Tōhoku Earthquake & Tsunami
At 14:46 local time on March 11, 2011, the Pacific Plate slipped beneath the Okhotsk Plate by as much as 80 meters along a 500-kilometer rupture — the fourth-largest earthquake ever recorded. Six minutes later, a tsunami nearly 40 meters tall overtopped seawalls along the Sanriku coast.
The magnitude 9.1 event released energy equivalent to roughly 600 million Hiroshima bombs. Honshu shifted 2.4 meters east. Japan's main island moved permanently closer to North America. Earth's axis itself tilted by an estimated 17 centimeters.
The tsunami inundated 561 square kilometers of coastline within 90 minutes. The Fukushima Daiichi nuclear plant's seawall — designed for waves up to 10 meters — was overtopped by a 14-meter wave that flooded backup generators, triggering a station blackout and three core meltdowns over the following days.
Roughly 19,759 people died. 2,553 remain missing. The economic damage of around $235 billion makes it the costliest natural disaster in recorded history.
The USGS PAGER system rated the quake's potential impact as RED within 30 minutes — the highest alert level — and tsunami warnings reached the entire Pacific Rim within an hour, from Hawaii to Chile.