44 years ago, on January 23, 1973, a previously-unknown fissure in the Earth beneath the small Icelandic island of Heimaey opened up less than a mile from the town of Vestmannaeyjar, which had a population of about 5,000 at the time. Within a day’s time, almost the entire island was safely evacuated, and geologists began to monitor the eruption. The newly-formed Eldfell volcano erupted for about six months, covering much of Vestmannaeyjar in ash, destroying several hundred homes, and sending lava flows toward the harbor—at one point raising the water temperature to 111° F (44° C). An enormous and largely-successful effort was made to slow and control the lava flow by pumping seawater and spraying the leading edge of the flows. Within a year after the end of the eruption, most residents had returned, and today, the island remains inhabited, with a population of about 4,500.