Gunung Bromo (Mount Bromo) is a small but active volcanic cinder cone on the Indonesian island of Java. Bromo is located in the center of the Sandsea Caldera, itself only a portion of the larger Tengger Caldera (a caldera is the circular depression in the center of a volcano’s summit). The Sandsea caldera formed around 8,000 years ago, in what must have been a massive eruption. Subsequent volcanic activity formed the cluster of cinder cones in the caldera’s center, including Bromo.
The historical record indicates eruptions of Bromo every few years since 1804, and geologic evidence indicates eruptions at least several hundred years earlier. The most recent eruption occured in 2004, and tragically killed two tourists.
This image shows most of the Sandsea Caldera, along with Gunung Bromo and the older volcanoes on the caldera floor. A small plume of steam is visible rising out of Mt. Bromo. DigitalGlobe’s IKONOS satellite, capable of 4-meter per-pixel color imagery, and 1-meter per-pixel resolution panchromatic imagery, acquired the data on July 8, 2001.
NASA image by Robert Simmon, based on data copyright DigitalGlobe.
The approximately 4-kilometer-wide Dendi Caldera includes some of this silica-rich volcanic rock: the rim of the caldera, visible in this astronaut photograph, is mostly made of poorly consolidated ash erupted during the Tertiary Period (approximately 65–2 million years ago).