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While 12 years have already passed since the 2011 Tohoku-oki earthquake (M9.0), postseismic deformation of the earthquake is still ongoing. In order to detect the postseismic deformation of the Tohoku-oki earthquake, we have been performing repeating observations at seafloor sites for the GNSS-Acoustic (GNSS-A) geodetic observation technique since 2012 using both manned research vessels and an unmanned surface vehicle, called Wave Glider (WG), as a sea surface platform. We developed and tested a system to conduct the GNSS-A observations using the WG in 2019 and have continuously operated the system twice a year since 2020, visiting many (around 15) observation sites. Based on the observation data collected using research vessels and the WG, we estimated the displacement time series of the seafloor transponder array of each site. The spatio-temporal variations in seafloor crustal deformation after the 2011 Tohoku-oki earthquake indicate that the viscoelastic relaxation is the primary cause of the westward motion around the main rupture area of the M9 event, while the afterslip on the shallow plate interface played an important role in producing eastward displacements in the region south to the main rupture area. With respect to the region north to the main rupture area, no distinct spatial deformation pattern has been observed. This implies that multiple factors, i.e., viscoelastic relaxation, afterslip, interplate locking, and episodic slow slip events, are responsible for the complicated spatial deformation in this region. We will also report the current conditions of the equipment for GNSS-A observations in the presentation., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

1) Background: Although many studies have supported the efficacy of multi-sensory environment (MSE) in reducing behavioral and psychological symptoms, and improving quality of life for patients with disabilities and caregivers, these studies didn't offer how to identify a high-risk candidate who would harm from MSE. Thus, this study was to propose a method to classify the high-risk group of cardiac arrest during MSE interventions through the relation between QT and RR intervals (QT-RR interval). 2) Methods: Eight disabled patients were participated in experiments to experience the virtual aquarium for 15 min with a projector and music. The QT-RR relation was measured by electrocardiography, then the risk was evaluated by computing the shortest distance from the mean of QT-RR relation to the standard curve. 3) Results: It was found that the risk of original cardiac arrest for the five patients was averagely 4.7 times higher than that for the three patients. It was considered that the five patients with higher risk came from the 0.6 times slower QT interval. 4) Conclusion: It was concluded that the proposed method to classify the high-risk group through QT-RR relation was good for the prevention of cardiac arrest through the unintended sudden strong stimulation.

HOBITSSIII was a 12 day (19–30 June) Wellington to Wellington RV Tangaroa voyage (TAN1607) to recover previously deployed Absolute Pressure Gauges (APGs) along the northern Hikurangi margin. APGs measure vertical displacement of the seafloor. One APG from University of Texas Institute of Geophysics, UTIG and 5 APGs from Kyoto University were recovered. Five APGs from Kyoto University were also deployed on the TAN1607 voyage and will be recovered in mid-2017. Three separate 8–12 hour GPS-Acoustic surveys were completed by Tohoku University personnel in the vicinity of 3 ocean bottom GPS-A transponders. The GPS-A surveys will be used to determine horizontal rates of motion at the offshore Hikurangi margin. Heat flow measurements were also conducted at 4 sites. Heat flow surveys add to previous measurements made on the RV Roger Revelle in May 2015. 266 km of 2.0–6.0 kHz chirp sub-bottom profiler data were acquired across the Tuaheni Landslide Complex in preparation for scientific drilling in 2017 and 2018. When TAN1607 data are added to the collective offshore geophysical datasets, they will increase the tectonic and geological knowledge of the northern Hikurangi margin.