Periodic dike intrusions at K?-lauea volcano, Hawai'i

research. In this study, we (1) analyzed the spatial and temporal occurrence of rift zone dikes, including both intrusive and eruptive activity, which have not previously been studied together, (2) document regular recurrence intervals between rift zone dikes, and (3) correlate these intervals with extensional flank deformation. Eruptions at Kilauea volcano frequently occur along rift zones extending east and southwest that are fed by a magmatic conduit at -2?3 km below the surface. A 35-yr-long east rift zone (ERZ) eruption began in 1983 (Heliker and Mattox, 2003) and ended when the Pu?u ???? vent collapsed on 30 April 2018. In 2018, the largest eruption in Kilauea?s recorded history occurred, during which its summit caldera collapsed as magma drained to feed massive lava flows in the lower ERZ (Neal et al., 2019). On 4 May 2018, a M 6.9 flank earthquake occurred Forecasting heightened magmatic activity is key to assessing and mitigating global volcanic hazards, including eruptions from lateral rift zones at basaltic volcanoes. At K?-lauea volcano, Hawai?i (United States), planar dikes intrude its east rift zone (ERZ) and repeatedly affect the same segments. Here we show that K?-lauea?s upper and middle ERZ dikes in the last four decades intruded at regular intervals of -8 or -14 yr. Segments with shorter recurrence intervals are adjacent to faster-moving parts of the flank, and -1?5 MPa of tension accumulates from flank spreading in the time between dike events. Intrusion frequency was neither advanced nor delayed during magma supply variations, supporting the role of longterm flank motion on the timing of dike intrusions. Although fewer historical dikes have occurred near the 2018 CE eruption site in the lower ERZ and the adjacent slowly sliding lower eastern flank, similar tension accumulated between the 1955 and 2018 eruptions. Regular dike intrusion recurrence intervals indicate the importance of including both extrusive and (commonly neglected) intrusive activity in eruption hazard analyses.