Subaqueous Pyroclastic Flows from Krakatau and Tambora Volcanoes, Indonesia

印度尼西亚的克拉卡托火山(1883年)和坦博拉火山(1815年)的历史性喷发将超过40千米的火山碎屑物质释放到海洋中，主要是以巨大的重力流的形式。有了以前的资金，克拉卡托火山周围的海底沉积物样本已经通过分流部署的取心系统获得。这项研究的重点是两个短暂岛屿的起源，Steers和Calmeyer，这两个岛屿是由于1883年灾难性的喷发而形成于克拉喀托最北端的。水下地质填图和沉积岩心的初步研究表明，这两个岛屿是由水下生成的火山碎屑流进入大海形成的。这些发现为围绕海啸起源的争议提供了新的线索，这些海啸与火山喷发有关，并在事件爆发阶段对克拉喀陶岛的命运产生了影响。用于补充的新资金将用于对1990年收集的样品和现有的坦博拉1815矿藏样品进行研究。将对水下火山碎屑流沉积中的浮石和岩屑进行热退磁研究，以确定侵位温度，并研究海水在水下运输和沉积过程中作为冷冻剂的作用。还将进行详细的颗粒尺寸、组分丰度和图像分析，以评估热的火山碎屑流与海水相互作用的性质。这些结果将对理解这些事件的喷发过程具有重要意义，为地质记录中古代收敛边缘序列提供了火山碎屑沉积的现代类似物。

The historic explosive eruptions of Krakatau (1883) and tambora(1815) volcanoes in Indonesia discharged over 40 km 3 of pyroclastic material into the sea, mostly as voluminous gravity flows. With previous funding samples have been obtained of the submarine deposits areound Krakatau volcano by a diver.deployed coring system. The study focussed on the origin of two ephmeral islands, Steers and Calmeyer, that formed to the nortwest of Krakatau as a result of the catastrophic 1883 eruption. Underwater geologic mapping and preliminary examination of sediment cores indicate that the two islands were formed by the entrance of subaerially.generated pyroclastic flows into the sea. The findings have shed new light on the controversy surrounding the origing of devstating tsunamis associated with the eruption and the fate of Krakatau island during the paroxymal stage of the event. New funds for as additional will be used to carry outstudies on the samples collected in 1990 and existing samples of the tambora 1815 deposits. Thermal demagnetization studies on pumice and lithic clasts from the subaqueous pyroclastic flow deposits will be made to determine emplacement temperatures and investigate the role of seawater as colling agent during subaqueous transport and deposition. Detailed grain size, component abundance, and image analysis will also be carried out to evaluate the nature of hot, pyroclastic flow interactions with seawater. These result will be significant in terms of understanding the eruptive processes of these event sand providing modern analogues of volcaniclastic sedimentation that can be applied to ancient convergent margin sequences in the geologic record.