Sakurajima

Sakurajima (Cherry Blossom Island) is an active stratovolcano located in Kagoshima Prefecture in Kyushu, Japan. It is one of the most active volcanoes in the world, with persistent activity that produces frequent, small-scale explosive eruptions—often several times a day.

The volcano is the symbol of Kagoshima City, a metropolis of over 600,000 people located just 8 kilometers (5 miles) across the bay. This proximity makes Sakurajima one of the most closely studied volcanoes on Earth, as the daily lives of the citizens are directly affected by its mood. It is common to see residents using umbrellas on sunny days to shield themselves from falling ash.

Geological Origins and Setting

Sakurajima is a post-caldera cone situated within the massive Aira Caldera. This caldera, which measures about 20 kilometers in diameter, was formed by a cataclysmic eruption approximately 22,000 years ago. The northern half of Kagoshima Bay (Kinko Bay) is actually the flooded floor of this ancient super-volcano.

Structure

The modern volcano began building up about 13,000 years ago on the southern rim of the Aira Caldera. It consists of three peaks:

• Kita-dake (North Peak): The highest point at 1,117 meters, currently dormant.
• Naka-dake (Middle Peak): 1,060 meters.
• Minami-dake (South Peak): 1,040 meters, the site of most historical and current activity.

Eruptive History

Sakurajima’s history is marked by a cycle of explosive vulcanian activity interspersed with major effusive eruptions.

The 1914 Taisho Eruption

Until 1914, Sakurajima was an island. On January 11 of that year, the volcano unleashed its most powerful eruption of the 20th century.

• Precursors: Massive earthquake swarms warned the residents, allowing most of the 20,000 islanders to evacuate in time.
• Lava Flows: Huge volumes of lava flowed for months, filling the narrow strait between the island and the Osumi Peninsula to the east.
• Land Connection: By the time the eruption ended, Sakurajima was no longer an island; it was a peninsula connected to the mainland.

Modern Activity (1955–Present)

Since 1955, the volcano has been in a state of near-constant activity. The Minami-dake crater and, more recently, the Showa Crater (on the eastern slope) are the main vents.

• Vulcanian Explosions: These distinct, cannon-like blasts eject ash plumes 1,000 to 3,000 meters into the air and throw volcanic bombs onto the upper slopes.
• Ashfall: Kagoshima City regularly receives coatings of grey ash. The city has developed specialized street sweepers and ash disposal bags to cope with the fallout.

Historical Eruptions: The Giants of the Past

Before 1914, Sakurajima had other massive outbursts.

• The Bunmei Eruption (1471-1476): A multi-year event that created the broad northern flank of the volcano (Kita-dake). Legends say the ash blocked the sun for weeks.
• The An-ei Eruption (1779): A catastrophic series of underwater and subaerial eruptions. It raised several small islands shin-jima (new islands) off the northeastern coast and caused tsunamis in the bay.

Living with the Volcano: The “Kagoshima Lifestyle”

Residents of Kagoshima have a unique relationship with their smoky neighbor.

• Ash Forecasts: The local weather report includes a “Wind Direction and Ashfall Forecast.” This determines whether you can hang your laundry outside or wash your car.
• Yellow Bags: You will see piles of yellow bags at designated collection points. These are for “Katsu-bai” (volcanic ash). Residents sweep the ash from their driveways into these bags for special municipal collection.
• School Hard Hats: Walking to school in Sakurajima, children wear bright yellow helmets not for construction, but for protection against sudden ballistic ejecta.

The Lava Coast: Yogan Nagisa Park

On the western coast, near the ferry terminal, lies a surreal park.

• Lava Sculptures: The 1914 lava flows created a jagged coastline of black basalt. The park features walking trails that wind through this “frozen fire.”
• Dinosaur Connection: Because the landscape looks so prehistoric, there are several dinosaur statues in the park, making it a favorite for families.
• The 100-Meter Footbath: As mentioned, this footbath is fed by brown, rusty-looking water. It is rich in iron and salt, said to be excellent for circulation. Sitting here at sunset, watching the ferry cross the darkened bay while the volcano glows red, is the quintessential Kagoshima experience.

The Legendary Ferry Udon

The Sakurajima Ferry is famous for its onboard noodle shop.

• The Challenge: The ride takes only 15 minutes.
• The Mission: Locals and tourists alike race to the udon counter to order and eat a bowl of piping hot tempura udon before the boat docks. It’s a “fast food” experience in the literal sense and a beloved local tradition.

The Legend of the Buried Torii

One of the most haunting sights on the island is the Kurokami Buried Shrine Gate.

• The Event: During the massive 1914 eruption, the village of Kurokami was buried under 2 meters of ash and pumice in a single day.
• The Memorial: The top beam of the village shrine’s Torii gate was left sticking out of the ground. The villagers chose not to dig it out, leaving it as a permanent memorial to the power of the volcano. It is a stark reminder of how quickly the landscape can change.

Arimura Lava Observatory: A Walk on the Moon

Located on the southern side of the volcano.

• The Terrain: This area is covered in jagged, blocky ‘a’a lava flows from 1914 and 1946.
• The Vegetation: It is a perfect place to study primary succession. You can see resilient Japanese black pines (Pinus thunbergii) gripping the bare rock, slowly turning the lava field back into a forest.
• Soundscape: Often, you can hear the deep rumblings and explosions from the Minami-dake crater while standing here, even if the peak is obscured by clouds.

The Kyoto University Volcano Research Center

Sakurajima is a living laboratory.

• The Observatory: The white, fortress-like building of the Kyoto University observatory monitors every tremor, tilt, and gas puff.
• Discoveries: Research here has pioneered methods in predicting eruptions using ground deformation. They can often predict an explosion hours in advance by measuring the swelling of the mountain as magma rises.

Volcanic Pottery

The ash isn’t just a nuisance; it’s art.

• Sakurajima Yaki: Local potters mix volcanic ash into their clay and glazes.
• The Colors: When fired, the iron-rich ash creates unique, metallic black and rust-colored glazes that shimmer like fresh lava. It is the ultimate souvenir: a piece of the volcano you can drink tea from.

Agriculture: Radishes and Oranges

Despite the constant ashfall, the soil at the foot of Sakurajima is incredibly fertile. The island is famous for two unique agricultural products:

Sakurajima Daikon

This is the world’s heaviest radish. These massive white radishes can grow to the size of a basketball and weigh over 30 kilograms (66 lbs). The loose, sandy volcanic soil allows the roots to expand without resistance.

Komikan Oranges

The Sakurajima Komikan is the world’s smallest mandarin orange. These tiny, sweet fruits grow in sheltered orchards across the island. The ash-rich soil is said to contribute to their intense sweetness.

Tourism and Visiting

Sakurajima is easily accessible and offers a unique opportunity to view an active volcano safely.

The Ferry

The Sakurajima Ferry runs 24 hours a day between Kagoshima Port and the volcano, taking just 15 minutes. It is a lifeline for residents and a popular attraction for tourists, offering stunning views of the smoking peak.

Observatories

While the summit itself is strictly off-limits (2km exclusion zone), several observation points offer safe viewing:

• Yunohira Observatory: Located at 373 meters elevation on the western slope, this is the highest point accessible to the public. It offers a close-up view of the rugged mountain face and the city across the bay.
• Arimura Lava Observatory: Located on the southern side, this boardwalk trail winds through the jagged, black lava fields from the 1914 and 1946 eruptions.

Footbaths

The Nagisa Park Footbath near the ferry terminal allows visitors to soak their feet in natural, volcanically heated water while gazing at the volcano. It is one of the longest footbaths in Japan (100 meters).

Monitoring and Safety

Sakurajima is one of the most heavily instrumented volcanoes in the world. The Japan Meteorological Agency (JMA) and Kyoto University’s Sakurajima Volcano Observatory monitor it around the clock.

Shelters

The island is dotted with reinforced concrete shelters. These are designed to protect residents and tourists from falling volcanic bombs (large rocks) in the event of a sudden, powerful explosion. Children on the island wear hard hats (“met”) when walking to and from school.

Disaster Prevention

Kagoshima City conducts annual large-scale evacuation drills. The entire population is well-versed in volcanic safety procedures, making it a model for “living with a volcano.”

Technical Facts

• Elevation: 1,117 m (3,665 ft)
• Location: 31.59°N 130.65°E
• Volcano Type: Stratovolcano (Post-caldera cone)
• Rock Type: Andesite / Dacite
• Status: Highly Active (Alert Level 3: Do not approach volcano)
• Key Feature: Connected to the mainland by 1914 lava flows