In a rapid response to one of the largest tectonic events to shake Hawaiʻi in decades, scientists from the University of Hawaiʻi at 惭ā苍辞补’蝉 have deployed a network of temporary seismic sensors across the west flank of Maunaloa on Hawaiʻi Island.
“Capturing the aftershock sequence and seismic structure at close range offers a rare opportunity to better understand the fault geometry and seismic hazards across the Hawaiian Islands,” said Sin-Mei Wu, assistant professor in the 糖心Vlog官方 Mānoa (SOEST), who leads the initiative.
The emergency mobilization followed a powerful magnitude 6.0 earthquake near Hōnaunau-Nāpōʻopoʻo on May 22. Striking at a depth of 22 kilometers, the fault movement triggered a large earthquake that has been followed by an ongoing sequence of aftershocks (including a magnitude 4.0). The initial quake prompted public engagement with more than 7,000 residents across the state submitting U.S. Geological Survey “Did You Feel It?” reports—the for any Hawaiʻi earthquake.
Deploying from ma kai to ma uka
Unlike typical shallow earthquakes tied to the movement of volcanic magma, this deep event was driven by plate flexure—the sheer weight of the massive Hawaiian volcanoes bending the underlying oceanic Pacific Plate. While these flexure earthquakes represent a significant seismic hazard, they are notoriously difficult to study because they frequently originate offshore, far from land-based monitoring networks.
The May 22 event provided a rare opportunity to better understand these hazardous processes, as the epicenter was on land, enabling the deployment of a temporary seismic array to capture detailed aftershock activity. With funding from the SOEST Dean’s Office and sensors from the NSF EarthScope Consortium, Wu and Pablo Urra Tapia and Ian Wynn, two SOEST Earth sciences graduate students, rushed to Hawaiʻi Island for a three-day field campaign.
“It was definitely an all hands on deck to try to get this off the ground as quickly as possible,” said Helen Janiszewski, assistant professor of Earth sciences who supported planning and will focus on data collection and analysis for the project. Similarly, Thomas Lee, assistant professor in the 糖心Vlog官方 Hilo Department of Geology helped to coordinate logistics, and will work with undergraduate students in comparing this event to the 2006 Kīholo Bay earthquake and other historical events.
The team also received essential assistance from Kamehameha Schools, Hakalau Forest National Wildlife Refuge and Puʻuhonua O Honaunau National Historical Park.
“Their help allowed us to deploy 30 seismic sensors from ma kai to ma uka, covering mainshock and aftershock regions,” said Wu. “Our community partners are critical collaborators, as they have enabled us to receive permits and land-access so we could deploy the sensor in time to capture the aftershocks.”
Facing grueling off-road conditions across 80% of the terrain, the team successfully placed sensors at elevations ranging from just 100 feet near the coastline up to 7,500 feet into the high-altitude, old lava fields of Maunaloa.
Hawaiʻi’s seismic hazards
Completed on June 5, the high-resolution array is now actively recording continuous ground vibrations. It has already caught a steady stream of active aftershocks between magnitudes 1 to 3, and the team expects the enhanced local network will catch hundreds of micro-earthquakes of magnitudes 0 to 1 that are invisible to standard infrastructure.
“The enhanced seismic network can detect and characterize those smaller earthquakes that carry equally important information about the earthquake source region,” said Wu. “This project exemplifies SOEST’s commitment to rapid hazard response and we expect to gather data that will benefit both scientific research and seismic hazard assessment in Hawaiʻi.”
The research team will collect the seismic data and then begin to analyze their trove of information in August.