Publications

Nestled in the crater of Oregon's majestic Mount Hood volcano is Crater Rock, a prominent feature known to thousands of skiers, climbers, and tourists who journey each year to the famous Timberline Lodge located high on the volcano's south flank. Crater Rock stands about 100m above the sloping crater floor and warm fumaroles along its base emit sulfur gases and a faint steam plume that is sometime

Four types of deformation occur in the Wineglass Welded Tuff on the northeast caldera rim of Crater Lake: (a) vertical tension fractures; (b) ooze-outs of fiamme: (c) squeeze-outs of fiamme; and (d) horizontal pull-apart structures. The three types of plastic deformation (b-d) developed in the lower part of the Wineglass Welded Tuff where degree of welding and density are maximum. Deformation orig

Conceptual models of the thermal structure of the Oregon Cascade Range propose either (1) a narrow zone of magmatic heat sources, flanked by shallow heat-flow anomalies caused by lateral ground-water flow; or (2) a wide zone of magmatic heat sources, with localized, generally negligible ground-water effects. The proposed narrow heat source coincides with the Quaternary volcanic arc, whereas the wi

Sublimates were sampled from high-temperature (up to 800°C) fumaroles at Merapi volcano, Indonesia in January 1984. Sampling is accomplished by inserting silica tubes into high-temperature vents. Volcanic gas flows through the tubes and sublimates precipitate on the inner walls in response to the temperature gradient. With decreasing temperature (800–500°C) in the tubes, there are five sublimate z

Thermodynamic evaluation and restoration procedures are applied to a set of 10 volcanic gas analyses obtained by modern collection and analytical methods. The samples were collected from a vigorously fuming fissure during episode 1 of the Puu Oo eruption of Kilauea Volcano in 1983. A variety of analytical techniques were used to determine the gas compositions. In most samples, the combined amounts

More than 40 historically active volcanic centers, each consisting of one or more volcanoes, are located on the Alaska Peninsula and Aleutian Islands (see map on next page). On average, at least one of these volcanoes erupts each year.

No abstract available.

In a handful of molten magma weighing about a pound, there is less than a tenth of an ounce, by weight, of idssolved gas-roughly the same weight as a pinch of table salt. Yet this tiny amount of gas produces spectacular lava foundations hundreds of meters high (see accompanying photograph). The fountain occurs as magma reaches the surface, because dissolved volcanic gases exolve and expand tremend

Active volcanoes on the island of Hawai'i provide scientists with exceptional opportunities to observe volcanic phenomena at close range. Such an opportunity occurred on November 24, 1992, when geologists from the Hawaiian Volcano Observatory (HVO) witnessed spectacular explosive interactions between lava and seawater on the southeast coast of the island. As seawater invaded submarine conduits tra

When the seismograph began to record the violent earth-shaking caused by yet another eruption of the Nevado del Ruiz volcano in Colombia, no one thought that a few hours later more than 23,000 people would be dead, killed by lahars (volcanic debris flows) in towns and villages several tens of kilometers away from the volcano. Before the fatal eruption the volcano was being monitored by scientists

On June 27, 1992, the Crater Peak vent on the south side of Mt. Spurr awoke from 39 years of dormancy and burst into subplinian eruption after 10 months of elevated seismicity. Two more eruptions followed in August and September. The volcano lies 125-km west of Anchorage, which is Alaska's largest city and an important international hub for air travel. The Alaska Volcano Observatory (AVO) was able

Many landslides and debris flows have originated from Mount Rainier since the retreat of glaciers from Puget Sound about 10,000 years ago. The recurrent instability is due to several factors--height of the steep-sided volcanic cone, frequent volcanic activity, continuous weakening of rock by steam and hot, chemical-laden water, and exposure of unstable areas as the mountains glaciers have receded.