Publication Date:
2015-02-18
Description:
We estimate the three-dimensional (3-D) P -wave attenuation structure beneath Kyushu, Japan, using a large number of high-quality waveform data. Our results show that the mantle wedge is characterized by high-attenuation regions in the fore-arc corner and in the back-arc beneath volcanoes, with the two regions separated by a low-attenuation area. The volcanic gap in central Kyushu is underlain by low attenuation below the Moho. High attenuation in the fore-arc is probably associated with serpentinized peridotite, while that in the back-arc is interpreted as an upwelling flow that is the source of arc magmas. The presence of low-attenuation mantle that separates the high-attenuation hydrated, fore-arc and back-arc mantle regions, suggests that fluids are supplied from two depth levels of the slab by different mechanisms. Low attenuation beneath the volcanic gap probably results from intricate 3-D mantle flow that is caused by tectonic processes such as back-arc extension and ridge collision.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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