Presentation Information
[O04-01]The case study of pyroclastic flow deposits for agriculture in Tokachidake Geopark area★Invited Papers
*Chiharu TOMIJIMA1 (1.Tokachidake Geopark Promotion Committee)
Keywords:
Geopark,Pyroclastic flow deposits,Agriculture
The Tokachidake Geopark, located in central Hokkaido and comprising the towns of Biei and Kamifurano, is characterized by large, undulating “rolling hills” that extend across both towns. These hills are interpreted as pyroclastic flow deposits (e.g., the Tokachi and Biei pyroclastic flows) formed by caldera eruptions that occurred approximately 2 Ma to 0.8 Ma (Ikeda and Mukoyama, 1983; Nishiki et al., 2017). Most of these deposits are now used for agriculture and serve as the agricultural foundation that supports local residents.
To prevent continuous cropping damage, farmers in this region practice crop rotation, cultivating different crops on the same land in a planned sequence over several years. Because various crops color each divided field across the hills, the landscape is known as the “Patchwork Hills,” which attracts visitors from Japan and abroad.
Although about two million years have passed and periglacial processes have softened the terrain, the slopes of the rolling hills remain extremely steep, posing significant challenges for farmers. For example, the straight road in Kamifurano, known as the “Roller Coaster Road,” extends for approximately 4 km, with pronounced undulations and a maximum elevation difference of more than 60 meters. This vividly illustrates the steep gradients of the surrounding farmland.
In this vast, steep terrain formed by ancient volcanic activities, settlement began about 140 years ago. Pioneer groups from Hyogo Prefecture settled in Biei, while those from Mie Prefecture settled in Kamifurano, breaking the first ground for cultivation. About 40 years after settlement, on May 24, 1926, the region was struck by a tragic volcanic disaster. Tokachidake, an active volcano that constantly emits fumarolic gases, erupted. The resulting volcanic mudflow claimed 144 lives (including missing persons) and affected farmland. Sulfur, a highly toxic substance, was mixed into the soil that had been painstakingly cultivated over many years.
Although residents of Kamifurano, which suffered particularly severe damage, had the option to relocate, they chose to remain. In addition to their initial land reclamation efforts, they undertook soil replacement and other measures to restore the land for agricultural production. Through renewed hard work, they revived the farmland and continued to coexist with the active volcano. In recent years, to improve efficiency across the vast fields, farmers have introduced automated tractors and other advanced agricultural machinery, and have shipped branded agricultural products from towns throughout Japan.
To prevent continuous cropping damage, farmers in this region practice crop rotation, cultivating different crops on the same land in a planned sequence over several years. Because various crops color each divided field across the hills, the landscape is known as the “Patchwork Hills,” which attracts visitors from Japan and abroad.
Although about two million years have passed and periglacial processes have softened the terrain, the slopes of the rolling hills remain extremely steep, posing significant challenges for farmers. For example, the straight road in Kamifurano, known as the “Roller Coaster Road,” extends for approximately 4 km, with pronounced undulations and a maximum elevation difference of more than 60 meters. This vividly illustrates the steep gradients of the surrounding farmland.
In this vast, steep terrain formed by ancient volcanic activities, settlement began about 140 years ago. Pioneer groups from Hyogo Prefecture settled in Biei, while those from Mie Prefecture settled in Kamifurano, breaking the first ground for cultivation. About 40 years after settlement, on May 24, 1926, the region was struck by a tragic volcanic disaster. Tokachidake, an active volcano that constantly emits fumarolic gases, erupted. The resulting volcanic mudflow claimed 144 lives (including missing persons) and affected farmland. Sulfur, a highly toxic substance, was mixed into the soil that had been painstakingly cultivated over many years.
Although residents of Kamifurano, which suffered particularly severe damage, had the option to relocate, they chose to remain. In addition to their initial land reclamation efforts, they undertook soil replacement and other measures to restore the land for agricultural production. Through renewed hard work, they revived the farmland and continued to coexist with the active volcano. In recent years, to improve efficiency across the vast fields, farmers have introduced automated tractors and other advanced agricultural machinery, and have shipped branded agricultural products from towns throughout Japan.