Formation of left-lateral fractures within the Summit Ridge shear zone, 1989 Loma Prieta, California, earthquake
Journal Article
·
· Journal of Geophysical Research
- Purdue Univ., West Lafayette, IN (United States)
The 1989 Loma Prieta, California, earthquake is characterized by the lack of major, throughgoing, coseismic, right-lateral faulting along strands of the San Andreas fault zone in the epicentral area. Instead, throughout the Summit Ridge area there are zones of tension cracks and left-lateral fracture zones oriented about N45 deg W, that is, roughly parallel to the San Andreas fault in this area. The left-lateral fractures zones are enigmatic because their left-lateral slip is opposite to the right-lateral sense of the relative motion between the Pacific and North American plates. We suggest that the enigmatic fractures can be understood if we assume that coesiesmic deformation was by right-lateral shear across a broad zone, about 0.5 km wide and 4 km long, beneath Summit Ridge. Contrary to most previous reports on the Loma Prieta earthquake, which assert that coseismic, right-lateral ground rupture was restricted to considerable (greater than 4 km) depths in the epicentral area, we find that nearly all the right-lateral offset is represented at the ground surface by the Summit Ridge shear zone.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 79464
- Journal Information:
- Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: B12 Vol. 98; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ground fracturing at the southern end of Summit Ridge caused by October 17, 1989 Loma Prieta, California, earthquake sequence (maps of Summit Ridge Shear Zones, en echelon tension cracks, complex and compound fractures, and small faults that formed coactively with the earthquake sequence)
Near-fault measurement of postseismic slip associated with the 1989 Loma Prieta, California, earthquake
Triggered slip on the Calaveras fault during the magnitude 7. 1 Loma Prieta, California, earthquake
Technical Report
·
Tue Dec 30 23:00:00 EST 1997
·
OSTI ID:677053
Near-fault measurement of postseismic slip associated with the 1989 Loma Prieta, California, earthquake
Journal Article
·
Sat Sep 01 00:00:00 EDT 1990
· Geophysical Research Letters (American Geophysical Union); (USA)
·
OSTI ID:6400348
Triggered slip on the Calaveras fault during the magnitude 7. 1 Loma Prieta, California, earthquake
Journal Article
·
Sun Jul 01 00:00:00 EDT 1990
· Geophysical Research Letters (American Geophysical Union); (USA)
·
OSTI ID:6148022