Massive New Year’s Day earthquake in Japan revealed a rare ‘dual initiation’ mechanism, study finds
A powerful earthquake that struck Japan’s Noto Peninsula on New Year’s Day 2024 has revealed surprising new details about seismic activity in the region. The 7.5 magnitude quake, which caused over 280 deaths and damaged more than 83,000 homes, was found to have an unusual origin: it started nearly simultaneously at two different points along the faultline, leading to a rare “dual-initiation” event.
A breakthrough in earthquake research
Geologists have discovered that this dual initiation caused the seismic rupture to encircle and break through a previously unknown barrier on the fault. The intense pressure from both sides of this barrier resulted in a powerful burst of energy, explaining the intense shaking experienced across the Noto Peninsula.
Prior to the main earthquake, several intense seismic swarms—smaller tremors that often precede larger quakes—were recorded in the area. To investigate the connection between these swarms and the main event, an international team of researchers from the United States, France, China, and Japan analyzed geospatial data and seismic wave recordings.
New insights from a unique seismic event
The study, led by Lingsen Meng, an associate professor of earth, planetary, and space sciences at UCLA, along with UCLA graduate student Liuwei Xu and UC Santa Barbara geophysics professor Chen Ji, has revealed groundbreaking insights into earthquake dynamics. The researchers discovered that the earthquake initiated in two separate locations on the fault, a phenomenon that had previously been seen mostly in simulations.
“The earthquake started in two places and circled together,” Meng explained. “The first one started waves that traveled fast and triggered a different epicenter. Then both parts propagated outward together and met in the middle, where the barrier was, and broke it.”
This dual initiation mechanism surprised scientists because it increases the potential for stronger shaking and greater damage, a risk not typically associated with single-point origin earthquakes.
Advanced technology enables discovery
The ability to detect this dual initiation process was made possible by Japan’s extensive network of seismic monitoring stations, as well as the use of GPS and satellite radar data. “We grabbed all the data we could find! It’s only through all of this data together that we got really good resolution on this fault and could get into these fine details,” Meng said.
The researchers suggest that similar dual initiation events may be more common than previously thought, but often go undetected due to a lack of comprehensive data in other regions.
The findings, published in the journal Science, provide a deeper understanding of how complex earthquakes can be and highlight the importance of advanced monitoring technology in earthquake-prone regions. This research could help improve future predictions and preparations for similar seismic events, potentially saving lives and reducing damage.
The study not only sheds light on the specific dynamics of the 2024 Noto Peninsula earthquake but also opens new avenues for investigating the mechanisms behind other large-scale seismic events worldwide.