BICHROMATIC EXCITATION OF LONG-PERIOD RAYLEIGH AND AIR WAVES BY THE MOUNT PINATUBO AND EL CHICHON VOLCANIC-ERUPTIONS
BICHROMATIC EXCITATION OF LONG-PERIOD RAYLEIGH AND AIR WAVES BY THE MOUNT PINATUBO AND EL CHICHON VOLCANIC-ERUPTIONS
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DOI：
10.1029/92gl00685
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发表时间：
1992-04-24
影响因子：
5.2
通讯作者：
ZURN, W
中科院分区：
文献类型：
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作者：
WIDMER, R;ZURN, W
我们探测到了一种新的强大的低频地震能量来源，它与一些猛烈的火山喷发有关。对于我们已经确定了这一新来源的两次喷发，光谱是双色的，由两条窄的、相位相干的谱线组成。1982年4月4日El Chichon喷发以3.76和5.14 MHz为中心，1991年6月15日以3.68和4.44 MHz为中心。皮纳图博火山喷发。在后者长达8小时的喷发期间，共振频率的变化不到20微赫。震源的强度足以激发绕地球旋转的表面波。我们从这些观测中得出结论，火山能够激发“和谐震动”的周期比以前观察到的要长得多。我们首选的震源模型涉及到局部大气振荡和喷发过程之间的反馈。对这一反馈负责的物理学仍有待猜测。
We have detected a new powerful source of low-frequency seismic energy which is associated with some violent volcanic eruptions. For the two eruptions for which we have identified this new source the spectrum is bichromatic, consisting of two narrow, phase coherent spectral lines. These bands were centered on 3.76 and 5.14 mHz for the April 4, 1982 El Chichon eruption, and on 3.68 and 4.44 mHz for the June 15, 1991 Mt. Pinatubo eruption. During the latter, 8 hour long eruption the resonance frequencies varied by less than 20-mu-Hz. The strength of the source is sufficient to excite globe circling surface waves. We conclude from these observations that volcanoes can excite "harmonic tremors" at much longer periods than previously observed. Our preferred source model involves feedback between local atmospheric oscillations and the eruption process. The physics responsible for this feedback remains subject to speculations.