Remote sensing of dangerous volcanoes

摘要

Semeru is an extremely active volcano in Indonesia. Gaining access to the summit cone of the volcano is both difficult and dangerous. In order to gain information on the geomorphology and structural geology of the volcano along with data on the distribution of pyroclastic density current deposits can however, be achieved through remote sensing. Semeru is the highest mountain in Java at 3676 m, and is the southernmost edifice in the Semeru-Tengger volcanic massif. The surrounding area is heavily populated with approximately 600 000 people living in the city of Malang and the surrounding area just 40 km or so from the volcano. The summit cone is bare of vegetation and covered by tephra, but the flanksof the volcano have dense evergreen forest and the equatorial monsoonal climate produces as much as 2000-3 700 mm rainfall per year, with extreme rainfall events of 200 mm of rain in a 24-hour period occurring every 5 years on average. Short lived eruption columns form every day and pyroclastic flows occur once every five years on average. Semeru is also known to be one of the most effective lahar producers on earth. During the rainy season, semeru produces small to medium scale lahars (<= 0.1 million m~3) every week, with at least five very large lahars (> 5 million m~3) since 1884.