Japan's northeast jolted by 4.5-magnitude quake as authorities eye rising seismic activity

The northeast of Japan was struck by an earthquake with a preliminary magnitude of 4.5 on Monday afternoon, although no tsunami warning was issued, Japan's weather agency said.

According to the Japan Meteorological Agency (JMA), no damage or injuries were reported following the tremor which occurred at 3:26 p.m. local time with its epicenter in Aomori Prefecture at a depth of 10 kilometers.

On the Japanese seismic scale of seven, the temblor registered a lower five in some southeastern parts of the prefecture and around four in Hachinohe, the second-biggest city in the prefecture with an estimated population of 231,337 people.

The earthquake and tsunami that pummeled Japan's eastern seaboard on March 11, 2011, was followed by multiple aftershocks in the weeks and months following the quake, with seismologists believing that since then and due to other seismic activity in the Pacific region, the likelihood is that further quake and volcanic activity is imminent in Japan, particularly along the The Median Tectonic Line (MTL).

Seismologists still attribute smaller quakes like Monday's jolt in the northeast to aftershocks connected to the 2011 megaquake, while knowing that rising seismic activity could be a precursor of the next big one to hit.

The MTL is the longest tectonic line in Japan, which runs for about 1000 km. The tectonic line runs east to west, from eastern Kyushu to southwestern Honshu, and also curves to the northeast in central Honshu.

Multiple fault lines in Japan, including the Izu Trench, which hosts a chain of more than 100 volcanoes on its seabed has also shown signs of more activity recently, confirming Japan as the most seismically active region in the world, with an earthquake occurring every five minutes, according to the JMA.

The highly active Izu Trench aside, Japan is home to 110 active volcanoes, some of which are under warning from the JMA for the public to avoid due to increased activity recently.

Last September Mount Ontake, which straddles Nagano and Gifu prefectures and lies west of Tokyo, erupted without warning, killing more than 60 hikers.

Mount Hakone in the popular hot spring resort town near Mount Fuji, has also been given an alert level recently due to increased activity.

Japan's iconic Mount Fuji itself, located on Honshu Island is also an active stratovolcano and while it hasn't erupted since 1707 is often under scrutiny by the JMA and other authorities for potential activity, with visitors and hikers to the popular World Heritage site sometimes being advised to wear helmets, dust masks and goggles when climbing.

But it is Sakurajima, located off Kyushu, that is the volcano currently garnering the most attention and is widely regarded as one of the world's most active volcanoes.

Authorities have said that the current activity along the Izu Trench, combined with the current volcanic activity on the mainland, as well as a recent 15 meter upheaval of land out of the sea in Northern Hokkaido, are all "reasonable" indications of an "imminent event." Endite