The focus thermal study around the spreading center of southwestern Okinawa trough

Studies of Seismic Velocities in Subduction Zones from Continuous Ocean Bottom Seismometer Data

“…While their seismic profile did not cross any hydrothermal vents, the deployment in this study covers volcanic outcrop (Figure 5.20), and the deployment is beside a high heat flow spot (red circle in Figure 5.2). Within our study region, the heat flow in the south of the basin is higher than that in the north of the basin (Chen et al, 2020), which might be a consequence of asymmetric spreading.…”

“…High heat flows (Yamano et al, 1989;Kinoshita and Yamano, 1997;Shyu and Liu, 2001) indicate continuous spreading and volcanism in the mid and southern Okinawa Trough. East of my study region, there is a spot (the red circle in Figure 5.2) with particularly high heat flow (3000 mW/m 2 ) compared to the surroundings (Yamano et al, 1989;Shyu and Liu, 2001;Gutscher et al, 2016;Liu et al, 2016;Wu et al, 2019;Chen et al, 2020). Chen et al (2020) suggested there is a magma chamber beneath it and the hydrothermal fluid here might mix with the magmatic body.…”

“…East of my study region, there is a spot (the red circle in Figure 5.2) with particularly high heat flow (3000 mW/m 2 ) compared to the surroundings (Yamano et al, 1989;Shyu and Liu, 2001;Gutscher et al, 2016;Liu et al, 2016;Wu et al, 2019;Chen et al, 2020). Chen et al (2020) suggested there is a magma chamber beneath it and the hydrothermal fluid here might mix with the magmatic body. The magmatism is intense in the rift center, and linear magnetic stripes are identified in the southern Okinawa Trough (Kimura, 1985;Sibuet et al, 1987;Liang et al, 2002;Liu et al, 2016).…”

“…The asymmetric spreading is considered to be caused by the combination of kinematic and stress conditions that prevail within the central North Island. In the southwestern Okinawa Trough, heat flow measurements (about 110 mW/m 2 on average, varying from 9 to 437 mW/m 2 ; Shyu and Liu, 2001) are high and are related to continental rifting and seafloor spreading (Liu et al, 2016;Chen et al, 2020). Unlike the Central Volcanic Region of New Zealand, the southwestern Okinawa Trough is lack of seismometer deployment to provide us a high resolution lithosphere depth to investigate if the depths on the two sides of the rifting axis are different.…”

“…5. Studies of shear wave velocity structure in the southwestern Okinawa Trough from continuous OBS data Shyu and Liu, 2001) in the southwestern Okinawa Trough are high and are related to continental rifting and seafloor spreading (Liu et al, 2016;Chen et al, 2020).…”