SAKURAJIMA VOLCANO: ERUPTIONS, ACTIVITY, VISITING

SAKURAJIMA

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1991 eruption at Sakurajima Sakurajima (across Kagoshima Bay and Kinko-wan Bay from Kagoshima) is regarded as one of the world’s most active volcanoes. It belches out dangerous gases and produces ash showers on a regular basis that cover Kagoshima in a snowfall-like blanket of gray. Sakurajima has been producing steam and ash almost continuously since 1955.

Sakurajima consist of three peaks: 1,117-meter-high Kita-dake, 1,060-meter-high Naka-dake, and 1,040-meter-high Minami-dake. Minami-dake contains the crater where most of the volcano’s activity takes place. On the slopes of the volcano are deep layers of lava and ash. In some places there is incredibly fertile soil that produces white radishes that weigh 24 kilograms (80 pounds).

Sakurajima, which means “cherry blossom island”, is the name of the island and volcano. It faces Kagoshima, a city of over 600,000, across Kagoshima Bay. When the volcano erupts, people say the ash feels like a slight tingling on your skin or being bombarded by tiny insects. If you stay outside long enough your lower arms become covered in grey powder with consistency of finely ground pepper. Often the powdery precipitation stops after a few minutes, but if it doesn’t and the rain comes, it’s can be like printing ink dripping from the sky. [Source: JNTO]

Mt. Sakurajima lies to the south of the Aira caldera. On the southern side of the volcano lies the Ata caldera. The topography of Mt. Sakurajima continues to change tremendously due to the volcano's many eruptions, such as the large-scale eruption 100 years ago (in 1914) in which larva created a land bridge between the island and the Osumi Peninsula. The volcano is about 50 kilometers (31 miles) from a nuclear reactor that was switched on in August 2015 after it had been turned off because of the Fukushima crisis that followed the earthquake and tsunami in 2011.

Visiting Sakurajima

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It is not possible to hike to the top of Sakurajima but is it possible to bicycle around it on a road that follows the coast around the entire peninsula. Stops along the way, include small towns, rock beaches, lavas flows, and hot springs.

At Shioyagamoto port the sea is a bright turquoise color because of the effect of microbes feeding on nutrients released by the hot springs. Bicycles can be rented at a shop near the ferry terminal. The bicycles are not in very good shape so be prepared for that.

One stretch of the road traverses a A monstrous lava flow produced by the 1914 eruption that buried Torishima Island. The Kurokami Buried Torii is a remnant from before 1914. At Arimura Lava Formation Observatory you can wander around on wooden walkways that winds through lava flows. The Yunochira Observatory is at the top of a steep road, about a third of the way up the western slope of the volcano. Although it not possible to climb around the top of Sakurajima you can hike on the lower slopes on hiking trails that lead to lookouts with good views such as Yunoshira Observatory.

Sakurajima Visitor Center has displays in geology, volcanic eruption and natural history and offers easy-to-understand displays, overviews, and a variety of information about the nature of Sakurajima Volcano and its history of eruptions. It features an eruption experience section, a video section, and more, letting visitors experience the still-active Sakurajima Volcano through computers and hi-vision imagery. Location: Sakurajima Yokoyama Town 1722-29, Kagoshima City, Kagoshima Prefecture, Tel: 099-293-2443 Hours Open: 9:00am- 17:00, Closed Open daily throughout the year; Website: sakurajima.gr.jp

Websites: Kagoshima Tourism site kagoshima-kankou.com Wikipedia Wikipedia ; Sakurajima: National catalogue of the active volcanoes in Japan - Japan Meteorological Agency PDF data.jma.go.jp/svd Sakurajima Volcano Research Center svo.dpri.kyoto-u.ac.jp Getting There: Kagoshima is accessible by ferries from Kagoshima that run several times an hour. Lonely Planet Lonely Planet

Sakurajima Activity

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eruption in 2000 A record high 996 eruptions was recorded at Sakurajima in 2011, the highest number since record keeping began in 1955, the local meteorological observatory said.. Sakurajima recorded 548 eruptions in 2009 and a record 896 in 2010. In January 2010 there were more than 100 eruptions with some of them sending lava flowing down its sides, shooting ash skyward, and producing purple lightning bolts. Most of the eruptions have been in the 800-meter-high Showa vent not the larger 1,000-meter-high Minamidake vent.

Kyodo reported: “At the 800-meter Showa crater, which erupted in June 2006 for the first time in 58 years, 994 eruptions were observed in 2011. Two eruptions were observed at the Minamidake vent, at about 1,000 meters elevation, the Kagoshima Meteorological Observatory said. The observatory warned the volcano in the middle of Kagoshima Prefecture is becoming increasingly active. But eruptions at the Showa crater are relatively small and no signs of imminent large eruptions have been observed, it added. Sakurajima erupted 548 times in 2009 and 896 times in 2010, breaking the previous record of 474 times in 1985 for three consecutive years through 2011. The Japan Meteorological Agency defines an explosive eruption as one accompanied by an explosive release of gas, ash or rock. [Source: Kyodo, January 3, 2012]

Ichiro Ohara wrote in the Yomiuri Shimbun, “After I set up my camera about four kilometers from one of Sakurajima’s craters, a huge pillar of fire suddenly erupted in the dark night sending lava spewing down the mountain and turning the surface a glowing red. This kind of explosive eruption was observed 450 times last year on Sakurajima island in Kagoshima. As of Feb. 15 this year, eruptions already have been observed 127 times. Toshihide Fukamichi, 73, former head of the town association of the Mochiki district in Kagoshima, is worried that residents are becoming less cautious, saying, “Eruptions have become a normal occurrence, so people tend to shrug them off as there is no element of surprise.”[Source: Ichiro Ohara, Yomiuri Shimbun, February 27, 2015]

“According to the Kagoshima-based Sakurajima Volcano Research Center of Kyoto University’s Disaster Prevention Research Institute, the mountain has been swelling due to an increase in magma and other reasons. Below ground on the island’s northern side, the center confirmed the existence of a large magma reservoir, equivalent to the amount of magma that caused the 1914 Taisho eruption in which 58 people died or went missing.

Sakurajima Eruption Preparedness

In the Kagoshima area there are daily eruption reports along with the weather on television so residentscan gage the impact of wind direction and other factors on ash falls. Fruit hanging from the trees is wrapped in white paper to protect it, graves in cemeteries have their own roofs, and people carry umbrellas despite the sunshine, all in case it suddenly starts raining ash. People who live in the most dangerous areas keep an emergency pack at the entrance of their houses, with food and extra clothes for a week, in case they have to evacuate with little warning.

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Sakurajima In August 2015, Japan’s weather agency told thousands of residents near Kagoshima to prepare for a possible evacuation after officials raised their alert to its second-highest level after picking up increasing seismic activity around the volcano Sakurajima “The possibility for a large-scale eruption has become extremely high for Sakurajima,” the agency said, warning residents to exercise “strict caution” and prepare for a possible evacuation. The warning applies to a part of the island, which is home to more than 4,000 people. [Source: Agence France-Presse, August 15, 2015]

Many of the residents in the most dangerous areas near the volcano are elderly. Ichiro Ohara wrote in the Yomiuri Shimbun, “ Fukamichi has created a map showing at a glance the locations of houses of people who have difficulty moving around by themselves and people aged 65 or older who live alone. If the worst happens, these people are supposed to be taken to an evacuation center by vehicles owned by a construction company in the neighborhood. [Source: Ichiro Ohara, Yomiuri Shimbun, February 27, 2015]

“Shimo Iwashita, 84, who lives alone in the Sakurajima Saido district in the northern area of the island, has prepared a helmet and an emergency bag packed with such items as extra clothes, flashlight and emergency food at the entrance of her house. Preparing an emergency pack is her custom after she moved to Sakurajima, her husband’s hometown, 32 years ago. She checks the bag’s contents at least once a month. “I think Sakurajima is a good place with rich nature, but I feel scared even now,” said Iwashita, looking up as smoke rose from the volcano. “Masato Iguchi, 56, head of the center, warns people, saying, “It’s important not to forget to make appropriate preparations on the assumption that a large-scale eruption could occur at any time.”

Major Sakurajima Eruptions

There were major eruptions at Sakurajima in 1914, 1915, 1946, 1955 and 1960. Often the eruption are hard to predict. Alerts for a an eruption in August 2008 were not issued until eruptions and pyroclastic flows were observed.

The first record of a Sakurajima eruption was in A.D. 708. The Sakurajima eruption in 1914 was the largest ever in Japan in historical times. That one came as no surprise. The ground around the volcano rumbled for days. In Kagoshima 417 earthquakes were recorded in the 30 hours before the mountain exploded. The eruptions produced 3 billion tons of lava, with lava covering many villages and transforming Sakurajima from an island into a peninsula by filling in a 400-meter-wide, 70-meter-deep strait.

In 1987 Sakurajima spewed out molten rock and gases more than 100 times. "It's like a soda bottle with its cap off instead of on," a geologist told Discover magazine. "A small amount of lava is released pretty constantly, rather than a large amount all at once, as at Mt. St Helens." Sakurajima erupts so often that hard hats are mandatory for Japanese students visiting the foot of volcano. Annual volcano drills prepare residents for a disaster.

On October 7, 2000, Sakurajma erupted from the Minami-dake peak, sending ash more than five kilometers into the sky. The same volcano had 178 small eruptions in March 2015 alone, most from the Shoawa crater, and produced one in May 2015 that created a plume 4.3-kilometers high. [Source: Kyodo, Japan Times, May 29, 2015]

Since the 1914 eruption of Sakurajima there been no eruptiosn affecting a large area.

Taisho Eruption of Sakurajima

The 1914 Taisho eruption of Sakurijima volcano was Japan’s highest intensity and magnitude eruption of the twentieth century. According to the abstract of a paper on the subject. “After a 35-year period of quiescence, the volcano suddenly rewoke a few days before the eruption, when earthquakes began to be felt on Sakurajima Island. The eruption began on January 12, 1914, from two fissures located on opposite sides of the volcano, and was characterized by a complex time evolution and changes in eruptive styles. The eruption began with a subPlinian explosive phase in which two convective columns rose from the two fissures. Both plumes were sustained for at least 2 days. This resulted in deposition of a widely dispersed tephra sequence. After this phase, the eruption evolved to a final, waning phase, shifting toward effusive activity that lasted until April 1914. During the first weeks, effusive activity was also accompanied by ash emission. [Source: “The 1914 Taisho eruption of Sakurajima volcano: stratigraphy and dynamics of the largest explosive event in Japan during the twentieth century”, A. Todde, R. Cioni, M. Pistolesi, N. Geshi & C. Bonadonna , Bulletin of Volcanology volume 79, Article number: 72, September 26, 2017]

“The complex sequence of events, characterized by contemporaneous explosive and effusive activity, is typical of several recently observed mid-intensity eruptions, such as during the 2011 eruption of Cordón Caulle, Chile. The stratigraphic sequence of the eruptive deposits from the Taisho eruption comprises alternating coarse-to-fine lapilli beds with ash beds dispersed toward the ESE and SE. These deposits can be subdivided into three lapilli-bearing units (Units T1, T2 and T3, which correspond to the subPlinian phase) and one ash-bearing unit (Unit T4, which corresponds to the final ash venting, accompanying the first day/weeks of lava flow activity). Grain size analyses from each unit reveal a marked polymodal distribution generally described by the sum of two or three Gaussian subpopulations. Both the modes and the relative amounts of the coarse subpopulations vary with distance from vent, with those of the fine subpopulation remaining nearly constant.

“Within the vertical sequence, component analysis shows a progressive increase in lithic fragments, suggesting that conduit enlargement continued until the final stages of the eruption. The estimated volume of the tephra deposit of the subPlinian phase of the eruption is 0.33 ± 0.11 km3 (dense rock equivalent (DRE) volume = 0.09 ± 0.03 km3). The height of the eruption column was also assessed by using four different isopleth maps compiled based on different strategies for the characterization of the largest clasts. The maximum height attained by the eruption column is estimated at 15.0 ± 1.2 km above the vent, resulting in a maximum mass discharge rate of 3.6 ± 1.2 × 107 kg s−1 (calculated taking into account the strong effect of wind advection). Finally, different classification schemes were applied to classify the eruption, which generally straddles the fields between Plinian and subPlinian.”

Sakurajima Eruption in August 2013

The last major explosive eruption of Sakurajima was in August 2013 when seent a plume of gas, smoke and ash five kilometers into the sky, it spewed ash as far as Kagoshima and sent rocks flying into populated areas, causing damage but no major injuries. The same mountain had 178 small eruptions in March 2015 alone and produced one in May 2015 that created a plume 4.3-kilometers high. [Source: Kyodo, Japan Times, May 29, 2015]

The Japan News reported: “Kagoshima residents were busy cleaning up volcanic ash on Monday, a day after Mt. Sakurajima spewed ash as high as 5,000 meters to blanket the city of 600,000 people. According to the Kagoshima Local Meteorological Observatory, the explosive eruption from the Showa vent occurred at 4:31 p.m. Ash reached a height of 5,000 meters, the highest recorded from the Showa vent since the observatory started monitoring the active volcano in 1955. [Source: Japan News/Asia News Network, August 20, 2013]

“Volcanic rocks measuring 50 centimeters in diameter were observed at the Third Station of the mountain, or 1,300 to 1,800 meters from the Showa vent, the observatory said. It also confirmed a small pyroclastic flow about one kilometer long. The observatory predicts no further major eruptions from the volcano for the time being. The city of Kagoshima, meanwhile, mobilized about 60 ash-cleaning and water-spraying vehicles from early Monday morning. The observatory reported about 120 grams of volcanic ash falling per square meter of ground from January to July this year. On Sunday alone, however, it recorded 13 grams of ash. Ash fell over a wide area in this eruption," said a Kagoshima city official. "We'll attempt to clean it up in three days."

Image Sources: Wikimedia Commons, Volcano Research Center University of Tokyo, United States Geological Survey (USGS)

Text Sources: Volcano Research Center University of Tokyo, United States Geological Survey (USGS), Japan Meteorological Agency New York Times, Washington Post, Los Angeles Times, Yomiuri Shimbun, Japan News, Japan Times, Japan National Tourist Organization (JNTO), National Geographic, The New Yorker, Smithsonian magazine, Encyclopedia.com, Live Science, The Conversation, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Google AI, Wikipedia, The Guardian and various websites, books and other publications.

Last updated August 2026