SEABEAM DEPTH CHANGES ASSOCIATED WITH RECENT LAVA FLOWS, COAXIAL SEGMENT, JUAN-DE-FUCA RIDGE - EVIDENCE FOR MULTIPLE ERUPTIONS BETWEEN 1981-1993

After a swarm of earthquakes was detected on the CoAxial segment of th e Juan de Fuca Ridge in June-July 1993, the area was resurveyed with S eaBeam multibeam sonar to search for depth changes associated with a s ubmarine volcanic eruption. Quantitative comparison of the 1993 SeaBea m survey with surveys in 1981/82 and 1991 shows one area of seafloor d epth change (up to 29 m) between 1991-93 exactly where a pristine lava flow was discovered. In addition, two other depth anomalies (up to 37 m and 20 m) are identified between 1981-91, evidence that other recen t eruptions have occurred along this spreading ridge segment.