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Chapter F. The Loma Prieta, California, Earthquake of October 17, 1989 - Tectonic processes and models

January 1, 1994

If there is a single theme that unifies the diverse papers in this chapter, it is the attempt to understand the role of the Loma Prieta earthquake in the context of the earthquake 'machine' in northern California: as the latest event in a long history of shocks in the San Francisco Bay region, as an incremental contributor to the regional deformation pattern, and as a possible harbinger of future large earthquakes.

One of the surprises generated by the earthquake was the rather large amount of uplift that occurred as a result of the reverse component of slip on the southwest-dipping fault plane. Preearthquake conventional wisdom had been that large earthquakes in the region would probably be caused by horizontal, right-lateral, strike-slip motion on vertical fault planes.

In retrospect, the high topography of the Santa Cruz Mountains and the elevated marine terraces along the coast should have provided some clues. With the observed ocean retreat and the obvious uplift of the coast near Santa Cruz that accompanied the earthquake, Mother Nature was finally caught in the act. Several investigators quickly saw the connection between the earthquake uplift and the long-term evolution of the Santa Cruz Mountains and realized that important insights were to be gained by attempting to quantify the process of crustal deformation in terms of Loma Prieta-type increments of northward transport and fault-normal shortening.

Citation Information

Publication Year 1994
Title Chapter F. The Loma Prieta, California, Earthquake of October 17, 1989 - Tectonic processes and models
DOI 10.3133/pp1550F
Authors Robert W. Simpson
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Professional Paper
Series Number 1550
Index ID pp1550F
Record Source USGS Publications Warehouse
USGS Organization Earthquake Hazards Program; Earthquake Science Center