EXCITATION MECHANISM OF ATMOSPHERIC-PRESSURE WAVES FROM THE 1980 MOUNT ST-HELENS ERUPTION
EXCITATION MECHANISM OF ATMOSPHERIC-PRESSURE WAVES FROM THE 1980 MOUNT ST-HELENS ERUPTION
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DOI：
10.1111/j.1365-246x.1985.tb06412.x
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发表时间：
1985-01-01
期刊：
影响因子：
--
通讯作者：
BOLT, BA
中科院分区：
文献类型：
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作者：
MIKUMO, T;BOLT, BA
1980 年 5 月 18 日圣海伦斯火山喷发产生的大气压力波已被加利福尼亚州伯克利的灵敏微气压计清楚地记录下来。该记录显示了三种具有不同群速度的波。压力波可以用直达波A1、对映行波A2和环绕波A3来解释，所有这些都由在低层大气中传播的几种声重力模式组成。适合伯克利站的合成气压图是根据低层大气结构的动态响应以及源特性的各种假设计算出来的。合成和观测的气压图之间的比较提供了对源处向上粒子速度的时间历史范围、源尺寸和源在爆炸区域上传播的速度以及圆周路径上的平均耗散效应的估计。结果表明，A1 记录上的两个主要压缩脉冲与第一次（横向）爆炸和第二次（垂直）爆炸的压力波的到达相关，尽管推断的爆炸间时间间隔与地震观测估计的时间间隔不一致。
Atmospheric pressure waves from the Mount St Helens eruption 1980 May 18 have been clearly recorded by a sensitive microbarograph at Berkeley, California. The record shows three types of waves with different group velocities. The pressure waves can be interpreted in terms of direct waves A1, antipodean travelling waves A2 and circumnavigating waves A3, all of which are composed of several acoustic-gravity modes propagated in the lower atmosphere. Synthetic barograms appropriate to the Berkeley station have been calculated on the basis of the dynamic response of the lower atmospheric structure, together with various assumptions of source properties. Comparisons between synthetic and observed barograms provide estimates for ranges of the time history of upward particle velocity at the source, source dimensions and the velocity of the source spreading over the blast zone, as well as for the average dissipation effects over the circumferential path. The results suggest that two major compression pulses on the A1 record correlate with the arrival of pressure waves from the first (lateral) blast and second (vertical) blast, although the inferred interblast time interval is not consistent with that estimated from seismic observations.