Publications

As part of our DOE-funded proposal to characterize gas hydrate in the Gulf of Mexico using marine electromagnetic methods, a collaboration between SIO, LLNL, and USGS with the goal of measuring the electrical properties of lab-created methane (CH4) hydrate and sediment mixtures was formed. We examined samples with known characteristics to better relate electrical properties measured in...

The value of slope stability analyses for gaining insight into the geologic conditions that would facilitate the growth of gully alcoves on Mars is demonstrated in Gasa crater. Two-dimensional limit equilibrium methods are used in conjunction with high-resolution topography derived from stereo High Resolution Imaging Science Experiment (HiRISE) imagery. These analyses reveal three...

The compositional, thermophysical and geologic characteristics of surface units in Iapygia and Tyrrhena Terra (60°E–100°E, 0°–30°S) provide new insights into the compositional stratigraphy of the region. Intercrater plains are dominated by two surface units. The older unit (unit 1) is deficient in olivine and more degraded and likely consists of a mixture of impact, volcanic and...

Damage to fault-zone rocks during fault slip results in the formation of a channel of low seismic-wave velocities. Within such channels guided seismic waves, denoted by Fg, can propagate. Here we show with core samples, well logs and Fg-waves that such a channel is crossed by the SAFOD (San Andreas Fault Observatory at Depth) borehole at a depth of 2.7 km near Parkfield, California, USA...

Hidden in plain sight, Oregon's massive Newberry Volcano is the largest volcano in the Cascades volcanic arc and covers an area the size of Rhode Island. Unlike familiar cone-shaped Cascades volcanoes, Newberry was built into the shape of a broad shield by repeated eruptions over 500,000 years. About 65,000 years ago a major explosion and collapse event created a large volcanic...

No abstract available.

Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not

In the aftermath of the devastating magnitude-9.0 earthquake and tsunami that struck the Tohoku region of Japan on March 11, attention quickly turned away from a much smaller, but also highly destructive earthquake that struck the city of Christchurch, New Zealand, just a few weeks earlier, on Feb. 22. Both events are stark reminders of human vulnerability to natural disasters and...

The U.S. Geological Survey (USGS) is investigating how the social networking site Twitter, a popular service for sending and receiving short, public text messages, can augment USGS earthquake response products and the delivery of hazard information. Rapid detection and qualitative assessment of shaking events are possible because people begin sending public Twitter messages (tweets) with...

The April 4, 2010 (Mw7.2), El Mayor-Cucapah, Baja California, Mexico, earthquake is the strongest earthquake to shake the Salton Trough area since the 1992 (Mw7.3) Landers earthquake. Similar to the Landers event, ground-surface fracturing occurred on multiple faults in the trough. However, the 2010 event triggered surface slip on more faults in the central Salton Trough than previous...

Video-based observations of wave runup, setup, and swash from 10 dynamically diverse field experiments are presented. These data were used to develop widely applicable empirical parameterizations for wave setup, incident band swash height, infragravity band swash height, and the 2-percent exceedance level for wave runup. Details regarding the experiments, data analysis, and empirical

This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the Potato Creek watershed in the Apalachicola-Chattahoochee-Flint River basin, Georgia. These datasets were acquired on February 27, 2010.