Ancient Japan's Volcanic Apocalypse Caused Varied Human Responses, Study Finds

An international research team led by Lund University has found that the Kikai-Akahoya volcanic eruption, which struck Japan approximately 7,300 years ago, resulted in varied and complex demographic changes across prehistoric communities[1][3]. This challenges earlier ideas that the disaster either completely wiped out nearby populations or left them largely unaffected[3][12].

The study offers new insight into human resilience and adaptation in the face of catastrophic natural disasters, showing that ancient societies employed diverse strategies to cope with sudden environmental shocks[2][9].

What the records show

The new study, titled "Divergent Demographic Responses to the Kikai-Akahoya Volcanic Catastrophe in Mid-Holocene Japan," was published in Science Advances[3][8]. The international team, which included researchers from Lund University and Cambridge University, analyzed changes in prehistoric population patterns before and after the eruption[5][11]. They used newly developed statistical models and radiocarbon dates to examine demographic patterns across 61 hexagonal study areas in Japan[10][11].

The research uncovered a "surprising mix of population decline, migration, adaptation, and growth" across the Japanese archipelago[1]. While areas in southern Kyushu, near the eruption's epicenter, experienced major depopulation and lasting cultural disruption, some communities in close proximity to the volcano actually increased their populations after the catastrophe[7][14]. In contrast, more distant regions of Japan that had shown population growth before the eruption experienced stagnation or even decline afterward, a far-reaching effect not previously recognized[1][4]. This suggests that earlier views of either total collapse or complete continuity were too simplistic[3][12].

The Kikai-Akahoya eruption

The Kikai-Akahoya eruption was one of the largest volcanic events of the Holocene epoch, registering a seven on the Volcanic Explosivity Index[2][9]. The largely submarine volcano, located south of Kyushu, exploded with little warning, unleashing powerful earthquakes and enormous tsunamis across the Japanese islands[3][11]. It then blanketed the landscape with meters of volcanic ash, which devastated coastlines, rivers, and forests for decades, or even centuries in the hardest-hit areas[3][11]. At the time, Jomon hunter-gatherer communities lived across Japan, relying on hunting, fishing, and gathering for survival[3][5][10].

What changed and for whom

The disaster caused significant loss of life, particularly in areas closest to the eruption[2][9]. However, the study found that survivors were resourceful[12]. People migrated, established new social relationships, developed innovative economies, and found creative ways to exist and eventually thrive in the altered post-disaster environment[2][9][12]. For instance, survivors from southern Kyushu moved to the north of the island, where their culture continued to expand[7]. This adaptability meant that despite widespread destruction, the human response was not uniformly negative, showcasing a complex picture of resilience[6][13].

What we could not confirm

The precise reasons for population stagnation or decline in distant parts of Japan were not definitively established by the study's findings[1][4]. While the research suggested possible explanations such as temporary climate disruptions or severe tooth wear in key food sources like deer and wild boar, the extent of these factors was not detailed[1][4].