Ground Deformation Associated with the 2004-2005 Unrest of Asama Volcano, Japan(＜Special Section＞The 2004 Eruption of Asama Volcano(2))
Ground Deformation Associated with the 2004-2005 Unrest of Asama Volcano, Japan(＜Special Section＞The 2004 Eruption of Asama Volcano(2))
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与2004-2005年日本浅间火山动荡有关的地面变形（＜专题＞2004年浅间火山喷发（2））
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
Y. Morita
中科院分区：
文献类型：
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作者：
Y. Aoki;Hidefumi Watanabe;E. Koyama;J. Oikawa;Y. Morita
火山周围的全球定位系统 (GPS) 站点连续记录了与 2004 年至 2005 年日本中部浅间火山动荡相关的地面变形。 GPS 数据显示，火山从 7 月下旬开始明显膨胀，距 2004 年 9 月 1 日第一次中等规模喷发大约 1 个月。直到撰写本文时，变形一直持续。我们用侵入弹性、各向同性和均匀介质中的矩形堤坝来模拟变形场。因为这些参数与变形场呈非线性关系。我们使用模拟退火来估计模型参数及其不确定性，模拟退火是一种通过随机搜索最佳参数来解决非线性反问题的工具。结果表明，变形场可以很好地模拟，在侧翼以西约 6 公里处有近乎垂直的堤坝侵入。侵入堤坝的位置被限制在1公里以内。堤坝的倾角与垂直方向的夹角限制在 10 度以内。预计堤防走向为N71.3W（+/-7.5度），与区域应力场东西向挤压一致。由于观测到的变形仅达10毫米，堤坝的形状和深度约束较差；我们估计堤坝顶部低于海平面 1.2 +/- 1.6 公里。尽管如此，侵入堤坝的总体积相对较好地被限制为 6.48 +/- 187 万立方米，置信区间为 95%。
Ground deformation associated with the 2004-2005 unrest of Asama Volcano, central Japan, was recorded with continuous Global Positioning System (GPS) sites around the volcano. The GPS data shows clear inflation of the volcano starting late July, approximately 1 month before the first moderate-size eruption on September 1, 2004. Deformation has been continuing up to the time of writing of this abstract. We modeled the deformation field with a rectangular dike intruded in the elastic, isotropic, and homogeneous medium. Because these parameters have nonlinear relationship with the deformation field. we estimated the model parameters and their uncertainties with the Simulated Annealing, a tool for solving a nonlinear inverse problem with random search for optimum parameters. The result shows that the deformation field is modeled well with intrusion of a near-vertical dike at approximately 6 km west of the flank. Location of the intruded dike is constrained within 1 km. Dip of the dike is constrained within 10 degrees from vertical. Estimated strike of the dike is N71.3W (+/- 7.5 degrees), which is consistent with the regional stress field, east-west compression. Because the observed deformation was only up to 10 mm, shape and depth of the dike is poorly constrained; we estimated the top of the dike at 1.2 +/- 1.6 km below the sea level. Nevertheless, total volume of the intruded dike is relatively well constrained as 6.48 +/- 1.87 million cubic meters with a 95 percent confidence interval.