Slow-motion earthquake that travels miles in weeks captured in action

Researchers from the University of Texas at Austin have, for the first time, directly captured a slow slip earthquake traveling along the Nankai Fault off the coast of Japan. Using sensitive borehole sensors installed nearly 1,500 feet below the seafloor, the team recorded the gradual release of tectonic pressure over weeks as the fault slowly "unzipped" along a 20-mile stretch. These slow slip earthquakes, which unfold over days or weeks rather than seconds, are a relatively recent discovery and are believed to play a critical role in the earthquake cycle by gradually accumulating and releasing stress along fault lines. The study, published in the journal Science, revealed that the slow slip events initiated about 30 kilometers inland from the trench and migrated seaward at a rate of 1 to 2 kilometers per day, reaching close to or possibly breaching the trench itself. These events coincided with tremors and very-low-frequency earthquakes in a zone characterized by high pore fluid pressure and low stress, providing key