We Finally Know What Caused Those Three Months Of Earthquake Swarms In Yellowstone

Researchers believe they now know what caused a swarm of earthquakes that occurred in and around Yellowstone National Park’s active supervolcano system last summer, and no, it’s not the imminent doom of a looming apocalyptic eruption.  Known as the 2017 Maple Creek swarm, this batch of earthquakes was one of the most “persistent” earthquake swarms observed beneath the western edge of the park. The main episode lasted more than three months and produced thousands of earthquakes and, though most were very small, a few were large enough to be felt throughout the park. Writing in Caldera Chronicles, a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory, US Geological Survey (USGS) seismologist David Shelley says that the patterns of this swarm suggests that the earthquakes were likely caused by water diffusing through cracks in the Earth’s subsurface and not the movement of magma (although that can sometimes generate earthquake swarms at volcanic sites). “The involvement of this water may in part explain why these swarms are sometimes long-lived, why they expand dramatically over time, and why the fault structures are so complex,” Shelly wrote. “This also may explain why swarms are common in volcanic areas, where water is a byproduct released from deeper magma as it cools. We often see chemical evidence for this type of water at surface springs and fumaroles.”...MORE