USING REPEATING GLACIAL EARTHQUAKES TO STUDY TEMPORAL VARIABILITY IN SUBGLACIAL CONDITIONS

On many ice streams and glaciers driving stress is largely balanced by regions of enhanced basal traction known as sticky spots. One potential consequence of a sticky spot is stick–slip behavior at the ice–bed interface. Similar to motion along earthquake faults, this may result in the generation of seismic waves that can be observed remotely. Thus, seismogenic sticky spots offer a window into the physics of basal motion. Changes in effective normal stress over a sticky spot can allow transitions between stick–slip and stable sliding behavior, providing a potential mechanism to track long-term changes in physical conditions near the ice–bed interface. We will discuss several examples of repeating Antarctic glacial earthquakes, including several that are long-lived (>5 years). Repeating events are characterized by nearly identical waveforms and represent repeated motion over a single sticky spot. We will highlight how time series of repeating events can be used to track fluctuation in effective normal pressure. Additionally, we will show how complex interactions between neighboring sticky spots can be used to explore subglacial conditions.