Mount Kurikoma's 1,627 meters are deceptive. The volcano's composition is mostly andesitic to dacitic rock that formed atop elevated Tertiary-era tuffs and sedimentary layers, meaning the mountain's actual volcanic volume is far smaller than its height suggests. The earliest lava eruptions flowed north and south roughly 500,000 years ago, followed by the construction of Higashi-Kurikoma. The volcanic cone called Magusadake was last active about 100,000 years ago. At the summit, a caldera breached to the north contains the Tsurugi-dake cone. A major active reverse fault runs east to southeast of the summit, a reminder that the geologic forces building this mountain remain very much alive. The volcano's base is a jumble of pyroclastic deposits, welded tuffs, and crumbly secondary volcaniclastic sediments -- materials that, under the right conditions, can move catastrophically.

Showa Lake sits near Kurikoma's summit, a small crater lake formed during the volcano's last confirmed eruption in November 1944. That eruption was modest -- a VEI-1 event, a burst of steam and volcanic ejecta -- but it poisoned the Iwaki River downstream, turning the water a sickly color and killing fish along its length. Today, Showa Lake is a milky, highly acidic pool where volcanic gases still seep from below. Dead trees protrude from the water's surface, killed by the toxic fumes. Climbing is restricted near the lake because of the volume of gas still spewing from the ground. Before the 1944 eruption, at least two phreatic eruptions occurred between 5,400 and 915 years ago, and the earliest recorded eruption dates to 915 AD. The volcano's eruptive history is sparse but its geothermal signature is persistent.

At 8:43 AM on June 14, 2008, a magnitude 7.2 earthquake struck roughly ten kilometers northeast of Mount Kurikoma. The Iwate-Miyagi Nairiku earthquake was an inland event, centered directly beneath the volcanic terrain, and its effects on Kurikoma's flanks were devastating. Scientists detected 4,161 individual landslides triggered by the shaking, most concentrated on the hanging wall side of the seismic fault. One debris flow near the summit mobilized 1.5 million cubic meters of material and traveled ten kilometers downslope. The largest single failure -- the Aratozawa landslide -- measured 1,300 meters long, 900 meters wide, and over 100 meters thick, displacing an estimated 67 million cubic meters of earth. Landslide dams blocked rivers throughout the region, creating temporary lakes. The longest dam, at Yubama, stretched about one kilometer. The crumbly volcaniclastic deposits that formed Kurikoma's base had become its greatest vulnerability.

Despite its violent geology, Mount Kurikoma is the centerpiece of Kurikoma Quasi-National Park and draws thousands of visitors each year. The mountain's fame rests largely on its autumn foliage. The color change begins near the summit in mid-September and descends to the mountain's base by mid-October, creating a gradient of reds, oranges, yellows, and greens so striking that the phenomenon earned the name 'Kami no Juutan' -- the Carpet of the Gods. Hot springs dot the mountain's lower slopes, fed by the same geothermal system that powers the summit fumaroles. Hiking trails wind through beech forests and alpine meadows, passing wildflowers in summer and snow in winter. The geopark designation at the mountain's base, established partly in response to the 2008 earthquake, now teaches visitors about the landscape's dual nature: the same volcanic forces that create the hot springs and fertile slopes also produced the landslides that scarred the mountain's flanks.