Upward migration of Vesuvius magma chamber over the past 20,000 years
Upward migration of Vesuvius magma chamber over the past 20,000 years
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DOI：
10.1038/nature07232
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发表时间：
2008-09
期刊：
影响因子：
64.8
通讯作者：
B. Scaillet;B. Scaillet;M. Pichavant;M. Pichavant;R. Cioni
中科院分区：
文献类型：
--
作者：
B. Scaillet;B. Scaillet;M. Pichavant;M. Pichavant;R. Cioni
预测维苏威火山未来的喷发对火山学家来说是一项重要的挑战，因为它的重新觉醒可能会威胁到火山附近70万居民的生命。岩浆储层的深度是预测下一次喷发危险性的关键，这是控制岩浆性质和喷发方式的主要参数之一。岩石学研究表明，在过去的活动期间，岩浆库位于3至16公里（参考文献）之间。地球物理调查已经成像了地震衰减的一些程度，其中最浅的是在8-9公里的深度，这些已经初步解释为优先岩浆聚集的程度。通过对维苏威火山四个主要爆炸事件的物质进行实验相平衡，我们在这里表明，在公元79年（庞贝）和公元472年（波莱纳）事件之间，为喷发活动提供补给的储层从7-8公里深度迁移到3-4公里深度。如果算上18.5 kyr前的Pomici di Base事件和1944年维苏威火山喷发的数据，水库的总向上迁移量为9-11公里。上地壳优先岩浆池水平的变化可归因于上升岩浆的挥发性含量和浮力的差异，以及破火山口形成或火山扩张后局部应力场的变化。储层迁移以及对取食速率的可能影响，应纳入用于确定维苏威火山预期喷发情景的参数中。
Forecasting future eruptions of Vesuvius is an important challenge for volcanologists, as its reawakening could threaten the lives of 700,000 people living near the volcano,. Critical to the evaluation of hazards associated with the next eruption is the estimation of the depth of the magma reservoir, one of the main parameters controlling magma properties and eruptive style. Petrological studies have indicated that during past activity, magma chambers were at depths between 3 and 16 km (refs ). Geophysical surveys have imaged some levels of seismic attenuation, the shallowest of which lies at 8–9 km depth, and these have been tentatively interpreted as levels of preferential magma accumulation. By using experimental phase equilibria, carried out on material from four main explosive events at Vesuvius, we show here that the reservoirs that fed the eruptive activity migrated from 7–8 km to 3–4 km depth between thead79 (Pompeii) andad472 (Pollena) events. If data from the Pomici di Base event 18.5 kyr ago and the 1944 Vesuvius eruption are included, the total upward migration of the reservoir amounts to 9–11 km. The change of preferential magma ponding levels in the upper crust can be attributed to differences in the volatile content and buoyancy of ascending magmas, as well as to changes in local stress field following either caldera formation or volcano spreading. Reservoir migration, and the possible influence on feeding rates, should be integrated into the parameters used for defining expected eruptive scenarios at Vesuvius.