Insights From Two Decades of Seismicity at Columbia Glacier

Abstract We use Columbia Glacier as a case study to demonstrate how seismically cataloged calving events in Alaska can track glacier evolution over two decades. By combining this catalog—a serendipitous byproduct of earthquake monitoring—with terminus positions, bathymetry, glacier thickness, surface velocity, and environmental records, we show how this seismicity responds to changes in the glacier. We find that fjord bathymetry at the terminus is a strong control on seismicity. As the glacier recedes into shallow water, the number of glacier quakes increases due to the transition to grounded conditions, which favor serac failure. We find evidence that glacier speed, precipitation, and warm ocean temperatures raise the rate of cataloged glacier quakes. We also observe that the energy of individual quakes increases with the elevation of the terminus. Our results highlight potential future uses of the cataloged calving record in Alaska that spans more than a dozen other glacier systems.