Report on Llaima (Chile) — January 1999
Bulletin of the Global Volcanism Network, vol. 24, no. 1 (January 1999)
Managing Editor: Richard Wunderman.
Llaima (Chile) Hybrid seismicity and gas-and-ash emissions prompt increase in alert status
Please cite this report as:
Global Volcanism Program, 1999. Report on Llaima (Chile) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 24:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199901-357110.
38.692°S, 71.729°W; summit elev. 3125 m
All times are local (unless otherwise noted)
An intense white fumarolic plume was seen at Llaima during the second week of November 1998, along with intermittent gas emissions and occasional ash. Personnel at Conguillio National Park also reported that on a crater visit they noted landslide material on one flank. Fumarolic gas-and-ash columns rose ~1,000 m above the summit and typical emissions of steam were also seen.
During 27-29 January 1999 personnel from the Observatorio Volcanológico de los Andes del Sur (OVDAS) installed a portable digital seismic station in the Green Lake area. The portable station is composed of an L4-C seismograph and a small computer powered by a 12-volt battery. An average of 25 long-period events per hour having frequencies of 1.0-1.2 Hz and durations of 30-40 seconds were registered during the sampling period. Many events associated with intense degassing in the central crater at the time were also registered with frequencies between 0.8 and 1 Hz. Energy reached maximum values of 95 RSAM units. Three isolated high-frequency, long-period events were registered. These events had unusual characteristics and could have been hybrids.
The presence of some hybrid seismic events suggests that the alert status be raised to "Green," the first level of the traffic-light system used by OVDAS.
Geologic Background. Llaima, one of Chile's largest and most active volcanoes, contains two main historically active craters, one at the summit and the other, Pichillaima, to the SE. The massive, dominantly basaltic-to-andesitic, stratovolcano has a volume of 400 km3. A Holocene edifice built primarily of accumulated lava flows was constructed over an 8-km-wide caldera that formed about 13,200 years ago, following the eruption of the 24 km3 Curacautín Ignimbrite. More than 40 scoria cones dot the volcano's flanks. Following the end of an explosive stage about 7200 years ago, construction of the present edifice began, characterized by Strombolian, Hawaiian, and infrequent subplinian eruptions. Frequent moderate explosive eruptions with occasional lava flows have been recorded since the 17th century.
Information Contacts: Gustavo Fuentealba and Paola Peña, Observatorio Volcanológico de Los Andes del Sur (OVDAS), Servicio Nacional de Geología e Minería (SERNAGEOMIN), Manantial 1710-Carmino del Alba, Temuco, Chile (URL: http://www.sernageomin.cl/).