Intensity 5+ Earthquake Hits Aichi, Japan; 22 Injured Reported

A strong earthquake struck the Tokai region of Japan around 1:04 a.m. on Nov. 8 (Japan time), and the Japan Meteorological Agency (JMA) recorded a maximum seismic intensity of 5+ in Chita City, Aichi Prefecture. The Chunichi Shimbun reported that 22 people were injured in Aichi and Shizuoka prefectures as of 1:00 p.m. that day.

The JMA said the quake does not point to any particular change in the locking status between plates along the Nankai Trough, according to the summary published by the news site note.

Epicenter moved from Shizuoka to Aichi

After re-examining its data, the JMA corrected the epicenter from eastern Shizuoka Prefecture to eastern Aichi Prefecture. The agency sometimes revises earthquake information after review. In the past, a re-examined magnitude has led it to change a “no concern for tsunami” message to a tsunami advisory. The sources do not report a tsunami warning or advisory for this earthquake, and they do not give its magnitude or depth.

First intensity 5+ in Aichi in 29 years

This is the first time in 29 years that an intensity of 5+ or higher has been observed within Aichi Prefecture. The previous one was the Western Aichi Prefecture earthquake of March 16, 1997. Intensity here refers to the JMA seismic intensity scale, which measures shaking at a given location rather than the energy of the quake itself.

What the JMA said about the Nankai Trough

At a press conference early on Nov. 8, the JMA addressed whether the quake relates to a Nankai Trough earthquake, the large event expected to cause widespread damage mainly in the Tokai region. The agency said the quake “does not indicate any particular change” in the locking status between plates along the trough. The JMA thereby took a negative view of any direct connection between the two.

The Nankai Trough earthquake has an assumed focal region along the plate boundary from Suruga Bay to Hyuga-nada. Such earthquakes are said to have occurred repeatedly at intervals of roughly 100 to 150 years. The most recent was the Showa Nankai earthquake in 1946.

Why it matters

An intensity of 5+ is the strongest shaking recorded in Aichi in nearly three decades, and the injury count spans two prefectures. The JMA’s statement on the Nankai Trough addresses the question many residents of the Tokai region ask after a strong quake, and the agency answered that plate locking along the trough has not changed. Readers in the area should follow instructions from local emergency officials and the JMA for current information.

Source: note