The 1707 Hōei Earthquake: An In-Depth Look

On October 28, 1707, Japan experienced one of the most devastating natural disasters in its history—the Hōei earthquake. Striking off the southwestern coast near Tosa Province (present-day Kōchi Prefecture), it is estimated to have had a magnitude of 8.6. This powerful seismic event was part of Japan’s tumultuous geophysical environment and had far-reaching consequences.

Key Events Leading Up to the Earthquake

Japan is located at the convergence of several tectonic plates, making it prone to seismic activity. The Hōei earthquake occurred along the Nankai Trough, an active seismic zone known for generating large megathrust earthquakes. Prior to 1707, the region had experienced several significant quakes, with local populations accustomed to the risk, albeit with limited preparation due to the era’s technological constraints.

The Earthquake Itself

Timing and Location

• Date: October 28, 1707
• Magnitude: Estimated to be 8.6
• Epicenter: Off the southwestern coast of Japan, near present-day Kōchi Prefecture
• Depth: Approximately 25 kilometers

Immediate Impact

The earthquake’s primary effects were felt across the southern part of Honshu and Shikoku islands. Accounts from the time describe severe shaking that lasted for several minutes, causing widespread structural damage to towns and cities, including considerable devastation in Osaka and Kyoto.

The Tsunami

In addition to the immediate shaking, the earthquake generated a massive tsunami that further compounded the disaster’s effects. Waves reportedly reached up to 25 meters high in some coastal areas, obliterating ports and coastal settlements. Thousands of people were killed as the tsunami swept away homes, flattened infrastructure, and disrupted agricultural production, leading to widespread starvation.

Aftermath and Consequences

The aftermath of the Hōei earthquake and tsunami was dire:

• Human Casualties: While precise numbers are difficult to ascertain, estimates suggest tens of thousands of lives were lost due to the earthquake and subsequent tsunami.
• Economic Impact: The destruction of agricultural land and infrastructure led to severe economic hardship. The period following the disaster was marked by economic decline as communities struggled to recover.
• Cultural and Social Changes: The disaster prompted improvements in construction techniques and inspired cultural artworks such as ukiyo-e prints that depict the chaos and resilience seen during the disaster period.
• Volcanic Activity: Notably, the shaking is believed to have triggered the eruption of Mount Fuji just 49 days later, on December 16, 1707.

Broader Historical Significance

The Hōei earthquake stands as one of the most powerful and consequential earthquakes in Japan’s recorded history. It highlights the challenges faced by a nation in a seismically active region and underscores the vulnerability of coastal populations to natural disasters. The events of 1707 contributed to advancements in understanding seismic activity and disaster preparedness, influencing future generations in Japan and beyond. The legacy of the Hōei earthquake is a testament to human resilience and adaptation in the face of natural calamities.