Mount Asama, one of Japan's most active volcanoes, erupted in a violent event known as the Tenmei eruption, which began in August of 1783. This eruption was characterized by a series of explosive eruptions and the subsequent release of ash and volcanic debris. The immediate consequences were devastating, as pyroclastic flows and falls of ash blanketed the surrounding areas, resulting in the loss of approximately 1,400 lives. The eruption significantly altered the landscape and severely impacted local agriculture. The thick layers of ash buried crops and rendered farmland unproductive, which fostered dire conditions for the local population. As the months progressed, these hardships led to widespread famine in the region.

The prolonged effects of the eruption were catastrophic. The ensuing famine, caused by the destruction of crops and livestock, resulted in the deaths of an estimated additional 20,000 individuals. Communities in and around the Kanto region faced immense challenges as governmental authorities struggled to provide relief. Reports from Japan during this time indicate that social stability was significantly affected, leading to unrest and uprisings in certain areas. The eruption exposed the deep vulnerabilities in rural Japanese society to natural disasters, prompting discussions about disaster preparedness and response in future administrations.

Furthermore, the Tenmei eruption contributed to the shift in demographics and economic structures in Japan, as populations migrated in search of more stable agricultural conditions. It emphasized the critical need for improved agricultural practices and innovations to cope with volcanic activity. This event remains a crucial chapter in understanding the interactions between natural disasters and human societies in early modern Japan.