Hakusan

Geography & Climate

Hakusan is located in Japan, within the Nankai Volcanic Arc of the broader Western Pacific Volcanic Regions. Situated at 36.16° N, 136.77° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. At 2,702 meters above sea level, Hakusan rises above the surrounding terrain into montane or subalpine conditions. The elevation creates distinct ecological zones along its flanks, from forested lower slopes to exposed rocky terrain near the summit. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Hakusan sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Japan near Hakusan, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Hakusan has 20 recorded eruptions in the geological database, spanning from 3550 BCE to 1659 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 200 BCE, reaching VEI 4 on the Volcanic Explosivity Index. Notable eruptions include 1579 CE (VEI 3), 1554 CE (VEI 3), 1548 CE (VEI 3). With an average interval of roughly 260 years between eruptions over a span of 5,209 years, this is one of the more frequently active volcanoes in the database. This persistent activity suggests a robust and well-supplied magma system beneath the volcano.

Significance

With a maximum recorded VEI of 4, Hakusan has demonstrated the capacity for significant explosive eruptions that can impact regional aviation, agriculture, and communities tens of kilometers from the summit. VEI 4 eruptions produce ash columns reaching 15-25 kilometers into the atmosphere. Its 20 recorded eruptions make it one of the most prolific volcanoes in our database, reflecting a persistent and well-documented eruptive history that has provided volcanologists with extensive data for understanding eruption patterns and forecasting future activity.

GVP Reference Summary

Hakusan is a complex andesitic-dacitic stratovolcano near the western coast of central Honshu. It was constructed over a high basement of sedimentary rocks in a region of very heavy snowfall that has contributed to erosional dissection. Holocene eruptions have consisted of phreatic or phreatomagmatic explosions from several summit craters. Partial collapse of the summit produced a debris avalanche down the E flank during the mid-Holocene. Eruptions were recorded over almost a thousand-year period until the 17th century.

— Smithsonian Institution, Global Volcanism Program