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Aeromagnetic survey over US to advance geomagnetic research Aeromagnetic survey over US to advance geomagnetic research

A proposed high-altitude survey of the United States offers an exciting and cost effective opportunity to collect magnetic-anomaly data. Lockheed Martin Missile and Space Company is considering funding a reimbursable ER-2 aircraft (Figure 1) mission to collect synthetic aperture radar (SAR) imagery at an altitude of about 21 km over the conterminous United States and Alaska. The...
Authors
T.G. Hildenbrand, R.J. Blakely, W. J. Hinze, Gordon R. Keller, R.A. Langel, M. Nabighian, W. Roest

Site-response maps for the Los Angeles region based on earthquake ground motions Site-response maps for the Los Angeles region based on earthquake ground motions

Ground-motion records from aftershocks of the 1994 Northridge earthquake and main-shock records from the 1971 San Fernando, 1987 Whittier Narrows, 1991 Sierra Madre, and 1994 Northridge earthquakes are used to estimate site response in the urban Los Angeles, California, area. Two frequency bands are considered, 0.5-1.5 Hz and 2.0-6.0 Hz. Instrument characteristics prevented going to...
Authors
Stephen H. Hartzell, Stephen C. Harmsen, Arthur D. Frankel, David L. Carver, Edward Cranswick, Mark E. Meremonte, John A. Michael

The Loma Prieta, California, Earthquake of October 17, 1989: Main shock characteristics The Loma Prieta, California, Earthquake of October 17, 1989: Main shock characteristics

The October 17, 1989, Loma Prieta, Calif., earthquake (0004:15.2 G.m.t. October 18; lat 37.036º N., long 121.883º W.; 19-km depth) had a local magnitude (ML) of about 6.7, a surface-wave magnitude (MS) of 7.1, a seismic moment of 2.2x1019 N-m to 3.5x1019 N-m, a source duration of 6 to 15 s, and an average stress drop of at least 50 bars. Slip occurred on a dipping fault surface about 35...
Authors
Paul A. Spudich, Gregory C. Beroza, George Choy, John Boatwright, Stephen H. Hartzell, Gordon L. Stewart, Carlos Mendoza, Stephen Horton, John G. Anderson, Andres J. Mendez, Hiroo Kanamori, Kenji Satake, Michael Lisowski, Mark Hunter Murray, Jerry L. Svarc, Grant Marshall, Ross S. Stein, Karen McNally, Gerald W. Simila, Judy G. Brown, J.L. Nabelek, Ze’ev Reches, Mark D. Zoback, Jamison Steidl, Ralph J. Archuleta, Aaron A. Velasco, Thorne Lay, Jiajun Zhang, David J. Wald, Donald V. Helmberger, Thomas H. Heaton, Chesley R. Williams, Paul Segall, Francis T. Wu, Mingdong Wu, J.W. Rudnicki

Look before you build: Geologic studies for safer land development in the San Francisco Bay area Look before you build: Geologic studies for safer land development in the San Francisco Bay area

This Circular provides a general description of the types of geologic hazards that exist throughout the United States. In nontechnical language this book describes how geologic information can be incorporated in the land-use development process and contains useful discussion of several examples from the San Francisco Bay area and elsewhere in the United States of how geologic information...
Authors
Martha Blair-Tyler

Inventory of landslides triggered by the 1994 Northridge, California earthquake Inventory of landslides triggered by the 1994 Northridge, California earthquake

The 17 January 1994 Northridge, California, earthquake (M=6.7) triggered more than 11,000 landslides over an area of about 10,000 km?. Most of the landslides were concentrated in a 1,000-km? area that includes the Santa Susana Mountains and the mountains north of the Santa Clara River valley. We mapped landslides triggered by the earthquake in the field and from 1:60,000-scale aerial...
Authors
Edwin L. Harp, Randall W. Jibson

Geomagnetism applications Geomagnetism applications

The social uses of geomagnetism include the physics of the space environment, satellite damage, pipeline corrosion, electric power-grid failure, communication interference, global positioning disruption, mineral-resource detection, interpretation of the Earth's formation and structure, navigation, weather, and magnetoreception in organisms. The need for continuing observations of the...
Authors
Wallace H. Campbell

Can magma-injection and groundwater forces cause massive landslides on Hawaiian volcanoes? Can magma-injection and groundwater forces cause massive landslides on Hawaiian volcanoes?

Landslides with volumes exceeding 1000 km3 have occurred on the flanks of Hawaiian volcanoes. Because the flanks typically slope seaward no more than 12 °, the mechanics of slope failure are problematic. Limit-equilibrium analyses of wedge-shaped slices of the volcano flanks show that magma injection at prospective headscarps might trigger the landslides, but only under very restrictive...
Authors
R.M. Iverson
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