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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Rockfalls at Augustine Volcano, Alaska: The influence of eruption precursors and seasonal factors on occurrence patterns 1997-2009
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Rockfalls at Augustine Volcano, Alaska: The influence of eruption precursors and seasonal factors on occurrence patterns 1997-2009

机译：阿拉斯加奥古斯丁火山的山石塌陷：爆发的前兆和季节因素对发生模式的影响1997-2009

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Rockfalls have been recorded in seismic data at Augustine Volcano from 1997 to the present Typical events last about 30 s and have frequencies > 4 Hz on stations within 5 km of the summit. Many rockfalls are well recorded on summit seismic stations, suggesting that they originate from the steep summit dome. Typical background years such as 2003 or 2004 had several dozen events in the summer and fall (June to November) that were strong enough to trigger an automatic event detection system. For example, 17 rockfalls were recorded in 2003; mostly in late summer when air temperatures were warm and rainfall rates were highest, and 28 events were recorded in 2004, also in late summer. In 2005, about eight months before the onset of the eruption of Augustine in January 2006, there was a significant increase in the number of rockfalls detected. This increase of surface rockfall activity occurred at nearly the same time as precursory earthquake activity increased beneath Augustine. Overall there were more than 340 rockfalls in 2005, consisting of both short (less than 30 s) and long (greater than 30 s) duration events. The high rate of rockfalls in 2005 constitutes a new class of precursory signal that needs to be incorporated into long-term monitoring strategies at Augustine and elsewhere. During the eruption, numerous rockfalls continued to occur, and block-and-ash flows dominated the seismic records when the volcano began a phase of dome growth and collapse. The high rates of rockfalls continued after the eruption ended, due the new unstable lava dome and adjacent tephra at the summit As of 2009 the rockfall rates are still high, but are declining steadily.
机译：从1997年至今，在奥古斯丁火山的地震数据中已经记录了落石事件。典型事件持续约30 s，在距山顶5公里以内的站点频率> 4 Hz。在顶峰地震台站上有很多落石记录，表明它们来自陡峭的顶峰圆顶。典型的背景年份（例如2003或2004）在夏季和秋季（6月至11月）发生了几十起事件，足以触发自动事件检测系统。例如，2003年记录了17次落石事件。大多数情况是在夏末，气温升高，降雨率最高，2004年也有夏末记录了28起事件。在2005年，大约是2006年1月奥古斯丁爆发前的8个月，发现的落石数量显着增加。与奥古斯丁以下的前兆地震活动增加几乎同时发生了地面落石活动的增加。总体而言，2005年有340多个岩崩，包括短时间（少于30秒）和长时间（大于30秒）事件。 2005年的高落石率构成了一类新的先兆信号，需要将其纳入奥古斯丁和其他地区的长期监测策略中。在火山喷发期间，继续发生无数的崩塌，火山爆发时，火山活动开始了圆顶的生长和坍塌，大量的碎屑和灰烬流主导了地震记录。喷发结束后，由于新的不稳定的熔岩穹顶和邻近的特非拉火山在山顶结束，高落石率仍在继续。截至2009年，落石率仍然很高，但仍在稳步下降。

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