 In June 1999, 1,863 earthquakes were recorded over 5 days, and a hydrothermal temperature increase was observed at the Main Endeavour segment.In September 2001, 14,215 earthquakes were detected over a 25-day period in the Middle Valley segment.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.