Tracking giant earthquakes in the Ring of Fire 11.03.2021 Many processes behind giant earthquakes are still not understood. Ten years after the Tohoku-oki earthquake in Japan, an international team aims to unravel the sedimentary archive of past earthquakes in the Japan Trench. Michael Strasser from the Sedimentary Geology Working Group is one of the scientific leaders of the deep sea-expedition in the framework of the IODP. Image: Research vessel Kaimei. (Credit: JAMSTEC) Exactly ten years ago today, on 11 March 2011, Japan was unexpectedly struck by one of the most severe earthquakes ever recorded, resulting in a disaster. The Tohoku-oki earthquake registered 9.0 on the moment magnitude scale (Mw) – a - precise scientific indication of the strength of earthquakes: it triggered a tsunami with enormous destructive force that killed thousands of people and resulted in a nuclear disaster at the Fukushima-Daiichi nuclear power plant. Smaller earthquakes are not unusual in Japan, as the country is located on the so-called Pacific Ring of Fire, a tectonically highly active area. "The entire spectrum of possible earthquake processes can be studied there. Of particular interest to us are strong earthquakes, i.e. earthquakes with a moment magnitude of nine or more. Which processes lead to such strong earthquakes and how often they occur is still not fully understood," explains Michael Strasser, head of the Sedimentary Geology Working Group at the Department of Geology and Austrian Core Facility for scientific core analysis at the University of Innsbruck. The expedition is led by Strasser together with Dr. Ken Ikehara from the National Institute of Advanced Industrial Science and Technology (AIST) in Japan. "In order to better understand the causes and frequency of giant earthquakes, we will use cores from the deep sea as a prehistoric seismograph. In the sediment sequences from the deep sea, we can find deformation structures that were triggered by past strong earthquakes and reconstruct their intensity and frequency far into the past," the geologist explains. A closer look into this geological past is now the aim of the Expedition 386 "Japan Trench Paleoseismology" of the International Ocean Discovery Program (IODP). A team of scientists will leave the port of the city of Yokusuka on 13 April 2021 on board of the research vessel