The Dangers of Living By Sakurajima
Sakurajima is one of the world’s most active volcanoes. Some years it erupts over 1,000 times and this bad-tempered beast is just eight kilometers from the 600,000 residents of Kagoshima. Mostly, it remains just a daily nuisance than a serious problem. But a few months ago, Sakurajima showered this city with 100,000 tons of ash, turning day into night and sending people scrambling for cover. Its 500th eruption of the year sent plumes more than five kilometers into the sky and reminded everyone here just how vulnerable they are to the volcano. Volcanologist Masato Iguchi has been studying Sakurajima for more than 30 years, and while he’s not worried just yet about another big eruption, he does warn that pressure underneath the volcano is rising.
Although no lava flows have occurred since 1946, activity from the Sakurajima volcano continues to affect the surrounding area. For example, ash emitted from eruptive activities has caused crop damaged and traffic disruption, and wet volcanic ash caused the island's electrical grid to short circuit in 1980. During the 1970s and 1980s, sporadic volcanic explosions caused shock waves that broke windows and car windshields, and the volcanic activity regularly affects air traffic arriving and departing from the nearby Kagoshima Airport.
Although no lava flows have occurred since 1946, activity from the Sakurajima volcano continues to affect the surrounding area. For example, ash emitted from eruptive activities has caused crop damaged and traffic disruption, and wet volcanic ash caused the island's electrical grid to short circuit in 1980. During the 1970s and 1980s, sporadic volcanic explosions caused shock waves that broke windows and car windshields, and the volcanic activity regularly affects air traffic arriving and departing from the nearby Kagoshima Airport.
Safety Precautions
The city conducts regular evacuation drills to ensure the safety of the populous. This drill is conducted every year on the 12th of January, which is the memorial day for the devastating eruption of 1914. They use ferryboats, helicopters, and aircrafts to make sure everyone could get out of the city safely if there was ever and unexpected explosion. Kagoshima also built refuge shelters where people could hide in safely if ever an extreme eruption were to suddenly occur. As a safety precaution, local children wear helmets when they’re out doors to protect themselves against rocks and debris. Students wear masks and goggles when outside to prevent ash getting into their mouths and eyes.
Observatory
The Sakurajima Volcano Observatory was set up in 1960 to monitor Sakurajima's eruptions.The observatory has a view of the summit midway up the mountain where you can feel the power of the active volcano spewing smoke up close. The observatory monitors:
- Likely activity is signalled by swelling of the land around the volcano as magma below begins to build up. At Sakurajima, this is marked by a rise in the seabed in Kagoshima Bay – tide levels rise as a result.
- As magma begins to flow, melting and splitting base rock can be detected as volcanic earthquakes. At Sakurajima, they occur two to five kilometers beneath the surface. An underground observation tunnel is used to detect volcanic earthquakes more reliably.
- Groundwater levels begin to change, the temperature of hot springs
may rise and the chemical composition and amount of gases released may
alter.
- As an eruption approaches, tiltmeter systems measure minute movements of the mountain. Data is relayed in real-time to monitoring systems at SVO.
- Seismometers detect earthquakes which occur immediately beneath the crater, signaling the onset of the eruption. They occur 1 to 1.5 seconds before the explosion.
- With the passing of an explosion, the tiltmeter system records the settling of the volcano.