Sakurajima; An Explosive Meteorological Wonder

Japan has a volcano that is named Sakurajima, found in the Prefecture of Kagoshima. Sakurajima, when translated directly, means “Cherry Blossom Island” - though it is not an island anymore, nor does it have cherry blossoms. It does, however, have layers of hardened lava that have flowed out over the years. 

Sakurajima is one of the largest, most active, and destructive composite volcanoes in the world; erupting continuously, hundreds of times in a year, emitting large amounts of volcanic ash into the air. Legend has it that it was named after a local high-ranking dignitary called “Sakurajima Tadanobu”. Another legend says that was named after a goddess called Konohana Sakuyahime.

The Sakurajima Volcano in Japan: An Important Part of Japanese Geological History

Sakurajima is located within the Aira Caldera. The Aira Caldera, which is 17 x 23 km wide, was formed around 22,000 years ago when magma from underneath exploded out in Plinian form ejecting and blasting out into the air pumice, rocks, and ash. As a result, the magma collapsed the chamber underneath. More activity within the caldera later formed Sakurajima 13,000 years ago. The first recorded explosion of Sakurajima was 963 AD. 

This volcano is tectonic in origin, and most of its explosions are strombolian, meaning that they are mostly of sporadic bursts and stay mostly atop the summit. But it also has been recorded that it had Plinian eruptions in 1471-1476, 1779-1782 and in 1914. The volcano had not been active for quite a while until 1914. 

Several earthquakes were occurring frequently, warning the people that an eruption was imminent and most evacuated to safer grounds. On January 11, 1914, the volcano blew out lava with such force that it formed a strait that connected the island with the mainland, forming a peninsula. A very deadly earthquake soon followed two days later, on January 13, 1914, wherein 35 people perished. Since then, the island became connected with the Osumi Peninsula in the east.

The Sakurajima volcanic cone has 3 principal peaks. Kitadake (“north peak” is the tallest at a meter count of 1,117), Nakadake (“middle peak” at 1060 meters high) and Minamidake (“southern peak” at 1040 meters high) and which is the most active since 1955 with most of its eruptions coming from the Showa Crater.

The Volcano Eruption Timeline of the Sakurajima from the Early 2000’s

Activity in 2000-2005 had low to medium levels of activity, with 150-200 eruptions per year. One strong explosion occurred on the 7th of October 2000, producing eruption columns as tall as 5 km above the crater. Abundant ash fall was seen, damaging car windshields.

Activity for 2006-2010 saw moderate explosions at 1-5-day intervals. Explosions reaching plume heights of around 2 km occurred every 1-5 days. On the 4th of June 2006, the first eruption outside the summit crater happened in 58 years. The eruption continued and off until the next morning.

In 2009, an increase of activity was noted with plume heights of a maximum of 5 km altitude. On the 10th of March and 9th of April 2009, a vulcanoid explosion produced a pyroclastic flow that fell 1 km to the east, and bombs were thrown to as far as 1.3 km. 

2011-2013 had many significant eruptions, topping it with an eruption on the 18th of August. In 2013, it ejected a plume of ash 5000 meters up in the air that kept Kagoshima City in darkness. It was registered as the 500th eruption of the year. 2013 had a recorded amount of 1097 explosions. 

The next year, 2014, had 471 explosions. By the 5th of February 2016, there was an explosion, and then a long rest. On July 26, 2016, it blew up once more, fiercely spewing ash 5000 meters high. This year, 2017, there is still an ongoing activity of explosions several times a day, every day.

The Map: The Location of the Sakurajima in Japan

Sakurajima is off the coast of Kagoshima, right across Kagoshima aquarium. It looks like an independent, circular island with a small connection to the mainland. It has a volcano almost at its center. Around Mount, Sakurajima is other identified mountains, such as Mt. Ontake, and Hikinodaria among others. There are many roads in this mountainous region, so the map shows both the ridges of the mountain and these networks. 

You may download a map of Sakurajima from Google Maps, and it will show you just how and where the mountain is raised map using lines to show where they elevate. It is also the most comprehensive and constantly updated map you can rely on. 

How the Plate Boundary Works in Japan 

Kyushu, Japan, where Sakurajima is located at the southernmost part of, is surrounded by destructive plate boundaries. It has the Eurasian Plate (which is a Continental Plate) on one side, and the Philippine Plate (which is an Oceanic Plate) on the side. These two Plates rest on a “subduction zone”, meaning they push each other, or collide, forming a trench or convergent boundary. 

When an Oceanic and Continental Plate converge, the thinner Plate which is the Oceanic one goes under the Continental Plate which is thicker. The friction caused by this results in a rise of temperature and pressure, causing rocks to melt and form magma. Some of the magma cools and solidifies, forming mountains. Yet some break through the surface of the earth because of the build-up of trapped water and gas. This is how intense volcanic eruptions happen and destructive earthquakes suddenly arise. 

The magma builds up in magma chambers trying to exit out of a vent in its crust, resulting in a volcanic eruption. Aside from volcanic eruptions, powerful undersea earthquakes are also produced from sudden changes in the ocean floor. When the waves reach land, it can sometimes turn into a large and terrifyingly devastating tsunami.

The reason Japan has so many volcanoes and earthquakes is that its islands lie in between these plates that continuously shift. 

A Case Study on the Sakurajima

The Japanese archipelago has more than a hundred volcanoes and is located within the Pacific Ring of Fire. This Ring of Fire or Circum-Pacific Belt is an arc–like area in the Pacific where a large percentage of earthquakes happen, and where most of the world’s most active and dormant volcanoes are located. Sakurajima is just one of many active volcanoes in the Ring of Fire, and a potential danger to the Japanese population, Sakurajima was assigned a Decade Volcano in 1991, making it worthy of closer study as part of the United Nations' International Decade for Natural Disaster Reduction. 

Sakurajima has actively been erupting since 1950, and its ash and lava have since buried buildings and farmlands. When the volcano has a vicious eruption, acid rain kills all surrounding flora and fauna. Its billowing smoke polluting the air with Sulphur dioxide and carbon dioxide makes the locals breathe with difficulty. Everything around gets covered in ash. Earthquakes may come before and even after an eruption causing many deaths.

Sakurajima is just 8 km away from a population of 680,000 residents, in the east of the city of Kagoshima, in the northern part of Kagoshima Bay. At the bottom of the volcano reside approximately 7000 people. Their lives are very much in danger if the volcano erupts intensely. Kagoshima Bay is very important industrially as an active trading and fishing port, and it would cause a big economic disaster if it were to be covered in lava, killing the fish in it. 

All Under Control

Fortunately, with Japan being a wealthy country, can afford to spend money protecting its people. Since the volcano is very well observed, it will not likely to cause many deaths. Aircraft are sent to measure the amount of gas the volcano emits. They made sure to place tilt meters to measure very small changes from the vertical level, either on the ground or on the side of the volcano. Boreholes are placed to measure water temperatures as magma temperature builds up. The volcano has seismometers placed in tunnels to monitor earthquakes. 

Channels made of concrete are built on the side of the volcano to divert dangerous mudflows. Evacuation routes and drills are made known to all. Shelters are built against volcanic bombs. The hot springs are continuously monitored for any changes in temperature. Students and children are made to wear helmets, goggles, and masks to protect from breathing ash. All these things together help protect each person from the hazards an eruption may bring. 

Though volcanoes can be disastrous they also can be beneficial. Farmland around the volcano is very fertile because of its high mineral content and most of the land near Sakurajima is used to grow tea, rice, Daikon radish and even mandarins.

Latest News and Reports on Sakurajima in Japan Times 

The Japan Times has many reports on Sakurajima on their website. On January 12, 2016, the news was “Kagoshima Holds Annual Disaster Drill for Mount Sakurajima”, as residents around the area practiced drills on what to do if the volcano were to have a large eruption. Consequently, things got heated up with the Volcano, and Japan Times came out on February 5, 2016, with “Mount Sakurajima Erupts in Fiery Blast”.

A few months later, trouble at Sakurajima started again and made it on the world news on July 26, 2016. It reported, “Kagoshima’s Sakurajima’s Volcano Erupts, Spews Plume 5000 Meters Up”. By December 31, 2016, an article titled “Buried Alive in the Shadow of a Kyushu Volcano” came out as a travel feature. The latest one to date was published on August 25, 2017. Japan Times reported “Drinking to Health and History on Kagoshima” as a travel article about Kagoshima’s culture and a little bit of about its notorious volcano. 

A Guide to Visiting the Sakurajima

Kagoshima is so closely associated to Sakurajima that it uses it as its symbol. Tourists flock to and from the area to see it. Though it may look like an island (and it used to be one), an explosion connected it to the city of Tarumizu. Despite its possibility of erupting, many people still like around Sakurajima, and make a living off the location's tourism industry. If you plan to visit soon, it’s best for you to have an arsenal of information about the area to help you get around. 

How to Get There

There are 28 connected-flights from Tokyo to Kagoshima. From there, travelers visiting Sakurajima can take the ferry for a 15-minute sail from Kagoshima city. You can rent a private car and load it on the ferry or hop on a tour bus and tour around the lava coastal roads of Sakurajima. 

Sights to See Related to the Sakurajima

The Kurokami Buried Shrine Gate showing the effects of past explosions. It is a gate that  ¾ buried in what the volcano expelled in an explosion last 1914. You can literally see a fraction of the gate sticking out from the ground.

As for the crater of the Sakurajima itself, tourists are not allowed to approach it any closer than two kilometers away. The reason are there are many observatories around Sakurajima where eruptions can be observed from about three kilometers away. 

There are many observatories to choose from, such as the Arimura Lava Observatory, the Yunohira Observatory, the Karasujima Observatory and the Kurokami Observation Point. The Nagisa Park Foot Baths are great to rest your weary feet after trekking the mountain and enjoying the different views. The Magma Onsen with hot spring baths is a great way to rejuvenate as well, after a long day of touring the area.

Sakurajima is still at it, continuously billowing smoke, and is believed to have accumulated large magma reservoir. Though it is predicted by experts from both Bristol University and the local Volcano Research Centre that it is due for quite the large explosion soon, it serves as a beautiful meteorological reminder to its observers of how nothing stays the same except change – and that just like a volcano, change can be quite unpredictable.