The 1996 Gorda Ridge event detection and response activities: historical perspective and future implications

Ridge axis magmatic events, including diking and eruptive phases, are episo dic perturbations that trigger a sequence of interrelated and rapidly evolv ing geophysical, chemical and biological processes associated with the form ation of ocean crust. Access to the US Navy's Sound SUrveillance System (SO SUS) in 1993 via PMEL-NOAA's T-Phase Monitoring system launched the scienti fic community from mere reliance on serendipitous encounters of magmatic ev ents to their remote detection at the initiation of an event's distinctive seismic signature and subsequent 'directed' rapid and follow-up field respo nses. This capability offers exceptional opportunities to observe and quant ify covariation among related seismic and hydrothermal processes and to pro vide basic new constraints on maturing models of submarine volcano-hydrothe rmal systems. The detection of a seismic swarm on the northern Gorda Ridge on 28 February 1996 prompted a multi-cruise response to investigate any new lava flows an d event- and chronic-style hydrothermal discharge associated with suspected dike intrusion and eruptive activity. The results of these studies are des cribed in the 12 papers composing this special issue on the detection of an d response to mid-ocean ridge magmatic events. The successes and limitation s of the Gorda Ridge event response series as well as previous event respon se efforts clearly demonstrate the need for greater pre-event coordination and preparation, (C) 1999 Elsevier Science Ltd. All rights reserved.