An international team of researchers has uncovered critical insights into the forces behind the devastating 2011 Tohoku earthquake and tsunami, following an unprecedented deep-sea drilling operation. The project, known as the Japan Trench Fast Drilling Project (JFAST), involved drilling boreholes directly into the fault zone that ruptured during the magnitude 9.0 earthquake.
The drilling, conducted through the seafloor of the Japan Trench, allowed scientists to retrieve core samples and gather data on the physical properties of the fault. This marks the first time a fault zone that had recently moved tens of meters during an earthquake has been directly examined, according to researchers involved in the project.
The 2011 Tohoku-oki earthquake caused widespread destruction across northeast Honshu, resulting in over 15,000 deaths and an estimated $200 to $300 billion in economic losses. The urgency to understand the event prompted the Integrated Ocean Drilling Program (IODP) to initiate JFAST shortly after the disaster.
Scientists focused on understanding the unprecedented slip of 40 to 60 meters that occurred on the shallow portion of the megathrust fault, which was the primary cause of the massive tsunami. The project aimed to estimate the stress state in the fault region through borehole breakouts and analyze the geologic structures within the plate boundary fault zone.
In January 2025, a marine research team embarked on the deep-sea drilling vessel Chikyu to continue investigations related to the 2011 earthquake. Recent analysis of data obtained from the world’s deepest scientific ocean drilling has revealed latest details about the earthquake’s power. The findings are expected to contribute to improved earthquake and tsunami hazard assessments in the region.
The research team has not yet publicly released a comprehensive report detailing all findings, and further analysis of the core samples is ongoing. The Chikyu remains engaged in ongoing research in the area.
