Geochemical and Textural Constraints on Eruptive Behavior of Merapi Volcano, Indonesia

印度尼西亚默拉皮火山喷发行为的地球化学和结构约束

• 批准号: 0230208
• 负责人: Tanya Furman
• 金额: $ 17.05万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0230208&HistoricalAwards=false
• 关键词: Geochemical; Textural; Constraints; Eruptive; Behavior

FurmanEAR- 0230208Merapi Volcano in Central Java, Indonesia, is one of Earth's most active and dangerous volcanoes. This stratovolcano has been active for over 40,000 years, with nearly continuous eruptive activity over the past century. Merapi is particularly feared because of the potentially explosive nature of its activity, and because several hundred thousand people live in high-risk areas on the volcano flank. This project uses a combination of tephrostratigraphic, geochemical and CSD techniques to address the rheological (e.g., thermal state, magma composition, glass chemistry, crystal nucleation and growth rate) controls on the full spectrum of Merapi's eruptive behavior. The results of this project will provide fundamental information on magma reservoir and conduit conditions and processes, as well as insights on the potential for future larger-scale explosive activity.The intellectual merit of the research derives from the application of detailed textural analysis of lavas and tephras to the identification of intensive parameters associated with eruptive activity. That is, one can relate crystal size distribution patterns of individual eruptive units to the detailed chemical, barometric and thermal history of Merapi volcano. Analysis of melt inclusions in olivine crystals also provides insight into late-stage magmatic processes, including helping to distinguish crystal growth related to decompression from that resulting from magma mixing or hybridization. When used in conjunction with our textural analyses, this technique provides a powerful method for evaluating magma ascent rates and residence times. This information is critical to the study of explosive volcanic systems because the eruptive intensity is linked directly to both the residence time of magma within the chamber and the degree of solidification that occurs within the reservoir and conduit. In volcanic systems that tend to be highly crystalline (e.g., Merapi lavas contain up to 50% crystals upon eruption), magma that is nearly solidified may fill the eruptive vent to substantial depths, effectively plugging the vent system and leading to infrequent but very dangerous eruptions. Using chemical and textural data, it becomes possible to gauge the conditions leading to violent eruptions. By recognizing precursor signals to major eruptions, the ability to anticipate catastrophic situations can be improved. The broader implications of this project include both human resource development and potential assistance for volcanic hazard mitigation. This project will fund the doctoral research of one female graduate student at Penn State and the postdoctoral research of a female Indonesian volcanologist from the Volcanological Survey of Indonesia. The work will strengthen an extant relationship between Penn State and the Volcanological Survey of Indonesia that has focused on monitoring active volcanoes with the goal of improving disaster preparedness. In recent decades Merapi has had fairly small eruptive events with a frequency of two to five years. The geologic record, however, indicates that this recent activity encompasses only a small portion of the full range of explosivity that has occurred in the past. At least seven eruptions between 3000-250 years ago were larger and farther-reaching explosive events than any recorded in the 20th century. Unfortunately, current hazard assessment and contingency planning is based primarily upon small eruptive events, while the earlier record of major explosive eruptions suggests that effective planning needs to consider the full range of Merapi's eruptive behavior. It is anticipated that this study will enable researchers to identify precursor events to major eruptions that will prove useful in modern hazard mitigation efforts.

位于印度尼西亚爪哇中部的默拉皮火山是地球上最活跃和最危险的火山之一。 这座成层火山已经活跃了40，000多年，在过去的世纪里几乎持续不断地喷发。 默拉皮火山特别令人担心，因为它的活动具有潜在的爆炸性，而且数十万人生活在火山侧翼的高风险地区。 该项目使用灰岩地层学、地球化学和CSD技术的组合来解决流变学（例如，热状态，岩浆成分，玻璃化学，晶体成核和生长速率）控制了默拉皮火山喷发行为的全方位。 这一项目的结果将提供关于岩浆库和管道条件和过程的基本资料，以及关于未来大规模爆炸活动潜力的见解，这项研究的知识价值来自对熔岩和火山岩进行详细的结构分析，以确定与喷发活动有关的密集参数。 也就是说，人们可以将个别喷发单位的晶体尺寸分布模式与默拉皮火山的详细化学、气压和热历史联系起来。 对橄榄石晶体中熔融包裹体的分析也提供了对后期岩浆过程的深入了解，包括帮助区分与减压有关的晶体生长与岩浆混合或杂交有关的晶体生长。 当与我们的结构分析结合使用时，这种技术提供了一种评估岩浆上升速率和停留时间的强有力的方法。 这一信息对于研究爆发性火山系统至关重要，因为喷发强度与岩浆在岩浆房内的停留时间以及储层和管道内发生的凝固程度直接相关。 在倾向于高度结晶的火山系统中（例如，默拉皮火山熔岩在喷发时含有高达50%的晶体），几乎凝固的岩浆可能会填充喷发口到相当深的地方，有效地堵塞了喷口系统，导致罕见但非常危险的喷发。 利用化学和纹理数据，可以衡量导致猛烈喷发的条件。 通过识别重大火山爆发的前兆信号，可以提高预测灾难性情况的能力。 该项目的更广泛影响包括人力资源开发和可能为减轻火山灾害提供的援助。 该项目将资助宾夕法尼亚州立大学一名女研究生的博士研究和印度尼西亚火山调查局一名印度尼西亚女火山学家的博士后研究。 这项工作将加强宾夕法尼亚州立大学和印度尼西亚火山调查局之间的现有关系，该调查局的重点是监测活火山，以改善备灾工作。 近几十年来，默拉皮火山爆发的频率相当小，为2 - 5年一次。 然而，地质记录表明，最近的活动只包括过去发生的全部爆炸性的一小部分。 在3000-250年前，至少有7次火山爆发是20世纪记录的规模更大、影响更深远的爆炸事件。 不幸的是，目前的危险评估和应急计划主要是基于小的喷发事件，而早期的重大爆炸性喷发记录表明，有效的规划需要考虑默拉皮火山喷发行为的全部范围。 预计这项研究将使研究人员能够确定重大火山爆发的前兆事件，这将证明对现代减灾工作是有用的。