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

印度尼西亚中爪哇的默拉皮火山是地球上最活跃和最危险的火山之一。这座层状火山已经活跃了4万多年，在过去的一个世纪里几乎一直在喷发。默拉皮火山尤其令人担忧，因为它的活动具有潜在的爆炸性，而且有数十万人生活在火山侧面的高风险地区。该项目结合了地层、地球化学和CSD技术，对默拉皮火山喷发行为的全谱进行流变学控制（如热状态、岩浆成分、玻璃化学、晶体成核和生长速率）。该项目的结果将提供关于岩浆储层和管道条件和过程的基本信息，以及对未来更大规模爆炸活动的潜在见解。该研究的智力价值来自于对熔岩和熔岩的详细结构分析的应用，以确定与喷发活动相关的密集参数。也就是说，人们可以将单个喷发单元的晶体大小分布模式与默拉皮火山详细的化学、气压和热历史联系起来。对橄榄石晶体中熔体包裹体的分析也提供了对晚期岩浆过程的洞察，包括帮助区分与减压相关的晶体生长与岩浆混合或杂交的晶体生长。当与我们的结构分析结合使用时，该技术为评估岩浆上升速率和停留时间提供了一种强大的方法。这些信息对爆炸性火山系统的研究至关重要，因为喷发强度与岩浆在岩浆房内的停留时间以及在储层和管道内发生的凝固程度直接相关。在高结晶的火山系统中（例如，默拉皮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满喷发口，直到相当深的地方，有效地堵塞了喷口系统，导致罕见但非常危险的喷发。利用化学和结构数据，就有可能评估导致剧烈喷发的条件。通过识别主要火山爆发的前兆信号，可以提高预测灾难性情况的能力。这个项目的更广泛影响包括人力资源开发和为减轻火山灾害提供潜在援助。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学调查的一名印度尼西亚女性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与印度尼西亚火山调查局之间现有的关系，后者的重点是监测活火山，目的是改善备灾工作。近几十年来，默拉皮火山发生了相当小的喷发事件，频率为2到5年。然而，地质记录表明，这种最近的活动只包括过去发生的全部爆炸性活动的一小部分。在3000-250年前，至少有7次喷发比20世纪有记录的任何一次喷发都要大，影响范围也更远。不幸的是，目前的危险评估和应急计划主要是基于小型喷发事件，而早期的大型喷发记录表明，有效的计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，这将在现代减灾工作中证明是有用的。

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.