The 1871 Lāna‘i Earthquake in the Hawaiian Islands

Abstract

Abstract The historic Lāna‘i earthquake of 1871 is reappraised based on new science. This 1871 event occurred between O‘ahu and Maui, where currently 80% of the State of Hawai‘i population resides. I focus on expanding the considered modified Mercalli intensities (MMIs) applied in prior seismic hazard analyses and the application of an earthquake MMI–magnitude, duration–magnitude, and fault-scaling relations. Compared with the MMI–distance trend of the 2019 Mw 7.1 Ridgecrest, California, earthquake, the Lāna‘i event appears larger. The 1871 earthquake and other M≥4.9 earthquakes (measured instrumentally) trend along the Moloka‘i fracture zone (MFZ), suggesting a tectonic relationship. The MFZ near Hawai‘i is the boundary between ∼85 and ∼100  Ma age lithosphere. Consistent with the preponderance of available evidence and new science, I propose a hypothetical, revised Mw∼7.5 earthquake model of the 1871 Lāna‘i earthquake associated with the MFZ. This seismic event may credibly be considered as the third largest earthquake statewide in Hawai‘i’s history and the largest historic earthquake northwest of the Big Island of Hawai‘i.