Global Positioning System detection and energy estimation of the ionospheric wave caused by the 13 July 2003 explosion of the Soufriere Hills Volcano, Montserrat
Global Positioning System detection and energy estimation of the ionospheric wave caused by the 13 July 2003 explosion of the Soufriere Hills Volcano, Montserrat
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DOI：
10.1029/2008jb005722
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发表时间：
2009-02-05
影响因子：
3.9
通讯作者：
Mattioli, Glen S.
中科院分区：
文献类型：
--
作者：
Dautermann, Thomas;Calais, Eric;Mattioli, Glen S.
已知火山爆发或浅层地震会触发声波和重力波，这些波以次声速度在大气中传播。在电离层高度，中性粒子和自由电子之间的耦合会引起电子密度的变化，这可以用双频全球定位系统（GPS）测量来检测。利用在加勒比收集的全球定位系统数据，我们确定了2003年7月13日苏弗里埃山火山（蒙特塞拉特，小安的列斯群岛）发生大规模火山爆发后的电离层扰动。频谱分析显示，峰值集中在1和4兆赫，类似于以前的观测和理论，表明重力和声波成分。我们检索的水平速度类似于624米/秒的声学组件，这意味着向上传播类似于33度，射线追踪结果一致。我们使用一个N波压力源在地面结合射线追踪传播的中性压力波的声波模型，这占了大气的色散特性，同时保存总的声能。等离子体速度来自中性速度使用磁流体动力学动量方程的有限差分解。电荷密度的连续性方程用于计算相应的电子密度变化，然后沿沿着卫星到接收器视线对电子密度变化进行数值积分，同时考虑卫星位移。我们最大限度地减少观测波形和模型波形之间的不匹配，以估计苏弗里埃山火山与山顶圆顶倒塌相关的主要爆炸事件的总声能释放为1.53 x 10（10）J。这种方法可以应用于任何足够大的爆炸，只要在近到中等距离的来源提供全球定位系统数据。
Volcanic explosions or shallow earthquakes are known to trigger acoustic and gravity waves that propagate in the atmosphere at infrasonic speeds. At ionospheric heights, coupling between neutral particles and free electrons induces variations of electron density detectable with dual-frequency Global Positioning System (GPS) measurements. Using GPS data collected in the Caribbean, we identified an ionospheric perturbation after a major volcanic explosion at the Soufriere Hills Volcano (Montserrat, Lesser Antilles) on 13 July 2003. Spectral analysis reveals peaks centered at 1 and 4 mHz, similar to those in previous observations and consistent with theory, suggesting both gravity and acoustic wave components. We retrieve a horizontal velocity of similar to 624 m/s for the acoustic component, which implies upward propagation at similar to 33 degrees, consistent with ray-tracing results. We model the acoustic wave using an N-wave pressure source at ground level combined with ray tracing to propagate the neutral pressure wave; this accounts for the dispersive characteristics of the atmosphere while conserving total acoustic energy. Plasma velocity is derived from neutral velocity using a finite difference solution of the magnetohydrodynamic momentum equation. The continuity equation for charge densities is used to compute corresponding electron density variations, which are then numerically integrated along satellite-to-receiver line of sights, simultaneously accounting for the satellite displacements. We minimize the misfit between observed and model waveforms to estimate a total acoustic energy release of 1.53 x 10(10) J for the primary explosion event at Soufriere Hills Volcano associated with the peak dome collapse. This method can be applied to any explosion of sufficient magnitude, provided GPS data are available at near to medium range from the source.