Séminaire ISTerre

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Secular change in velocity and coseismic change in attenuation detected by using ACROSS

vendredi 30 avril 2021 - 11h00

Shuhei TSUJI - Nagoya University, Japan
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I will introduce two studies with an artificial seismic source, ACROSS. 
ACROSS is an artificial seismic source designed for precise monitoring  of underground structures and excite stable seismic waves continuously.  We take advantage of the characteristics of the ACROSS signals in  detecting small variations in seismic velocity and attenuation.
The  first study is a finding of secular change in velocity in the Tokai  region, Japan. We monitored changes in travel time over 10 years at 13  stations within 35 km from an ACROSS source and found a secular change  in travel time that continues over the observation period.
The second  one is a finding of an anisotropic change in attenuation associated with an earthquake at Awaji Island, Japan.
We developed a method to monitor  changes in amplitude and applied it to an in-situ dataset. As a result,  an increase in attenuation is observed at earthquakes. We also analyzed  velocity change at the earthquakes and compare anisotropy of changes in  velocity and attenuation. As a result, a larger increase in attenuation  was observed in the direction with a larger decrease in velocity.

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Equipe organisatrice : Ondes et structures

Séminaire uniquement en visio

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/97295763658?pwd=Z0Y4OEJtNXFOMnRwcFlXNWl1eFpSQT09
Meeting ID : 972 9576 3658
Passcode : 783219