权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Understanding the driving forces behind recent changes in the eruptive behaviour of Merapi volcano, Java, Indonesia

了解印度尼西亚爪哇默拉皮火山近期喷发行为变化背后的驱动力

基本信息

批准号：
NE/I029927/1
负责人：
Ralf Gertisser
金额：
$ 6.68万
依托单位：
Keele University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FI029927%2F1
关键词：
Understanding driving forces behind recent

项目摘要

In October and November 2010, Merapi volcano (Java, Indonesia) had its biggest eruption since 1872. Merapi, which literally means "Fire Mountain" in Javanese, is one of Indonesia's most active and dangerous volcanoes with a history of deadly eruptions. Before 2010, these eruptions have usually been characterised by several months of viscous lava effusion at the summit of the steep-sided volcano, forming lava domes which, when big enough, collapse gravitationally generating relatively small pyroclastic flows. These flows are mixtures of lava dome fragments, smaller volcanic particles (ash) and hot gases that travel down the flanks of the volcano at high velocities of > 100 km/hour and, in the case of Merapi, typically reach distances of a few kilometres from the volcano. With a few exceptions only, this eruptive behaviour has been so typical of Merapi for at least the last two centuries that the pyroclastic flows generated by the gravitational failure of lava domes are often referred to in the literature as Merapi-type nuées ardentes (glowing clouds).In 2010, the eruptive behaviour of Merapi has changed. The unforeseen, large-magnitude explosive events were very different to previous episodes that followed Merapi's usual pattern of dome growth and collapse. On 26 October 2010, pyroclastic flows, generated during explosive eruption phases, swept down the flanks of the volcano, killing at least 34 people. The events were preceded by enhanced levels of seismicity and summit deformation that started in early September 2010. After days of high level activity, with glowing avalanches from a newly formed lava dome, pyroclastic flows and sporadic explosions generating a 7-km-high, sustained eruption column on 4 November, an unusually large explosive eruption on 5 November generated pyroclastic flows that extended up to 15 km from the volcano. Associated surges swept across Merapi's south flank, devastating villages and causing more fatalities. Since then, the death toll has risen to > 300 people, making this eruption the worst volcanic disaster at Merapi in 80 years.This project seeks to exploit a "once-in-a-century" opportunity to capitalise on these unexpected events at Merapi through a detailed investigation of the rocks formed during the 2010 eruption. These rocks preserve a record of the sub-surface processes that operated inside the volcano before the eruption occurred. Through the use of modern micro-analytical techniques and measurements of different radioactive isotopes that decay quickly within months, decades or millennia in the rocks, we can unravel these processes (which are the driving forces behind the unusual explosive behaviour of Merapi in 2010) and their timescales. The shortest radionuclide, 210Po, has a half-life of only 138 days and can tell us about the degassing of the magma and other processes that occurred in the weeks and months before the eruption. Because of its short half-life, 210Po must be analysed quickly after the eruption and before it has decayed completely to its daughter isotope 206Pb. Once we have established where in the crust beneath Merapi the magma feeding the 2010 eruption has come from and the processes of pre- and syn-eruptive crystallisation and degassing during magma ascent to the surface, we will compare the results with analytical data we have already collected on rock samples from the preceding eruptive episode in 2006, which followed Merapi "normal" (i.e. less explosive) eruptive behaviour. Ultimately, we will attempt to link the results obtained by analysing the rocks from the eruptions to the surface manifestations of these processes (e.g., seismic signals, ground deformation, gas flux) recorded through continuous geophysical monitoring of the volcano by our Indonesian colleagues.

2010年10月和11月，默拉皮火山（印度尼西亚爪哇）发生了自1872年以来最大的喷发。默拉皮火山在爪哇语中的字面意思是“火山”，是印度尼西亚最活跃、最危险的火山之一，有过致命的喷发历史。在2010年之前，这些火山喷发的特点通常是在陡峭的火山山顶上喷出几个月的粘性熔岩，形成熔岩圆顶，当足够大时，会在重力作用下坍塌，产生相对较小的火山碎屑流。这些熔岩流是熔岩穹丘碎片、较小的火山颗粒（火山灰）和热气的混合物，以每小时100公里以上的高速沿火山两侧向下流动，在默拉皮，通常到达离火山几公里的地方。除了少数例外，这种喷发行为至少在过去的两个世纪里一直是默拉皮火山的典型特征，熔岩圆顶重力破裂产生的火山碎屑流在文献中通常被称为默拉皮火山型nuées ardentes（发光云）。2010年，默拉皮火山的喷发行为发生了变化。这场不可预见的大规模爆炸事件与之前的事件非常不同，之前的事件遵循了默拉皮通常的圆顶增长和崩溃模式。2010年10月26日，火山爆发阶段产生的火山碎屑流从火山两侧席卷而下，造成至少34人死亡。在这些事件发生之前，2010年9月初开始的地震活动和山顶变形水平提高。经过数天的高强度活动，新形成的熔岩穹丘产生炽热的雪崩，11月4日火山碎屑流和零星爆炸产生了7公里高的持续喷发柱，11月5日异常大的爆炸性喷发产生了火山碎屑流，延伸到火山15公里外。伴随而来的巨浪席卷了默拉皮的南翼，摧毁了村庄，造成更多的死亡。从那时起，死亡人数已经上升到超过300人，使这次喷发成为默拉皮80年来最严重的火山灾害。该项目旨在通过对2010年喷发期间形成的岩石进行详细调查，利用“百年一遇”的机会，利用默拉皮的这些意外事件。这些岩石保存了火山爆发前在火山内部运作的地下过程的记录。通过使用现代微观分析技术和测量岩石中在数月、数十年或数千年内迅速衰变的不同放射性同位素，我们可以解开这些过程（这是2010年默拉皮火山异常爆炸行为背后的驱动力）及其时间尺度。最短的放射性核素210 Po的半衰期只有138天，可以告诉我们火山喷发前几周和几个月发生的岩浆脱气和其他过程。由于210 Po的半衰期很短，因此必须在爆发后和完全衰变为子同位素206 Pb之前迅速进行分析。一旦我们确定了2010年喷发的岩浆来自默拉皮火山下的地壳，以及岩浆上升到地表过程中的喷发前和喷发时的结晶和脱气过程，我们将把结果与我们已经收集的2006年前一次喷发的岩石样本分析数据进行比较，它遵循默拉皮“正常”（即爆炸性较小）的喷发行为。最后，我们将试图将分析喷发岩石所获得的结果与这些过程的表面表现联系起来（例如，地震信号、地面变形、气体流量），这是我们的印度尼西亚同事通过对火山进行持续地球物理监测所记录的。