| Abstract: | 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.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 minutes N and 130??20 minutes 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 (approx. 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. |
| Genre: | Article |
| ProdID: | 70021684 |
| Citation Author: | Chadwell, C. D.; Hildebrand, J. A.; Spiess, F. N.; Morton, J. L.; Normark, W. R.; Reiss, C. A. |
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| Citation End Page: | 2528 |
| Citation Issue: | 16 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geophysical Research Letters |
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| Citation Number Of Pages: | 4 |
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| Citation Publisher: | American Geophysical Union |
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| Citation Search Results Text: | No spreading across the southern Juan de Fuca ridge axial cleft during 1994-1996; 1999; Article; Journal; Geophysical Research Letters; Chadwell, C. D.; Hildebrand, J. A.; Spiess, F. N.; Morton, J. L.; Normark, W. R.; Reiss, C. A. |
| Citation Start Page: | 2525 |
| Citation Volume: | 26 |
| Citation Year: | 1999 |
| Type: | citation/reference |
| Text: | No spreading across the southern Juan de Fuca ridge axial cleft during 1994-1996; 1999; Article; Journal; Geophysical Research Letters; Chadwell, C. D.; Hildebrand, J. A.; Spiess, F. N.; Morton, J. L.; Normark, W. R.; Reiss, C. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Fri, 1 Jan 1999 00:00 -0600 |
| Publisher: | American Geophysical Union |
