Observations of deep long-period (DLP) seismic events beneath Aleutian arc volcanoes; 1989-2002
Observations of deep long-period (DLP) seismic events beneath Aleutian arc volcanoes; 1989-2002
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DOI：
10.1016/j.jvolgeores.2004.07.005
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发表时间：
2004-12-15
影响因子：
2.9
通讯作者：
Moran, SC
中科院分区：
文献类型：
--
作者：
Power, JA;Stihler, SD;Moran, SC
1989年10月12日至2002年12月31日期间，阿拉斯加火山观测站（AVO）在阿留申群岛弧的11个火山中心下方发现了162个深层长周期（DLP）事件。这些事件通常发生在中下地壳深度（1045 km），其特征是出现阶段、扩展的尾波和 1.0 至 3.0 Hz 之间的强谱峰。观测到的波速和质点运动表明主要相位是纵波和横波。 DLP 震中通常延伸到活火山周围的广阔区域（5-20 公里）。阿留申 DLP 的平均位移减少量为 26.5 cm(2)，最大事件的位移减少量为 589 cm(2)（或 M-L 2.5）。阿留申 DLP 事件既可以作为单独事件发生，也可以作为一系列事件发生，其中多个事件在 1-30 分钟内发生。在序列中，各个 DLP 经常被具有相似频谱特征的低振幅火山震动分开。偶尔，位于相似深度的火山构造地震也包含在 DLP 序列中。最多，阿留申火山 DLP 似乎松散地围绕着主火山喷口，并作为背景地震活动的一部分发生。一种可能的解释是，它们反映了地壳下部和中部广阔区域内岩浆上升的相对稳态过程。在斯普尔山，DLP 地震活动始于 1992 年的喷发，然后缓慢下降，直到 1997 年。在 Shishaldin 火山，DLP 地震活动在 1999 年 4 月 19 日喷发前约 10 个月发生了短暂的增加。这些观察结果表明，中下地壳和最上地幔的喷发活动与岩浆通量之间存在联系。由 Elsevier B.V. 出版
Between October 12, 1989 and December 31, 2002, the Alaska Volcano Observatory (AVO) located 162 deep long-period (DLP) events beneath 11 volcanic centers in the Aleutian arc. These events generally occur at mid- to lower-crustal depths (1045 km) and are characterized by emergent phases, extended codas, and a strong spectral peak between 1.0 and 3.0 Hz. Observed wave velocities and particle motions indicate that the dominant phases are P- and S-waves. DLP epicenters often extend over broad areas (5-20 km) surrounding the active volcanoes. The average reduced displacement of Aleutian DLPs is 26.5 cm(2) and the largest event has a reduced displacement of 589 cm(2) (or M-L 2.5). Aleutian DLP events occur both as solitary events and as sequences of events with several occurring over a period of 1-30 min. Within the sequences, individual DLPs are often separated by lower-amplitude volcanic tremor with a similar spectral character. Occasionally, volcano-tectonic earthquakes that locate at similar depths are contained within the DLP sequences.At most, Aleutian volcanoes DLPs appear to loosely surround the main volcanic vent and occur as part of background seismicity. A likely explanation is that they reflect a relatively steady-state process of magma ascent over broad areas in the lower and middle portions of the crust. At Mount Spurr, DLP seismicity was initiated by the 1992 eruptions and then slowly declined until 1997. At Shishaldin Volcano, a short-lived increase in DLP seismicity occurred about 10 months prior to the April 19, 1999 eruption. These observations suggest a link between eruptive activity and magma flux in the mid- to lower-crust and uppermost mantle. Published by Elsevier B.V.