Scientists monitoring a supervolcano responsible for the biggest eruption on the planet in 5,000 years have raised an alert. A shift in the activity of Taupō, in New Zealand, has been detected recently, with hundreds of small quakes hitting the area, reports the Star.
So for the first time since a measuring system was introduced in 1994, the alert level for the formidable supervolcano has been raised from 0 to 1 out of six. The last time Taupō, at the centre of the country's north island, exploded was 1,800 years ago - the most violent eruption seen in the last 5,000 years.
Another - much larger - eruption occurred about 26,000 years ago that created an ash cloud that covered the Southern Hemisphere. Major erruptions are estimated to take place every thousand years.
The threat level has been raised by the geological agency GeoNet after nearly 700 earthquakes since May. However, the experts insist the chance of an eruption “remains very low”, with the largest of recent earthquakes on reaching a magnitude of 4.5 on the Richter scale which goes up to nine.
GeoNet said in a statement: “We interpret the ground uplift and earthquake activity to be caused by the movement of magma and the hydrothermal fluids inside the volcano. We have also sampled springs and gas vents around the lake for changes in chemistry that may be related to the earthquake and ground uplift.”
Since 1870, 17 episodes of unrest have been recorded at Taupō but none more threatening than level 2 of the alert system, had it existed at the time.
GeoNet added: “The Volcanic Alert Level reflects the current level of volcanic unrest or activity and is not a forecast of future activity. Volcanic unrest at volcanoes like Taupō could continue for months or years and not result in an eruption.”
When it exploded nearly 1,800 years ago, Taupō covered lakeside areas in rock and pyroclastic flows dozens of feet deep and blanketing much of the North Island in at least 1 cm of ash. Wind the clocks back even further to about 26,000 years ago, and the supervolcano erupted to created the large basin that formed today's lake. Between those historic dates, at least 27 other smaller eruptions are known to have happened.
