Focused Study of Interweaving Hazards Across the Caribbean

Braun J.J, Mattioli G.S., Calais E. Focused Study of Interweaving Hazards Across the Caribbean. EOS Vol. 93, No 9, 28 Feb 2012.

The Caribbean is a region of lush vegetation, beaches, active volcanoes, and significant mountain ranges, all of which create a natural aesthetic that is recognized globally. Yet these very same features, molded through geological, oceanic, and atmospheric processes, also pose natural hazards for the developing countries in the Caribbean. The rise in population density, migration to coastal areas, and substandard building practices, combined with the threat of natural hazards, put the region’s human population at risk for particularly devastating disasters. These demographic and social characteristics exist against a backdrop of the threat of an evolving climate, which produces a more vigorous hurricane environment and a rising average sea level. The 12 January 2010 earthquake in Haiti and Hurricane Ike (2008) both caused widespread destruction and loss of life, illustrating the need for a scientific focus on the underlying natural hazards of the Caribbean. Prompted by these and other events, a new National Science Foundation (NSF)– funded initiative known as the Continuously Operating Caribbean Observation Network (COCONet), which commits roughly $7 million over 5 years to a collaborative natural hazard research team, was formed in 2010. This team includes researchers from UNAVCO, Purdue University, University of Puerto Rico at Mayagüez, and the University Corporation for Atmospheric Research (UCAR)

Map showing susceptibility to earthquake-induced landsliding, San Juan Metropolitan Area, Puerto Rico

Santiago Marilyn, Map showing susceptibility to earthquake-induced landsliding, San Juan Metropolitan Area, Puerto Rico, 2 plate.em>

Analysis of slope angle and rock type using a geographic information system indicates that about 66 percent of the San Juan metropolitan area (SJMA) has low to no susceptibility to earthquake-induced landslides. This is at least partly due to the fact that 45 percent of the SJMA is constructed on slopes of 3 degrees or less, which are too gentle for landslides to occur. The areas with the highest susceptibility to earthquake-induced landslides account for 6 percent of the surface area. Almost one-quarter (23 percent) of the SJMA is moderately susceptible to earthquake-induced landslides. These areas are mainly in the southern portions of the SJMA where housing development pressures are currently high because of land availability and the esthetics of greenery and hillside views. The combination of new development and moderate earthquakeinduced landslide susceptibility may indicate that the southern portions of the SJMA may be at greatest risk.

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.
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