Article (refereed) – Published version

IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.

[1]  P. Talling,et al.  Coring disturbances in IODP piston cores with implications for offshore record of volcanic events and the Missoula megafloods , 2014 .

[2]  M. Manga,et al.  Late Pleistocene stratigraphy of IODP Site U1396 and compiled chronology offshore of south and south west Montserrat, Lesser Antilles , 2014 .

[3]  D. Clague,et al.  Mapping the Nuuanu and Wailau landslides in Hawaii , 2013 .

[4]  P. Talling,et al.  Timing and emplacement dynamics of newly recognised mass flow deposits at ~8–12ka offshore Soufrière Hills volcano, Montserrat: How submarine stratigraphy can complement subaerial eruption histories , 2013 .

[5]  V. Pinel,et al.  Consequences of volcano sector collapse on magmatic storage zones: Insights from numerical modeling , 2013 .

[6]  M. Leng,et al.  Timing, origin and emplacement dynamics of mass flows offshore of SE Montserrat in the last 110 ka: Implications for landslide and tsunami hazards, eruption history, and volcanic island evolution , 2013 .

[7]  E. Cortijo,et al.  Role of large flank-collapse events on magma evolution of volcanoes. Insights from the Lesser Antilles Arc , 2012 .

[8]  E. Sumner,et al.  Planform geometry, stacking pattern, and extrabasinal origin of low strength and intermediate strength cohesive debris flow deposits in the Marnoso-arenacea Formation, Italy , 2012 .

[9]  M. Urlaub,et al.  Widespread and progressive seafloor-sediment failure following volcanic debris avalanche emplacement: Landslide dynamics and timing offshore Montserrat, Lesser Antilles , 2012 .

[10]  M. Manga,et al.  Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin , 2012 .

[11]  J. Rice,et al.  Nucleation of slip‐weakening rupture instability in landslides by localized increase of pore pressure , 2012 .

[12]  M. Urlaub,et al.  Combinations of volcanic-flank and seafloor-sediment failure offshore Montserrat, and their implications for tsunami generation , 2012 .

[13]  R. Wynn,et al.  Sedimentological and geochemical evidence for multistage failure of volcanic island landslides: A case study from Icod landslide on north Tenerife, Canary Islands , 2011 .

[14]  A. Le Friant,et al.  A new model for the evolution of La Réunion volcanic complex from complete marine geophysical surveys , 2011 .

[15]  C. Berndt,et al.  Multiple widespread landslides during the long‐term evolution of a volcanic island: Insights from high‐resolution seismic data, Montserrat, Lesser Antilles , 2011 .

[16]  J. Beget,et al.  Volcano collapse along the Aleutian Ridge (western Aleutian Arc) , 2011 .

[17]  S. Labanieh,et al.  The eruptive history of Morne Jacob volcano (Martinique Island, French West Indies): Geochronology, geomorphology and geochemistry of the earliest volcanism in the recent Lesser Antilles arc , 2010 .

[18]  A. Dufresne,et al.  Substrate deformation associated with the Jocotitlán edifice collapse and debris avalanche deposit, Central México , 2010 .

[19]  P. Tapponnier,et al.  Active faulting induced by slip partitioning in Montserrat and link with volcanic activity: New insights from the 2009 GWADASEIS marine cruise data , 2010 .

[20]  S. Loughlin,et al.  Eruption of Soufrière Hills (1995–2009) from an offshore perspective: Insights from repeated swath bathymetry surveys , 2010 .

[21]  D. Long,et al.  3D seismic evidence of internal structure within Tampen Slide deposits on the North Sea Fan: are chaotic deposits that chaotic? , 2010, Journal of the Geological Society.

[22]  Melanie J. Leng,et al.  Evidence for carbonate platform failure during rapid sea‐level rise; ca 14 000 year old bioclastic flow deposits in the Lesser Antilles , 2009 .

[23]  R. Robertson,et al.  Debris avalanche deposits offshore St. Vincent (West Indies): Impact of flank-collapse events on the morphological evolution of the island , 2009 .

[24]  M. James,et al.  The influence of edifice slope and substrata on volcano spreading. , 2008 .

[25]  J. Komorowski,et al.  Radiometric dating of three large volume flank collapses in the Lesser Antilles Arc , 2008 .

[26]  Finn Løvholt,et al.  Oceanic propagation of a potential tsunami from the La Palma Island , 2008 .

[27]  R. Sparks,et al.  Anatomy of a submarine pyroclastic flow and associated turbidity current: July 2003 dome collapse, Soufrière Hills volcano, Montserrat, West Indies , 2008 .

[28]  J. Lénat,et al.  Growth and collapse of the Reunion Island volcanoes , 2008 .

[29]  R. Sparks,et al.  Late Pleistocene tephrochronology of marine sediments adjacent to Montserrat, Lesser Antilles volcanic arc , 2008, Journal of the Geological Society.

[30]  J. Komorowski,et al.  Volcano flank instability in the Lesser Antilles Arc: Diversity of scale, processes, and temporal recurrence , 2007 .

[31]  G. Mattioli,et al.  Prehistoric Stratigraphy of the Soufrière Hills–South Soufrière Hills Volcanic Complex, Montserrat, West Indies , 2007, The Journal of geology.

[32]  G. Boudon,et al.  Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system , 2006 .

[33]  G. Pedersen,et al.  Submarine landslides: processes, triggers and hazard prediction , 2006, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[34]  N. Fournier,et al.  Submarine pyroclastic deposits formed at the Soufrière Hills volcano, Montserrat (1995–2003) : what happens when pyroclastic flows enter the ocean? , 2006 .

[35]  J. Cartwright,et al.  Frontally confined versus frontally emergent submarine landslides: A 3D seismic characterisation , 2006 .

[36]  G. Fryer,et al.  Tsunami Generation by Submarine Mass Failure. II: Predictive Equations and Case Studies , 2005 .

[37]  R. Sparks,et al.  Geomorphological evolution of Montserrat (West Indies): importance of flank collapse and erosional processes , 2004, Journal of the Geological Society.

[38]  P. Heinrich,et al.  Numerical simulation of the last flank‐collapse event of Montagne Pelée, Martinique, Lesser Antilles , 2003 .

[39]  P. Tapponnier,et al.  Arc parallel extension and localization of volcanic complexes in Guadeloupe, Lesser Antilles , 2002 .

[40]  J. Komorowski,et al.  Submarine evidence for large-scale debris avalanches in the Lesser Antilles Arc , 2001 .

[41]  S. Day,et al.  Cumbre Vieja Volcano—Potential collapse and tsunami at La Palma, Canary Islands , 2001 .

[42]  S. Krastel,et al.  Submarine landslides around the Canary Islands , 2001 .

[43]  B. Voight.  Structural stability of andesite volcanoes and lava domes , 2000, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[44]  V. Pinel,et al.  The effect of edifice load on magma ascent beneath a volcano , 2000, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[45]  R. Macdonald,et al.  The Lesser Antilles volcanic chain : a study in arc magmatism. , 2000 .

[46]  M. Canals,et al.  The most recent megalandslides of the Canary Islands: El Golfo debris avalanche and Canary debris flow, west El Hierro Island , 1997 .

[47]  R. Iverson,et al.  U. S. Geological Survey , 1967, Radiocarbon.

[48]  J. Schneider,et al.  Du volcan au sédiment: la dynamique du talus volcanoclastique sous-marin de Gran Canaria, canaries (Atlantique oriental, Leg ODP 157) , 1997 .

[49]  B. Voight,et al.  Failure of volcano slopes , 1997 .

[50]  D. Masson,et al.  A giant landslide on the north flank of Tenerife, Canary Islands , 1995 .

[51]  B. Voight,et al.  Introduction to the Harry Glicken memorial special issue on “models of magmatic processes and volcanic eruptions” , 1995 .

[52]  P. Bouysse,et al.  The Lesser Antilles Island Arc , 1990 .

[53]  G. Boudon,et al.  The primitive volcano of Mount Pelée: its construction and partial destruction by flank collapse , 1989 .

[54]  William R. Normark,et al.  The Giant Submarine Alika Debris Slide, Mauna Loa, Hawaii , 1988 .

[55]  G. Wadge.  The dykes and structural setting of the volcanic front in the Lesser Antilles island arc , 1986 .

[56]  G. Wadge.  Comparison of volcanic production rates and subduction rates in the Lesser Antilles and Central America , 1984 .

[57]  G. Boudon,et al.  Flank failure–directed blast eruption at Soufrière, Guadeloupe, French West Indies: A 3,000-yr-old Mt. St. Helens? , 1984 .

[58]  P. Bouysse,et al.  Donnees sur la structure de l'arc insulaire des Petites Antilles, entre Ste-Lucie et Anguilla , 1983 .

[59]  R. Sparks,et al.  Volcanogenic Sedimentation in the Lesser Antilles Arc , 1980, The Journal of Geology.

[60]  義記 岡.  Late Pleistocene の海面変化に関する諸問題 , 1970 .

[61]  S. Watt.  University of Birmingham New insights into the emplacement dynamics of volcanic island landslides , 2014 .

[62]  R. Taylor,et al.  Chapter 20 Multi-stage collapse events in the South Soufrière Hills, Montserrat as recorded in marine sediment cores , 2014 .

[63]  B. Voight,et al.  Chapter 1 An overview of the eruption of Soufrière Hills Volcano, Montserrat from 2000 to 2010 , 2014 .

[64]  M. Urlaub,et al.  Insights into the emplacement dynamics of volcanic landslides from high-resolution 3D seismic data acquired offshore Montserrat, Lesser Antilles , 2013 .

[65]  B. Voight,et al.  Undrained Sediment Loading Key to Long-Runout Submarine Mass Movements: Evidence from the Caribbean Volcanic Arc , 2012 .

[66]  C. Berndt,et al.  Insights into pyroclastic flow emplacement from high-resolution 3D seismic data from Montserrat, Lesser Antilles , 2012 .

[67]  B. Voight,et al.  Unique and remarkable dilatometer measurements of pyroclastic flow-generated tsunamis , 2007 .

[68]  Steven N. Ward,et al.  Landslide tsunami , 2003 .

[69]  C. Deplus,et al.  Large-scale flank collapse events during the activity of Montagne Pelée, Martinique, Lesser Antilles , 2003 .

[70]  Neil C. Mitchell,et al.  Slope failures on the flanks of the western Canary Islands , 2002 .

[71]  R. Sparks,et al.  The volcanic evolution of Montserrat using 40Ar/39Ar geochronology , 2002, Geological Society, London, Memoirs.

[72]  B. Voight,et al.  The 26 December (Boxing Day) 1997 sector collapse and debris avalanche at Soufrière Hills Volcano, Montserrat , 2002, Geological Society, London, Memoirs.

[73]  L. Siebert.  Landslides resulting from structural failure of volcanoes , 2002 .

[74]  G. Boudon,et al.  L'ı̂le de la Dominique, à l'origine des avalanches de débris les plus volumineuses de l'arc des Petites Antilles , 2002 .

[75]  R. Sparks,et al.  The eruption of Soufrière Hills Volcano, Montserrat: overview of scientific results , 2002 .

[76]  H. Schmincke,et al.  Volcanic evolution of Gran Canaria reconstructed from apron sediments: Synthesis of VICAP project drilling (ODP Leg 157) , 1998 .

[77]  P. Cole.  Volcano Instability on the Earth and Other Planets , 1997 .

[78]  P. Labazuy.  Recurrent landslides events on the submarine flank of Piton de la Fournaise volcano (Reunion Island) , 1996, Geological Society, London, Special Publications.

[79]  R. Reid,et al.  Late Quaternary sedimentation in the Lesser Antilles island arc , 1996 .

[80]  Robin T. Holcomb,et al.  Large landslides from oceanic volcanoes , 1991 .

[81]  William R. Normark,et al.  Prodigious submarine landslides on the Hawaiian Ridge , 1989 .

[82]  D. R. Crandell.  Gigantic debris avalanche of Pleistocene age from ancestral Mount Shasta Volcano, California, and debris-avalanche hazard zonation , 1989 .

[83]  M. Paterne.  Reconstruction de l'activité explosive des volcans de l'Italie du Sud par téphrochronologie marine , 1985 .