کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4712951 1638414 2010 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Using infrasound waves from eruption video to explain ground deformation preceding the eruption of Suwanosejima volcano, Japan
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Using infrasound waves from eruption video to explain ground deformation preceding the eruption of Suwanosejima volcano, Japan
چکیده انگلیسی

Combined video, infrasound and seismic observations were conducted at Suwanosejima volcano in August 2005, and the processes producing infrasound radiation at the onset of an eruption were examined based on the results of the observations. Infrasound waveforms were found to exhibit a slow weak pressure increase (preceding phase) 0.7 s before the large rapid main compression phase. These pressure changes induced a subtle H2O phase change in steam discharged from the crater, which could not be easily recognized in the normal video images. However, propagation of the pressure waves could be identified by image processing as luminance variations above the crater. These variations coincided with the compression phase of the infrasound wave. The origin time of the preceding phase estimated from the arrival times of an infrasound wave at two different stations and the luminance data was almost identical to the time when, based on the seismic signals, a vertical expansion occurred at a depth of about 0.5 km beneath the crater bottom. Considering the eruption processes of Sakurajima volcano, it was concluded that the preceding phase of the infrasound wave was caused by swelling of the ground surface at the crater bottom due to this expansion beneath the crater. In the case of the Suwanosejima eruption, the volumetric change due this ground uplift was estimated to be 30–40 m3. The origin time of the subsequent main phase of the infrasound wave coincided with the onset of volcanic material ejection. This suggests that the crater bottom, which acted as a lid to the pressurized magma and gases before the eruption, failed due to the expansion that occurred during the 0.7 s period prior to the eruption.

Research highlights
► Geophysical observation was done at Suwanosejima volcano, Japan.
► Swelling and failure processes of crater bottom at eruption onset were revealed.
► In particular visual and infrasound observation were helpful to do it.
► They might be a key to understand whole eruption sequences in detail.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Volcanology and Geothermal Research - Volume 196, Issues 3–4, 1 October 2010, Pages 287–294
نویسندگان
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