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Geographic relations of landslide distribution and assessment of landslide hazards in the Blanco, Cibuco, and Coamo basins, Puerto Rico Geographic relations of landslide distribution and assessment of landslide hazards in the Blanco, Cibuco, and Coamo basins, Puerto Rico

Landslide occurrence is common in mountainous areas of Puerto Rico where mean annual rainfall and the frequency of intense storms are high and hillslopes are steep. Each year, landslides cause extensive damage to property and occasionally result in loss of life. Landslide maps developed from 1:20,000 scale aerial photographs in combination with a computerized geographic information...
Authors
M. C. Larsen, A. J. Torres-Sanchez

New trends in active faulting studies for seismic hazard assessment New trends in active faulting studies for seismic hazard assessment

No abstract available.
Authors
Enzo Boschi, D. Giardini, D. Pantosti, Gianluca Valensise, Ramon Arrowsmith, Peter W. Basham, R. Burgmann, Anthony J. Crone, Alan Hull, Robin K. McGuire, David Schwartz, Kerry Sieh, Steven N Ward, Robert S. Yeats

Some facts about aftershocks to large earthquakes in California Some facts about aftershocks to large earthquakes in California

Earthquakes occur in clusters. After one earthquake happens, we usually see others at nearby (or identical) locations. To talk about this phenomenon, seismologists coined three terms foreshock , mainshock , and aftershock. In any cluster of earthquakes, the one with the largest magnitude is called the mainshock; earthquakes that occur before the mainshock are called foreshocks while...
Authors
Lucile M. Jones, Paul A. Reasenberg

Rationale and preliminary operational plan for a high-altitude magnetic survey over the United States Rationale and preliminary operational plan for a high-altitude magnetic survey over the United States

A proposed high-altitude survey of the U.S. with an ER-2 to collect radar data offers an exciting and cost-effective opportunity to collect magnetic anomaly data. At this workshop, a group of magnetic specialists addressed this opportunity by discussing the need for high-altitude magnetic data and by formulating a preliminary operational plan to acquire such data. The high-altitude...
Authors
T.G. Hildenbrand, R.J. Blakely, R. E. Bracken, Lynn Edwards, Doug Hardwick, W. J. Hinze, Vic Labson, Hal Malliot, Misac Nabighian, Bruno Nilsson, Jeff Phillips, J.M. Quinn, Walter Roest

Ground-truth studies of west coast and Gulf of Mexico submarine fans Ground-truth studies of west coast and Gulf of Mexico submarine fans

No abstract available.
Authors
Homa J. Lee, Robert E. Kayen, Brian D. Edwards, Michael E. Field, James V. Gardner, William C. Schwab, David C. Twichell

Integration of orthophotographic and sidescan sonar imagery: an example from Lake Garda, Italy Integration of orthophotographic and sidescan sonar imagery: an example from Lake Garda, Italy

Digital orthophotos of Lake Garda basin area are available at the scale of up to 1:10,000 from a 1994 high altitude (average scale of 1:75,000) air photo coverage of Italy collected with an RC30 camera and Panatomic film. In October 1994 the lake bed was surveyed by USGS and CISIG personnel using a SIS 1000 Sea-Floor Mapping System. Subsystems of the SIS-1000 include high resolution...
Authors
Giuseppe Gentili, David C. Twichell, Bill Schwab

Reflected seismic waves and their effect on strong shaking during the 1989 Loma Prieta, California, earthquake Reflected seismic waves and their effect on strong shaking during the 1989 Loma Prieta, California, earthquake

Our data indicate that critical and postcritical reflections from crustal layers and the Moho produced increased shaking at discrete distances along the San Francisco Peninsula during the 1989 Loma Prieta earthquake. These reflections may have produced an increase in amplitude that is as much as 10 times greater than that of the direct arrival. Peak amplitude-distance patterns measured...
Authors
Rufus D. Catchings, W.M. Kohler

Airborne hunt for faults in the Portland-Vancouver area Airborne hunt for faults in the Portland-Vancouver area

Geologic hazards in the Portland-Vancouver area include faults entirely hidden by river sediments, vegetation, and urban development. A recent aerial geophysical survey revealed patterns in the Earth's magnetic field that confirm the existence of a previously suspected fault running through Portland. It also indicated that this fault may pose a significant seismic threat. This discovery...
Authors
Richard J. Blakely, Ray E. Wells, Thomas S. Yelin, Peter H. Stauffer, James W. Hendley
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