Magma movement from Nāpau down to Leilani Triggered the 4th May 2018 Mw 7.0 Hawaii earthquake

Kejie Chen, Jonathan D. Smith, Jean-Philippe Avouac, Zhen Liu, & Song Y. Tony

Submitted August 15, 2018, SCEC Contribution #8664, 2018 SCEC Annual Meeting Poster #286

On 4th May 2018, a Mw 7.0 earthquake struck the south flank of Kīlauea, Hawaii, where volcanic activities have aggravated since late April. To investigate the possible cause-and-effect relationship between the magma movement and this earthquake, we have determined a co-seismic slip model based on geodetic, seismic and tsunami records and explored its relationship to the preceding stress evolution determined from modeling GPS time series from June 2012 to 20th April 2018. The Kilauea and Mauna Loa summits inflated at ~0.01 km3/yr, ~0.005 km3/yr, respectively, over that time period forcing ~25 cm/yr of seaward creep on the basal decollement beneath the southern flank of Mauna Loa. GPS and InSAR measurements from 20th April to 4th May 2018 imply opening by about 1 m of a 45 km long dyke. The dyke extends from Nāpau Crater, where it lies at depth between ~4 km and 8 km, to Leilani Estates, where it surfaces and where the eruption commenced. The magmatic inflation, dyking and creep on the decollement resulted in a U-shaped zone of stress unloading, fringed by a zone of stress build up which guided the rupture during the Mw 7.0 earthquake.

Chen, K., Smith, J., Avouac, J., Liu, Z., & Y. Tony, S. (2018, 08). Magma movement from Nāpau down to Leilani Triggered the 4th May 2018 Mw 7.0 Hawaii earthquake. Poster Presentation at 2018 SCEC Annual Meeting.

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