Vault-housed extensometers recorded a rapid initial pulse before precursory magma reservoir inflation related to the 2011 eruption of Shinmoe-dake, Japan

Previous studies of the major eruption at Shinmoe-dake volcano, Japan, in January 2011 suggested that gradual injection of magma from a deep source into a shallow reservoir began in December 2009 and led to the major eruption. To investigate the initial phase of this injection event, we examined extensometer data from the Isa Observatory,  ~ 18.5 km from the summit of Shinmoe-dake, and discovered a strain change event that spanned about 3 days in December 2009. The size of the strain change is comparable to those observed during each sub-Plinian eruption in 2011. The source of the rapid strain change appears to be deeper than the estimated location of the magma reservoir that directly supplied magma to the 2011 eruption sequence. These observations suggest that rapid injection of magma from the deep magmatic plumbing system in December 2009 triggered the continuous ascent of additional magma from depth, which in turn drove the climactic eruptions in January 2011. Extensometers also recorded two rapid strain change events of the same order of magnitude and with similar characteristics in December 2006 and August 2008; however, noticeable inflation of the edifice was not detected immediately following either event. This suggests that transient injection of magma into a shallow reservoir is not always followed immediately by a gradual recharge process

Effects of the Tsunami Generated by the 1662 Hyuga-Nada Earthquake off Miyazaki Prefecture, Japan

1662年日向灘地震の新たな断層モデルを構築 --地球物理学と地質学の検証に基づく初の成果--. 京都大学プレスリリース. 2023-01-24.The Hyuga-nada region is located in the southwestern part of the Nankai Trough in the Pacific Ocean, where M7 class interplate earthquakes have been repeatedly occurring because of the subduction of the Philippine Sea Plate. The largest earthquake recorded in history for the Hyuga-nada region was the Hyuga-nada earthquake of 1662, which occurred off Miyazaki Prefecture in the southeastern area of Kyushu region, Japan, generating a tsunami. The region is also an area where slow earthquakes are active at the shallow part of the plate boundary. It is confirmed by the 2011 Tohoku earthquake that the active area of shallow slow earthquakes also became a tsunami source area. We hypothesize that the unusually large tsunami of 1662 was caused by the coseismic slipping of the active source area of shallow slow earthquakes. We constructed the fault model of the 1662 Hyuga-nada earthquake based on recent geophysical observations. A numerical simulation of the tsunami was carried out using the fault model constructed based on hypotheses. The total seismic moment was 9.8 × 10²⁰ Nm (Mw 7.9) estimated from the fault model. The estimated fault model can explain the distribution of the likely tsunami event deposits which were recognized in this study and also have been reported by other studies and tsunami heights in historical records. Hypotheses based on geophysical findings have been found to be correct

Curved-Tip Disposable Injector (OUReP Injector) to Insert Photoelectric Dye-Coupled Polyethylene Film (OUReP) as Retinal Prosthesis into Subretinal Space of Rabbit Eyes

The photoelectric dye-coupled thin polyethylene film functions as a novel type of retinal prosthesis in subretinal space of the eye. We previously reported a novel disposable injector to insert the thin film into subretinal space of the rabbit eye by vitreous surgery. The injection system composed of two separate parts, injector and loader. A circular film in 5 mm to 10 mm diameter was pulled into a transparent tube of the loader with a commercial 25-gauge forceps. The loader tube was joined with a sleeve to tube tip of the injector. The film in the loader was pushed with a plunger for the loader into the injector tube tip. The loader with the sleeve was removed from the injector tip, and the tube tip with the film was filled with solution. This study reported a small-bore curved-tip disposable injector with outer diameter of 1.6 mm. A curved-tip polypropylene tube was formed by the process of heating and cooling of the tube inserted with a curved guide wire. The plunger for the curved-tip tube was made of a polyphenylsulfone tip connected with a press-fitting inner polypropylene tube to a nylon rod. Bleb retinal detachment in 4 surgically aphakic eyes of rabbits were induced by infusing solution into subretinal space with a 38-gauge polyimide tip, and a retinal tear was made at the edge of retinal detachment with 25-gauge diathermy. The injector tip with the rolled film in 6 mm diameter was inserted from 2 mm wide scleral incision into vitreous and then into subretinal space. The rolled films were released into subretinal space with the tip end inserted into the retinal tear, and the released films were confirmed to stay under the retina with no additional aid. Dissection one month after surgeries confirmed successful implantation of 4 films into subretinal space of each rabbit eye. The curved-tip injector could release the rolled film into the subretinal space without additional effort, compared with the straight-tip injector, and would help surgeons implant photoelectric dye-coupled thin film retinal prosthesis easily at vitreous surgery