YELLOWSTONE NATIONAL PARK — This week’s Caldera Chronicles takes readers on a trip through the center of the Earth.
Shaul Hurwitz, a research hydrologist with the U.S. Geological Survey, wrote the weekly column about the antipode of Yellowstone National Park (YNP). An antipode is the point on Earth’s surface that lies directly opposite another location. According to Hurwitz, not all antipodes have the exact same distance between them because the Earth is not a perfect sphere. The average distance between antipodes is 7,918 miles, twice the average radius of the Earth. The antipode of the Yellowstone Caldera is found in the southern Indian Ocean near the Kerguelen Plateau.
“This plateau is a large, mostly submerged volcanic and magmatic province that was created about 130 million years ago,” wrote Hurwitz. “The plateau formed due to the Kerguelen hotspot following the breakup of the Gondwana supercontinent. … A small portion of the plateau is above sea level, forming the remote Kerguelen Islands (a French territory), where during the winter less than 50 people live, and the Heard and McDonald Islands (an Australian territory), which are UNESCO World Heritage sites.”
The Kerguelen Plateau, which is nearly three times the size of California, and the associated islands are very remote, therefore visual observations of volcanic eruptions are rare. The Kerguelen hotspot still drives some active volcanoes in the plateau. In the past few decades, some eruptions have been documented by satellite observations, but likely more remain undocumented. Heard Island is home to two volcanic structures: Big Ben Volcano with a glacier-covered cone, and Mt. Dixon.
“Little is known about the structure of Big Ben because of its extensive ice cover, which is shrinking rapidly, but several subglacial eruptions have been reported,” wrote Hurwitz. “Big Ben last erupted on February 11, 2026, and based on satellite observations produced an ash plume rising to 7.3 kilometers (24,000 feet).”
The largest of the McDonald Islands is smaller than half a square mile in area. In December 1996 and January 1997, volcanic plumes were observed from the island. In March 1997, the crew on a passing vessel noticed a steaming vent and lava flow deposits. According to Hurwitz, a 2001 satellite image of the island showed that it had more than doubled in area since previous observations just a year earlier.
