Vanessa Heyvaert and Ed Garrett, scientists of the Royal Belgian Institute of Natural Sciences (RBINS), are in Japan searching for evidence of past earthquakes and tsunamis.

The two geologists are members of the QuakeRecNankai (QRN) team, searching for evidence that will tell them about the history of great earthquakes and tsunamis along the Nankai Trough in Japan.

After the devastation caused in north east Japan by the Tohoku earthquake in 2011, these scientists are focusing on another area of Japan where one tectonic plate dives beneath another. The fault between the plates, the Nankai subduction zone, is known to produce big earthquakes and major tsunamis, but the maximum size and the frequency of recurrence are not well known. Large earthquakes occurred along parts of the subduction zone in 1944 and 1946, but other areas have not experienced major seismic activity for much longer periods.

The QRN team seeks to answer questions including:

• How frequently do earthquakes and tsunamis occur?
• Can sediment archives extend earthquake records back into prehistory?
• Do earthquakes always occur in the same ‘segments’ of the subduction zone?
• How often do segments combine to generate larger earthquakes?
• How large are the largest earthquakes that the subduction zone can generate?

To answer these questions Drs Heyvaert and Garrett are looking for sand layers and abrupt environmental changes in coastal lowlands and lakes. Sediments from these locations and the microscopic plants and animals contained within them provide evidence on the timing and location of past earthquakes and tsunamis in this region. By understanding the past occurrence of these events, the scientific community will be better able to recognize and quantify the seismic hazard faced by individuals, businesses and governments in this highly populated and economically important area.

The RBINS scientists are blogging about their progress in Japan on the QuakeRecNankai blog. You can also follow the team on twitter @QuakeRecNankai.