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Strain accumulation north of Los Angeles, California, as a function of time, 1977–1992 Strain accumulation north of Los Angeles, California, as a function of time, 1977–1992

No significant change in the rate of strain accumulation in a 40×120 km trilateration network spanning the San Gabriel mountains was observed from 1977.5 to 1991.8 despite an apparent increase in seismicity (ML > 4.5) beginning in late 1987 in the northern Los Angeles basin immediately to the south. The observed deformation (0.13±0.01 µstrain/yr right‐lateral shear across a vertical...
Authors
James C. Savage, Michael Lisowski

Evolution of the Precambrian lithosphere: Seismological and geochemical constraints Evolution of the Precambrian lithosphere: Seismological and geochemical constraints

Several recent models of crustal evolution are based on the belief that the thickness of the continental crust is proportional to its age, with ancient crust being the thickest. A worldwide review of seismic structure contradicts this belief and falsifies these models, at least for the Archean. Proterozoic crust has a thickness of 40–55 km and a substantial high‐velocity (>7 km/s) layer...
Authors
R. Durrheim, Walter D. Mooney

Crustal velocity structure of the northern Yukon-Tanana upland, central Alaska: Results from TACT refraction/wide-angle reflection data Crustal velocity structure of the northern Yukon-Tanana upland, central Alaska: Results from TACT refraction/wide-angle reflection data

The Fairbanks North seismic refraction/ wide-angle reflection profile, collected by the U.S. Geological Survey Trans-Alaska Crustal Transect (TACT) project in 1987, crosses the complex region between the Yukon-Tanana and Ruby terranes in interior Alaska. This region is occupied by numerous small terranes elongated in a northeast-southwest direction. These seismic data reveal a crustal...
Authors
Bruce C. Beaudoin, Gary S. Fuis, William J. Lutter, Walter D. Mooney, Thomas E. Moore

Crustal structure and composition of the southern Foothills Metamorphic Belt, Sierra Nevada, California, from seismic data Crustal structure and composition of the southern Foothills Metamorphic Belt, Sierra Nevada, California, from seismic data

The Foothills Metamorphic Belt is an accreted terrane consisting of Paleozoic and Mesozoic metamorphic rocks that separates the Great Valley from the Sierra Nevada batholith in northern and central California. Until recently, the only available geophysical data for this area were reconnaissance refraction surveys, and gravity and magnetic data. New insights into the structure of the deep...
Authors
Kate Miller, Walter D. Mooney

Early warning system for aftershocks Early warning system for aftershocks

A prototype early warning system to provide San Francisco and Oakland, California a few tens-of-seconds warning of incoming strong ground shaking from already-occurred M ≧ 3.7 aftershocks of the magnitude 7.1 17 October 1989 Loma Prieta earthquake was operational on 28 October 1989. The prototype system consisted of four components: ground motion sensors in the epicentral area, a central...
Authors
W. H. Bakun, F.G. Fischer, E.G. Jensen, J. VanSchaack

The Loma Prieta, California, Earthquake of October 17, 1989: Strong ground motion The Loma Prieta, California, Earthquake of October 17, 1989: Strong ground motion

Strong ground motion generated by the Loma Prieta, Calif., earthquake (MS~7.1) of October 17, 1989, resulted in at least 63 deaths, more than 3,757 injuries, and damage estimated to exceed $5.9 billion. Strong ground motion severely damaged critical lifelines (freeway overpasses, bridges, and pipelines), caused severe damage to poorly constructed buildings, and induced a significant...
Authors
Roger D. Borcherdt, A. Gerald Brady, A.F. Shakal, V.F. Cormier, Wei-Jou Su, Jeffry L. Stevens, Steven M. Day, John E. Vidale, Ornella Bonamassa, Paul G. Somerville, Nancy F. Smith, Robert Graves, Gary Glassmoyer, Kyle Rollins, Michael D. Mchood, Roman D. Hryciw, Matthew Homolka, Scott E. Shewbridge, Harvey Carlisle, Nicholas Sitar, Rodrigo Salgado, Pedro de Alba, J. Benoit, Daniel G. Pass, John Carter, T. Leslie Youd, E. H. Field, Susan E. Hough, K.H. Jacob, Paul A. Friberg, Arthur D. Frankel, R. Busby, Robert A. Williams, Edward Cranswick, Kenneth W. King, Grant T. Lindley, Ralph J. Archuleta, Janice M. Murphy, Steven G. Wesnousky

Static stress changes and the triggering of earthquakes Static stress changes and the triggering of earthquakes

To understand whether the 1992 M = 7.4 Landers earthquake changed the proximity to failure on the San Andreas fault system, we examine the general problem of how one earthquake might trigger another. The tendency of rocks to fail in a brittle manner is thought to be a function of both shear and confining stresses, commonly formulated as the Coulomb failure criterion. Here we explore how...
Authors
Geoffrey King, Ross S. Stein, Jian Lin

Chapter C. The Loma Prieta, California, Earthquake of October 17, 1989 - Fire, police, transportation and hazardous materials Chapter C. The Loma Prieta, California, Earthquake of October 17, 1989 - Fire, police, transportation and hazardous materials

The papers in this chapter discuss some of the failures and successes that resulted from the societal response by a multitude of agencies to the Loma Prieta earthquake. Some of the lessons learned were old ones relearned. Other lessons were obvious ones which had gone unnoticed. Still, knowledge gained from past earthquakes spawned planning and mitigation efforts which proved to be...
Authors
Charles R. Scawthorn

Crustal structure beneath the Kenya Rift from axial profile data Crustal structure beneath the Kenya Rift from axial profile data

Modelling of the KRISP 90 axial line data shows that major crustal thinning occurs along the axis of the Kenya Rift from Moho depths of 35 km in the south beneath the Kenya Dome in the vicinity of Lake Naivasha to 20 km in the north beneath Lake Turkana. Low Pn velocities of 7.5–7.7 km/s are found beneath the whole of the axial line. The results indicate that crustal extension increases...
Authors
J. Mechie, Gordon R. Keller, C. Prodehl, S. Gaciri, L.W. Braile, Walter D. Mooney, D. Gajewski, K.-J. Sandmeier

The Loma Prieta, California, earthquake of October 17, 1989: Tectonic processes and models The Loma Prieta, California, earthquake of October 17, 1989: Tectonic processes and models

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...
Authors
Robert W. Simpson, John H. Shaw, Richard E. Bischke, J. Suppe, Gianluca Valensise, Susan Y. Schwartz, Daniel L. Orange, Robert S. Anderson, Paul A. Reasenberg, Paul Bodin, Roger G. Bilham, Kevin P. Furlong, David Verdonck

The KRISP 90 seismic experiment-a technical review The KRISP 90 seismic experiment-a technical review

On the basis of a preliminary experiment in 1985 (KRISP 85), a seismic refraction/wide-angle reflection survey and a teleseismic tomography experiment were jointly undertaken to study the lithospheric structure of the Kenya rift down to depths of greater than 200 km. This report serves as an introduction to a series of subsequent papers and will focus on the technical description of the...
Authors
C. Prodehl, J. Mechie, U. Achauer, Gordon R. Keller, M.A. Khan, Walter D. Mooney, S.J. Gaciri, J.D. Obel
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