Though earthquakes occur frequently in all areas of Japan, the Sanriku area (Aomori, Iwate, Miyagi) and the prefectures along the Sea of Japan coast (Fukui, Ishikawa, Niigata) have historically been prone to the most seismic activity.

In 2026, the area considered to be at the highest risk for a major earthquake is the Nankai Trough, a subduction zone off the southwestern coast of Japan's main island, Honshu. Seismologists and the Japan Meteorological Agency (JMA) have long warned that this area has a roughly 70–80% probability of producing a "mega-thrust" earthquake (Magnitude 8 or 9) within the next few decades. This potential disaster, known as the Nankai Trough Earthquake, could affect a massive swath of the country from the Kanto region (Tokyo) all the way to Kyushu. Additionally, the Tokyo Metropolitan Area itself remains under constant "Direct-Hit" threat from various active fault lines directly beneath the city. In early 2026, recent seismic activity has also focused attention on the Tohoku region and the Noto Peninsula, which continue to experience significant aftershocks and crustal movements following major events in recent years. Japan's advanced early warning systems and strict building codes are designed for these specific high-risk zones, as the country is situated at the intersection of four major tectonic plates.