Endeavour Ridge Seismicity Prompts Rapid-Response Cruise

A five and half day swarm of small earthquakes was detected on the Endeavour segment of the Juan de Fuca Ridge offshore of the northwest coast of Washington beginning the morning of Sunday, February 27, 2005. Seismic monitoring by NOAA Vents Program scientists using the SOSUS array detected 3,742 earthquakes, the largest reaching a magnitude of 4.9. A rapid response geological survey of the area carried out 6 days later found no new lavas or hydrothermal disturbances at the seafloor, suggesting that the events were caused by an intrusion of magma from deep beneath the ridge crest.