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Guebuem Kim - One of the best experts on this subject based on the ideXlab platform.
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Tracing nitrogen sources fueling coastal green tides off a Volcanic Island using radon and nitrogen isotopic tracers.
Science of The Total Environment, 2019Co-Authors: Hyung-mi Cho, Guebuem Kim, Kyung-hoon ShinAbstract:Abstract The main sources of nutrients fueling coastal green tides off a Volcanic Island surrounded by an oligotrophic ocean are obscure, although they result in many societal and ecosystem problems. In this study, we attempted to trace the source inputs of nutrients in coastal waters off a Volcanic Island, Jeju, Korea, where the formation of green tides is perennial, using a radioisotope (222Rn) and stable isotopes (δ15N and δ18O) as tracers. Sampling of groundwater, seawater, fish-farm water, and Ulva spp. was performed during April and July 2015. The contribution of submarine fresh groundwater discharge (SFGD) to the dissolved inorganic nitrogen input was >70%, with additional inputs from aqua-cultural activities and bottom sediments. The δ15N-NO3 and δ18O-NO3 values in the coastal seawater and groundwater indicate that the main source of NO3− is fertilizer, rather than other potential sources, such as aquacultural wastewater, sewage/manure contamination, or precipitation, in this region. The δ15N value (+7.3–+7.7‰) in Ulva spp. also indicates the same source. Thus, our results suggest that the rapid infiltration of land N-fertilizer and subsequent leakage into the coastal ocean through submarine groundwater discharge (SGD) results in green tide massive occurrence in coastal waters off a high-permeability Volcanic Island.
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Dependence of coastal water pH increases on submarine groundwater discharge off a Volcanic Island
Estuarine Coastal and Shelf Science, 2015Co-Authors: Jung-hyun Lee, Guebuem KimAbstract:Abstract During the past few decades, excessive input of nutrients and organic matter, in addition to global ocean acidification, has resulted in significant changes in the water pH of coastal ocean. In this study, we investigated the effect of submarine groundwater discharge (SGD) on pH variations in the coastal waters of Hwasun Bay off the Volcanic Island of Jeju, Korea, which is situated in the oligotrophic open ocean. In this region, salinities of all coastal waters depend primarily on SGD because of the lack of any contributions from the river or stream waters. We observed a significant increase in pH along the lower-salinity plume zone, extending 0.5 km horizontally from the bottom to the surface ( 2 = 0.82) between salinity and pH. A simple two-endmember (submarine groundwater and offshore seawater) mixing model showed that this pH increase was caused by an enhanced biological production, which resulted from the SGD-driven nutrient inputs, rather than from groundwater dilution itself. Since a number of local and regional studies showed that SGD-driven fluxes of nutrients are comparable to or higher than their riverine fluxes, our results from an SGD-dominated environment suggest that SGD may have a significant influence on the coastal biogeochemical changes such as acidification, deoxygenation, and eutrophication.
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dissolved organic matter in the subterranean estuary of a Volcanic Island jeju importance of dissolved organic nitrogen fluxes to the ocean
Journal of Sea Research, 2013Co-Authors: Tae Hoon Kim, Intae Kim, Eunhwa Kwon, Shinah Lee, Guebuem KimAbstract:Abstract We observed the origin, behavior, and flux of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), colored dissolved organic matter (CDOM), and dissolved inorganic nitrogen (DIN) in the subterranean estuary of a Volcanic Island, Jeju, Korea. The sampling of surface seawater and coastal groundwater was conducted in Hwasun Bay, Jeju, in three sampling campaigns (October 2010, January 2011, and June 2011). We observed conservative mixing of these components in this subterranean environment for a salinity range from 0 to 32. The fresh groundwater was characterized by relatively high DON, DIN, and CDOM, while the marine groundwater showed relatively high DOC. The DON and DIN fluxes through submarine groundwater discharge (SGD) in the groundwater of Hwasun Bay were estimated to be 1.3 × 10 5 and 2.9 × 10 5 mol d − 1 , respectively. In the seawater of Hwasun Bay, the groundwater-origin DON was almost conservative while about 91% of the groundwater-origin DIN was removed perhaps due to biological production. The DON flux from the entire Jeju was estimated to be 7.9 × 10 8 mol yr − 1 , which is comparable to some of the world's large rivers. Thus, our study highlights that DON flux through SGD is potentially important for delivery of organic nitrogen to further offshore while DIN is readily utilized by marine plankton in near-shore waters under N-limited conditions.
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large fluxes of rare earth elements through submarine groundwater discharge sgd from a Volcanic Island jeju korea
Marine Chemistry, 2011Co-Authors: Intae Kim, Guebuem KimAbstract:Abstract To evaluate the role of submarine groundwater discharge (SGD) as a source of rare earth elements (REEs) in the coastal ocean, we estimated the SGD associated discharge of REEs into two semi-enclosed coastal bays off a Volcanic Island, Jeju, Korea. The coastal brackish groundwater showed pronounced enrichments of middle REEs (MREE) relative to light REEs (LREE) and heavy REEs (HREE) when normalized against the upper continental crust (UCC), whereas seawater samples outside the bays showed a HREE enrichment pattern. The enrichment of both MREE and HREE was clearly identified in bay waters, resulting from mixing between groundwater and offshore seawater. The mass balances of REEs demonstrated that the REE fluxes through SGD were two to three orders of magnitude higher than those that occurred through the other sources, such as diffusion from bottom sediments and atmospheric dust fallout. The SGD-driven Nd flux from the entire Jeju Island during this summer was approximately 120 ± 60 mol d− 1, which is comparable to the Nd fluxes from major rivers (i.e., Mississippi River). Our results imply that highly permeable oceanic Islands are particularly important for REE fluxes to the ocean.
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Influence of trace element fluxes from submarine groundwater discharge (SGD) on their inventories in coastal waters off Volcanic Island, Jeju, Korea
Applied Geochemistry, 2011Co-Authors: Jiwon Jeong, Guebuem Kim, Seunghee HanAbstract:Abstract The concentrations of trace elements in groundwater and seawater were measured in a coastal embayment (Bangdu Bay) of a Volcanic Island (Jeju) off the southernmost coast of Korea in August and December of 2009. The concentrations of trace elements (Al, Mn, Fe, Co, Ni, and Cu) in the groundwater in summer were approximately 20-fold higher than those in winter, with good correlation to each other. Overall, the concentrations of most of the trace elements in the groundwater were 3- to 70-fold higher than those in the seawater of this Bay. Simple budget calculations showed that large fluxes of submarine groundwater discharge (SGD)-driven trace elements were responsible for the unusually enhanced concentrations of trace elements (particularly for Al, Fe and Co) in the summer seawater. The results imply that the temporal changes in SGD-driven trace element fluxes are large and may contribute considerably to the budget of trace elements in the coastal ocean, particularly off a highly permeable Volcanic Island.
Peter J. Talling - One of the best experts on this subject based on the ideXlab platform.
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Origin of spectacular fields of submarine sediment waves around Volcanic Islands
Earth and Planetary Science Letters, 2018Co-Authors: Ed L. Pope, Peter J. Talling, Martin Jutzeler, Matthieu J.b. Cartigny, James Shreeve, Ian C. Wright, Richard J. WysoczanskiAbstract:Understanding how large eruptions and landslides are recorded by seafloor morphology and deposits on Volcanic Island flanks is important for reconstruction of Volcanic Island history and geohazard assessment. Spectacular fields of bedforms have been recognised recently on submerged flanks of Volcanic Islands at multiple locations worldwide. These fields of bedforms can extend over 50 km, and individual bedforms can be 3 km in length and 150 m in height. The origin of these bedform fields, however, is poorly understood. Here, we show that bedforms result from eruption-fed supercritical density flows (turbidity currents) in some locations, but most likely rotational landslides at other locations. General criteria are provided for distinguishing between submarine bedforms formed by eruptions and landslides, and emphasise a need for high resolution seismic datasets to prevent ambiguity. Bedforms associated with rotational landslides have a narrower source, with a distinct headscarp, they are more laterally confined, and internal bedform structure does not suggest upslope migration of each bedform. Eruption-fed density currents produce wide fields of bedforms, which extend radially from the caldera. Internal layers imaged by detailed seismic data show that these bedforms migrated up-slope, indicating that the flows that produced them were Froude supercritical. Due to the low density contrast between interstitial fluid and sediment, the extent and dimensions of submarine eruption-fed bedforms is much greater than those produced by pyroclastic density currents on land.
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multi stage Volcanic Island flank collapses with coeval explosive caldera forming eruptions
Scientific Reports, 2018Co-Authors: James E Hunt, Michael Cassidy, Peter J. TallingAbstract:Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small ( 300 km3), but can also occur in complex multiple stages. Here, we show that multistage retrogressive landslides on Tenerife triggered explosive caldera-forming eruptions, including the Diego Hernandez, Guajara and Ucanca caldera eruptions. Geochemical analyses were performed on Volcanic glasses recovered from marine sedimentary deposits, called turbidites, associated with each individual stage of each multistage landslide. These analyses indicate only the lattermost stages of subaerial flank failure contain materials originating from respective coeval explosive eruption, suggesting that initial more voluminous submarine stages of multi-stage flank collapse induce these aforementioned explosive eruption. Furthermore, there are extended time lags identified between the individual stages of multi-stage collapse, and thus an extended time lag between the initial submarine stages of failure and the onset of subsequent explosive eruption. This time lag succeeding landslide-generated static decompression has implications for the response of magmatic systems to un-roofing and poses a significant implication for ocean Island volcanism and civil emergency planning.
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Composition, geometry, and emplacement dynamics of a large Volcanic Island landslide offshore Martinique: From volcano flank-collapse to seafloor sediment failure?
Geochemistry Geophysics Geosystems, 2016Co-Authors: M. Brunet, Osamu Ishizuka, Georges Boudon, Peter J. Talling, Anne Le Friant, Sara Lafuerza, Matthew J. Hornbach, Elodie Lebas, Hervé GuyardAbstract:Landslides are common features in the vicinity of Volcanic Islands. In this contribution, we investigate landslides emplacement and dynamics around the Volcanic Island of Martinique based on the first scientific drilling of such deposits. The evolution of the active Montagne Pelee volcano on this Island has been marked by three major flank-collapses that removed much of the western flank of the volcano. Subaerial collapse volumes vary from 2 to 25 km3 and debris avalanches flowed into the Grenada Basin. High-resolution seismic data (AGUADOMAR-1999, CARAVAL-2002, and GWADASEIS-2009) is combined with new drill cores that penetrate up to 430 m through the three submarine landslide deposits previously associated to the aerial flank-collapses (Site U1399, Site U1400, Site U1401, IODP Expedition 340, Joides Resolution, March–April 2012). This combined geophysical and core data provide an improved understanding of landslide processes offshore a Volcanic Island. The integrated analysis shows a large submarine landslide deposit, without debris avalanche deposits coming from the volcano, comprising up to 300 km3 of remobilized seafloor sediment that extends for 70 km away from the coast and covers an area of 2100 km2. Our new data suggest that the aerial debris avalanche deposit enter the sea but stop at the base of submarine flank. We propose a new model dealing with seafloor sediment failures and landslide propagation mechanisms, triggered by Volcanic flank-collapse events affecting Montagne Pelee volcano. Newly recognized landslide deposits occur deeper in the stratigraphy, suggesting the recurrence of large-scale mass-wasting processes offshore the Island and thus, the necessity to better assess the associated tsunami hazards in the region.
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Submarine record of Volcanic Island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine Volcanic Island landslides by IODP Expedition 340
Geochemistry Geophysics Geosystems, 2015Co-Authors: A. Le Friant, Osamu Ishizuka, Georges Boudon, Martin R. Palmer, Peter J. Talling, Benoit Villemant, T. Adachi, Mohammed Aljahdali, Christoph Breitkreuz, M. BrunetAbstract: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.
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New Insights into the Emplacement Dynamics of Volcanic Island Landslides
Oceanography, 2014Co-Authors: Sebastian F L Watt, Peter J. Talling, James E HuntAbstract:Volcanic Islands form the highest topographic structures on Earth and are the sites of some of the planet's largest landslides. These landslides can rapidly mobilize hundreds of cubic kilometers of rock and sediment, and potentially generate destructive tsunamis on ocean-basin scales. The main unknown for tsunami hazard assessment is the way in which these landslides are emplaced. Understanding of landslide dynamics relies on interpretation of deposits from past events: it is necessary to understand where material within the deposit originated and the temporal sequence of the deposit's formation. The degree of fragmentation in a Volcanic landslide is controlled by its relative proportions of dense lavas and weak pyroclastic rocks; fragmentation is generally reduced during subaqueous relative to subaerial transport. In the submarine environment, the seafloor-sediment substrate commonly fails during emplacement of a Volcanic landslide. However, in many cases, this sediment failure remains almost in situ as a deformed package rather than disaggregating to form a debris flow. Because seafloor sediment makes up a large proportion of many landslide deposits around Volcanic Islands, the magnitude of the primary Volcanic failure cannot be readily assessed without a clear understanding of deposit constituents. Both the dimensions of the Volcanic failure and the way in which it fails are of key importance for tsunami generation. Turbidite deposits suggest that some Volcanic landslides occur in multiple retrogressive stages. This significantly reduces potential tsunami magnitude relative to models that assume emplacement of the landslide in a single stage.
Intae Kim - One of the best experts on this subject based on the ideXlab platform.
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dissolved organic matter in the subterranean estuary of a Volcanic Island jeju importance of dissolved organic nitrogen fluxes to the ocean
Journal of Sea Research, 2013Co-Authors: Tae Hoon Kim, Intae Kim, Eunhwa Kwon, Shinah Lee, Guebuem KimAbstract:Abstract We observed the origin, behavior, and flux of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), colored dissolved organic matter (CDOM), and dissolved inorganic nitrogen (DIN) in the subterranean estuary of a Volcanic Island, Jeju, Korea. The sampling of surface seawater and coastal groundwater was conducted in Hwasun Bay, Jeju, in three sampling campaigns (October 2010, January 2011, and June 2011). We observed conservative mixing of these components in this subterranean environment for a salinity range from 0 to 32. The fresh groundwater was characterized by relatively high DON, DIN, and CDOM, while the marine groundwater showed relatively high DOC. The DON and DIN fluxes through submarine groundwater discharge (SGD) in the groundwater of Hwasun Bay were estimated to be 1.3 × 10 5 and 2.9 × 10 5 mol d − 1 , respectively. In the seawater of Hwasun Bay, the groundwater-origin DON was almost conservative while about 91% of the groundwater-origin DIN was removed perhaps due to biological production. The DON flux from the entire Jeju was estimated to be 7.9 × 10 8 mol yr − 1 , which is comparable to some of the world's large rivers. Thus, our study highlights that DON flux through SGD is potentially important for delivery of organic nitrogen to further offshore while DIN is readily utilized by marine plankton in near-shore waters under N-limited conditions.
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large fluxes of rare earth elements through submarine groundwater discharge sgd from a Volcanic Island jeju korea
Marine Chemistry, 2011Co-Authors: Intae Kim, Guebuem KimAbstract:Abstract To evaluate the role of submarine groundwater discharge (SGD) as a source of rare earth elements (REEs) in the coastal ocean, we estimated the SGD associated discharge of REEs into two semi-enclosed coastal bays off a Volcanic Island, Jeju, Korea. The coastal brackish groundwater showed pronounced enrichments of middle REEs (MREE) relative to light REEs (LREE) and heavy REEs (HREE) when normalized against the upper continental crust (UCC), whereas seawater samples outside the bays showed a HREE enrichment pattern. The enrichment of both MREE and HREE was clearly identified in bay waters, resulting from mixing between groundwater and offshore seawater. The mass balances of REEs demonstrated that the REE fluxes through SGD were two to three orders of magnitude higher than those that occurred through the other sources, such as diffusion from bottom sediments and atmospheric dust fallout. The SGD-driven Nd flux from the entire Jeju Island during this summer was approximately 120 ± 60 mol d− 1, which is comparable to the Nd fluxes from major rivers (i.e., Mississippi River). Our results imply that highly permeable oceanic Islands are particularly important for REE fluxes to the ocean.
James E Hunt - One of the best experts on this subject based on the ideXlab platform.
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multi stage Volcanic Island flank collapses with coeval explosive caldera forming eruptions
Scientific Reports, 2018Co-Authors: James E Hunt, Michael Cassidy, Peter J. TallingAbstract:Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small ( 300 km3), but can also occur in complex multiple stages. Here, we show that multistage retrogressive landslides on Tenerife triggered explosive caldera-forming eruptions, including the Diego Hernandez, Guajara and Ucanca caldera eruptions. Geochemical analyses were performed on Volcanic glasses recovered from marine sedimentary deposits, called turbidites, associated with each individual stage of each multistage landslide. These analyses indicate only the lattermost stages of subaerial flank failure contain materials originating from respective coeval explosive eruption, suggesting that initial more voluminous submarine stages of multi-stage flank collapse induce these aforementioned explosive eruption. Furthermore, there are extended time lags identified between the individual stages of multi-stage collapse, and thus an extended time lag between the initial submarine stages of failure and the onset of subsequent explosive eruption. This time lag succeeding landslide-generated static decompression has implications for the response of magmatic systems to un-roofing and poses a significant implication for ocean Island volcanism and civil emergency planning.
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New Insights into the Emplacement Dynamics of Volcanic Island Landslides
Oceanography, 2014Co-Authors: Sebastian F L Watt, Peter J. Talling, James E HuntAbstract:Volcanic Islands form the highest topographic structures on Earth and are the sites of some of the planet's largest landslides. These landslides can rapidly mobilize hundreds of cubic kilometers of rock and sediment, and potentially generate destructive tsunamis on ocean-basin scales. The main unknown for tsunami hazard assessment is the way in which these landslides are emplaced. Understanding of landslide dynamics relies on interpretation of deposits from past events: it is necessary to understand where material within the deposit originated and the temporal sequence of the deposit's formation. The degree of fragmentation in a Volcanic landslide is controlled by its relative proportions of dense lavas and weak pyroclastic rocks; fragmentation is generally reduced during subaqueous relative to subaerial transport. In the submarine environment, the seafloor-sediment substrate commonly fails during emplacement of a Volcanic landslide. However, in many cases, this sediment failure remains almost in situ as a deformed package rather than disaggregating to form a debris flow. Because seafloor sediment makes up a large proportion of many landslide deposits around Volcanic Islands, the magnitude of the primary Volcanic failure cannot be readily assessed without a clear understanding of deposit constituents. Both the dimensions of the Volcanic failure and the way in which it fails are of key importance for tsunami generation. Turbidite deposits suggest that some Volcanic landslides occur in multiple retrogressive stages. This significantly reduces potential tsunami magnitude relative to models that assume emplacement of the landslide in a single stage.
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sedimentological and geochemical evidence for multistage failure of Volcanic Island landslides a case study from icod landslide on north tenerife canary Islands
Geochemistry Geophysics Geosystems, 2011Co-Authors: Peter J. Talling, James E Hunt, Russell B Wynn, D G Masson, Damon A H TeagleAbstract:[1] Volcanic Island landslides can pose a significant geohazard through landslide-generated tsunamis. However, a lack of direct observations means that factors influencing tsunamigenic potential of landslides remain poorly constrained. The study of distal turbidites generated from past landslides can provide useful insights into key aspects of the landslide dynamics and emplacement process, such as total event volume and whether landslides occurred as single or multiple events. The northern flank of Tenerife has undergone multiple landslide events, the most recent being the Icod landslide dated at ∼165 ka. The Icod landslide generated a turbidite with a deposit volume of ∼210 km3, covering 355,000 km2of seafloor off northwest Africa. The Icod turbidite architecture displays a stacked sequence of seven normally graded sand and mud intervals (named subunits SBU1–7). Evidence from subunit bulk geochemistry, volume, basal grain size, Volcanic glass composition and sand mineralogy, combined with petrophysical and geophysical data, suggests that the subunit facies represents multistage retrogressive failure of the Icod landslide. The basal subunits (SBU1–3) indicate that the first three stages of the landslide had a submarine component, whereas the upper subunits (SBU4–7) originated above sea level. The presence of thin, non-bioturbated, mud intervals between subunit sands suggests a likely time interval of at least several days between each stage of failure. These results have important implications for tsunamigenesis from such landslides, as multistage retrogressive failures, separated by several days and with both a submarine and subaerial component, will have markedly lower tsunamigenic potential than a single-block failure.
Sebastian F L Watt - One of the best experts on this subject based on the ideXlab platform.
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from catastrophic collapse to multi phase deposition flow transformation seafloor interaction and triggered eruption following a Volcanic Island landslide
Earth and Planetary Science Letters, 2019Co-Authors: Sebastian F L Watt, Jens Karstens, Aaron Micallef, Christian Berndt, Morelia Urlaub, Melanie Ray, Anisha Desai, Maddalena Sammartini, Ingo Klaucke, Christoph BottnerAbstract:Abstract The current understanding of tsunamis generated by Volcanic-Island landslides is reliant on numerical models benchmarked against reconstructions of past events. As the largest historical event with timed tsunami observations, the 1888 sector collapse of Ritter Island, Papua New Guinea provides an outstanding opportunity to better understand the linked process of landslide emplacement and tsunami generation. Here, we use a combination of geophysical imaging, bathymetric mapping, seafloor observations and sampling to demonstrate that the Ritter landslide deposits are spatially and stratigraphically heterogeneous, reflecting a complex evolution of mass-flow processes. The primary landslide mass was dominated by well-bedded scoriaceous deposits, which rapidly disintegrated to form an erosive Volcaniclastic flow that incised the substrate over much of its pathway. The major proportion of this initial flow is inferred to have been deposited up to 80 km from Ritter. The initial flow was followed by secondary failure of seafloor sediment, over 40 km from Ritter. The most distal part of the 1888 deposit has parallel internal boundaries, suggesting that multiple discrete units were deposited by a series of mass-flow processes initiated by the primary collapse. The last of these flows was derived from a submarine eruption triggered by the collapse. This syn-collapse eruption deposit is compositionally distinct from pre- and post-collapse eruptive products, suggesting that the collapse immediately destabilised the underlying magma reservoir. Subsequent eruptions have been fed by a modified plumbing system, constructing a submarine Volcanic cone within the collapse scar through at least six post-collapse eruptions. Our results show that the initial tsunami-generating landslide at Ritter generated a stratigraphically complex set of deposits with a total volume that is several times larger than the initial failure. Given the potential for such complexity, there is no simple relationship between the volume of the tsunamigenic phase of a Volcanic-Island landslide and the final deposit volume, and deposit area or run-out cannot be used to infer primary landslide magnitude. The tsunamigenic potential of prehistoric sector-collapse deposits cannot, therefore, be assessed simply from surface mapping, but requires internal geophysical imaging and direct sampling to reconstruct the event.
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from gradual spreading to catastrophic collapse reconstruction of the 1888 ritter Island Volcanic sector collapse from high resolution 3d seismic data
Earth and Planetary Science Letters, 2019Co-Authors: Jens Karstens, Sebastian F L Watt, Aaron Micallef, Christian Berndt, Morelia Urlaub, Melanie Ray, Ingo Klaucke, Sina Muff, Dirk Klaeschen, Michel KuhnAbstract:Abstract Volcanic Island flank collapses have the potential to trigger devastating tsunamis threatening coastal communities and infrastructure. The 1888 sector collapse of Ritter Island, Papua New Guinea (in the following called Ritter) is the most voluminous Volcanic Island flank collapse in historic times. The associated tsunami had run-up heights of more than 20 m on the neighboring Islands and reached settlements 600 km away from its source. This event provides an opportunity to advance our understanding of Volcanic landslide-tsunami hazards. Here, we present a detailed reconstruction of the 1888 Ritter sector collapse based on high-resolution 2D and 3D seismic and bathymetric data covering the failed Volcanic edifice and the associated mass-movement deposits. The 3D seismic data reveal that the catastrophic collapse of Ritter occurred in two phases: (1) Ritter was first affected by deep-seated, gradual spreading over a long time period, which is manifest in pronounced compressional deformation within the Volcanic edifice and the adjacent seafloor sediments. A scoria cone at the foot of Ritter acted as a buttress, influencing the displacement and deformation of the western flank of the volcano and causing shearing within the Volcanic edifice. (2) During the final, catastrophic phase of the collapse, about 2.4 km3 of Ritter disintegrated almost entirely and traveled as a highly energetic mass flow, which incised the underlying sediment. The irregular topography west of Ritter is a product of both compressional deformation and erosion. A crater-like depression underlying the recent Volcanic cone and eyewitness accounts suggest that an explosion may have accompanied the catastrophic collapse. Our findings demonstrate that Volcanic sector collapses may transform from slow gravitational deformation to catastrophic collapse. Understanding the processes involved in such a transformation is crucial for assessing the hazard potential of other volcanoes with slowly deforming flanks such as Mt. Etna or Kilauea.
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New Insights into the Emplacement Dynamics of Volcanic Island Landslides
Oceanography, 2014Co-Authors: Sebastian F L Watt, Peter J. Talling, James E HuntAbstract:Volcanic Islands form the highest topographic structures on Earth and are the sites of some of the planet's largest landslides. These landslides can rapidly mobilize hundreds of cubic kilometers of rock and sediment, and potentially generate destructive tsunamis on ocean-basin scales. The main unknown for tsunami hazard assessment is the way in which these landslides are emplaced. Understanding of landslide dynamics relies on interpretation of deposits from past events: it is necessary to understand where material within the deposit originated and the temporal sequence of the deposit's formation. The degree of fragmentation in a Volcanic landslide is controlled by its relative proportions of dense lavas and weak pyroclastic rocks; fragmentation is generally reduced during subaqueous relative to subaerial transport. In the submarine environment, the seafloor-sediment substrate commonly fails during emplacement of a Volcanic landslide. However, in many cases, this sediment failure remains almost in situ as a deformed package rather than disaggregating to form a debris flow. Because seafloor sediment makes up a large proportion of many landslide deposits around Volcanic Islands, the magnitude of the primary Volcanic failure cannot be readily assessed without a clear understanding of deposit constituents. Both the dimensions of the Volcanic failure and the way in which it fails are of key importance for tsunami generation. Turbidite deposits suggest that some Volcanic landslides occur in multiple retrogressive stages. This significantly reduces potential tsunami magnitude relative to models that assume emplacement of the landslide in a single stage.
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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
Science & Engineering Faculty, 2013Co-Authors: Jessica Trofimovs, A. Le Friant, Peter J. Talling, Sebastian F L Watt, Jodie K. Fisher, R. S. J. Sparks, Malcolm B. Hart, Christopher W. Smart, Michael Cassidy, Steven Grahame MoretonAbstract:Mass flows on Volcanic Islands generated by Volcanic lava dome collapse and by larger volume flank collapse, can be highly dangerous locally and may generate tsunamis that threaten a wider area. It is therefore important to understand their frequency, emplacement dynamics and relationship to Volcanic eruption cycles. The best record of mass flow on Volcanic Islands may be found offshore, where most material is deposited, and where intervening hemipelagic sediment aids dating. Here we analyse what is arguably the most comprehensive sediment core data set collected offshore from a Volcanic Island. The cores are located southeast of Montserrat, on which the Soufriere Hills volcano has been erupting since 1995. The cores provide a record of mass flow events during the last 110 ka. Older mass flow deposits differ significantly from those generated by the repeated lava dome collapses observed since 1995. The oldest mass flow deposit originated through collapse of the basaltic South Soufriere Hills at 103-110 ka, some 20-30 ka after eruptions formed this Volcanic centre. A ~1.8 km3 blocky debris avalanche deposit that extends from a chute in the Island shelf records a particularly deep-seated failure. It likely formed from a collapse of almost equal amounts of Volcanic edifice and coeval carbonate shelf, emplacing a mixed bioclastic-andesitic turbidite in a complex series of stages. This study illustrates how Volcanic Island growth and collapse involved extensive, large-volume submarine mass flows with highly variable composition. Run-out turbidites indicate that mass flows are emplaced either in multiple stages or as single events.
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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
Geochemistry Geophysics Geosystems, 2013Co-Authors: Jessica Trofimovs, Peter J. Talling, Sebastian F L Watt, Jodie K. Fisher, R. S. J. Sparks, Malcolm B. Hart, Christopher W. Smart, Michael Cassidy, Le A Friant, Steven Grahame MoretonAbstract:[1] Mass flows on Volcanic Islands generated by Volcanic lava dome collapse and by larger-volume flank collapse can be highly dangerous locally and may generate tsunamis that threaten a wider area. It is therefore important to understand their frequency, emplacement dynamics, and relationship to Volcanic eruption cycles. The best record of mass flow on Volcanic Islands may be found offshore, where most material is deposited and where intervening hemipelagic sediment aids dating. Here we analyze what is arguably the most comprehensive sediment core data set collected offshore from a Volcanic Island. The cores are located southeast of Montserrat, on which the Soufriere Hills volcano has been erupting since 1995. The cores provide a record of mass flow events during the last 110 thousand years. Older mass flow deposits differ significantly from those generated by the repeated lava dome collapses observed since 1995. The oldest mass flow deposit originated through collapse of the basaltic South Soufriere Hills at 103–110 ka, some 20–30 ka after eruptions formed this Volcanic center. A ~1.8 km3 blocky debris avalanche deposit that extends from a chute in the Island shelf records a particularly deep-seated failure. It likely formed from a collapse of almost equal amounts of Volcanic edifice and coeval carbonate shelf, emplacing a mixed bioclastic-andesitic turbidite in a complex series of stages. This study illustrates how Volcanic Island growth and collapse involved extensive, large-volume submarine mass flows with highly variable composition. Runout turbidites indicate that mass flows are emplaced either in multiple stages or as single events.
