Premium
No spreading across the Southern Juan de Fuca Ridge axial cleft during 1994–1996
Author(s) -
Chadwell C. David,
Hildebrand John A.,
Spiess Fred N.,
Morton Janet L.,
Normark William R.,
Reiss Carol A.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900570
Subject(s) - seafloor spreading , geology , ridge , plate tectonics , pacific plate , seismology , deformation (meteorology) , mid ocean ridge , geodesy , oceanography , tectonics , paleontology , subduction
Direct‐path acoustic measurements between seafloor transponders observed no significant extension (−10±14 mm/yr) from August 1994 to September 1996 at the southern Juan de Fuca Ridge (44°40′ N and 130°20′ W). The acoustic path for the measurement is a 691‐m baseline straddling the axial cleft, which bounds the Pacific and Juan de Fuca plates. Given an expected full‐spreading rate of 56 mm/yr, these data suggest that extension across this plate boundary occurs episodically within the narrow (∼ 1 km) region of the axial valley floor, and that active deformation is occurring between the axial cleft and the plate interior. A cleft‐parallel 714‐m baseline located 300 m to the west of the cleft on the Pacific plate monitored system performance and, as expected, observed no motion (+5±7 mm/yr) between the 1994 and 1996 surveys.