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Rapid spilling of 22 acre-feet of water down the steep, 3-mile channel of Ophir Creek killed one, injured four, and destroyed or damaged five houses. Flow evolved into debris flow enroute, and compounded in volume over 30 times.
A late Wisconsin volcano erupted onto the JurassicCretaceous sedimentary bedrock of Augustine Island in lower Cook Inlet in Alaska. Olivine basalt interacting with water erupted explosively. Rhyolitic eruptive debris then swept down the south volcano flank while late Wisconsin glaciers from mountains on western mainland surrounded the island. Early to middle Holocene deposits probably erupted onto the island but are now largely buried. About 5,200, 3,750, 3,500, and 2,275 yr B.P. Augustine ash fell 70 to 110 km away. Since about 2,300 yr B.P. several large eruptions deposited coarse-pumice fall beds on the volcano flanks; many smaller eruptions dropped sand and silt ash. The steep summit erupting viscous andesite domes has repeatedly collapsed into rocky avalanches that flowed into the sea. After a collapse, new domes rebuilt the summit. One to three avalanches shed east before about 2,100 yr B.P., two large ones swept east and southeast between about 2,100 and 1,700 yr B.P., and one shed east and east-northeast between 1,700 and 1,450 yr B.P. Others swept into the sea on the volcano’s south, southwest, and north-northwest between about 1,450 and 1,100 yr B.P., and pyroclastic fans spread southeast and southwest. Pyroclastic flows and surges poured down the west and south flanks and a debris avalanche plowed into the western sea between about 1,000 and 750 yr B.P. A small debris avalanche shed south-southeast between about 750 and 390 yr B.P., and large lithic pyroclastic flows went southeast. From about 390 to 200 yr B.P., three rocky avalanches swept down the west-northwest, north-northwest, and north flanks. The large West Island avalanche reached far beyond a former sea cliff and initiated a tsunami. Augustine’s only conspicuous lava flow erupted on the north flank. In October 1883 a debris avalanche plowed into the sea to form Burr Point on the north-northeast; then came ashfall, pyroclastic surge, and pyroclastic flows. Eruptions in 1935 and 1963–64 grew summit lava domes that shed coarse rubbly lithic pyroclastic flows down the southwest and south flanks. Eruptions in 1976 and 1986 grew domes that shed large pyroclastic flows northeast, north, and north-northwest. The largest debris avalanches off Augustine sweep into the sea and radiate tsunami about lower Cook Inlet.
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No abstract available.
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This program is designed to facilitate conducting sliding-block analysis (also called permanent-deformation analysis) of slopes in order to estimate slope behavior during earthquakes. The program allows selection from among more than 2,100 strong-motion records from 28 earthquakes and allows users to add their own records to the collection. Any number of earthquake records can be selected using a search interface that selects records based on desired properties. Sliding-block analyses, using any combination of rigid-block (Newmark), decoupled, and fully coupled methods, are then conducted on the selected group of records, and results are compiled in both graphical and tabular form. Simplified methods for conducting each type of analysis are also included.
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The collapse of the north face of Mount St. Helens on May 18, 1980, and the debris avalanche that resulted blocked outflow from Spirit Lake and Coldwater and South Fork Castle Creeks. Spirit Lake began to increase in size and lakes began to form in the canyons of Coldwater and South Fork Castle Creeks. Coldwater and Castle Lakes would have overtopped their respective blockages in late 1981 or early 1982. Catastrophic flooding would have occurred from the breakout of Coldwater Lake while serious flooding probably would have resulted from the breakout of Castle Lake. As a result, the level of both lakes was stabilized with spillways in 1981. The three blockages are stable against liquefaction and gravitationally induced slope failure. The existence of groundwater in the blockages was observed in piezometers installed between 1981 and 1983. Groundwater mounds with water levels above lake level exist under the crest of all of the blockages.
Case studies where time of failure is known for rainfall-triggered debris flows can be used to estimate the parameters of a hazard model in which the probability of failure is a function of time. As an example, a time-dependent function for the conditional probability of a soil slip is estimated from independent variables representing hillside morphology, approximations of material properties, and the duration and rate of rainfall. If probabilities are calculated in a GIS (geomorphic information system ) environment, the spatial distribution of the result for any given hour can be displayed on a map. Although the probability levels in this example are uncalibrated, the method offers a potential for evaluating different physical models and different earth-science variables by comparing the map distribution of predicted probabilities with inventory maps for different areas and different storms. If linked with spatial and temporal socio-economic variables, this method could be used for short-term risk assessment.
The integration of remote-sensing and in-situ observations, and assimilation of these observations into high-resolution mesoscale models was described. It was observed that the greatest loss of life and property is the direct result of the storm because of the high winds and heavy rain. The research were conducted to develop a warning system that included satellite observations to track dangerous level of precipitation and hurricane. The focus of the continuum project was to improve the ability to predict the evolution of the Earth system.
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