Most volcanic activity happens underwater—nearly 80%! One major site is the Axial Seamount, an underwater volcano about 300 miles off Oregon’s coast. Scientists say it may erupt again “any day now,” though it won’t threaten people.

The Axial Seamount lies 5,000 feet beneath the Pacific Ocean and has erupted in 1998, 2011, and 2015. When it last erupted, the sea floor sank nearly 8 feet. “It has already inflated to the level that it reached before the last three eruptions,” said geophysicist William Wilcock, referring to the buildup of magma.

Currently, the volcano is swelling and showing signs of increased pressure. However, daily earthquakes—around 200 to 300, with occasional spikes—are still fewer than the 2,000 daily quakes before the 2015 eruption.

Despite this activity, there’s no danger to people. Scientists are closely monitoring the site, calling it a valuable opportunity to study underwater eruptions. The volcano is “under a state of critical stress,” and researchers are watching how tides may influence earthquake frequency by adding or relieving pressure on the crust.

Whatever happens, it’s another chance for scientists to learn more about Earth’s hidden volcanic forces.