Each of these events was reported to have lasted longer than a month but was small and confined to the crater (Simkin et al, 1981).

年，每次爆炸都有报告显示持续周期一个多月，但规模小，而且只发生在火山口内。Simkin et al。

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The crater analysis for Al-alloy targets of different ballistic properties by metallography is presented in this paper.

本文用金相试验的方法对抗弹性能不同的铝合金靶板，作了弹坑解剖分析。

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