The Bōsō Peninsula in Japan was struck by a major tsunami on 4 November 1677, caused by an earthquake at the southern end of the Japan Trench. It was felt onshore with only a maximum of 4 on the JMA intensity scale, but had an estimated magnitude of 8.3–8.6 Mw. The disparity between the maximum intensity and the magnitude estimated from the tsunami suggest that this was a tsunami earthquake. There no records of significant damage caused by the shaking, but the resulting tsunami caused widespread damage and an estimated 569 people were killed.
Why this event still matters
Historical incidents shape the rules that protect people today — building codes, evacuation policy, warning systems and inspection regimes almost always trace back to a specific disaster. Studying 1677 Bōsō earthquake alongside current events is how preparedness improves.
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