A large magnetic anomaly has been discovered in New Zealand

Researchers from GNS Science, a New Zealand research institute, have mapped the bottom of Lake Rotorua, Refers to Space magazine. These new maps cover 55 square kilometers, or approximately 68% of the bottom of water bodies. They uncovered craters, an ancient river, but also a large magnetic anomaly.

Lake Rotorua, famous for its hydrothermal activity Famous Maori love story What happened there, located in the heart of the crater of an ancient extinct volcano. The New Zealand Tourism Authority website states Clouds of steam form around the lake's shores and sulfur gives the water its color “Green and Blue Magic.”. It's the first time scientists have drawn detailed maps of one of the country's largest lakes.

Metamorphic rock

Discovering this anomaly proved to be a team effort. In fact, the Royal New Zealand Navy collected part of the data provided by GNS Science scientists and studied the lake floor using a multibeam echosounder (a type of sonar). This made it possible to detect magnetic anomalies. Cornel de Ronde, principal investigator at GNS Science, explains: “Normally, when you run a magnetometer on volcanic rocks, you get very positive anomalies, but in this case, we got negative anomalies.”

Igneous rocks generally contain… Magnetite, a highly magnetic metal. But in Lake Rotorua, experts believe hydrothermal fluids passed through the rocks and turned magnetite into pyrite (a golden-colored mineral type), which has almost no magnetic signal. This could explain the negative irregularities.

Not every tourist who goes swimming in Rotorua can imagine what's happening beneath their feet, but for scientists, seeing these maps is like putting… “Finally the glasses”said Cornel de Ronde.