Scientists examined an extraordinary 120 years of data from KÄ«lauea Volcano on Hawai’i Island, revealing century-long patterns of deformation and stress changes for the first time, particularly focusing on the significant 1975 magnitude 7.7 Kalapana earthquake.
Researchers from the University of Hawai’i at Manoa’s Department of Earth Sciences analyzed an unprecedented 120-year dataset from KÄ«lauea Volcano on Hawai’i Island. They discovered, for the first time, century-spanning patterns of deformation and shifts in stress. Their investigation centered on the impactful 1975 Kalapana earthquake, which generated a 20-foot tsunami. The findings were recently published in the Journal of Geophysical Research: Solid Earth.
“Understanding KÄ«lauea’s historical changes enhances our knowledge of volcanic and seismic risks,” stated lead author Lauren Ward Yong, who conducted this research for her doctoral thesis at the UH Manoa School of Ocean and Earth Science and Technology (SOEST). “It provides essential insights into the evolution of stress in volcanic systems, improving our ability to predict and interpret future earthquakes and volcanic activity.”
The research underscores the potential hazards associated with the décollement, a significant fault zone beneath Kīlauea, where two rock masses are in motion against each other. This ongoing movement drives the volcano further south and increases the risk of substantial earthquakes alongside complicated volcanic activity in the area.
Yong and her co-authors examined the deformation and stress variations of the volcano from 1898 to 2018 through the analysis of six distinct geodetic datasets. The study included 338,396 earthquake observations and over 15,000 measurements of surface displacement, which facilitated the creation of a computational model that mirrored the displacements and stress conditions before, during, and post the major 1975 Kalapana earthquake. This model identified crucial structural features—fault planes, rift zones, and magma chambers—that contributed to these changes.
Changes in stress and motion
The 1975 Kalapana earthquake was found to have dramatically impacted the area’s stress and deformation state. Before 1975, there was no indication of slip—a process where two rock masses slide past each other—at the location of the significant earthquake’s origin.
“This indicates that the area was likely locked by friction and gradually accumulating stress prior to the rupture,” Yong noted. “We also found that KÄ«lauea’s south flank, a geological active region extending from the volcano’s summit to the coast, showed more complex and increased displacement leading up to the Kalapana earthquake compared to the time after it.”
The research team discovered that the average slip along KÄ«lauea’s décollement decreased from 10 centimeters per year before the 1975 earthquake to just four centimeters per year afterward. These changes in slip and stress distribution along the décollement suggest alterations in mechanical properties like friction, which affect the region’s seismic and volcanic activities over time.
Improving readiness for hazards
“Communities in Hawai’i live near active volcanoes and face considerable seismic threats,” Yong remarked. “This study enhances preparedness for hazards and strengthens UH’s dedication to advancing science for the safety and well-being of Hawai’i’s residents and ecosystems by uncovering insights from significant historical events.”
KÄ«lauea’s historical data provides crucial understanding of the intricate connections between magmatic processes and earthquake cycles. Building on this work, Yong and her team aim to enhance their models by investigating deeper into essential properties of KÄ«lauea’s structural elements, like friction on fault planes, to better understand how changes in stress can lead to seismic and magmatic activity.
