SGER: Extent and Impact of Distal Ash Fallout From the May 2008 Eruption of Chaiten, Chile

SGER：2008 年 5 月智利 Chaiten 喷发造成的远端火山灰沉降的范围和影响

• 批准号: 0838115
• 负责人: Charles Connor
• 金额: $ 2.62万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838115&HistoricalAwards=false
• 关键词: SGER; Extent; Impact; Distal; Ash

This Small Grant for Exploratory research will support the travel of a team of scientists from the University of South Florida (USF) to collaborate with an international group of volcanologists in Argentina that are currently studying the new volcanic deposits from the ongoing eruption of Chaitén volcano in Chile. Chaitén volcano began erupting on May 2, 2008, apparently after approximately 9,500 years of quiescence. This ongoing eruption is already the largest in South America since the 1991 eruption of Hudson volcano, and creates a unique opportunity to sample tephra fallout from the eruption in detail, particularly because the tephra fallout is distributed primarily eastward, across Argentina. The team from USF, together with their international collaborators, plan a rapid response to this event by sampling tephra fallout across southern Argentina, the most distal and easily eroded parts of the deposit, in June and early July, 2008. The primary goal of this excursion will be to measure the variation of thickness, grain-size, and mass loading across a widespread tephra fall deposit. Such data will allow the determination of the volume of erupted material; and will provide a test of the current models of tephra dispersal and deposition. In addition, they will work with colleagues to determine the physical and chemical characteristics of the readily-soluble salts associated with freshly-fallen tephra. Such data provide essential information for determining the potential geochemical impact of ash fallout. It is also planned to measure the grain-size characteristics of fine airborne-ash (both freshly falling, and re-suspended), using actively-pumped filters, an essential input for models of the potential health impacts of volcanic ashfall. Ultimately, they plan to use the TEPHRA2 numerical model developed over the past decade to model tephra fallout from the Chaitén eruption. Although this and other fallout models have been widely used to forecast volcano hazards there has not yet been an opportunity to validate these models for large explosive volcanic eruptions that have been directly observed and sampled soon after tephra deposition. Thus, the Chaitén eruption provides a rare opportunity to collect data to validate and improve the TEPHRA 2 numerical model. For example, the ability to forecast deposition of very fine ash hundreds of kilometers from the erupting volcano has not yet been adequately tested yet represents a major health and economic impact. With the data collected in the field, the team will use TEPHRA2, coupled with nonlinear inversion techniques, to estimate eruption parameters (column height, duration, mass flow), and compare with observations of the eruption. All results will be available to the volcanology community via the IAVCEI Tephra Working Group website.

这笔探索性研究的小额赠款将支持南佛罗里达大学 (USF) 的一个科学家团队与阿根廷的一个国际火山学家小组合作，该小组目前正在研究来自正在喷发的 Chaitén 火山的新火山沉积物。智利柴滕火山在大约 9,500 年的平静之后于 2008 年 5 月 2 日开始喷发，这已经是自 2008 年以来南美洲最大规模的一次喷发。 1991 年哈德逊火山喷发，为详细采样火山喷发的火山灰尘埃创造了一个独特的机会，特别是因为火山灰尘埃尘埃主要分布在整个阿根廷东部，来自南佛罗里达大学的团队与他们的国际合作者一起计划快速应对。 2008 年 6 月和 7 月初，我们对阿根廷南部的火山灰沉降物进行了采样，该地区是沉积物最远且最容易被侵蚀的部分。这次旅行的主要目标是测量广泛的火山灰沉积物的厚度、颗粒尺寸和质量负载的变化，这些数据将有助于确定喷发物质的体积；并将提供对当前火山灰扩散和沉积模型的测试。此外，他们将与同事合作确定与新落下的火山灰相关的易溶盐的物理和化学特征，这些数据为确定火山灰沉降物的潜在地球化学影响提供了重要信息。使用主动泵送过滤器测量空气中细小火山灰（新落下的和重新悬浮的）的粒度特征，这是火山灰落下的潜在健康影响模型的重要输入，最终，他们计划使用 TEPHRA2 数值。过去十年开发的模型，用于模拟 Chaitén 喷发的火山灰沉降物，尽管该模型和其他沉降物模型已广泛用于预测火山灾害，但尚未有机会验证这些模型。火山灰沉积后不久就被直接观察到和采样的大型爆炸性火山喷发因此，Chaitén 喷发提供了收集数据以验证和改进 TEPHRA 2 数值模型的难得机会，例如，预测非常细的火山灰沉积的能力。距离喷发火山数百公里的地方尚未经过充分测试，但尚未对健康和经济产生重大影响。根据现场收集的数据，该团队将使用 TEPHRA2 并结合非线性反演。技术，估计喷发参数（柱高度、持续时间、质量流量），并与喷发观测结果进行比较。所有结果将通过 IAVCEI Tephra 工作组网站提供给火山学界。