Time: 10:00-11:00 on 6th May (Monday), 2019
Venue: Lecture Hall (221), Building No.16,Weijin Campus, Tianjin University
Title: Helium anomalies suggest a fluid pathway from mantle to trench during the 2011 Tohoku-Oki earthquake
Speaker: Dr. Yuji Sano (University of Tokyo & Tianjin University)
Dr. Yuji Sano graduated from the University of Tokyo in 1978, and was awarded Degree of Master in Science in 1980 and Doctor in Science in 1983. He was Research Associate in the University of Tokyo from 1983 to 1990, Associate Professor in Hiroshima University from 1990 to 1993, and Professor in Hiroshima University from 1993 to 2001. Since 2001, he moved to the Atmosphere and Ocean Research Institute of Tokyo University as a full professor.
Professor Sano is an internationally renowned experimental and applied geochemist who specializes in geochemical studies of volatile elements and isotopes (noble gases, carbon and nitrogen) in the Earth's environment. He pioneered systematic research on the cycle of volatile elements in geological environments such as island arc volcano; first established Japan's first large-scale ion probe analysis facility (SHRIMP), and for the first time created a U-Pb dating method for apatite which has been applied to the study of the origin of life on Earth and the age of lunar mineral formation; the establishment of a noble gas laboratory for atmospheric and marine environments, and the Nano Ion Probe (NanoSIMS) laboratory for ancient marine and planetary science research.
So far, Professor Sano has published 253 SCI papers, including 7 Nature, 2 Science, and 4 Nature sister journals. The total citation number is as high as 6,725 and the H index is 42. Because of the excellent research outcomes and outstanding academic contributions, Professor Sano has received many national and international awards. In particular, he was elected as a Fellow of the American Geophysical Union (AGU Fellow) in 2012, and Geochemistry Fellow of the International Geochemical Society and the European Society of Geochemistry in 2019. He was also selected as an Honorary Professor of Tianjin University in 2019.
Abstract：Geophysical evidence suggests that fluids along fault planes have an important role in generating earthquakes; however, the nature of these fluids has not been well defined. The 2011 magnitude 9.0 Tohoku-Oki earthquake ruptured the interface between the subducting Pacific plate and the overlying Okhotsk plate. Here we report a sharp increase in mantle-derived helium in bottom seawater near the rupture zone 1 month after the earthquake. The timing and location indicate that fluids were released from the mantle on the seafloor along the plate interface. The movement of the fluids was rapid, with a velocity of 4 km per day and an uncertainty factor of four. This rate is much faster than what would be expected from pressure-gradient propagation, suggesting that over-pressurized fluid is discharged along the plate interface.
