Analyses of unusual long-period earthquakes with extended coda recorded at Katmai National Park, Alaska, USA
Analyses of unusual long-period earthquakes with extended coda recorded at Katmai National Park, Alaska, USA
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对美国阿拉斯加卡特迈国家公园记录的异常长周期地震的分析
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
S. Angelis
中科院分区：
文献类型：
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作者：
S. Angelis
[1]一群6个长周期（LP）事件缓慢衰减尾波振幅和持续时间长达120秒，位于山附近的地震台站记录。2004年12月8日至21日，阿拉斯加卡特迈国家公园的格里格斯火山。频谱分析揭示了波形的准单色特征，由2.5 Hz模式主导，经常伴有较弱的高频发作（6.0-9.0 Hz）。质点运动方位角和倾角显示了所有信号的主导WNW-ESE偏振方向，并表明地震能量是由稳定的源在浅层辐射的。阻尼系数在0.0014和0.0063之间，通过拟合指数衰减模型来估计信号的尾波;相应的品质因子范围从78到351。波形的源被建模为填充有流体/气体混合物的谐振腔。
[1] A swarm of six long-period (LP) events with slowly decaying coda wave amplitudes and durations up to 120 s, was recorded by seismic stations located in the proximity of Mt. Griggs, a fumarolically active volcano in the Katmai National Park, Alaska, during December 8–21, 2004. Spectral analyses reveal the quasi-monochromatic character of the waveforms, dominated by a 2.5 Hz mode frequently accompanied by a weaker high-frequency onset (6.0–9.0 Hz). Particle motion azimuths and inclination angles show a dominant WNW-ESE direction of polarization for all the signals, and suggest that seismic energy is radiated by a stable source at shallow depth. Damping coefficients between 0.0014 and 0.0063 are estimated by fitting an exponential decay model to the signal's coda; corresponding quality factors range from 78 to 351. The source of the waveforms is modelled as a resonant cavity filled with a fluid/gas mixture.