Magma accumulation beneath Santorini volcano, Greece, from P-wave tomography
Magma accumulation beneath Santorini volcano, Greece, from P-wave tomography
复制标题
DOI：
10.1130/g47127.1
复制
发表时间：
2020-03-01
期刊：
影响因子：
5.8
通讯作者：
Papazachos, C. B.
中科院分区：
文献类型：
--
作者：
McVey, B. G.;Hooft, E. E. E.;Papazachos, C. B.
尽管有多学科的证据表明希腊圣托里尼火山下的地壳岩浆堆积，但浅层岩浆系统的结构和熔体含量仍然缺乏约束。我们使用三维（3-D）速度模型从断层反演的有源地震P波旅行时间，以确定一个显着的低速异常（-21%），从2.8公里至5公里的深度低于北方破火山口盆地。这种异常是一致的深度估计喷发前的存储和最近的通货膨胀插曲，支持解释浅岩浆体，导致地震衰减和射线弯曲。一系列的合成试验表明，几何形状恢复良好，而熔体含量的范围（4%-13%至完全熔融）是允许的。一个薄的糊状物区域（2%-7%至3%-10%熔体）从主岩浆体向东北方向延伸，观察到构造岩浆线性构造限制的低速。这一异常终止于Kolumbo西北部;在3至5公里深的海山下几乎没有融化。这些结构上的限制表明，地壳的伸展和ediscuitary负载控制的几何形状的岩浆积累，并强调，浅地壳仍然有利于熔体存储后不久，火山口形成的喷发。
Despite multidisciplinary evidence for crustal magma accumulation below Santorini volcano, Greece, the structure and melt content of the shallow magmatic system remain poorly constrained. We use three-dimensional (3-D) velocity models from tomographic inversions of active-source seismic P-wave travel times to identify a pronounced low-velocity anomaly (-21%) from 2.8 km to 5 km depth localized below the northern caldera basin. This anomaly is consistent with depth estimates of pre-eruptive storage and a recent inflation episode, supporting the interpretation of a shallow magma body that causes seismic attenuation and ray bending. A suite of synthetic tests shows that the geometry is well recovered while a range of melt contents (4%-13% to fully molten) are allowable. A thin mush region (2%-7% to 3%-10% melt) extends from the main magma body toward the northeast, observed as low velocities confined by tectono-magmatic lineaments. This anomaly terminates northwest of Kolumbo; little to no melt underlies the seamount from 3 to 5 km depth. These structural constraints suggest that crustal extension and edifice loads control the geometry of magma accumulation and emphasize that the shallow crust remains conducive to melt storage shortly after a caldera-forming eruption.