TEMPERATURE PATTERNS AND INCREASE OF SURFACE ACTIVITY AT MICKEY HOT SPRINGS, OREGON

The Mickey Hot Springs hydrothermal area in southeastern Oregon is one of the hottest and most active hydrothermal areas in the Pacific Northwest. The area is one of three major hydrothermal areas east of Steens Mountain. At Mickey Hot Springs, 29 major springs are scattered throughout an area approximately 4 hectares and are separated into two geographical clusters. The most significant thermal feature in the area is the unofficially named “Mickey Geyser,” which is currently the only known active natural geyser in the continental United States outside of Yellowstone National Park, capable of erupting up to two meters.

Research of visual, photographic, and written observations from research articles, social media posts and photos, and scholarly journals suggest that surface activity at Mickey Hot Springs has been increasing over the past several decades. Since 1982, several major thermal features have developed or expanded, including “Mickey Geyser” itself.

Starting in March 2017, three HOBO U23 Pro v2 Temperature Data Loggers have been deployed at Mickey Hot Springs, taking a temperature reading every 5 minutes. One data logger is within the outflow of “Mickey Geyser” about two meters from the main vent. The second data logger is on the outflow of UTF (Unnamed Thermal Feature)-26. The final data logger is deployed approximately 15 meters downstream of the confluence of UTF-26’s outflow and the main outflow channel of the group. The temperature traces show strong influences from barometric pressure, with drops in temperature following drops in barometric pressure. Furthermore, All three temperature traces show a sinusoidal repeating pattern of temperature fluctuation with wavelengths of roughly 3 to 5 days and temperature amplitudes of 10 degrees.