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Two volcanoes on the Indonesian island of Java simultaneously released plumes of ash and/or steam on June 8, 2006. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard NASA’s Terra satellite caught both volcanoes in the act.
In the west, Merapi Volcano emits the larger, thicker plume. This opaque volcanic plume blends in with the nearby clouds. In the east, Semeru Volcano emits the smaller, thinner plume. Both volcanoes sport “hotspots”—red outlines where the satellite has detected surface temperatures much hotter than the surroundings. Both volcanoes also send their plumes westward with the wind.
The simultaneous eruptions that sometimes occur in Merapi and Semeru, along with their proximity to each other, suggest that they are both affected by the same tectonic processes underground. Volcanoes are just one symptom of seismicity in Java; Indonesian authorities were already warily watching Merapi in late May 2006 when an earthquake struck the region.
NASA image created by Jesse Allen, Earth Observatory, using data provided courtesy of the MODIS Rapid Response team.
Mount Merapi was gearing up for an eruption in late April 2006. It erupted in early May, sending searing gas down its slopes. The volcano followed this eruption with more emissions of steam and ash in the summer of 2006.