Qualla: 1944 Tōnankai earthquake

1944 Tōnankai earthquake: Introduction

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit As6022014, CC BY-SA 3.0. At 1:35 in the afternoon on December 7, 1944 -- exactly three years after Pearl Harbor -- the seafloor off Japan's Pacific coast lurched. The 1944 Tōnankai earthquake, magnitude 8.1, was the strongest earthquake anywhere in the world that year. Along the coast of the Kii Peninsula and the Tōkai region, the ground shook at intensities that would later be classified as severe on the Mercalli scale. Within minutes, the ocean drew back from the shore. Then it returned as a wall of water ten meters high. Japan was already reeling from the war. Now the earth itself had turned against it. By the time the shaking stopped and the waters receded, 1,223 people were dead and another 2,135 lay seriously injured.

Image: As6022014 | CC BY-SA 3.0

1944 Tōnankai earthquake: The Trough That Never Sleeps

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit User:Lincun: derivative work: Mikenorton (talk), CC BY-SA 3.0. The southern coast of Honshū runs parallel to the Nankai Trough, a 700-kilometer-long submarine trench where the Philippine Sea plate dives beneath the Eurasian plate. This convergent boundary is one of the most seismically active zones on Earth. The Nankai megathrust has five di...

Image: User:Lincun: derivative work: Mikenorton (talk) | CC BY-SA 3.0

1944 Tōnankai earthquake: A Coastline Shattered

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Mikenorton, CC BY-SA 3.0. The eastern face of the Kii Peninsula bore the worst of the damage, particularly the cities of Shingū and Tsu. The shaking alone destroyed 26,146 houses. Eleven buildings burned to the ground. Then came the tsunami, which obliterated a further 3,059 homes. Nearly 47,000 additiona...

Image: Mikenorton | CC BY-SA 3.0

1944 Tōnankai earthquake: Waves Across the Pacific

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Mikenorton, CC BY-SA 3.0. The maximum recorded tsunami wave height was ten meters on the Kumano coast in Mie Prefecture. Run-ups exceeding five meters struck multiple locations along the coasts of both Mie and Wakayama Prefectures. But the tsunami did not stop at Japan's shores. It propagated across the e...

Image: Mikenorton | CC BY-SA 3.0

1944 Tōnankai earthquake: A Clock Still Ticking

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Mikenorton, CC BY-SA 3.0. The 1944 Tōnankai earthquake was not an isolated event but a chapter in a recurring saga. The segment of the Nankai megathrust immediately to the east of the 1944 rupture zone -- segment E -- has not broken since 1854, making it overdue by historical standards. Seismologists cons...

Image: Mikenorton | CC BY-SA 3.0