The discovery of LFEs originates in Japan at the Nankai trough and is in part due to the nationwide collaboration of seismological research following the Kobe earthquake of 1995 . Low frequency earthquakes in Japan were first observed in a subduction setting where the Philippine Sea plate subducts at the Nankai trough near Shikoku . The low-frequency continuous tremor researchers observed was initially interpreted to be a result of dehydration reactions in the subducting plate . The source of these tremors occurred at an average depth of around 30 kilometers , and they were distributed along the strike of the subduction interface over a length of 600 kilometers . Similar to Cascadia , these low frequency tremors occurred with slow slip events that had a recurrence interval of approximately 6 months . The later discovery of LFEs forming tremor confirmed the widespread existence of LFEs at Japanese subduction zones , and LFEs are widely observed and believed to occur as a result of SSEs
Kobe earthquake
Great Hanshin earthquake
Slow earthquake