1. Seismic activity recorded by a single OBS/H near the active Longqi hydrothermal vent at the ultraslow spreading Southwest Indian Ridge (49°39′ E)
- Author
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Qiu Lei, Vera Schlindwein, Haijiang Zhang, Cai Liu, Yunlong Liu, You Tian, Chunhui Tao, and Wang Hanchuang
- Subjects
geography ,geography.geographical_feature_category ,Hydrophone ,010505 oceanography ,0211 other engineering and technologies ,Ocean Engineering ,02 engineering and technology ,Geotechnical Engineering and Engineering Geology ,Oceanography ,01 natural sciences ,Hydrothermal circulation ,Tectonics ,Volcano ,13. Climate action ,Ridge ,Passive seismic ,14. Life underwater ,Microearthquake ,Geology ,Seismology ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Hydrothermal vent - Abstract
In this paper, we describe the results of a first pilot experiment of passive seismic monitoring near the active Longqi hydrothermal vent at the Southwest Indian Ridge during Chinese cruise DY115-30. During 102-day experiment, we recorded over 2,000 seismic events on a single ocean bottom seismometer with hydrophone close to the hydrothermal field. We classified these events into the following three classes based on their time–frequency characteristics: (1) volcano tectonic microearthquakes (VTMs); (2) regional earthquakes; (3) short-duration events (SDEs). We preliminarily located the 1,277 VTMs using a singlestation location method. Our results revealed hypocenters primarily beneath the axial valley ridge which is about 10 km away from hydrothermal vent and extending to the upper mantle at a depth of 15 km. Two discrete swarms of VTMs occurred during our survey period. The SDEs show a complex frequency characteristics ascribed to clusters of monochromatic waves around different frequencies. This suggests that SDEs result from combination of harmonic waves resonating in fluid-filled pipes and cracks.
- Published
- 2018