Having a robust warning and monitoring system in place is a key plank for keeping people safe around these volcanoes given that about 500 of them have erupted in the past, according to the US Geological Survey. Most recently – the White Island volcano in New Zealand.
While the White Island eruption was not altogether unexpected, as the country’s authorities had raised alert levels before the eruption, experts said warning systems were not triggered due to its lack of lava flows.
Here is how some countries use these monitoring systems to keep locals and visitors safe.
Some of them, including Mount Bromo in East Java and Bali’s Mount Agung, are popular with both local and international tourists.
An interactive map shows the status of Indonesia‘s active volcanoes on Dec 18, 2019. (Screengrab: MAGMA)
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Scientists from the Volcano Group at Nanyang Technological University’s Earth Observatory of Singapore (EOS) told CNA that monitoring agencies commonly measure earthquake activity, ground deformations and gases emitted by the volcano for any “unrest” or changes.
Together with visual monitoring, the data is then used to “attribute a volcanic alert level which reflects the current state of activity” – which tourists should pay attention to, said the scientists.
In Indonesia, a volcano will be assigned one of four alert levels which can be checked on the MAGMA website and app. Non-Bahasa Indonesia speakers can use the Google translation function to switch the language to English.
This photo taken on Nov 29, 2017 shows a foreign couple taking selfies near the restricted area for Mount Agung in Karangasem on the Indonesian resort island of Bali. (Photo: AFP/JUNI KRISWANTO)
ICELAND’S EYJAFJALLAJÖKULL: AIRSPACE DISASTER
Iceland is increasingly popular with Singaporeans seeking a taste of adventure – like chasing the northern lights and scaling glaciers.
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The island-nation experienced a tourism boom, ironically, after the Eyjafjallajökull (pronounced AY-uh-fyat-luh-YOE-kuutl) volcano erupted in 2010, spewing so much ash and dust, causing the biggest shutdown of European airspace since World War II.
Passengers check electronic board displaying flight information after the cancellation of flights at Arlanda Airport outside Stockholm, on Apr 15, 2010. (File photo: AFP/PONTUS LUNDAHL/SCANPIX SWEDEN)
Daily updates on volcanic activities are provided on the Icelandic Meteorological Office website.
In the case of a moderately active volcano like Eyjafjallajökull, for example, the “unrest” that immediately preceded the eruption was “subtle and difficult to detect”, unlike in highly active volcanoes, said Freysteinn Sigmundsson of the Nordic Volcanological Centre at the University of Iceland.
Before an eruption, gas would rise out of the magma, causing the air in the volcano’s crater to slosh back and forth – creating sound waves like those from a woodwind instrument – the Nature Research report explained.
Since its creation in 2010, the system successfully predicted 57 out of 59 eruptions in the following eight years, according to a study in the Journal Of Geophysical Research: Solid Earth.
This early-warning system is now being tested in Iceland.
Smoke rises from Mount Etna over the city of Giarre, Catania, on Dec 26, 2018. (Photo: AFP/GIOVANNI ISOLINO)
Mount Etna last erupted on Christmas Eve last year, prompting a partial closure of Sicilian airspace.
“You’re covering a lot of ground really fast, so if there is an ash cloud that has suddenly popped up, then the pilots need to know that information as soon as possible,” said John Lyons, a geophysicist at the Alaska Volcano Observatory, as quoted by Nature Research.
“Every minute counts.”
JAPAN’S MOUNT ONTAKE: WHEN J-ALERT WAS SILENT
This handout picture taken by Joint Staff on Oct 7, 2014 shows Japan’s Self Defense Force soldiers searching missing for climbers on the ash covered top of Mount Ontake at Nagano prefecture. (File photo: AFP/JIJI PRESS)
This handout picture taken by the Tokyo Fire Department on Sep 28, 2014 shows firefighters carrying an injured climber on Mount Ontake in Nagano prefecture one day after the volcano erupted. (File photo: AFP/TOKYO FIRE)
Unpredictable eruptions may happen for different reasons, said the EOS.
“For example, if there is no or little pressure build-up (due to an open vent), the warning signals might be too small to be recorded,” said the scientists, adding that the authorities‘ monitoring strategy determines “whether they send the information in real-time and the type of data analyses” that can be performed.
Disaster-prone Japan operates a highly sophisticated system to disseminate alerts – dubbed J-Alert – through various media, including TV, radio, the Internet and loudspeaker vans. Foreigners can even receive J-Alert updates in English through an app created by public broadcaster NHK World.
A leaflet informs the public about Japan’s disaster alert system. (Screengrab: Japan Meteorological Agency)
Adventurers wishing to trek Japan’s slopes, including Mount Fuji, should bear in mind that while the risk of being caught in an eruption is small, it “is nonetheless a real one”, The Japan Times warned.
“When climbing up or near volcanoes, always pay close attention to official warnings, signs and announcements. Carry a flashlight, and if possible, eye goggles and a small radio,” advised the Japan Meteorological Agency.