USING NEAR REAL TIME PRECIPITATION ESTIMATES FROM METEOROLOGICAL SATELLITE DATA AS A CONTRIBUTION TO EARLY WARNING ON LAHARS AT CENTRAL AMERICAN VOLCANOES

Fast floods, currents and lahars caused by strong and/or long lasting rains represent mayor hazards at Central American volcanoes. An extreme example was the event at Casita volcano, Nicaragua, where around 2000 people were killed during Hurricane Mitch in 1998. Year by year, smaller events occur in the flanks of the volcanoes affecting population and infrastructures. In the last years, only at a few sites endangered by lahars, early warning systems were deployed, based mainly on rain gauge data. Meteorological stations are generally very sparse in the Central American volcanic chain and weather radars do not exist. Still, for most of the endangered areas there is no appropriate monitoring in place.

As a contribution to early warning measures in the Central American volcanoes, a software system was developed to evaluate, in near real time, precipitation estimates derived from meteorological satellite data. These precipitation estimates are obtained from the experimental Hydroestimator (NESDIS/NOAA) which makes use of the known correlation of the upper cloud temperature with rain intensity. Twice per hour, the software downloads via INTERNET the Hydroestimator data for Central America and the Caribbean. It checks for the sites of Central American Volcanoes the precipitation estimates accumulated during the last 1, 3, 6, 12 and 24 hours. If the accumulated precipitation surpasses certain levels the system emits warning messages by email. The messages contain not only text but also the corresponding precipitation map. The precipitation estimates for the volcanoes are also published in a Web site together with local and regional precipitation maps in near real time.

This work is part of a larger development for early warning on landslides in Central America and is supported by the project on the Mitigation of Georisks in Central America executed by BGR/Germany in cooperation with Central American institutions and with another project on landslide early warning in Nicaragua executed by NGI/Norway in cooperation with Instituto Nicaragüense de Estudios Territoriales (INETER).