On November 10, 2023, Kristín Jónsdóttir, head of the Icelandic Meteorological Office’s department of volcano research, was having a rare day off. “It was my 50th birthday,” she said. Then everything began to shake. She would spend the day staring at her phone, watching the earthquakes bloom across maps of Iceland’s Reykjanes Peninsula. The peninsula experiences fissure eruptions...