Environmental Impacts of Hurricane Irma on the British Virgin Islands

随着今年四场强烈风暴在美洲和加勒比海岸线登陆，2017年飓风季节突显出需要更好地了解大西洋地区对飓风的地理和时间控制。这一快速项目是了解5级飓风对英属维尔京群岛阿内加达(BVI)现有古冲刷记录的影响的独特机会，阿内加达是受飓风伊尔玛影响最大的岛屿之一。研究小组将仔细比较极端海浪淹没造成的伊尔玛飓风之前和之后的沿海沉积，以此作为改进对易受飓风和海啸淹没的海岸线的危险风险评估的重要一步。这项工作将提供有关飓风和海啸危害的重要新信息，不仅对英属维尔京群岛，而且对其他加勒比岛屿，包括美属维尔京群岛和波多黎各的岛屿。通过评估飓风伊尔玛沉积的沉积物，该小组将开发一种重要的现代5级风暴模拟，这将有助于解释加勒比地区洪水(和周期性海啸)沉积的长期地质记录，这将使加勒比国家能够更好地准备、应对、恢复和减轻未来飓风的影响。英属维尔京群岛阿内加达冲刷沉积物和巨石的分布情况捕捉到了有关飓风伊尔玛风暴潮的重要信息(流动深度、淹没距离)。通过详细的多学科实地和实验室分析，该小组打算调查与飓风伊尔玛登陆阿尼加达有关的环境影响和冲刷沉积，以：(1)记录已知的5级飓风的风暴潮特征和相关沉积沉积；(2)评估风暴潮对沉积物和巨石的冲刷深度和距离；(3)将伊尔玛飓风沉积作为与较早的冲刷记录的基础，包括阿尼加达沿海池塘内的一系列推断的海啸沉积。这些数据将被用来重新评估以前记录的跨越过去数千年的冲刷记录，并将确定过去主要风暴(例如，2010年和2017年的飓风)和海啸(1755年里斯本地震)在该地点堆积的沉积矿床之间的异同。根据从伊尔玛飓风中吸取的经验教训，对阿内加达洪水泛滥记录的重新评估可用于重建与风暴和海啸相关的频率、强度和物理影响的千禧年尺度模式。这种对极端海浪事件的深入了解将改进对受这两种形式的海洋洪水影响的海岸线的危险预测、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.