Overview

• Geologists discovered the 13-foot-wide, 109°F pool on April 10, 2025, during routine maintenance of temperature logging stations in the Porcelain Basin sub-basin west of Tree Island.
• Satellite imagery shows no feature before December 19, 2024, a developing cavity by January 6, 2025, and a fully formed pool by February 13, 2025.
• Infrasound sensors recorded weak low-frequency acoustic signals on December 25, January 15 and February 11 without corresponding seismic activity, indicating multiple small blasts.
• USGS scientists conclude that successive minor hydrothermal explosions ejected rocks and silica mud, creating a depression that filled with hot, silica-rich water.
• The active pool remains stable and situated away from visitor boardwalks and is under continuous monitoring for further geothermal changes.