Rainfall Triggers Significant Speed Increases in Alaskan Glacier Surges
Boise State University researchers have discovered that heavy precipitation can accelerate Alaskan glaciers by as much as 251 percent during slow-flow periods. According to Interesting Engineering, the study utilized GPS data from Turner Glacier to track how water pressure influences ice movement across different phases of the surge cycle, revealing complex drainage behaviors.
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The investigation into Turner Glacier by Boise State University researchers provides a clearer picture of how surge-type glaciers behave under changing weather conditions. By comparing GPS records with modeled rainfall and data from Yakutat Airport, the team demonstrated that precipitation acts as a critical catalyst for movement. The study challenges the traditional understanding of glacier drainage as a simple binary system. Instead, the persistent response to rainfall across both active and quiet phases suggests that inefficient subglacial channels remain a factor throughout the glacier's life cycle. This research, as detailed by Interesting Engineering, helps scientists predict how glacial runoff and movement might shift as regional precipitation patterns fluctuate.
"inefficient drainage can allow water pressure to build beneath a glacier, reducing friction between the ice and the ground."
Research published by Interesting Engineering details how the Sít’ Kusá glacier in Alaska responds to heavy rainfall events. By analyzing 10 GPS sensors recording data every 15 seconds, scientists from Boise State University compared movement patterns during a 2020 to 2021 surge with a quiescent phase occurring between 2022 and 2024. The data indicates that precipitation impacts glacier velocity regardless of the current flow state, though the intensity and timing of these accelerations vary significantly.
During the active surge phase, the glacier reached peak speeds of 24.6 feet per day, representing a 116 percent increase over its average surge velocity. These events typically began roughly 12 hours after rainfall commenced and lasted for an average of 66.5 hours. Interestingly Engineering reports that while speed-ups occurred more frequently during the surge phase, the percentage increase was actually higher during the slower quiescent period. During these calmer years, rainfall events triggered a 251 percent speed increase, though the total movement was limited to approximately 4.9 feet per day.
The study suggests that these speed fluctuations are driven by the efficiency of the subglacial drainage system. When drainage is inefficient, water pressure builds between the ice and the ground, reducing friction and allowing for faster sliding. While the quiescent phase showed signs of more efficient water transport, the fact that rain still triggered acceleration suggests that some inefficient drainage components remain active throughout the entire cycle.
Interestingly Engineering notes that the lower sections of the glacier exhibited the most dramatic acceleration in both phases. Researchers also observed that exceptionally long periods of rain could occasionally cause a temporary slowdown during a surge, though the glacier typically returned to its previous high-speed state within two weeks. This behavior suggests that subglacial drainage systems do not simply toggle between two fixed states but rather evolve dynamically in response to environmental inputs.
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Rainfall significantly accelerates glacial movement by increasing subglacial water pressure. These findings indicate that drainage systems remain partially inefficient year-round, allowing even minor precipitation to trigger substantial velocity shifts during both surge and quiet phases.