There is nothing particularly unusual about Mount Etna flinging lava, volcanic ash, or molten rocks into the air. Yet even experienced Etna watchers have been wowed by the intensity of the volcano’s unrest in February 2021. Southeast Crater is one of four summit craters on the volcano and the youngest; it formed in 1971. At times, lava fountains soared as high as 1.5 kilometers (0.9 miles), about 3 times the height of One World Trade Center, the tallest building in the United States. Paroxysms of similar intensity have occurred at Mount Etna at least four times since 1989, and the volcano has produced roughly 250 paroxysms of various strengths since 1977, said Boris Behncke, also with INGV.