of shear zones: The common form of surface rupture produced by the 28 June 1992 Landers, California, earthquake
Author: Johnson, A.M.Creator Type: Personal
Author: Cruikshank, K.M.Creator Type: PersonalCreator Info: Purdue Univ., West Lafayette, IN (United States). Richard H. Jahns Engineering Geology Lab.
Author: Fleming, R.W.Creator Type: PersonalCreator Info: Geological Survey, Denver, CO (United States)
Sponsor: United States. Department of Energy. Office of Energy Research.Contributor Type: OrganizationContributor Info: USDOE Office of Energy Research, Washington, DC (United States)
Name: Geological Survey (U.S.). Denver Federal Center.Place of Publication: Denver, ColoradoAdditional Info: Geological Survey, Denver, CO (United States)
- Creation: 1993-12-31
- Content Description: Surface rupturing during the 28 June 1992, Landers, California earthquake, east of Los Angeles, accommodated right-lateral offsets up to about 6 m along segments of distinct, en echelon fault zones with a total length of about 80 km. The offsets were accommodated generally not by faults -- distinct slip surfaces -- but rather by shear zones, tabular bands of localized shearing. In long, straight stretches of fault zones at Landers the rupture is characterized by telescoping of shear zones and intensification of shearing: broad shear zones of mild shearing, containing narrow shear zones of more intense shearing, containing even-narrower shear zones of very intense shearing, which may contain a fault. Thus the ground ruptured across broad belts of shearing with subparallel walls, oriented NW. Each broad belt consists of a broad zone of mild shearing, extending across its entire width (50 to 200 m), and much narrower (a few m wide) shear zones that accommodate most of the offset of the belt and are portrayed by en echelon tension cracks. In response to right-lateral shearing, the slices of ground bounded by the tension cracks rotated in a clockwise sense, producing left lateral shearing, and the slices were forced against the walls of the shear zone, producing thrusting. Even narrower shear zones formed within the narrow shear zones, and some of these were faults. Although the narrower shear zones probably are indicators to right-lateral fault segments at depth, the surface rupturing during the earthquake is characterized not by faulting, but by zones of shearing at various scales. Furthermore, understanding of the formation of the shear zones may be critical to understanding of earthquake faulting because, where faulting is associated with the formation of a shear zone, the faulting occurs late in the development of the shear zone. The faulting occurs after a shear zone or a belt of shear zones forms.
- Physical Description: Medium: P; Size: 29 p.
- Keyword: Cracks
- Keyword: Ruptures
- STI Subject Categories: 58 Geosciences
- Keyword: Maps
- Keyword: California
- Keyword: Earthquakes
- Keyword: Shear
- Keyword: Geologic Faults
- Keyword: Rock Mechanics
- Other Information: PBD: 1993
Name: Office of Scientific & Technical Information Technical ReportsCode: OSTI
Name: UNT Libraries Government Documents DepartmentCode: UNTGD
- Other: DE99000961
- Report No.: USGS-OFR--93-348
- Grant Number: FG02-93ER14365
- DOI: 10.2172/677052
- Office of Scientific & Technical Information Report Number: 677052
- Archival Resource Key: ark:/67531/metadc702180
- Display Note: OSTI as DE99000961