After more than 9,000 years of dormancy, Chile’s Chaitén Volcano erupted violently on May 2, 2008. In the months that followed, the volcano spewed ash across Patagonia and released pumice that made its way into the nearby gulf. Chaitén also sent lahars—avalanches of volcanic ash, water, and mud—into the town of the same name.
The town of Chaitén lies roughly 10 kilometers (6 miles) from the volcano. The Formosat satellite captured this image on December 5, 2008. Similar to an image acquired on May 19, 2008, this picture shows the town clogged with volcanic ash, with blocks of rooftops cresting the debris. West of town, ash forms fan-shaped deposits in what used to be Chaitén’s harbor. Choked with ash, Río Blanco truly appears white. Compared to the image from May, however, the river is wider, especially along the eastern edge of the town. Likewise, the volcanic deposits along the coast are larger.
If a volcano has ejected substantial quantities of ash and rock, and the area receives sufficient rainfall, lahars may follow. Land surface features affect how lahars flow, and lahars in turn reshape the landscape. This evolving interaction between lahars and topography makes the rock flows challenging to predict. Lahars inundated the town of Chaitén in the months that followed the May 2008 eruption. According to the Smithsonian Institution’s Global Volcanism Program, by May 12, lahars carried by the Río Blanco had covered the lower halves of single-storey buildings near the river, and dislodged some structures closest to the river. Subsequent lahars reached farther into the town and destroyed a bridge. Lahars also covered Chaitén airfield.
Chaitén is a caldera volcano, formed when the summit collapsed into the subterranean magma chamber after it was completely emptied during an eruption. After its eruption in May 2008, the volcano released ongoing plumes of ash and steam, and a new lava dome formed inside the crater.
Formosat image © 2008 Dr. Cheng-Chien Liu, National Cheng-Kung University, and Dr. An-Ming Wu, National Space Organization, Taiwan. Caption by Michon Scott.