During 29 March to 3 April 2005, the lava lake inside Villarrica's crater remained active, with Strombolian explosions occurring. Some gas explosions were observed to hurl volcanic bombs as far as ~ 300 m. According to a news report, the Oficina Nacional de Emergencia reported that unusual seismicity was recorded during early April 2005. Fresh ash deposits were seen outside of the crater. Visitors were banned from climbing the volcano.

Since the beginning of 2005, relatively consistent and continuous MODIS/MODVOLC thermal anomalies were recorded during 1 January through 25 March, 7-21 July, 31 August through 26 September, 17 October through 25 December 2005, and 23 January through 4 September 2006 (figure 21). The gaps between these periods are probably artificial, due to such interference as cloud cover or other phenomena that obscured satellite observations. For example, the activity reported above for late March through early April 2005 did not generate MODIS/MODVOLC thermal anomalies.

Figure 21. Thermal anomalies at Villarrica from the MODIS/MODVOLC satellite observations, January 2005 to 18 September 2006. Anomalies are from both the Aqua and Terra satellites. Courtesy of the HIGP MODIS Thermal Alert System.

Geological Summary. The glacier-covered Villarrica stratovolcano, in the northern Lakes District of central Chile, is ~15 km south of the city of Pucon. A 2-km-wide caldera that formed about 3,500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesite cone at the NW margin of a 6-km-wide Pleistocene caldera. More than 30 scoria cones and fissure vents are present on the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Eruptions documented since 1558 CE have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks.

Information Contacts: HIGP MODIS Thermal Alert System, Hawai'i Institute of Geophysics and Planetology (HIGP), University of Hawaii and Manoa, 168 East-West Road, Post 602, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).