Global positioning system measurements of ground deformation caused by magma intrusion and lava discharge: the 1990-1995 eruption at Unzendake volcano, Kyushu, Japan
Global positioning system measurements of ground deformation caused by magma intrusion and lava discharge: the 1990-1995 eruption at Unzendake volcano, Kyushu, Japan
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DOI：
10.1016/s0377-0273(98)00119-x
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发表时间：
1999-04-01
影响因子：
2.9
通讯作者：
Mori, H
中科院分区：
文献类型：
--
作者：
Nishi, K;Ono, H;Mori, H
自1991年1月以来，在日本九州云善武火山周围进行的全球定位系统（GPS）测量检测到了岩浆侵入和熔岩喷出引起的地面变形。在间歇性的潜水和蒸汽岩浆喷发阶段，地面是膨胀的。在熔岩穹丘的增长和云曾达克火山频繁的火山碎屑流之后，地面开始放气。这些地面变形的膨胀和收缩的Mogi的源模型（点源模型）位于约6公里以西的活跃的火山口在11公里的深度，在一个asepersion区域的解释。观察到的水平位移矢量在充气期间径向地指向远离估计的压力源，并且在放气期间指向压力源。由估计的压力源收缩计算的参考GPS站的水平位移与其他GPS基线系统观测到的实际水平位移吻合良好。这些观测结果证实了我们对压力源的估计。根据地表变形量与熔岩排出量之间的关系，推测火山喷发时既有深部岩浆补给，又有火山口岩浆排出。据估计，岩浆以1.1x10（5）m（3）/天的平均速率进入水库;岩浆侵入最迟于1989年12月开始，持续了1.9x10（3）天。(C)1999 Elsevier Science B. V.保留所有权利。
Global positioning system (GPS) measurements made around Unzendake volcano, Kyushu, Japan, since January 1991 have detected ground deformation caused by magma intrusion and lava discharge. In the intermittent phreatic and phreatomagmatic eruption stage, the ground was inflating. After growth of the lava dome and following frequent pyroclastic flows at Unzendake volcano, the ground began deflating. These ground deformations are explained by the inflation and deflation of a Mogi's source model (a point source model) located about 6 km west of the active crater at a depth of 11 km, at an aseismic region. The observed horizontal displacement vectors pointed radially away from the estimated pressure source during inflation and pointed to the pressure source during deflation. The horizontal displacements at the reference GPS station calculated from contraction of the estimated pressure source coincide well with the actual horizontal displacements observed from other GPS baseline systems. These observations validate our estimates for the pressure source. Based on the relation between the deformation volume of the ground surface and the discharged volume of the lava, it is estimated that during the eruption there was magma supply from the deeper portion as well as magma discharge at the crater. Magma is estimated to be supplied to the reservoir at an average rate of 1.1x10(5) m(3)/day; magma intrusion began in December 1989 at the latest and continued for 1.9 x 10(3) days. (C) 1999 Elsevier Science B.V. All rights reserved,.