Environmental Impacts of Hurricane Irma on the British Virgin Islands

随着今年四场强烈风暴登陆美国和加勒比海岸线，2017年飓风季节凸显了更好地了解大西洋地区飓风的地理和时间控制的必要性。这个RAPID项目提供了一个独特的机会，可以了解5级飓风对英属维尔京群岛（BVI）阿内加达（Anegada）现有古冲过记录的影响，英属维尔京群岛（BVI）是受飓风“厄玛”影响最大的岛屿之一。该研究小组将仔细比较飓风“厄玛”之前和之后由极端海浪淹没造成的海岸沉积物，这是朝着改进易受飓风和海啸淹没影响的海岸线灾害风险评估迈出的重要一步。这项工作将不仅为英属维尔京群岛，而且为包括美属维尔京群岛和波多黎各在内的其他加勒比岛屿提供关于飓风和海啸危害的重要新信息。通过评估飓风Irma沉积的沉积物，该团队将开发一个重要的5级风暴的现代模拟，这将有助于解释加勒比地区冲积（和间歇性海啸）沉积物的长期地质记录，这将使加勒比国家能够更好地准备、应对、恢复和减轻未来的飓风影响。英属维尔京群岛阿内加达的冲积沉积物和巨石的分布捕捉到了有关飓风伊尔玛风暴潮的重要信息（水流深度、淹没距离）。通过详细的多学科领域和实验室分析，该团队打算调查与飓风“厄玛”登陆阿内加达有关的环境影响和冲过沉积物，以便：(1)记录已知5级飓风的风暴潮特征和相关沉积沉积物；(2)评估风暴潮冲刷深度和泥沙搬运距离；(3)使用飓风Irma沉积物作为与较早的冲过记录进行比较的基础，包括在Anegada沿海池塘内推断的一系列海啸沉积物。这些数据将用于重新评估过去几千年记录的冲积记录，并将确定该地区过去大风暴（如2010年和2017年的飓风）和海啸（1755年里斯本地震）所形成的沉积物之间的异同。基于从厄玛飓风中吸取的教训，对阿内加达的过冲记录进行了重新评估，可以用来重建与风暴和海啸相关的频率、强度和物理影响的千年尺度模式。这种对极端海浪事件的精细化理解，将改善受两种形式的海洋淹没影响的海岸线的灾害预测、准备和评估。

With four intense storms making landfall on American and Caribbean coastlines this year, the 2017 hurricane season highlights the need to better understand the geographic and temporal controls on hurricanes in the Atlantic region. This RAPID project represents a unique opportunity to understand the impact of a Category 5 hurricane on the existing paleo-overwash record at previously-studied field sites on Anegada, British Virgin Islands (BVI), one of the islands that sustained the greatest impact from Hurricane Irma. The research team will make careful comparisons between pre- and post-Irma coastal deposits resulting from extreme wave inundation as an important step towards improving the assessment of hazard risk for coastlines that are vulnerable to both hurricane and tsunami inundation. This work will provide important new information regarding hurricane and tsunami hazards, not only for the British Virgin Islands, but for other Caribbean islands including those of the U.S. Virgin Islands and Puerto Rico. By assessing the sediments deposited by Hurricane Irma, the team will develop an important modern analog of a Category 5 storm that will help interpret long-term geologic records of overwash (and episodic tsunami) deposits for the Caribbean region, which will enable Caribbean countries to better prepare for, respond to, recover from, and mitigate future hurricane impacts. The distribution of overwash sediments and boulders at Anegada, BVI captures important information regarding Hurricane Irma's storm surge (flow depths, inundation distances). Through detailed multidisciplinary field and laboratory analyses the team intends to investigate the environmental impacts and overwash deposits associated with Hurricane Irma's landfall on Anegada to: (1) document the storm surge characteristics and associated sedimentary deposit of a known Category 5 hurricane; (2) assess the depth of scour and distance of sediment and boulder transport by storm surge; and (3) use the Hurricane Irma deposit as a basis of comparison with older overwash records, including a series of inferred tsunami deposits within coastal ponds at Anegada. These data will be used to reassess previously documented overwash records that span the last several thousand years and will identify similarities and differences between the sedimentary deposits emplaced by past major storms (e.g., hurricanes in 2010 and 2017) and tsunamis (1755 Lisbon earthquake) at this location. This reassessment of the overwash record at Anegada, based on lessons learned from Hurricane Irma, can be used to reconstruct millennial scale patterns of frequency, intensity, and physical impacts associated with both storms and tsunamis. This refined understanding of extreme wave events will improve hazard prediction, preparedness, and assessment for coastlines impacted by both forms of marine inundation.