OVDAS-SERNAGEOMIN reported that satellite imagery and an area web camera showed no plumes rising from Cerro Hudson during 7-15 November. Seismic activity decreased significantly, reaching a low level characterized by no more than four earthquakes per hour and the absence of tremor. The Alert Level remained at Yellow, Level 4.

16 November 2011              Back to Top

OVDAS-SERNAGEOMIN reported that satellite imagery and an area web camera showed no plumes rising from Cerro Hudson during 7-15 November. Seismic activity decreased significantly, reaching a low level characterized by no more than four earthquakes per hour and the absence of tremor. The Alert Level remained at Yellow, Level 4.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN)

2 November 2011              Back to Top

On 2 November, OVDAS-SERNAGEOMIN reported that the Alert Level for Cerro Hudson was lowered to Yellow, Level 4, noting that the eruption that began on 26 October had ceased. ONEMI reported that the 140 evacuees were permitted to return home. Analysis of ash deposited on the edge of the crater during the eruption indicated the presence of juvenile basalt. During 1-6 November between 16 and 110 earthquakes per day were recorded and satellite images showed drifting plumes daily.

Sources: Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI) , Servicio Nacional de Geología y Minería (SERNAGEOMIN)

26 October 2011              Back to Top

OVDAS-SERNAGEOMIN reported three new craters at Cerro Hudson following increased seismicity that was detected during 25-26 October. At 1908 on 25 October an M 4.6 volcano-tectonic earthquake occurred at a depth of 19 km, followed by a seismic swarm starting at 2149. More than 100 events, with depths ranging from 15 to 25 km, were recorded through the next day; 12 of the events were M 3, and three events were M 4. Scientists aboard an overflight on 26 October observed a white plume with some ash content that rose 1.5 km and lahars in Rio Huemul, to the W. The Alert Level was raised to Level 5 - Red. A very low-frequency M 4.3 earthquake occurred that same day at a depth of 15 km.

Five earthquakes per hour were recorded between 1600 on 26 October and 1600 on 27 October. Most of the earthquakes were volcano-tectonic events with magnitudes lower that 3.6 and located W of the caldera at depths between 3 and 25 km. The earthquake hypocenters became shallower with time. The most significant event, a M 3.6, occurred at 0227 on 27 October and was located in the SW edge of the crater. Very low-frequency earthquakes possibly indicated magma movement.

SERNAGEOMIN staff aboard an overflight on 27 October observed three craters along the S, SE edge of the caldera, with diameters of 200, 300, and 500 m. Mostly white plumes rose above the two smaller craters. The larger, southern-most crater emitted a plume with a greater ash content that rose 5 km above the crater. Satellite imagery showed a plume drifting 12 km SE. In response to the raised Alert Level, ONEMI reported that 128 people were evacuated from areas within a 45-km radius of the volcano, defined as high-risk zone.

One earthquake per hour was recorded between 1600 on 27 October and 1600 on 28 October. The majority of the earthquakes were characterized as long-period with magnitudes less than 2.2. During an overflight on 28 October, scientists observed a gas plume with a very low ash content rise 3-4 km above the craters. Seismicity continued to decrease during 28-29 October. Scientists conducting an overflight noted that a gas plume with some ash rose 1 km above the craters and drifted 5-8 km NE. They also confirmed that a large lahar had traveled down the Rio Huemul and another branch of the river during the initial phase of the eruption. During another observation flight on 30 October, scientists saw plumes with minor ash rising 0.8 km from two of the three craters. ONEMI noted that the total number of evacuees had reached 140. On 31 October scientists observed gas plumes rising 0.5 km above the craters and drifting SE. On 1 November scientists observed an explosion and an accompanying ash plume that rose 1.5 km above the active craters. They also noted subsequent minor explosions and ash emissions.

Sources: Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI) , Servicio Nacional de Geología y Minería (SERNAGEOMIN)

Below is a summary of eruption dates and Volcanic Explosivity Indices (VEI).

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Branney M J, Gilbert J S, 1995. Ice-melt collapse pits and associated features in the 1991 lahar deposits of Volcan Hudson, Chile: criteria to distinguish eruption-induced glacier melt. {Bull Volc}, 57: 293-302

Fuenzalida-Ponce R, 1976. The Hudson volcano. {In}: Gonzalez-Ferran O (ed) {Proc Symp Andean & Antarctic Volcanology Problems (Santiago, Chile, Sept 1974)}, Rome: IAVCEI, p 78-87

Gonzalez-Ferran O, 1972. Distribucion del volcanismo activo de Chile y la reciente erupcion del Volcan Villarrica. {Instituto Geog Militar Chile}, O/T 3491

Gonzalez-Ferran O, 1995. {Volcanes de Chile}. Santiago: Instituto Geografico Militar, 635 p

Gutierrez F, Giocada A, Gonzalez Ferran O, Lahsen A, Mazzuoli R, 2005. The Hudson volcano and surrounding monogenetic centres (Chilean Patagonia): an example of volcanism associated with ridge-trench collision environment. {J Volc Geotherm Res}, 145: 207-233

Haberle S G, Lumley S H, 1998. Age and origin of tephras recorded in postglacial lake sediments to the west of the southern Andes, 44° to 47° S. {J Volc Geotherm Res}, 84: 239-256

Kilian R, Hohner M, Biester H, Wallrabe-Adams H J, Stern C R, 2003. Holocene peat and lake sediment tephra record from the southernmost Chilean Andes (53-55° S). {Rev Geol Chile}, 30: 23-37

Kratzmann D J, Carey S, Scasso R, Naranjo J-A, 2009. Compositional variations and magma mixing in the 1991 eruptions of Hudson volcano, Chile. {Bull Volc}, 71: 419-439

Naranjo J A, Moreno R, Banks N G, 1993. La erupcion del volcan Hudson en 1991 (46° S), region XI, Aisen, Chile. {Bol Serv Nac Geol Min Chile}, 44: 1-50

Naranjo J A, Stern C R, 1998. Holocene explosive activity of Hudson volcano, southern Andes. {Bull Volc}, 59: 291-306

Newhall C G, Dzurisin D, 1988. Historical unrest at large calderas of the world. {U S Geol Surv Bull}, 1855: 1108 p, 2 vol

Orihashi Y, Naranjo J A, Motoki A, Sumino H, Hirata D, Anma R, Nagao K, 2004. Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: new constraints from K-Ar ages. {Rev Geol Chile}, 31: 207-224

Smithsonian Institution-CSLP, 1968-75. [Event notification cards]. {Center for Short-Lived Phenomena (CSLP) Event Cards}

Stern C R, 2008. Holocene tephrochronology record of large explosive eruptions in the southernmost Patagonian Andes. {Bull Volc}, 70: 435-454

Stern C R, Naranjo J A, 1995. Summary of the Holocene eruptive history of the Hudson volcano. {In}: Bitschene P R, Mendia J (eds) {The August 1991 eruption of the Hudson volcano (Patagonian Andes): a thousand days after}, Univ Nac de la Patagonia San Juan Bosco, Serv Nac Geol, p. 160-164

The ice-filled, 10-km-wide caldera of the remote Cerro Hudson volcano was not recognized until its first 20th-century eruption in 1971. Cerro Hudson is the southernmost volcano in the Chilean Andes related to subduction of the Nazca plate beneath the South American plate. The massive, 1905-m-high Cerro Hudson covers an area of 300 sq km. The compound caldera is drained through a breach on its NW rim, which has been the source of mudflows down the Río de Los Huemeles. Two cinder cones occur north of the volcano and others occupy the SW and SE flanks. Hudson has been the source of several major Holocene explosive eruptions. An eruption about 6700 years ago was one of the largest known in the southern Andes during the Holocene; another eruption about 3600 years ago also produced more than 10 cu km of tephra. An eruption in 1991 was Chile's second largest of the 20th century and formed a new 800-m-wide crater in the SW part of the caldera.