By David Barber -
THE eruption of a New Zealand volcano for the first time in more than a century came yesterday as a dramatic reminder that the country lives in one of the world’s most geologically unstable regions on the Pacific Ring of Fire.
The state Institute of Geological and Nuclear Sciences constantly monitors 12 volcanic areas and logs more than 15,000 earthquakes a year, which have led the country to be nicknamed the Shaky Isles.
Few cause casualties or damage, thankfully for the 1.5 million residents of the largest city, Auckland, which is built on no fewer than 49 extinct volcanoes. But a magnitude-6.3 quake destroyed much of the centre of the second-largest city, Christchurch, in February last year, killing 185 people.
Seismic activity is always unpredictable as scientists noted after the 1,968-metre Mount Tongariro erupted late on Monday shortly before
midnight (1200 GMT) for the first time since a series of five eruptions in the late 19th century, the last in 1897.
Volcanologists said there was nothing unusual about a series of small quakes under the mountain that they had monitored in recent weeks and nothing to indicate it was about to blow.
It caused no casualties and made no impact, apart from a cloud of fine ash that stretched about 250 km coast-to-coast across the North Island, and it remained quiet yesterday after the eruption.
However, scientists confessed they have no idea whether it would stay that way.
They posted a volcanic alert for the island at a conservative two on a five-level scale.
Tongariro is one of three active volcanic mountains in a 78,651-hectare national park on the central North Island.
The tallest, Mount Ruapehu at 2,797 metres, last erupted in September 2007, and the 2,291-metre Ngauruhoe, which blew 45 times in the past century, has been quiet for 35 years although it constantly emits a plume of strong sulphurous gases from its crater.
The three mountains sit at the south-west end of a volcanic chain extending through White Island and the Kermadec Islands in the South Pacific, nearly 1,000 km north-east of Auckland, to Tonga, a further 1,000 km away.
White Island, 50 km off the east coast, consists entirely of a volcano, which is New Zealand’s most active. Its alert status was raised from a permanent one to two after an eruption and associated earthquake on Sunday.
Tourists can visit the island in controlled groups, but the Institute of Geological and Nuclear Sciences said eruptions can occur at any time with little or no warning and has advised visitors to take extra precautions.
New Zealand’s deadliest eruption was in June 1886 when Mount Tarawera on the North Island blew, burying three villages in heavy ash, killing 108 people and destroying the Pink and White terraces, which were considered one of the world’s great natural wonders.
The country’s largest lake, the 606-sq-km Taupo, also on the North Island, was created by a massive eruption 1,800 years ago.
Flights to and from provincial destinations, including renowned tourist spot Rotorua, were delayed or cancelled yesterday, and local highways were closed for a time, but there were no reports of damage or injury.
Meteorologists said the ash cloud was being blown eastwards towards the Pacific Ocean.
The last time Mount Tongariro erupted was in 1897, ending a decades-long period of intermittent activity, and Monday’s explosion could be the start of more such activity in the area.
Neighbouring Mount Ruapehu is the most active volcano in New Zealand, last erupting in 2007 when it sent a lahar, or mud slide, down the side of the mountain.
Major eruptions in 1995 and 1996 by Ruapehu resulted in widespread flights disruptions and the closure of ski fields on the mountain.