The Cascadia subduction zone experiences silent earthquakes every 14 months, which can even produce a magnitude 9.0 earthquake. Now, a new study has revealed that these so-called silent quakes are tied to fluid moving miles underground. After analyzing the Cascadia subduction zone, researchers observed that a seismically active region passing over from northern California to Vancouver Island, in which the oceanic Juan de Fuca plate is sliding under western North America. The analysis also revealed that the massive earthquake could also cause a tsunami in the region. Researchers believe a better knowledge of such silent quakes could eventually help bridge the gap in understanding between this well-observed earthquake cycle and the processes occurring deep inside the subduction zone.