Journal of Volcanology and Geothermal Research 155 (2006) 329–333 www.elsevier.com/locate/jvolgeores Short communication Abrupt climatic changes as triggering mechanisms of massive volcanic collapses Lucia Capra Instituto de Geografía, UNAM, CU Coyoacan, 04510, Mexico DF, Mexico Received 7 March 2006; received in revised form 31 March 2006; accepted 19 April 2006 Available online 5 June 2006 Abstract Abrupt climate change can trigger volcanic collapses, phenomena that cause the destruction of the entire sector of a volcano, including its summit. During the past 30 ka, major volcanic collapses occurred just after main glacial peaks that ended with rapid deglaciation. Glacial debuttressing, load discharge and fluid circulation coupled with the post-glacial increase of humidity and heavy rains can activate the failure of unstable edifices. Furthermore, significant global warming can be responsible for the collapse of ice-capped unstable volcanoes, an unpredictable hazard that in few minutes can bury inhabited areas. © 2006 Published by Elsevier B.V. Keywords: volcanic collapse; global warming 1. Introduction Wyk de Vries et al., 2001; Clavero et al., 2002). Several analogue experiments have been performed to demon- Although climate changes have been considered to be strate how faults can deform volcanoes that finally a triggering mechanism for large eruptions (Rampino et collapse (Van Wyk de Vries and Borgia, 1996; Lagmay et al., 1979; McGuire et al., 1997), they have not, so far, al., 2000; Acocella, 2005; Norini and Lagmay, 2005). been related to the collapse of volcanoes. Unstable This is probably a very common mechanism, but it is volcanoes, whatever the origin of their instability, can spatially localized and can occur in an indeterminate collapse from the same triggering mechanism (McGuire, period of time. In contrast, climatic changes can act 1996). Generally, the deposit originating from the widely, in a specific time span. For example, heavy rainy collapse can reflect the cause of the instability, but it is seasons characterized the last decade and were related to always difficult to determine the triggering mechanism. a change in climatic conditions due to global warming. When juvenile material (magma fragments) are present Prolonged rains associated with hurricanes were the in the sequence originating from the collapse, it is cause of massive landslides over large areas, such as obvious that magma was involved during the event, but Hurricane Mich that in 1998 devastated Central America when such features are not observable it is more difficult and promoted the flank collapse at Casita volcano in to determine why the volcano failed, and generally other Nicaragua, killing 2500 people (Scott et al., 2005). mechanisms such as volcano basement spreading were Here I suggest that most volcanic collapses in ice- involved (i.e. Socompa and Parinacota volcanoes, Van capped volcanoes, which occurred after the main glacial peaks during the late Pleistocene and Holocene, were E-mail address: [email protected]. probably induced by global warming. The model here 0377-0273/$ - see front matter © 2006 Published by Elsevier B.V. doi:10.1016/j.jvolgeores.2006.04.009 330 L. Capra / Journal of Volcanology and Geothermal Research 155 (2006) 329–333 presented is based on an extensive bibliographic hemisphere are documented by radiocarbon chronology investigation of all known cases of volcanic collapse on the Chilean Andean Piedmont, which shows glacial and their relations with the climatic conditions at the maxima at 13,900–14,890 (Oldest Dryas), 21,000, moment of the event. The main problem is the exact age 23,060 and 26,940 14C years BP. The last glaciation of the volcanic event, reported as an absolute date in ended with a massive collapse of ice lobes between 14 very few cases, whereas in other cases it is inferred and 13 ka 14C BP, which was also documented in both based on a stratigraphic correlation or geomorphic polar hemispheres (Lowell et al., 1995; Alley and Clark, observation and it is also generically defined. Despite 1999) and in the Huascaran tropical ice core from Peru this uncertainty, the model presented gives an indication (Thompson et al., 2000). Although the Younger Dryas of how climatic changes can induce such phenomena. had a more regional effect, it was observed in southern This is a topic that should be thoroughly investigated to Chile at 11,050 years BP, and penecontemporaneously prevent future hazards. in the Atlantic Ocean and in the Southern Alps of New Zealand at 10,500 14C years BP (Denton and Hendy, 2. Global climatic changes during Quaternary 1994; Hughen et al., 2000). Similarly, the 7500 14C years BP glacial event (8200 calendar years ago, Alley The late Pleistocene and Holocene geological record et al., 1997) was recorded in the North Atlantic and in indicates that several volcanic collapses occurred in subtropical environments, such as Mexico (Vázquez- limited time spans at 1.4–1.3 ka BP, at 1.0–0.9 ka BP Selem and Heine, 2004). and at ∼0.8 ka BP (Fig. 1, Table 1). During this same Oxygen isotopic data for the Older and Younger period, several abrupt deglaciations were reported at Dryas from Greenland ice cores suggest that, whereas different latitudes and some of these can be correlated increasing glaciation occurred slowly, deglaciation between hemispheres (Lowell et al., 1995; Clapperton, preceded quickly (Alley et al., 1997; Alley and Clark, 1998). The ages of glaciations in the southern 1999). The rapid deglaciation is an important factor in Fig. 1. Diagram showing the main glacial advances and retreats for the northern and southern hemispheres (modified from Clapperton, 1998; Lowell et al., 1995). Black circles correspond to the volcanoes that suffered flank collapses during Pleistocene and Holocene time. See Table 1 for volcano identification. L. Capra / Journal of Volcanology and Geothermal Research 155 (2006) 329–333 331 Table 1 Ages of volcanic collapses during Pleistocene and Holocene. To avoid inconsistency into the bibliography, some cites refer to papers where data recompilation was done, in which it is possible to found more detailed references No. Volcano name Country Elev. a.s.l. Collapse age Reference (yr BP) 1⁎ Parinacota Chile 6350 13,500 Francis and Wells (1988) 1 Parinacota Chile 6353 7790 Clavero et al. (2002) 2 Taapaca Chile 5860 14,000 Clavero and Sparks (2004) 3 Socompa Chile 6052 7200 Van Wyk de Vries et al. (2001) 4 Ollague Chile 5868 11,000 Feeley et al. (1993) 5 Tupungatito Chile/Argentina 6000 Holocene/Pleistocene Siebert and Simkin (2002) 6 Planchón-Peteroa Chile 4107 11,000 Siebert and Simkin (2002) 7 San Pedro-Pellado Chile/Argentina 3621 Late Holocene Siebert and Simkin (2002) 8 Antuco Chile 2979 9700 Thiele et al. (1998) 9 Callaqui Chile 3164 Holocene Siebert and Simkin (2002) 10 Calbuco Chile 2003 Pleistocene/Holocene Siebert and Simkin (2002) 11 Irruputunco Chile/Bolivia 5165 Holocene Siebert and Simkin (2002) 12 Tata Sabaya Bolivia 5430 12,000 Siebert and Simkin (2002) 13 TungurahuaI Ecuador 5023 14,000 Siebert and Simkin (2002) 14 Pico de Orizaba Mexico 5675 11,000–15,000 Carrasco-Nuñez et al. (1993) 15 Nevado de Colima Mexico 3850 18,500 Stoopes and Sheridan (1992) 16 Volcán de Colima Mexico 3600 9300 Capra et al. (2002) 17 Popocatépetl Mexico 5426 23,000 Capra et al. (2002) 18 Jocotitlán Mexico 3900 9600 Siebe et al. (1992) 19 Nevado de Toluca Mexico 4680 28,000 Caballero and Capra (2004) 20 Mt St Helens USA 2549 18,000–20,000 Siebert and Simkin (2002) 21 Baker USA 3285 6800 Siebert and Simkin (2002) 22 Adams USA 3742 6000 Siebert and Simkin (2002) 23 Egmont New Zealand 2518 23,000 Alloway et al. (1986) 23 Egmont New Zealand 2518 12,000–14,000 Alloway et al. (1986) 23 Egmont New Zealand 2518 6570 Alloway et al. (1986) 24 Meru Africa 4565 7800 Siebert and Simkin (2002) determining the instability of a rock mass, as discussed glacial climax, but start immediately after it during a below. period of rapid retreat. For example, the collapses of: (i) Antuco volcano (Chile), Volcán de Colima and 3. Climatic effects as triggering mechanisms of Jocotitlán (Mexico) occurred after the Younger Dryas; volcanic collapses (ii) Taacapa (Chile) and Egmont (New Zealand) volcanoes occurred after the Oldest Dryas; and (iii) The 1980 Mount Saint Helens eruption is the best Mero (Africa), Parinacota and Socompa (Chile) took known example of an historic volcanic collapse, during place after the 8200 14C cal. years glacial event. Mount which the north flank of the volcano deformed after Egmont (New Zealand) represents the best example 3 months of cryptodome intrusion and failed after a because, based on absolute dating, it collapsed at least magnitude 5 earthquake. Since this event, witnessed by twice immediately after the glacial maximum (Alloway many volcanologists, this type of phenomenon was et al., 1986). recognized in the eruptive history of many volcanoes, Based upon these observations, it is here proposed either active or inactive (Siebert, 1984). Looking at the that the “globally synchronous” volcanic collapse geological record, during the late Pleistocene and events, which occurred just after glacial maxima, were Holocene, several volcanic collapses occurred in limited triggered by global warming rather than seismic events time spans, whereas there are periods without a trace of as previously suggested (Francis and Wells, 1988). any edifice failure. Fig. 1 illustrates major volcanic This model do not excludes the possibility that the collapses and the synchroneity of the maximum volcano was already unstable due to other factors, such glaciations during the late Pleistocene and Holocene in as magmatic intrusions into the volcanic edifice, the northern and southern hemispheres. It is clear from accumulation of pyroclastic deposits, sub-volcanic this diagram that volcanic collapses are absent during a basement spreading and progressive weakening by 332 L.