Blast waves from violent explosive activity at Yasur Volcano, Vanuatu
Blast waves from violent explosive activity at Yasur Volcano, Vanuatu
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瓦努阿图亚苏尔火山剧烈爆炸活动产生的冲击波
DOI：
10.1002/2013gl057900
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发表时间：
2013
影响因子：
5.2
通讯作者：
E. Garaebiti
中科院分区：
文献类型：
--
作者：
E. Marchetti;M. Ripepe;D. D. Donne;R. Genco;A. Finizola;E. Garaebiti
次声和地震波形收集在暴力strombolian活动在Yasur火山（瓦努阿图）。平均约3000个地震事件显示出稳定的波形，证明在爆炸前约5-6秒存在低频（0.1-0.3 Hz）信号。次声波波形大多不对称，具有急剧的压缩（5-106 Pa）开始，随后是小的长期稀疏相。无论压力振幅如何，正相和负相之间的比率是恒定的。这些波形特征非常类似于爆炸波。红外图像显示，在爆炸性热气体/碎片云之前，有一个约20米厚的明显冷球形锋面，其移动速度在342至405米/秒之间。我们解释这个冷锋是由激波锋面通过引起的水汽凝结产生的。我们认为，暴力strombolian活动在Yasur驱动的超音速动力学与气体膨胀在1.1马赫数的管道内。
Infrasonic and seismic waveforms were collected during violent strombolian activity at Yasur Volcano (Vanuatu). Averaging ~3000 seismic events showed stable waveforms, evidencing a low‐frequency (0.1–0.3 Hz) signal preceding ~5–6 s the explosion. Infrasonic waveforms were mostly asymmetric with a sharp compressive (5–106 Pa) onset, followed by a small long‐lasting rarefaction phase. Regardless of the pressure amplitude, the ratio between the positive and negative phases was constant. These waveform characteristics closely resembled blast waves. Infrared imagery showed an apparent cold spherical front ~20 m thick, which moved between 342 and 405 m/s before the explosive hot gas/fragments cloud. We interpret this cold front as that produced by the vapor condensation induced by the passage of the shock front. We suggest that violent strombolian activity at Yasur was driven by supersonic dynamics with gas expanding at 1.1 Mach number inside the conduit.