Abstract
We examine spatial and temporal seismic velocity variations during the 2018 Lower East Rift Zone eruption and summit collapse activity in Kilauea by applying autocorrelation of seismic noise. We download the daily continuous seismic data recorded by the Hawaiian Volcano Observatory between January and August 2018 from the Incorporated Research Institutions for Seismology (IRIS). After the removal of the instrument response and other pre-processing, the seismic data are divided into hourly segments and bandpass filtered from 1 to 5 Hz. The autocorrelation functions are computed for a target station and channel and then stacked in 1-hour bins for each day during the study time period. The stacked autocorrelation functions are used to compute best-fitting stretching factors in the time domain for function pairs, which in turn are used to solve for the best-fitting set of velocity changes for the entire time period. Our results show a gradual velocity increase in March and April 2018 and an abrupt decrease about 10 days before the eruption, consistent with previous studies. We also observe a sharp increase in late May followed by a steady decrease in June at the summit stations, coincident in time with the explosive activities and the beginning of the episodic summit collapse events. In July, the stations in the East Rift Zone display a slow increase towards the end of the 2018 eruption, whereas the summit stations show flattened signals. Results based on the seismic data recorded at the temporary dense array by the University of Utah will also be presented for comparison.