Acoustic multipole source model for volcanic explosions and inversion for source parameters
Acoustic multipole source model for volcanic explosions and inversion for source parameters
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DOI：
10.1111/j.1365-246x.2012.05696.x
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发表时间：
2012-12-01
影响因子：
2.8
通讯作者：
Ruiz, Mario
中科院分区：
文献类型：
--
作者：
Kim, Keehoon;Lees, Jonathan M.;Ruiz, Mario
火山爆发伴随着大气中强烈的声压扰动。通过适当的源模型，这些声信号可以提供有关火山爆发动力学的宝贵信息。在刚性半空间边界之上导出了火山次声辐射的远场解，并基于半空间模型开发了一种简单的反演方法。根据次声波形同时估计声学单极子和偶极子源。反演程序的稳定性根据源参数的方差进行了评估，并且该程序在次声源周围至少有三个站时是可靠的。将该方法应用于厄瓜多尔通古拉瓦火山记录的次声观测，成功地产生了合理范围内具有可接受方差的源参数。偶极子源模型的方向性成功地解释了通古拉瓦爆炸中观测到的次声辐射的强方向性。反过来，由此产生的偶极子轴与通古拉瓦火山口的开口方向表现出良好的一致性，这被认为是偶极子源的起源。该方法具有通用性，可用于研究爆炸产生的任何单极子、偶极子或组合源。
Volcanic explosions are accompanied by strong acoustic pressure disturbances in the atmosphere. With a proper source model, these acoustic signals provide invaluable information about volcanic explosion dynamics. Far-field solutions to volcanic infrasound radiation have been derived above a rigid half-space boundary, and a simple inversion method was developed based on the half-space model. Acoustic monopole and dipole sources were estimated simultaneously from infrasound waveforms. Stability of the inversion procedure was assessed in terms of variances of source parameters, and the procedure was reliable with at least three stations around the infrasound source. Application of this method to infrasound observations recorded at Tungurahua volcano in Ecuador successfully produced a reasonable range of source parameters with acceptable variances. Observed strong directivity of infrasound radiation from explosions at Tungurahua are successfully explained by the directivity of a dipole source model. The resultant dipole axis, in turn, shows good agreement with the opening direction of the vent at Tungurahua, which is considered to be the origin of the dipole source. The method is general and can be utilized to study any monopole, dipole or combined sources generated by explosions.