|Statement||by Ariel E. Solano-Borrego.|
|The Physical Object|
|Pagination||, 76 leaves, bound :|
|Number of Pages||76|
MICROSEISMICITY ON THE GORDA RIDGE INTRODUCTION The Gorda ridge is an active spreading center that has the classi-cal profile of a slow spreading ridge, with a constant half spreading rate to the west of cm/yr and a varying one to the east of cm/yr (South) to cm/yr (North) (Atwater & Mudie, ). It has a. Gorda Ridge presents a primarily technical summary of recent advances in seafloor research related to mineral exploration of the only seafloor spreading center within the United States' Exclusive Economic Zone (EEZ). Spreading centers are known to be the locus of hydrothermal activity and to host mineral deposits of hydrothermal origin. The book includes sections on the . The book includes sections on the results of mineral exploration on Gorda Ridge, the newest technologies for mineral exploration and sampling on the seafloor, and the evolving field of hydrothermal vent biology and ecology. Abstract. Gorda Ridge is a relatively short ( km) segment of volcanic ocean ridge that extends from the Mendocino Fracture Zone (40° 20′ N) to the Blanco Fracture Zone (43° 00′ N) off the coast of Oregon and California.
The Gorda Ridge (41°36'"N °22'"W), aka Gorda Ridges tectonic spreading center, is located roughly kilometres ( mi) off the northern coast of California and southern g NE – SW it is roughly kilometres ( mi) in length. The ridge is broken into three segments; the northern ridge, central ridge, and the southern ridge, which contains the . The cessation of the midplate activity follows the occurrence of a large earthquake sequence in the adjacent Cascadia Subduction Zone in April It is proposed that the band of microseismicity and the three large midplate events reflect an accumulation of stress in the Gorda Plate, with the eventual termination. Proceedings of the Gorda Ridge Symposium May , , Portland, Oregon. Sponsored by The Gorda Ridge Technical Task Force Gorda Ridge presents a primarily technical summary of recent advances in seafloor research related to mineral exploration of the only seafloor spreading center within the United States' Exclusive Economic Zone (EEZ). . The graphs of Fig. 2 indicate that spreading at Gorda ridge S north of 41 has slowed considerably (nearly 70%) since 3 Ma B.P. (A similar percentage drop between two constant spreading rates on the southern Gorda ridge was inferred to have occurred suddenly at 2 Ma B.P. from deep-tow studies .).
The km-long North Gorda Ridge segment is located about km west of the southern Oregon coast and has deep 5- km-wide valleys at either ends with a shallower narrow axial valley at the center. This morphology, which in plan view resembles an hourglass, is typical of magmatically active spreading segments. Offshore of Northern California, where our catalog documents an even higher rate of seismicity in the incoming Gorda plate, normal faults originally formed near the Gorda ridge are reactivated under north‐south compression across the Gorda‐Pacific plate boundary as strike‐slip faults, causing extensive intraplate deformation (Gulick et al. Converted to motion vectors, they suggest the existence of at least two and possibly three Gorda plate segments. Assuming rigid plate tectonics, present motion between the northern and two southern segments should be NW-SE right-lateral at around 3 cm/yr and any fault between them should intersect the ridge near 42°N. The Gorda Ridge is a unique geological system in the Exclusive Economic Zone of the United States. This tectonically and volcanically active plate boundary has an unusual morphology for spreading centers in the Pacific Ocean: a deep, wide axial valley flanked by high ridges. Because of its location near the continental margin, part of the axial valley known as the Escanaba .