Japan: an example of an archipelago at high seismic risk

By Jacques Guillaume

L’Atlas Bleu / Preventing

Earthquake, tsunami, population, deadly disaster, Japanese archipelago.

This article presents a cartography of the main structural elements placing Japan in an intense seismic zone. It compares the population density of the archipelago with the inventory of earthquakes which occur over the 20th century. These elements show the vulnerability of this area. The example of the earthquake of march 11, 2011, reminds the chain of catastrophic events that led to the major nuclear accident in Fukushima.

Structural elements of intense seismicity…

Japan lies along the Pacific Ring of Fire, at the intersection of the Eurasian, Pacific and Philippines plates. Deep oceanic trenches just off the archipelago are evidence of very active subduction which manifests in a series of natural hazards (volcanism, earthquakes and tsunamis). The abundance of these hazards has forced Japanese society to adopt a stringent risk culture.

…on a densely populated archipelago

However, the country is not safe from fatal disasters (see table below) and the most recent, in March 2011, was particularly devastating. It is worth noting that it was not so much the earthquake as the resulting tsunami that caused this disaster, with the wave submerging and destroying almost all sea defences and suddenly flooding entire areas, from small coastal villages to large towns in the Sendai urban area.

In addition to the victims who died or went missing, more than 100,000 people were displaced which shows the level of disruption in those areas affected. To make matters worse, flooding at the Fukushima 1 nuclear power plant caused the cooling systems to shut down, leading to the meltdown of three reactors, a chain of explosions, and radioactive contamination in a populated zone which traditionally grew fruit and vegetables for the Greater Tokyo area. This made the incident one of the most serious nuclear disasters in history, alongside Chernobyl.

Jacques GUILLAUME, géographe, Chercheur associé à LETG-Nantes UMR 6554.

Jacques GUILLAUME, « Exemple d’un archipel à haut risque sismique : le Japon », L’atlas Bleu, Revue cartographique des mers et des littoraux. Mis en ligne le 11 janvier 2020,

(version digitale adaptée d’après l’article paru dans L’Atlas Permanent de la Mer et du Littoral n°7 « Risques littoraux et maritimes ». Ed. LETG-Nantes, 2015. p.9)

URL : https://atlas-bleu.cnrs.fr/

DOI : 10.35109/atlasbleu-eng.10017