A small town in New Zealand may be in a spot of geological trouble. A spate of recent earthquakes beneath the coastal settlement of Matata has bemused geophysicists, who have been unable to decide what might be causing them. Now, writing in the journal Science Advances, the culprit has been found: Magma has been forcing itself through the crust over the last five decades that, if it continues, will likely culminate in the birth of a new volcano.
New Zealand is no stranger to both considerable earthquakes and explosive volcanic activity, and Matata just lies within the Taupo Volcanic Zone, a V-shaped section of volcanic activity on the nation’s North Island. In this respect, then, a new magma chamber in the region isn’t entirely unexpected.
“There is every possibility the magma body under the Bay of Plenty coast has been there for centuries, and possibly even longer,” Ian Hamling, a researcher at GNS Science and the lead author of the study, told Stuff. However, this is a relatively novel place for magma to be crawling up into the crust – there hasn’t been any volcanic activity around Matata for the last 400,000 years.
Using both GPS data and satellite imagery, the team of researchers managed to detect a huge swath of land that appears to be heading skywards. This 400-square-kilometer (154-square-mile) strip of the North Island, centered roughly on Matata, has risen 40 centimeters (16 inches) since 1950, which explains the swarms of small earthquakes in the area.
The location of the magmatic upwelling, as seen on the margins of the Taupo Volcanic Zone. Ian Hamling
This roughly corresponds to there being a magma chamber 10 kilometers (6 miles) beneath it that contains 80,000 Olympic-sized swimming pools of magma. For comparison, the Yellowstone caldera’s magma chamber contains the equivalent of 240 million, so it falls way short of anything you’d expect for a “supervolcano.”
Still, it shouldn’t be dismissed as being a harmless magma chamber; after all, it’s likely to continue filling up with magma, and this part of the world has experienced some truly devastating eruptions in recent times, geologically speaking. So a future “supervolcanic” eruption is a theoretical possibility, but at this point, it’s hard to say how probable this scenario is.
“Although the ultimate fate of the magma remains unclear,” the authors write in their study, “its presence may represent the birth of a new magma chamber on the margins of arguably the world’s most active region of silicic volcanism, which has witnessed 25 caldera-forming eruptions over the last 1.6 million years.”
The Bay of Plenty contains multiple volcanoes, and the activity at Matata may signal the birth of the newest member of the family. Pictured here is Tauranga, along with an extinct volcano named Maunganui. Steve Heap/Shutterstock
Between 2004 and 2011, thousands of small earthquakes were generated as magma forced its way up through the shallow crust, and some may take this as a sign that an eruption is imminent. However, a volcano would only develop over the course of hundreds of thousands of years, and there’s even a possibility that it will run out of thermal energy, cool, and harden before one even appears.
With this in mind, the 650 or so inhabitants of Matata have, at present, very little to be concerned about. Hakuna matata, you could say.
In fact, knowing that these earthquakes were generated by magmatic activity, scientists are now able to monitor the area and track in real-time the movement of magma beneath the surface. Not only will this aid their ability to predict future earthquakes, but it will permit them to detect pulses of magma-based inflation occurring elsewhere on the North Island.