The Japanese Sendai Nuclear Plant Threatened by the Sakurajima Volcano

By T.V. Antony Raj

The lithosphere is the rigid, outermost shell on Earth. It comprises the crust and the part of the upper mantle that has an elastic behavior on, timescales of thousands of years or greater.

The scientific theory of plate tectonics describes the large-scale motion of Earth’s lithosphere. The geoscientific community accepted the theoretical model of plate tectonics developed during the first few decades of the 20th century based on the concept of continental drift. The concepts of seafloor spreading developed in the late 1950s and early 1960s.

The tectonic plates of the world were mapped in the second half of the 20th century.

The Earth’s lithosphere, the rigid outermost crust and upper mantle, is broken up into seven or eight major tectonic plates and many minor plates.

These massive slabs of the earth’s crust forever creep, slip, lock up and then jolt again. The typical annual lateral relative movement of the plates varies from zero to 100 mm.

Almost all creation of mountains, earthquakes, volcanic activity, and the formation of oceanic trenches occurs along these tectonic plate boundaries.

The islands that compose the Japanese nation sit on or near the boundary of four tectonic plates: the Pacific, North American, Eurasian and Filipino plates.

Also, Japan lies on the “Ring of Fire” also known as the circum-Pacific belt. – The Ring of Fire is a horseshoe-shaped band of fault lines in the basin of the Pacific Ocean, associated with a continuous series of oceanic trenches, volcanic arcs, and volcanic belts and tectonic plate movements. It has 452 volcanoes and has over 75% of the world’s active and dormant volcanoes. A large number of earthquakes and volcanic eruptions occur in this region.

Sendai Nuclear Power Plant

The Sendai Nuclear Power Plant, owned and operated by the Kyūshū Electric Power Company, is in the city of Satsumasendai in the Kagoshima Prefecture. It is located near five giant calderas, a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, with the closest one about 40 km away from the plant.

Before the earthquake and tsunami of March 2011, and the nuclear disasters that resulted from it, Japan had generated 30% of its electrical power from nuclear reactors. It had planned to increase electrical power production to 40%.

Nuclear energy was a national strategic priority in Japan, but there had been concern about the ability of Japan’s nuclear plants to withstand seismic activity.

The earthquake and tsunami of on March 11, 2011, caused the failure of the cooling systems at the Fukushima I Nuclear Power Plant. Japan then declared its first-ever nuclear emergency. This caused the evacuation of around 140,000 residents within 12 miles (20 km) of the plant.

On May 6, 2011, Prime Minister Naoto Kan ordered the shutdown of the Hamaoka Nuclear Power Plant as an earthquake of magnitude 8.0 or higher is likely to hit the area within the next 30 years.

Also, many other nuclear power plants, including the Sendai plant stopped generating electricity.

In the wake of the Fukushima Daiichi nuclear disaster in 2011, Japan set new safety standards for its nuclear reactor plants.

On September 10, 2014, the Japanese Nuclear Regulation Authority (NRA) declared the Sendai Nuclear Power Plant safe for operation.

On August 11, 2015, Kyushu Electric Power Co., restarted its operation by bringing online the No. 1 reactor at its Sendai power station according to the new safety standards. Now it is providing power to the nearby towns again. Sendai is the first of Japan’s nuclear power plants to be restarted.

The Sakurajima Volcano

View of Sakurajima from mainland Kagoshima in 2009

Sakurajima is an active composite volcano (stratovolcano) 990 km southwest of Tokyo. It is a former island in Kagoshima Prefecture in Kyushu, Japan. It is one of Japan’s most active volcanoes and erupts all the time. The lava flows of the 1914 eruption caused the former island to be connected to the Osumi Peninsula. The volcanic activity still continues, dropping large amounts of volcanic ash on the surroundings. Earlier eruptions built the white sands highlands in the region.

The Japan Meteorological Agency on its website said that it believes that a larger than the usual eruption could be in the offing since it detected multiple earthquakes in the area on Saturday morning. So, on Saturday, August 15, 2015, the agency raised the warning level for the volcanic island of Sakurajima from Level 3 to an unprecedented Level 4 (red). It has warned the residents in the villages on Sakurajima and has advised them to evacuate since stones could rain down on areas near the mountain’s base.

The Kagoshima prefectural government has formed an emergency response team.

The Kyushu Electric Power Company says a possible eruption on Mount Sakurajima will not affect the operation of its Sendai Nuclear Power Plant. The company made the comment after raising the alert level to 4. They said that they will collect the relevant data while proceeding with work to increase output as planned.

The Japanese Nuclear Regulation Authority (NRA) also says any possible eruption of the Sakurajima volcano will not affect the Sendai Nuclear Power Plant.