论文标题
将水热系统动力学和喷发活动相关联 - Piton de la fournaise火山的案例研究
Correlating hydrothermal system dynamics and eruptive activity -- A case-study of Piton de la Fournaise volcano, La R{é}union
论文作者
论文摘要
Piton de la Fournaise火山，La R {é}联合岛是一座玄武岩盾火山，在1998年至2008年之间进行了激烈的爆发活动。自我电位和火山的其他地球物理研究表明，在峰顶锥体中存在着一个已建立的水热系统的存在。本研究调查了piton de la fournaise的山顶锥体中水热系统的变化与喷发活性之间的关系。在这里，我们将热液活性部分的深度视为水热流是其路径最强烈的区域。已经通过多尺度小波断层扫描（MWT）分析了十项完整的自动负责调查，以表征1993年至2008年之间热液系统的深度变化。我们的MWT模型强烈支持存在与主基础结构相关的六个主要热液途径。这些途径中的每一个都是主要水热系统的一部分，并连接到深度的主要热液储层。根据我们的结果，在2006年和2008年，围绕Dolomieu火山口附近，水热活动切片位于2300至2500 m A.S.L.之间，这与2007年后偏转后孔口壁壁中观察到的富马罗带的升高非常相关。我们的结果表明，在研究期间，局部热液活性部分的深度发生了很大变化。在Quiescence（1993--1997）之间的过渡时，观察到与这些水热活性部分相关的主要潜在生成区域的垂直位移，分别在1998年和2007年的恢复量之间的垂直位移。从1999年到2008年3月，水热系统一直位于相对较浅的深度。通过定量确定16年来水热液的垂直位移，我们确定了水热系统与岩浆活性之间的显着联系。表面下方的热液系统深度是浅层系统内活性水平（火山的压缩/压缩）的指标。因此，当与长期火山监测结合使用时，这种方法可以大大促进检测火山活动变化的前体信号。
Piton de la Fournaise volcano, La R{é}union Island, is a basaltic shield volcano which underwent an intense cycle of eruptive activity between 1998 and 2008. Self-potential and other geophysical investigations of the volcano have shown the existence of a well-established hydrothermal system within the summit cone. The present study investigates the relationship between changes in the hydrothermal system and eruptive activity at the summit cone of Piton de la Fournaise. Here, we consider the depth of the hydrothermal activity section to be the area where the hydrothermal flow is the most intense along its path. Ten complete-loop self-potential surveys have been analyzed through multi-scale wavelet tomography (MWT) to characterize depth variations of the hydrothermal system between 1993 and 2008. Our MWT models strongly support the existence of six main hydrothermalflow pathways associated with the main edifice structure. Each of these pathways is part of the main hydrothermal system and is connected to the main hydrothermal reservoir at depth. In both 2006 and 2008, around Dolomieu crater, based on our results, the hydrothermal activity sections are located between 2300 and 2500 m a.s.l., which correlate well with the elevation of the observed fumarole belt within the post-2007-collapse crater wall. Our results show that the depths of the local hydrothermal activity sections change substantially over the investigated period. Vertical displacement of the main potential generation area, associated withthese hydrothermal activity sections, is observed on the order of several hundred meters at the transition between the period of quiescence (1993--1997) and the resumption of eruptive activity in 1998 and 2007, respectively. From 1999 to March 2008, the hydrothermal system was consistently located at relatively shallow depths.By quantitatively determining the vertical displacement of hydrothermal fluids over 16 years, we identify a significant link between hydrothermal system and magmatic activity. Hydrothermal system depth below the surface is an indicator of the activity level (pressurization/depressurization of the volcano) within the shallowmagmatic systems. Thus, when used in conjunction with long term volcano monitoring, this approach can contribute substantially to detection of the precursory signals of changes in volcanic activity.
