A mission to repair one of the most interesting GPS monitoring stations in Yellowstone - Caldera Chronicles
A mission to repair one of the most interesting GPS monitoring stations in Yellowstone
By Yellowstone Volcano Observatory November 17, 2025
Many of the monitoring sites in Yellowstone National Park are located in remote areas. When they go offline, a lot of preparation and effort is necessary to bring them back to functionality.
Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from Michael Poland, geophysicist with the U.S. Geological Survey and Scientist-in-Charge of the Yellowstone Volcano Observatory.
The continuous GPS station at White Like, designated WLWY (GPS stations are always given 4-character codes), is one of the most interesting in all of Yellowstone National Park. The station was installed in 1999 on the Sour Creek resurgent dome—one of two uplifted areas of Yellowstone caldera that formed due to magma accumulation shortly after the major caldera-forming eruption about 631,000 years ago (the other is the Mallard Lake dome, near Old Faithful).
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The Sour Creek resurgent dome continues to deform to this day, rising and falling by a few centimeters (about an inch) per year. Since 2015 the area has been subsiding (sinking), but prior to that there have been periods of uplift, for example, during 2004–2009. This persistent deformation was the reason that one of the first remote GPS stations in Yellowstone was installed in the White Lake area. The station is located almost 13 kilometers (about 8 miles) to the east of Hayden Valley and roughly 1.5 kilometers (about 1 mile) southwest of White Lake at the top of a hill. The site provides great sky view, which is critical for GPS, because there are only a few trees in the area. The backcountry location is far from any roads or trails, so the only way to realistically reach the site is by helicopter.
In summer 2024, the WLWY station malfunctioned. The GPS receiver that logs the data was still reachable by the radio link, but the antenna was not seeing any satellites and no data were being collected. Something was clearly wrong, but was it the antenna? Or the cable that connects the antenna to the receiver? Or perhaps something with the receiver hardware? There are a lot of things that can go wrong at remote monitoring stations, and maintaining the sites is a big job.
Owing to fire responses and search and rescue operations that occupied the park’s helicopter, it was not possible to visit the site in 2024. So engineers from the EarthScope Consortium, which operates GPS stations throughout the USA and beyond, planned a trip for summer 2025—a trip that finally happened on September 17 thanks to support from the Yellowstone National Park helitack crew.
The engineers loaded the helicopter with all of the tools and equipment they would need to diagnose and repair any problem that might be present at the station, as well as additional gear to perform some helpful upgrades. Upon arrival, the problem quickly became clear—water had accumulated around a connection in the antenna cable, causing corrosion. The engineers replaced the cable, restoring connectivity between the receiver and the antenna. The major problem was solved!
The engineers also moved the GPS receiver to a new location, close to the hub of solar and battery power, and added a new battery to the power system. Then, they replaced the radio link, which had connected the site to a radio hub at Mount Washburn several miles to the north, with a cellular modem. The new modem is much faster and allows data to be collected at high rates and even downloaded in real time, if needed—something that wasn’t possible using the older radio connection. Finally, the engineers added meteorological sensors that log temperature, barometric pressure, and other conditions—useful information when trying to understand how apparent motion of the GPS station might be related to changing weather.
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The improvements at WLWY should ensure that the site continues to provide high-quality ground deformation data from the Sour Creek resurgent dome for many years to come. Thanks to EarthScope engineers Brendan Hodge and Lia Lajoie for their excellent work!
For a video documenting the repair work, check out the Yellowstone Volcano Observatory October 2025 monthly update (https://www.youtube.com/watch?v=Efx6tBOe1yI)!
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