Larsen, M. C., M. T. Va´squez Conde, and R. A. Clark, Landslide
hazards associated with flash-floods, with examples from the December,
1999 disaster in Venezuela, in Coping with Flash Floods,
edited by E. Gruntfest and J. Handmer, NATO ASI Ser., in press,

Landslides and flash floods commonly occur together in response to intense and prolonged rainfall. Although these phenomena may be viewed by the popular media as distinct events, rainfall-triggered landslides and flash floods are part of a continuum of processes that includes debris flows, hyperconcentrated flows, and streamflow. This combination of processes has proven to be highly destructive in populated areas. Without careful planning of human settlements, the impacts of these types of disasters are likely to increase in the future. As stated by the Secretary General of the United Nations, Kofi Annan, “The term ‘natural disaster’ has become an increasingly anachronistic misnomer. In reality, human behavior transforms natural hazards into what should really be called unnatural disasters.”

Assessing Landslide Hazards

Keefer, D.K., Larsen, M.C., 2007. Assessing landslide hazards. Sciences 316, 1136–1137.

On 31 May 1970, a large earthquake shook the highest part of the Peruvian Andes. Millions of cubic meters of rock dislodged from a mountainside and initiated a rock avalanche that traveled more than 14 km in 3 min, burying a city and killing more than 25,000 people (1, 2). On 17 February 2006, a landslide of 15 million m3 that initiated on a slope weakened by long-term tectonic activity buried more than 1100 people on Leyte Island in the Philippines (3). Landslides such as these are a hazard in almost all countries, causing billions of dollars of damage and many casualties (4). Landslides also contribute to landscape evolution and erosion in mountainous regions (see the first figure). Here we discuss the latest strategies used to assess and mitigate landslide hazards.

Three-dimensional gravity modelling of a Trinidad mud volcano, West Indies

Arafin S., 2005. Three-dimensional gravity modeling of a trinidad mud volcano, West
Indies. Exploration Geophysics 36, 329–333.

The violent eruption of the Piparo mud volcano, Trinidad, in February 1997 demonstrated its destructive capability by completely burying 16 houses and a number of livestock under a 5 m thick mud pile. Unlike magmatic volcanoes, mud volcanoes involve very low energy, making geophysical methods such as seismology unsuitable for monitoring. Three-dimensional gravity modelling over the Tabaquite mud volcano suggests the presence of a large density contrast (–0.70 t.m-3). The density contrast being large and dynamic (i.e., it is absent at recently active mud volcanoes like Piparo) makes the gravity method a potential tool for monitoring mud volcanoes.
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