Fresh earthquake fears in Japan as scientists warn over plate stress levels

As Japan prepares to mark the fourth anniversary of the Great East Japan Earthquake, scientists have warned that stress levels in the tectonic plates that triggered the magnitude-9 tremor are once again building to worrying levels.

Writing in the British scientific journal Nature Geoscience, the international team of researchers has concluded that while the stresses that built up in the plates were released in the March 2011 quake – which triggered a tsunami and the crisis at the Fukushima nuclear plant – they have since recovered to levels measured before the tremor.

Predicting earthquakes remains a difficult science, admitted Bogdan Enescu, an associate professor at the University of Tsukuba and one of the authors of the report, which concludes that “large earthquakes may not have a characteristic location, size or recurrence interval, and might therefore occur more randomly distributed in time”.

While the recovery to stress levels beneath a tectonic plate is generally anticipated to take around 10 years after a major tremor, that recovery took a mere three years off the north-east coast of Japan, he said.

“We need to continue watching the figures closely,” he said. “And while some people say that we have already returned to a dangerous situation, there is the view on the other hand that it is good to be prepared for natural disasters of this type.”

Enescu and his colleagues from the Swiss Seismological Service in Zurich analysed a model that shows the relationship between the scale of a number of earthquakes that occurred along the Pacific Plate, which runs parallel to the coast of north-east Japan, from 1998 and their frequency.