Publications

Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of...

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000–May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates > 1000 times higher than during non-storm periods, primarily because of sediment...

The Mars Exploration Rover Opportunity discovered sulphate-rich sedimentary rocks at Meridiani Planum on Mars, which are interpreted by McCollom and Hynek as altered volcanic rocks. However, their conclusions are derived from an incorrect representation of our depositional model, which is upheld by more recent Rover data. We contend that all the available data still support an aeolian...

Irvine, Backstay, and Wishstone are the type specimens for three classes of fine-grained or fragmental, relatively unaltered rocks with distinctive thermal emission spectra, found as float on the flanks of the Columbia Hills. Chemical analyses indicate that these rocks are mildly alkaline basalt, trachybasalt, and tephrite, respectively. Their mineralogy consists of Na- and K-rich...

At an active volcano, Very-Long-Period (VLP) seismicity (with typical periods in the range 2-100 s) reflects pressure fluctuations resulting from unsteady mass transport in the sub-surface plumbing system, and hence provides a glimpse of the internal dynamics of the volcanic edifice. Understanding the fundamental fluid-flow mechanisms involved in the generation of VLP seismic events is...

In tropical and subtropical estuaries, gradients of primary productivity and salinity are generally invoked to explain patterns in community structure and standing crops of fishes. We documented spatial and temporal patterns in fish community structure and standing crops along salinity and nutrient gradients in two subtropical drainages of Everglades National Park, USA. The Shark River...

This paper quantifies atmospheric mercury (Hg) emissions from substrates and fumaroles associated with three hydrothermal systems: Lassen Volcanic Center, California (LVC); Yellowstone Caldera, Wyoming (YC); and Dixie Valley, Nevada (DV). Substrate Hg fluxes were measured using field chamber methods at thermal and nonthermal sites. The highest Hg fluxes (up to 541 ng m−2 h−1) were...

Seismic reflection profiles from three different surveys of the Cascadia forearc are interpreted using P wave velocities and relocated hypocentres, which were both derived from the first arrival travel time inversion of wide-angle seismic data and local earthquakes. The subduction decollement, which is characterized beneath the continental shelf by a reflection of 0.5 s duration, can be...

Since 1958, about ninety seismic refraction/wide angle reflection profiles, with a cumulative length of more than sixty thousand kilometers, have been completed in mainland China. We summarize the results in the form of (1) a new contour map of crustal thickness, (2) fourteen representative crustal seismic velocity–depth columns for various tectonic units, and, (3) a Pn velocity map. We...

The 1000-km-long Darlag–Lanzhou–Jingbian seismic refraction profile is located in the NE margin of the Tibetan plateau. This profile crosses the northern Songpan-Ganzi terrane, the Qinling-Qilian fold system, the Haiyuan arcuate tectonic region, and the stable Ordos basin. The P-wave and S-wave velocity structure and Poisson's ratios reveal many significant characteristics in the profile...

In many cases, the derivation of high-resolution digital terrain models (DTMs) from planetary surfaces using conventional digital image matching is a problem. The matching methods need at least one stereo pair of images with sufficient texture. However, many space missions provide only a few stereo images and planetary surfaces often possess insufficient texture. This paper describes a...

Resuspension, transport, and deposition of sediments over the continental shelf and slope are complex processes and there is still a need to understand the underlying spatial and temporal dynamical scales. As a step towards this goal, a two-dimensional slice model (zero gradients in the alongshore direction) based on the primitive flow equations and a range of sediment classes has been...