Historic hydrovolcanism at (): hazards implication Dario Pedrazzi1*, Károly Németh2, Adelina Geyer1, Antonio M. Álvarez-Valero3, Gerardo Aguirre-Díaz4, Stefania Bartolini1 1 Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Group of Volcanology, SIMGEO (UB-CSIC) C/ Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain 2 Volcanic Risk Solutions, CS-INR, Massey University, Private Bag 11 222, Palmerston North, New Zealand; 3 Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, Spain 4 POSVOLDEC Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Qro. 76230, Mexico (CTM2016-79617-P) Corresponding author (e-mail: [email protected]) (AEI/FEDER-UE)

INTRODUCTION GEOLOGICAL SETTING

a)a N Ÿ Deception Island (DI). SOUTH AMERICAN Ÿ Deception Island, South Shetland Archipelago, is located at Where? PLATE South Shettland Plate the southwestern end of the ; Ÿ Understanding the dynamics of magma-water North Scotia Ridge Ÿ The Bransfield Strait is a young (<1.4 Ma) back-arc basin, interaction at DI; SOUTH Objective Ÿ due to the subduction of the Phoenix plate under the Antarctic Characterizing the most likely eruptive SHETLANDS SCOTIA scenarios in the future. PHOENIX SFZ PLATE PLATE plate (Dalziel 1984); PLATE South Scotia Ridge Ÿ Deception Island consists of a <0.75 Ma (Valencio et al. Aluk Ridge Ÿ Detailed revision (field, petrology and HFZ 1979; Smellie 1988) horseshoe-shaped volcanic edifice, How geochemistry) of the historical hydrovolcanic post- Bransfield Rift SANDWICH interpreted as a tectonic fault-controlled collapse caldera South Shetland Trench caldera eruptions of DI. Fig.1b PLATE ANTARCTIC WEDDELL (Martí et al. 2013); PLATE PLATE 500 km Ÿ Three volcanic phases are recognized: pre, syn-and post- Ÿ Crimson Hill eruption (1825-1829); caldera (Smellie 2001, Martí et al. 2013); Ÿ Kroner Lake eruption (1829-1912); a) Simplified regional tectonic map and location of the Archipelago Ÿ Ÿ Post-caldera phase, 70 scattered eruptive vents inside the 1967, 1969 and 1970 eruptions. (modified from Ibañez et al. 2003). HFZ-Hero Fracture Zone, SFZ-Shetland Fracture Zone, b) S-Snow Island, L-Livingston Island, G- geological Setting of the South Shetland Islands Archipelago and location of Deception Island c) simplified geological map of Deception Island Greenwich Island, R-Robert Island, N-Nelson (after Smellie et al.2002; Martí et al. 2013). caldera, including the recent historical eruptions (1829-1970). (modified from Grad et al. 1992). Island, KG-King George Island

1967 ERUPTION 1970 ERUPTION

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I S S L L f) Simplified geological map of Deception I 1 m Island with a) isopach and b) isopleth maps of 1967 pyroclastic fall deposits. SSE NNW Stratigraphic logs from the 1967 eruption are also shown (both maps and stratigraphic logs are taken from Baker a, b) isopac map of 1970 eruption (modifed from Baker et al. 1975). Outcrops are shown et al. 1975), c) 1967 edifice Island just as well, c) Isolines of median diameter from 1970 samples (Pedrazzi et al. 2014), d) after the eruption (modified from Smellie general view of one of the 1970 craters-outcrop, e) bomb-enriched deposits, f) massive et al. 2002) and d) nowadays, e) 1967 lithic-rich deposit, g) general view of Lago Escondido, h) massive, unbedded and edifice land just after the eruption subordinate fine lapilli deposits, i) detail of a massive deposit. (modified from Smellie et al. 2002), f) S-scoria, I-ignimbrite, L-lava. Fig. Pedrazzi et al. 2018 lithics at 1967 outcrop. Fig. Pedrazzi et al. 2018

KRONER LAKE AND CRIMSON HILL ERUPTIONS 1969 ERUPTION

c) d) a) e)

e)

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a) Simplified geological map of Deception Island, b) simplified geological map of Kroner Lake eruption close to Whalers Bay (modified from Roobol 1973), c,d) Crimson Hill sequence with W E laminated layers and lithics of lava (BSF, Basaltic Shield Formation)and ignimbrite (OCTF, Outer Coast Tuff a) Isopach and b) isopleth maps of products from the 1969 eruption Formation), e) Kroner Lake, f) (taken from Baker et al. 1975), c, d) The area of interest of the eruption Outcrop at Kroner Lake with the main (from Smellie 2001) e) picture of 1969 eruption close to Pendulum sequence of lapilli and ash with some Cove, f) field picture of the destroyed Chilean base, g) field picture of laminated beds, g) scoria bed. Whaler’s Bay. Fig. Pedrazzi et al. 2018 Fig. Pedrazzi et al. 2018

DISCUSSION REFERENCES

Ÿ Baker PE, McReath I, Harvey MR, Roobol MJ, Davies TG (1975) The geology of the South Shetland Islands. V. Volcanic evolution of Ÿ (a) Kroner Lake and (b) Crimson Hill eruptions Deception Island. British Antarctic Survey. 78:81 PP Ÿ Dalziel IWD (1984) Tectonic evolution of a forearc terrane, southern occurred close to the current coastal margins Scotia Ridge, Antarctica. In: Dalziel IWD (ed) Tectonic evolution of a forearc terrane. Geological Society of America, Southern Scotia where shallow sea water or groundwater is Ridge. Ÿ Grad M, Guterch A, Środa P (1992) Upper crustal structure of present; Deception Island area, Bransfield Strait,West Antarctica. Antarct Sci 4(4):469–476 Ÿ “Land” centres of 1967 (c) and 1970 (d) Ÿ Ibáñez JM, Almendros J, Carmona E,Martí C, AbrilM(2003) The recent seismo-volcanic activity at Deception Island volcano. Deep- eruptions were due to the interaction between Sea Res II Top Stud Oceanogr 50(10):1611–1629. Ÿ Martí J, Geyer A, Aguirre-Diaz G (2013) Origin and evolution of the magma and a possibly fractured aquifer; Deception Island caldera (South Shetland Islands, Antarctica). Bull Volcanol 75(6):732 Ÿ “Island” centres started with a submarine Ÿ Pedrazzi D, Aguirre-Díaz G, Bartolini S, Martí J, Geyer A (2014) The 1970 eruption on Deception Island (Antarctica): eruptive eruption at shallow seawater, later evolving into a dynamics and implications for volcanic hazards. J Geol Soc 171(6):765–778. subaerial phase; Ÿ Pedrazzi D, Németh K, Geyer A, Álvarez-Valero A M, Aguirre- Día, G, Bartolini, S (2018). Historic hydrovolcanism at Deception Ÿ 1969 eruption (e) was due to magma-ice/snow Island (Antarctica): implications for eruption hazards. Bulletin of Volcanology 80(1):11 interaction. Ÿ Roobol MJ (1973) Historic volcanic activity at Deception Island. Brit Antarct Surv Bull 32:23–30 Ÿ Smellie JL (2001) Lithostratigraphy and volcanic evolution of Deception Island, South Shetland Islands. Antarct Sci 73(2):788–209 Ÿ Smellie JL, López-Martínez J, Headland RK, Hernández- Cifuentes F, Maestro A, Millar IL, Rey J, Serrano E, Somoza L, Thomson JW (2002) Geology and geomorphology of Deception Ÿ Hydrovolcanic activity from maars and tuff cones Island. (BAS Geomap Series, Sheets 6A and 6B).77pp is the cause of major direct volcanic hazards; Ÿ The availability of water or other external fluids

acted as first order agents to influence the style of FOR MORE INFORMATION hydrovolcanism; POSVOLDEC PAPER ABOUT ME Ÿ Ashfall, ballistics (1967, 1970, Kroner Lake) and a) Remains of the Chilean base after 1967 and 1969 eruptions; damage is due to fallout and jökulhlaup and b) a tourist cruise at (inside main Ÿ A map showing the possible type of PDCs (Crimson Hill) represent the main hazards hazards would be related to fallout and dilute PDCs), c) Spanish Base Gabriel de Castilla and d) Argentinian Base Decepción. Both bases, in the case of hydrovolcanic eruptions, hydrovolcanic activity to be expected during a related to hydrovolcanic activity; would be affected; as would be as already occurred to the Chilean and Norwegian future volcanic eruption at DI was created Ÿ Meltwater (jökulhlaup-1969). bases. Remains of e) British Base and f) Norwegian whaling station at Whalers Bay due to jökulhlaup as consequence of the 1969 eruption. Fig. Pedrazzi et al. 2018 (Pedrazzi et al. 2018).