Le massif de Bromo Tengger, situe dans l'est de l'ile de Java est un volcan composite qui s;est edifie pendant une tres longue periode, d'au mons 1,4 MA.
The Idjen caldera is classed as a Krakatoa type or stratocone caldera and is characterized by a caldera floor, a caldera escarpment, and older volcanic forms. The caldera diameter rangers from 14 by 16 km at the rim to 11 14 km at the floor with a maximum depth of 709m.
Caldera forming eruption is on of the important phenomena that caused direct huge damage of global impact not only for a short time but moreover for long periods. There have been three big caldera forming eruption in Indonesia within a period of 1000 years BP that affected global climate change, such as Rinjani (1257 AD), Tambora (1815 AD) and Krakatau (1883 AD).
This study was part of a cooperative project with the Indonesian Institute of Sciences, Bandung, Java, the Michigan Technological University group (W.I Rose, Jr., principle investigator) and the Hawaii Institute of Geophysics, University of Hawaii group (G.P.L. Walker, principle investigator).