Emplacement process and timing of large volcanic debris avalanches, Montserrat, Lesser Antilles: implications for volcanic and tsunami hazards

小安的列斯群岛蒙特塞拉特岛大型火山碎片雪崩的就位过程和时间：对火山和海啸灾害的影响

• 批准号: NE/G007667/1
• 负责人: Timothy Minshull
• 金额: $ 4.54万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG007667%2F1
• 关键词: Emplacement; process; timing; large; volcanic

IODP proposal 681 was submitted to drill ten sites around the volcanic islands of Montserrat, Dominica and Martinique in the Lesser Antilles. Six sites will target recent (< 250 ka) debris avalanches generated by large scale volcanic flank collapse. Four sites located beyond the debris avalanche deposits will recover turbidites generated by the debris avalanches, and a longer term (2-10 Ma) record of volcanic eruptions and magmatic evolution. IODP 681 would be a scientific first, as it would provide the first cores to penetrate submarine debris avalanche deposits resulting from volcanic flank collapse. These collapses are some of the largest-volume (1 to 1,000 km3) mass flows on Earth. Even smaller (1 to 10 km3) flank collapse events, such as those that we will study, transport a similar amount of sediment to that delivered annually by rivers to the ocean. Recent mapping around volcanic islands suggests that flank collapses are more frequent than previously thought, especially collapses on the scale that we will study. Collapse events therefore have important implications for volcanic and tsunami hazards worldwide. In particular, the magnitude of tsunami generated by volcanic flank collapse is highly controversial. Tsunami magnitude is strongly dependent on how debris avalanches are emplaced. A better understanding of avalanche emplacement is key for predicting tsunami magnitude more accurately. Dating debris avalanche deposits in these IODP drill cores will help to understand the timing of large-scale volcanic flank collapse, and the factors that trigger such collapse. We will determine whether collapse events are typically associated with volcanic eruptions, or with periods of rapid sea level change. IODP 681 cores will help to understand how debris avalanches can be emplaced, for instance by documenting the number and composition (and hence origin) of deposit sub-units. Drill cores will also document the long term (2-10 Ma) eruptive history of these volcanoes in unusual detail. This eruptive history will guide prognosis of future volcanic activity both in the Lesser Antilles, and help to understand cycles of volcanic island construction and destruction in other locations worldwide. Are there patterns in eruption style, and are these patterns influenced by the timing of flank collapse? What conditions precede particularly large explosive eruptions? Finally, IODP 681 will document long term magmatic evolution in order to understand how igneous processes (such as partial melting, magma differentiation and transport) generate arc crust. How is magmatic evolution related to eruptive history, and timing and scale of flank collapse? Swath bathymetry, backscatter and shallow cores are available for all ten sites in IODP 681, but we lack seismic data for two Montserrat sites and one Martinique site. The UKIODP site survey would provide the seismic data for the two sites around Montserrat, whilst a French GWADASEIS cruise would provide the seismic data offshore Martinique. The UKIODP site survey would itself result in a scientific first, by collecting the first 3-d seismic data for a volcanic debris avalanche. Although seismic surveys in other locations (e.g. Canary or Hawaiian Islands) have consistently failed to penetrate and image volcanic debris avalanche deposits, previous 2-d seismic surveys around Montserrat, Dominica and Martinique have shown that these particular deposits can be imaged successfully due to relatively shallow water depths and thin character. Combining the first 3-d seismic data from this site survey, and the first drill cores for debris avalanches from IODP 681, will provide powerful new insights into their timing, triggers and emplacement process. The uniquely high resolution seismic data acquired by this site survey will provide a key reason for IODP to fund Proposal 681, as these would then be the only debris avalanche deposits worldwide to have high resolution seismic surveys.

IODP 提案 681 已提交，旨在在小安的列斯群岛的蒙特塞拉特岛、多米尼加岛和马提尼克岛周围的十个火山岛进行钻探。六个地点将针对最近（< 250 ka）由大规模火山侧面塌陷产生的碎片雪崩。位于碎片雪崩沉积物之外的四个地点将恢复碎片雪崩产生的浊积岩，以及火山喷发和岩浆演化的长期（2-10 Ma）记录。 IODP 681 将是科学上的第一次，因为它将提供第一个岩心来穿透火山侧面塌陷造成的海底碎片雪崩沉积物。这些塌陷是地球上体积最大（1 至 1,000 平方公里）的质量流之一。即使是较小的（1 至 10 平方公里）侧塌陷事件（例如我们将要研究的事件），也会输送与河流每年向海洋输送的沉积物数量相似的沉积物。最近对火山岛周围的测绘表明，侧面塌陷比之前想象的更为频繁，尤其是我们将要研究的规模的塌陷。因此，塌陷事件对全球火山和海啸灾害具有重要影响。特别是，火山侧翼塌陷引发的海啸规模备受争议。海啸的强度很大程度上取决于碎片雪崩的安置方式。更好地了解雪崩的位置是更准确地预测海啸强度的关键。对这些 IODP 钻芯中的碎片雪崩沉积物进行测年将有助于了解大规模火山侧面塌陷的时间以及引发此类塌陷的因素。我们将确定崩塌事件通常是否与火山爆发有关，或者与海平面快速变化时期有关。 IODP 681 核心将有助于了解如何安置碎片雪崩，例如通过记录沉积子单元的数量和成分（以及来源）。钻芯还将异常详细地记录这些火山的长期（2-10 Ma）喷发历史。这段喷发历史将指导小安的列斯群岛未来火山活动的预测，并有助于了解世界其他地区火山岛建设和破坏的周期。喷发风格是否存在模式，这些模式是否受到侧面塌陷时间的影响？特别大规模的爆炸性喷发之前需要什么条件？最后，IODP 681 将记录长期岩浆演化，以了解火成岩过程（例如部分熔融、岩浆分异和输送）如何产生弧壳。岩浆演化与喷发历史、侧翼塌陷的时间和规模有何关系？ IODP 681 中的所有 10 个站点都提供了条带测深、后向散射和浅岩芯，但我们缺乏两个蒙特塞拉特站点和一个马提尼克岛站点的地震数据。 UKIODP 现场勘测将提供蒙特塞拉特岛周围两个地点的地震数据，而法国 GWADASEIS 巡航将提供马提尼克岛近海的地震数据。 UKIODP 现场调查本身将通过收集火山碎片雪崩的第一个 3D 地震数据而创造科学上的第一。尽管其他地点（例如加那利群岛或夏威夷群岛）的地震勘测一直未能穿透火山碎片雪崩沉积物并对其进行成像，但之前在蒙特塞拉特岛、多米尼加岛和马提尼克岛周围进行的二维地震勘测表明，由于相对而言，这些特定沉积物可以成功成像。水深浅，性格单薄。结合本次现场调查的第一个 3D 地震数据，以及 IODP 681 的第一个碎片雪崩钻芯，将为它们的时间、触发和就位过程提供强有力的新见解。此次现场勘测获得的独特高分辨率地震数据将为 IODP 资助 681 号提案提供关键理由，因为这些将成为全球唯一进行高分辨率地震勘测的碎片雪崩沉积物。

项目成果

Insights into the emplacement dynamics of volcanic landslides from high-resolution 3D seismic data acquired offshore Montserrat, Lesser Antilles

• DOI: 10.1016/j.margeo.2012.10.004
• 发表时间: 2013
• 期刊: Marine Geology
• 影响因子: 2.9
• 作者: G. Crutchley;J. Karstens;C. Berndt;P. Talling;S. Watt;M. Vardy;V. Hühnerbach;M. Urlaub;S. Sarkar;D. Klaeschen;M. Paulatto;A. Friant;E. Lebas;F. Maeno