Historic Hydrovolcanism at Deception Island (Antarctica): Eruptive Dynamics and Hazards Implications
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POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Historic hydrovolcanism at Deception Island (Antarctica): eruptive dynamics and hazards implications Dario Pedrazzi1, Károly Németh2, Adelina Geyer1, Antonio Álvarez-Valero3, Gerardo Aguirre-Díaz4, Stefania Bartolini1 1Group of Volcanology, Institute of Earth Sciences Jaume Almera-CSIC, Barcelona, Spain 2Volcanic Risk Solutions, CS-INR, Massey University, Palmerston North, New Zealand 3Departamento de Geología, Universidad de Salamanca Salamanca, Spain 4Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Mexico Main EGU2018-8215 | PICO | GMPV4.8/CL1.34 Presentation 2-minute madness POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Where? • Deception Island (Antarctica) POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) • Understanding the dynamics of magma-water interaction at Objective Deception Island • Characterising the most likely eruptive scenarios in the future • Detailed revision (field, petrology and geochemistry) of the historical How? hydrovolcanic post-caldera eruptions of Deception Island • Crimson Hill eruption (1825-1829) • Kroner Lake eruption (1829 -1912) • 1967, 1969 and 1970 eruptions POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Smellie et al. 2002 Pendulum Cove W E POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) • Hydrovolcanic activity from maars and tuff cones is the cause of major direct volcanic hazards. • These include ashfall and ballistics (1967, 1970, Kroner Lake) and PDCs (Crimson Hill). • A major concern at DI as a consequence of hydrovolcanic activity is related to ash emission. • Meltwater (jökulhlaup-1969). • A map showing the possible type of hydrovolcanic activity to be expected during a future volcanic eruption at Deception Island was created POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) MORE INFO? COME TO MY SPOT!!! Thanks for your attention POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Historic hydrovolcanism at Deception Island (Antarctica): eruptive dynamics and hazards implications Dario Pedrazzi1, Károly Németh2, Adelina Geyer1, Antonio Álvarez-Valero3, Gerardo Aguirre-Díaz4, Stefania Bartolini1 1Group of Volcanology, Institute of Earth Sciences Jaume Almera-CSIC, Barcelona, Spain 2Volcanic Risk Solutions, CS-INR, Massey University, Palmerston North, New Zealand 3Departamento de Geología, Universidad de Salamanca Salamanca, Spain 4Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Mexico Island’s Discussion Geological Historical Introduction main and Setting features eruptions conclusions References and Acknowledgements EGU2018-8215 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Introduction Where? • Deception Island (Antarctica) • Understanding the dynamics of magma-water interaction at Objective Deception Island • Characterising the most likely eruptive scenarios in the future • Detailed revision (field, petrology and geochemistry) of the historical How? hydrovolcanic post-caldera eruptions of Deception Island • Crimson Hill eruption (1825-1829) • Kroner Lake eruption (1829 -1912) • 1967, 1969 and 1970 eruptions POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Geological Setting • Deception Island, South Shetland Archipelago, is located at the southwestern end of the Bransfield Strait. • The Bransfield Strait consists of a young (<1.4 Ma) back-arc basin due to the Phoenix plate subduction under the Antarctic plate (Dalziel, 1984). • The Bransfield Basin has a characteristic graben structure. Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Geological Setting • Deception Island (<0.75-Ma) is a horseshoe-shaped volcanic edifice with an above-sea-level diameter of around 13 km. • The highest piks are at Mount Pond (540 m a.s.l.) and Mount Kirkwood (460 m a.s.l .). • Three main phases: pre-, syn- and post- caldera. • The post-caldera phase consists of at least 70 scattered eruptive vents inside the caldera and includes the recent historical eruptions (1829-1970) . Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Eastern Craters Chilean Base (1970) Deception Island (1967+1969) Macaroni Point Western Craters Costa Recta (1970) Mount Pond Telefon (1969) Bay Mount Pond Fumarole Port Bay Foster Baily Decepción Head Base British Base Neptunes (1969) Mount Bellows Kirkwod 4 km Martí et al. 2013 modified Gabriel de Castilla Base Croner Lake Pre-caldera deposits (XIX) Syn-caldera deposits Post-caldera deposits POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Historical eruptions 1967 Crimson Hill eruption (1825-1829) 1970 Kroner Lake eruption (1829-1912) 1969 Geochemistry eruption Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Crimson Hill Lago 1970 Escondido 1967 Telefon Bay Pendulum Cove 1 Foster 2 Bay • The original landform would have had a perimeter of about 3.5 km and a diameter of about 1.3 km. Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Crimson Hill 1 2 Pedrazzi et al. 2018 • Deposits affected by post-depositional palagonitisation. • Mainly laminated lithic-rich thin beds with poorly vesiculated scoria lapilli of red and black colour. Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Kroner Lake • The present-day Kroner Lake crater has an almost circular shape, 350 m by 300 m in diameter. • 0.005 Km3 bulk volume deposits. 1 2 Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Kroner Lake 1 2 • Poorly vesiculated scoria bombs and lapilli deposits with normal and reverse grading. • Subordinate well-vesiculated bombs, scoriae deposits, and thinly bedded layers. Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1967 • The eruption lead to the formation of a new island consisting of three overlapping pyroclastic cones with water-filled craters. • Formation of a “land” centre. Pedrazzi et al. 2018 Pedrazzi et al. 2014 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1967 • The 3-day-long eruption (3th to 6th of December 1967) produced a lithic rich sequence with poorly vesicular ash and lapilli beds to coarse lapilli and bombs (Baker et al., 1975). • Isopach map indicates a dominant north- westerly wind. • Isopleth map differs from the isopach map in showing an eastward elongation; this is probably because isopachs incorporate data for the entire eruption. • 0.05 Km3 bulk volume of deposits. Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) modified from Smellie et al. 2002 1967 modified from Smellie et al. 2002 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1970 • 13 “land” and “island” vents (Baker et al., 1975). • The land consisted of seven conical edifices aligned roughly NW–SE. • The "island" centres are a total of 6 vents. • 0. 1 Km3 bulk volume deposits. Pedrazzi et al. 2018 Pedrazzi et al. 2014 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1970 Pedrazzi et al. 2014 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1970 • At the “land” craters the sequence is mainly characterised by lithic- rich breccia beds. • The upper part is characterised by a continuous alternation of thick breccia beds and lapilli beds with Pedrazzi et al. 2014 planar stratification. POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1970 • At the “island” craters, poorly sorted, lithic rich breccia beds with some beds of poorly sorted coarse lapilli showing Pedrazzi et al. 2014 weak lamination. POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) 1969 • Subglacial eruption due to magma-ice interaction (Smelli et al., 2002). • Rapid generation of abundant meltwater (jökulhlaup). • Isopachs and isopleths maps indicate control by a northerly wind. modified from Smellie 2001 modified from Smellie et al. 2002 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Geochemistry • TAS diagram, samples are grouped within the alkaline and subalkaline fields (mainly basalts, trachybasalts, basaltic trachyandesites and trachyandesites) Pedrazzi et al. 2018 POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Discussion and Conclusions ü Magma-water interaction is one of the most relevant factors controlling recent post-caldera volcanic activity at DI: • field characteristics (tephra, blocks and bombs, and explosion breccia of fall and dilute PDCs origin) similar to other recent hydrovolcanic eruptions worldwide (1245 yr BP Asososca maar eruption, Nicaragua, Pardo et al,. 2009; 1913 maar-forming eruption in West-Ambrym, Vanuatu, Németh and Cronin, 2011), • low vesicularity of juveniles products, • enrichment of lithics, • palagonitization of matrix glass, • some of the cones were built directly at shallow seawater. ü Although some chemical variation, the availability of water or other external fluids acted as first order agents to influence the style of hydrovolcanism. POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Discussion and Conclusions ü Variable degrees of explosivity and corresponding eruption dynamics were observed. ü Crimson Hill and Kroner Lake eruptions occurred close to the current coastal margins where shallow sea water or groundwater is present. ü “Land” centres of 1967 and 1970 eruptions were due to the interaction between magma and a possibly fractured aquifer. ü “Island” centres started with a submarine eruption at shallow seawater, later evolving into a subaerial phase. ü 1969 eruption was due to magma-ice/snow Pedrazzi et al. 2018 interaction. POSVOLDEC (CTM2016-79617-P) (AEI/FEDER-UE) Discussion and Conclusions • Hydrovolcanic activity from maars and tuff cones is the cause of major direct volcanic hazards. • These include ashfall and ballistics (1967, 1970, Kroner Lake) and PDCs (Crimson Hill). • A major concern at DI as a consequence of hydrovolcanic activity