<P> In September 2001, 14,215 earthquakes were detected over a 25 - day period in the Middle Valley segment . </P> <P> Researchers at Oregon State University suggested the Axial Seamount had an eruption interval of approximately 16 years, which would place the next major Axial eruption in 2014 . In 2011, during a dive on the seamount, new lava flows were discovered and some instruments had been buried in lava flows, indicating the volcano had erupted since the last expedition to the ridge . This is considered the first successful forecast of a seamount eruption . The caldera floor dropped by more than 2 meters after the eruption, and the rate at which it inflates as Axial's magma chamber refills can be used to once again predict the next eruption . </P> <P> The ridge is a medium rate spreading center, moving outwards at a rate of approximately 6 centimeters per year . Tectonic activity along the ridge is monitored primarily with the U.S. Navy's Sound Surveillance System (SOSUS) array of hydrophones, allowing for real time detection of earthquakes and eruptive events . </P> <P> The Juan de Fuca Plate is being pushed east underneath the North American Plate, forming what is known as the Cascadia subduction zone off the coast of the Pacific Northwest . The plate does not subduct smoothly and can become' locked' with the North American plate . When this happens, strain builds up until the contact suddenly slips, triggering massive earthquakes up to or greater than magnitude 9 . Major earthquakes along this zone occur on average every 550 years and can have major impacts on the physical structure of the North American continent and seafloor . </P>

Average rate of seafloor spreading east of juan de fuca ridge