Triggering of the Mw 7.2 Hawaii Earthquake of 4 May 2018 by a Dike Intrusion

• Published in: Geophysical research letters 2019-03, Vol.46 (5), p.2503-2510
• Main Authors: Chen, Kejie, Smith, Jonathan D., Avouac, Jean‐Philippe, Liu, Zhen, Song, Y. Tony, Gualandi, Adriano
• Format: Article
• Language: English
• Subjects: Case studies; Cracks; Deformation; Deformation mechanisms; Earth; Earthquake damage; Earthquakes; Eruptions; Geological faults; Intrusion; Lava; Magma; Rift zones; Seismic activity; Seismology; Slump structures; Solifluction; Tectonics; Tsunamis; Unloading; Volcanic activity; Volcanic eruptions; Volcanoes
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2018GL081428

A Mw 7.2 earthquake struck the south flank of Kilauea, Hawaii, on 4 May 2018, following a period of volcanic unrest. To investigate its relationship with the stress changes induced by prior tectonic and magmatic activity, we model the coseismic slip distribution, preintrusion deformation, and dike intrusion using geodetic, seismic, and tsunami observations. The décollement beneath the south flank was creeping seaward by ~25 cm/year. Diking started on 20 April and led to fissure eruption on 3 May. The magmatic activity and creep resulted in an onshore U‐shaped zone of stress unloading, fringed by an off‐shore zone of stress buildup that apparently guided the 2018 rupture. It takes only 20 to 35 years at the preintrusion rate to accumulate a moment deficit equivalent to the moment that was released in 2018. This event falls short of balancing the moment budget since the 1975 Mw 7.7 earthquake. Plain Language Summary As one of the most active volcanoes on Earth, Kilauea volcanos in Hawaii are responsible for various deformation sources including summit reservoirs, rift zones, décollement faults, and slumps, which result in thousands of earthquakes each year. While most of the minor earthquakes (M