2024-03-29T11:10:47Z
https://repository.dl.itc.u-tokyo.ac.jp/oai
oai:repository.dl.itc.u-tokyo.ac.jp:00054060
2022-12-19T05:33:22Z
80:4453:8385
9:504:4455:8386
Precipitates on Beach Electrical Ground of Optical-cable-type Ocean-bottom Seismometer and Tsunami Meter System off the Sanriku Coast
三陸沖光ケーブル式海底地震・津波観測システムのビーチアース部分に発生した析出物の調査
田中, 伸一
160465
外西, 奈津美
160466
篠原, 雅尚
160467
Optical-cable-type ocean-bottom seismometer and tsunami meter system
Electrical power supply system
Beach ground
Precipitates
Chemical analysis
We found precipitates on the beach electrical ground (negative electrode) of the optical-cable-type ocean-bottom seismometer and tsunami meter system off the Sanriku coast (Sanriku system). These precipitates formed from 2014 to 2018. The DC voltage that feeds the Sanriku system began to increase and fluctuate in June 2017. This fluctuation suggests instability in the Sanriku system. To investigate the relationship between the precipitate growth and supply voltage fluctuation, we sampled and analyzed the precipitates in September 2018. The main components of the precipitates were calcium carbonate (CaCO3) and dolomite (CaMg(CO3)2), which are abundant in seawater. The metallic positive ions in seawater were drawn to the negative electrode, precipitating on the beach electrical ground and increasing its electrical resistance. This change in electrical resistance caused the observed DC voltage fluctuation. The beach electrical ground should be regularly cleaned to maintain the stability of the Sanriku system.
<論説>
departmental bulletin paper
東京大学地震研究所
2019
application/pdf
技術研究報告
25
1
9
https://repository.dl.itc.u-tokyo.ac.jp/record/54060/files/25_001-009.pdf
jpn