Maps that help mitigate volcanic hazards

January 22nd, 2009 - 5:00 pm ICT by ANI  

Washington, Jan 22 (ANI): A team of volcanologists has developed a program that would be able to help mitigate volcanic hazards, by mapping potential problem areas quickly.

We wanted to be able to predict the areas affected by pyroclastic flows from volcanoes, said Christina Widiwijayanti, post-doctoral fellow in geosciences. Pyroclastic flows and surges are the phenomena that kill most people when volcanoes erupt, she added.

A pyroclastic flow consists of hot rocks, ash and superheated gases that rapidly flow down from the area of dome collapse on a volcano.

Pyroclastic surges are similar, but less dense. They are a kind of hot ash hurricane that can escape the confines of river valleys. Both types of currents are dangerous and frequently lethal.

In many volcanic crises, a hazard map for pyroclastic flows and surges is sorely needed, but limited time, exposures or safety aspects may preclude fieldwork, and insufficient computational time or baseline data may be available for adequately reliable dynamic simulations of future pyroclastic flow or surge events, said the researchers.

The researchers, working with Steve P. Schilling, U.S. Geological Survey Cascades Volcano Observatory, looked at an existing procedure created by Schilling called LAHARZ, a geographical information system (GIS) method intended to map hazard zones for volcano-induced mudflows.

The approach worked for water-saturated mud flows, we thought maybe it would work for hot pyroclastic flows, said Barry Voight, professor emeritus of geosciences. So we looked at the eruption data and developed some new ways of forecasting areas of impact, particularly for the ash hurricanes, he added.

The researchers used data from eruptions of a variety of volcanoes including the Soufriere Hills Volcano, Montserrat; Mount Merapi, Indonesia; Mount Unzen, Japan, and Colima, Mexico to develop a predictive equation for mapping the hazard.

The equation considered the cross sectional area of the flows, the area covered and the amount of material in the flow, and is embedded in the GIS.

What we are doing is looking at the volcano to see, for each valley system, how far the hot flows of rock and ash can come, said Dannie Hidayat, post doctoral fellow in geosciences.

We can outline the area of potential surge damage and this can be used by decision makers on whether to evacuate or to put people on high alert to evacuate, Hidayat added.

Using this program, we can produce maps long before the eruption takes place and they can be kept on the shelf for immediate use, or we can produce maps as needed as soon as there is an indication of impending pyroclastic explosions, said Widiwijayanti. (ANI)

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