Comment on "Seismic Velocity Variations at Different Depths Reveal the Dynamic Evolution Associated With the 2018 Kilauea Eruption" by Liu et al.

Liu et al. (2022, https://doi.org/10.1029/2021GL093691) used Rayleigh waves extracted from the cross‐correlation of ambient noise recorded by two stations to monitor the seismic velocity variations associated with the 2018 Kı̄lauea eruption. However, their study ignored the fact that the tremors on the Island of Hawai'i were dominated by a source at the Kı̄lauea summit before the eruption. Close inspection of the waveforms of the station pair PAUD‐STCD shows a simple, mistakenly identified wave traveling direction in Liu et al. (2022, https://doi.org/10.1029/2021GL093691). A correct wave traveling direction agrees with the noise source model, where the dominant tremor source should be at the Kı̄lauea summit. Because of the drastic change in the tremor source after the eruption, the cross‐correlation of the tremor records may reflect predominantly changes in the source rather than in the medium properties between the two stations. Plain Language Summary: More and more studies are using seismic records to understand the volcano eruption process. A very recent study monitored the dyke intrusion near the Pu'u'ō'ō right after the start of the 2018 Kı̄lauea eruption, by observing increased seismic wave arrival times. However, after re‐inspecting the data, we find their study understood the source location emitting the seismic waves wrong. Thus, their observed increased seismic wave arrival times can no longer be explained by the proposed dyke intrusion in the rift zone. We further suspect that the temporal variations of the seismic source contributed greatly to the arrival time variations. Key Points: The tremor signals appeared on the ambient noise cross‐correlation functions (CCFs) should be from the Kı̄lauea summit, not Pu'u'ō'ōThe tremor sources changed after the beginning of the eruptionThe apparent temporal variations of the CCFs related to the tremors reflected the change of noise source rather than medium velocity [ABSTRACT FROM AUTHOR]