Publications
Filter Total Items: 2062
The Loma Prieta, California, earthquake of October 17, 1989: Aftershocks and postseismic effects The Loma Prieta, California, earthquake of October 17, 1989: Aftershocks and postseismic effects
While the damaging effects of the earthquake represent a significant social setback and economic loss, the geophysical effects have produced a wealth of data that have provided important insights into the structure and mechanics of the San Andreas Fault system. Generally, the period after a large earthquake is vitally important to monitor. During this part of the seismic cycle, the...
Authors
Paul A. Reasenberg, Lynn D. Dietz, William L. Ellsworth, Robert W. Simpson, John W. Gephart, Susan Y. Schwartz, Glenn D. Nelson, H. Guo, A. Lerner-Lam, William Menke, Susan E. Hough, Leif Wennerberg, K.S. Breckenridge, Jeff Behr, Roger G. Bilham, Paul Bodin, Arthur G. Sylvester, Jon S. Galehouse, R. Burgmann, Paul Segall, Michael Lisowski, Jerry L. Svarc, John Langbein, Mark F. Linker, J.R. Rice, M. T. Gladwin, R. L. Gwyther, R.H.G. Hart, Randall Mackie, Theodore R. Madden, Edward A. Nichols
Review of electric and magnetic fields accompanying seismic and volcanic activity Review of electric and magnetic fields accompanying seismic and volcanic activity
New observations of magnetic, electric and electromagnetic field variations, possibly related to recent volcanic and seismic events, have been obtained on Mt. Unzen in Japan, Reunion Island in Indian Ocean, the Long Valley volcanic caldera in California, and for faults in China and Russia, California and several other locations. For volcanic events, contributions from different physical...
Authors
M.J.S. Johnston
Composition of the crust in the Grenville and Appalachian Provinces of North America inferred from VP/VS ratios Composition of the crust in the Grenville and Appalachian Provinces of North America inferred from VP/VS ratios
We use the ratios between P and S wave velocities (VP/VS), derived from seismic refraction data, to infer the composition of the crust in the Grenville and the Appalachian Provinces of North America. The crust exhibits VP/VS increasing with depth from 1.64 to 1.84; there is a clear distinction between the Grenville Province (average VP/VS=1.81) and the Appalachian Province (average VP/VS...
Authors
G. Musacchio, Walter D. Mooney, James H. Luetgert, Nikolas I. Christensen
The variability of PSV response spectra across a dense array deployed during the Northridge aftershock sequence The variability of PSV response spectra across a dense array deployed during the Northridge aftershock sequence
This study addresses the variability of pseudo-velocity response spectra across an array deployed on stiff soil in the San Fernando Valley during the Northridge (Mw 6.7) aftershock sequence. The separation between stations ranged from 0.5 to 5 km, and the aftershock magnitudes ranged from 2.3 to 4.0. We find that 95-percent of observed response spectra are within a factor of 1.9 to 2.6...
Authors
Edward H. Field, Susan E. Hough
Some comparisons between recent ground-motion relations Some comparisons between recent ground-motion relations
We provide an overview of new ground-motion relations for eastern North America (ENA) developed over the last five years. The empirical-stochastic relations of Atkinson and Boore (1995) are compared to relations developed by the Electric Power Research Institute (EPRI, 1993; also Toro et al., 1994), Frankel et al. (1996), and the consensus ENA ground-motion values as reported by SSHAC...
Authors
Gail M. Atkinson, David Boore
Options for the Future of the US National Strong-Motion Program Options for the Future of the US National Strong-Motion Program
This report constitutes the requested 'Options Document'. This report considers three options. Option I assumes a constant level of financial support for Operating Expenses (OE) with not additional personnel support. Option II assumes a slight increase in OE support of $150K for FY 99 and beyond. Option III considers the role that a NSMP must play if the nation's urgent need to record...
Authors
Continents as lithological icebergs: The importance of buoyant lithospheric roots Continents as lithological icebergs: The importance of buoyant lithospheric roots
An understanding of the formation of new continental crust provides an important guide to locating the oldest terrestrial rocks and minerals. We evaluated the crustal thicknesses of the thinnest stable continental crust and of an unsubductable oceanic plateau and used the resulting data to estimate the amount of mantle melting which produces permanent continental crust. The lithospheric...
Authors
D.H. Abbott, R. Drury, Walter D. Mooney
Executive summary of vision and options for the future of the US National Strong-Motion Program Executive summary of vision and options for the future of the US National Strong-Motion Program
These reports are presented in response to a charge of the Earthquake Hazards Reduction Program (EHRP) Program Council of the U.S. Geological Survey to 'define the future of the USGS National Strong-Motion Program (NSMP)' (Appendix A). The council requested that a 'Vision Paper' and an 'Options Document' be prepared. Each of these reports is a separate document. The 'Executive Summary'...
Authors
Introduction to special section: The Trans-Alaska Crustal Transect (TACT) across Arctic Alaska Introduction to special section: The Trans-Alaska Crustal Transect (TACT) across Arctic Alaska
This special section of the Journal of Geophysical Research addresses the composition and structural evolution of the lithosphere in northern Alaska. Investigations reported in this section were mainly undertaken as part of the Trans‐Alaska Crustal Transect (TACT), an integrated geological and geophysical transect of the entire Alaskan lithosphere along a north‐south corridor undertaken...
Authors
George Plafker, Walter D. Mooney
Ophiolitic basement to the Great Valley forearc basin, California, from seismic and gravity data: Implications for crustal growth at the North American continental margin Ophiolitic basement to the Great Valley forearc basin, California, from seismic and gravity data: Implications for crustal growth at the North American continental margin
The nature of the Great Valley basement, whether oceanic or continental, has long been a source of controversy. A velocity model (derived from a 200-km-long east-west reflection-refraction profile collected south of the Mendocino triple junction, northern California, in 1993), further constrained by density and magnetic models, reveals an ophiolite underlying the Great Valley (Great...
Authors
N. J. Godfrey, B. C. Beaudoin, S.L. Klemperer, A. Levander, J. Luetgert, A. Meltzer, Walter D. Mooney, A. Trehu
Revised long-term creep rates on the Hayward Fault, Alameda and Contra Costa Counties, California Revised long-term creep rates on the Hayward Fault, Alameda and Contra Costa Counties, California
Although the Hayward fault is a source of major earthquakes, it also creeps or slips aseismically, and has done so steadily for several decades (certainly since 1921 and probably since 1869). Most of the fault creeps between 3 and 6 mm/yr, except for a 4- to 6-km-long segment near its south end that creeps at about 9 mm/yr. We present results of our recent surveys to recover angles and...
Authors
James J. Lienkaemper, Jon S. Galehouse
Vision for the future of the US National Strong-Motion Program Vision for the future of the US National Strong-Motion Program
This document provides the requested vision for the future of the National Strong-Motion Program operated by the US Geological Survey. Options for operation of the program are presented in a companion document. Each of the three major charges of the EHRP, program council pertaining to the vision document is addressed here. The 'Vision Summary' through a series of answers to specific...
Authors