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Topic: Gorda Ridge

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	Gorda Plate - Wikipedia, the free encyclopedia
		The westerly side is a divergent boundary with the Pacific Plate forming the Gorda Ridge.
		The subducting Gorda Plate is connected with the volcanoes in northern California, namely, Mount Shasta and Lassen Peak.
		The Gorda Plate and the Juan de Fuca Plate, are the last remaining fragments of the Farallon Plate, along with the Cocos Plate and Nazca Plate.
	en.wikipedia.org /wiki/Gorda_Plate (166 words)

	Research Highlights Juan de Fuca Ridge 2000 (Site not responding. Last check: 2007-10-22)
		The discovery of a midocean ridge (MOR) spreading center off the northwest coast of North America was first postulated in the late 1950's with the discovery of an undersea ridge and valley terrain.
		Gorda ridge spreads at the same rate as the JDFR and is extremely seismically active while the JDFR is aseismic.
		Endeavour Ridge was imaged by MCS in 1985 and a narrow (1 km) axial reflector was found at about 2.5 km depth beneath the ridge axis [Rohr et al., 1988].
	deeptow.whoi.edu /jdf.html (2413 words)

	Northern Gorda Ridge, Northeastern Pacific (Site not responding. Last check: 2007-10-22)
		The activity was located on the northernmost segment of the Gorda Ridge.
		The Gorda Ridge is a mid-ocean ridge (divergent plate boundary) about 120 miles (200 km) west of the coast of the state of Oregon.
		A similar seismic event was observed in June 1993 at the CoAxial Segment of the Juan de Fuca Ridge, which was later documented to be a lateral injection of magma with subsequent eruption.
	volcano.und.nodak.edu /vwdocs/current_volcs/gordo/gordo.html (269 words)

	MBARI - Mapping Program - West Coast Seamounts and Ridges Multibeam Survey
		The Gorda Ridge is an oceanic spreading center located off the coast of northern California and southern Oregon.
		The geologic setting and tectonics of the ridge were summarized by Clague and Holmes (1987) and Fisk and Howard (1993).The ridge axis has the typical deep axial valley of slow-spreading ridges.
		The ridge has a complex history due to spreading rate changes, intraplate deformation of the Gorda plate, and reorientation of the ridge axis (Wilson, 1986, 1989).
	www.mbari.org /data/mapping/seamounts/gorda_ridge.htm (444 words)

	Healy0102 (Site not responding. Last check: 2007-10-22)
		Gorda Ridge was selected as the operational area because it was convenient to Seattle and because it is similar to Gakkel Ridge in the high Arctic, which will be the main focus area of USCGC Healy's first major scientific expedition.
		The scientific return from the sampling and mapping of Gorda Ridge and adjoining fracture zones (see Section 5) shows the capabilities of Healy and her crew.
		Dredging was concentrated on the recently seismically active Jackson Segment of Gorda Ridge.
	www.uscg.mil /pacarea/iceops/heshake/Healy0102.htm (2822 words)

	ED&R Workshop Report (Site not responding. Last check: 2007-10-22)
		The pattern of the seismicity during the Gorda Ridge event, a rapid series of small earthquakes without a large "foreshock" and lasting roughly 3 weeks, was similar to that of the 1993 CoAxial event (Fox and Dziak, in press).
		The event was located on the northernmost segment of the Gorda Ridge near 42° 40’N and 126° 48’W in the vicinity of the ridge segment high ("Narrowgate").
		RIDGE is willing to generally maintain the web-site but its success depends on the input and updates from the community; the ERCC will 'encourage' participation from the research community.
	ridge.oce.orst.edu /edr/final-report.html (15886 words)

	The Escanaba Trough of Gorda Ridge: A Laboratory for Mineral-forming Processes - USGS Fact Sheet
		The Escanaba Trough of southern Gorda Ridge is a slowly-spreading ocean ridge that provides a unique perspective on the formation of world-class metal deposits.
		Because of the slow spreading rate of Gorda Ridge, it forms a deep trough that allows thick accumulations of sediment.
		The investigation of ocean ridges is relevant to our country's long-range resource picture and to the development of mineral-resource models.
	pubs.usgs.gov /fs/gorda-ridge (1107 words)

	Seismo-Watch Significant Earthquake Report - Gorda Ridge Volcanic Eruption, April 7, 2001
		The activity appears to be centered along the Jackson segment of the central Gorda Ridge and is too far from shore to propose any risk.
		The Gorda Ridge is a tectonic spreading center where two plates, the Pacific and Gorda, are moving in opposite directions from each other.
		The Gorda Ridge has produced two similar eruptions in recent times, one in 1996 and another in 1998.
	www.seismo-watch.com /EQS/AB/2001/010407.010.GordaEruption.html (376 words)

	dkadko-pubs
		Gorda Ridge Research Team, Hydrothermal Activity on the Gorda Ridge (1985).
		Radon-222 as a real time tracer of hydrothermal activity on the Gorda Ridge, Open File Report 0-86-14, State of Oregon, Department of Geology and Mineral Industries, 19 p.
		Evidence for high temperature venting on the Gorda Ridge, Northeast Pacific Ocean.
	www.rsmas.miami.edu /divs/mac/faculty/dkadko/dkadko-pubs.html (868 words)

	USA Today (Society for the Advancement of Education): More faults found off West Coast
		The Pacific Coast from northern British Columbia to Punta Gorda, near Cape Mendocino in California's Humboldt County, is the region known to geologists as the Cascadia Subduction Zone.
		The Gorda Plate, about 5,000,000 years old at the point where it enters the subduction zone, is a relatively young, hot, thin plate in geological terms.
		The Pacific Plate, south of the Gorda Plate, creeps northward about one inch a year along the California coast, compressing the Gorda Plate and triggering frequent small to moderately sized earthquakes within the plate.
	www.findarticles.com /p/articles/mi_m1272/is_2709_132/ai_n6059993 (507 words)

	Mid-ocean ridge research (Site not responding. Last check: 2007-10-22)
		The great majority of the Earth's volcanism occurs at spreading centers, most of which are under the ocean, forming the mid-ocean ridge system where new ocean crust is being created.
		The Earth's tectonic plates are slowly moving apart, and magma rises up to fill the gap, adding to the deep crust as sheeted dikes and sometimes flowing onto the seafloor as volcanic eruptions.
		The Gorda, Juan de Fuca and Endeavour Ridges have slow (~25 mm/yr) to moderate spreading rates, and are located off Oregon and Washington states and British Columbia.
	www.mbari.org /volcanism/Ridge/RidgeResearchTop.htm (252 words)

	Gorda Ridge Event, March 2005
		In summary, given that this recent sequence began with a large magnitude earthquake (5.2) and was followed by a relatively low number of events per hour that is consistent with aftershock activity, it seems likely this was a tectonic sequence and did not have a magmatic/hydrothermal component.
		Three magnitude 5.2, 5.1 and 4.3 earthquakes occurred on the northern Gorda Ridge segment over a 7.5 hr period beginning at 02:34Z on March 7.
		The SOSUS locations of these earthquakes is 42-32.1'N 126-55.2'W which is along a section of the Gorda Ridge that experienced a dike injection and seafloor eruption in 1996.
	www.pmel.noaa.gov /vents/acoustics/seismicity/nepac/gorda0305.html (186 words)

	05-14-02 SCIENTISTS DISCOVER HUNDREDS OF FAULTS OFF WEST COAST (Site not responding. Last check: 2007-10-22)
		The Pacific Coast from northern British Columbia to Punta Gorda, near Cape Mendocino in California's Humboldt County, is the region known to geologists as the Cascadia Subduction Zone, Chaytor said.
		The Gorda Plate, now about five million years old at the point where it enters the subduction zone, is a relatively young, hot and thin plate in geologic terms, Chaytor said.
		The Pacific Plate, south of the Gorda Plate, creeps northward about three centimeters a year along the California coast, compressing the Gorda Plate and triggering frequent small to moderately-sized earthquakes within the plate.
	oregonstate.edu /dept/ncs/newsarch/2002/May02/fault.htm (644 words)

	1999 Northcoast California Earthquakes of magnitude 4 or larger
		The earthquakes were associated with an undersea eruption on the Jackson segment of the Gorda Ridge.
		Submarine eruptions on the Gorda and Juan de Fuca ridges are relatively common, occurring on average about every two years.
		This was the largest of at least 13 earthquakes of magnitude 3.5 and larger centered on the Jackson segment of the northern Gorda ridge.
	www.humboldt.edu /~geology/earthquakes/01northcoast_eqs.html (508 words)

	Pacific Ocean ridge basalts (Site not responding. Last check: 2007-10-22)
		The ridge system in the Pacific is taken as beginning at 51 deg N, north of Vancouver Id and lies at first very close to the coast of N America.
		South of the Juan de Fuca Rise is the Gorda Ridge but along western USA whole sectors of spreading centre are being underthrust under the continent.
		The ridge sectors vary somewhat in composition, but even if 30,000 samples have been collected, this is proportionately a tiny sample when it is considered the ridge systems are a total of 45,000 miles long, being less than one sample per mile.
	www.geokem.com /oceanic-pacific.html (7080 words)

	Marine Fisheries Review: New ocean venting field found in eastern Pacific
		A team of government and academic scientists made the discovery in late October 1988 during a series of dives on the Gorda Ridge, using a U.S. Navy deep submergence vehicle, the DSV Sea Cliff, according to Peter Rona the team's chief scientist.
		The discovery was made as the party was carrying out geological and biological investigations of the northern Gorda Ridge.
		The expedition was coordinated by the Gorda Ridge Technical Task Force, a joint Federal-state working group established in 1984 by the secretary of the Department of the Interior and the governors of Oregon and California.
	www.findarticles.com /p/articles/mi_m3089/is_n1_v51/ai_9305387 (442 words)

	North Gorda Ridge Page
		In February 1996, an earthquake swarm was detected by the VENTS T-phase monitoring system on the northern Gorda Ridge.
		More information about this event can be found on the Gorda eruption homepage.
		Chadwick, W. Jr., Embley, R. W., and Shank, T. M., 1998, The 1996 Gorda Ridge eruption: Geologic mapping, sidescan sonar, and SeaBeam comparison results: Deep-Sea Research II, 45, 2547-2570.
	www.pmel.noaa.gov /vents/geology/gorda.html (228 words)

	Earth Change News on Earth Changes TV on the Web
		Scientists from NOAA used the T-phase Monitoring System to search for megaplumes from a possible eruption of the Jackson Segment of the Gorda Ridge that began on 3 April.
		The Jackson segment of the Gorda Ridge lies immediately SSW of the North Gorda segment, about 200 km W of the southern Oregon coast.
		A submarine lava flow was erupted in February-March 1996, near the center of the nearby North Gorda Ridge segment.
	www.earthchangestv.com /breaking/April_Part2_2001/0419jackson.htm (238 words)

	ED&R Workshop Announcement (Site not responding. Last check: 2007-10-22)
		With the second successful detection and response using the NE Pacific SOSUS system in 1996 on the northern Gorda Ridge, it is clear that we now have an accurate system for detection of volcanic intrusion/eruptions on one portion of the Mid-Ocean Ridge.
		In the case of the Gorda Ridge, event plumes were relocated over the Gorda Ridge more than three months after the onset of the most intense seismic episodes using a RAFOS float.
		Although several workshops within the past decade have discussed the importance of Mid-Ocean Ridge Event Detection and Response, there has not been an opportunity for the community to discuss the science, logistics, and technology of the detection and response to volcanic events in the SOSUS detection era.
	ridge.oce.orst.edu /edr/announce_edr.html (485 words)

	Kari Cooper - Gorda Ridge
		In addition to the uncertainty about the timescales of magma storage and differentiation which MOR systems share with subaerial systems, it is often more difficult to date recent undersea eruptions because the common dating alternatives used on land (historic activity witnessed by people, carbon dating of plant material overrun by flows) aren't available.
		Helens, where Ra/Ba in plag is higher than that predicted to be in equilibrium with the melt, despite major-element compositions consistent with crystal-liquid equilibrium.
		This precludes a straightforward age determination (although we can argue based on less direct evidence that the crystals are likely younger than ~1600 y) but, instead brings up the intriguing possibility that the crystals in the 96 Gorda flow grew rapidly and within a short time before eruption.
	www.geophys.washington.edu /cooper/Research/Gorda.html (373 words)

	UW Oceanography Faculty: Edward T. Baker (Site not responding. Last check: 2007-10-22)
		Baker, E.T., C.G. Fox and J.P. Cowen (submitted) In situ observations of the onset of hydrothermal discharge during the 1998 submarine eruption of Axial Volcano, Juan de Fuca Ridge.
		Cowen, J.P. and E.T. Baker (1998) The 1996 Gorda Ridge Event detection and response activities: Historical perspective and future implications.
		Cherkaoui, A.S.M., W.S.D. Wilcock and E.T. Baker (1997) Thermal fluxes associated with the 1993 diking event on the CoAxial Segment, Juan de Fuca Ridge: A model for the convective cooling of the dike.
	www.ocean.washington.edu /people/faculty/baker.pmel.noaa.gov.html (509 words)

	NOAA Ocean Explorer: Submarine Ring of Fire
		Largely because these ridges are close to major oceanographic research facilities, numerous important discoveries have been made in the Northeastern Pacific.
		Explorer Ridge is found northwest of the Juan de Fuca Ridge and offset by the Sovanco Fracture Zone.
		This technique has been used successfully on other portions of the Mid-Ocean Ridge to identify and localize active hydrothermal discharge (e.g., Baker et al., 1995) and to determine the first-order chemical composition of the fluids venting from the seafloor (Lupton et al., 1993; Baker et al., 1995).
	oceanexplorer.noaa.gov /explorations/02fire/background/plan/plan.html (987 words)

	Gorda Ridge Cruise Operations - USGS WR CMG
		On July 16, 1996, the NOAA ship Discoverer sailed from Seattle, Washington with 25 scientists (116 kb) from the USGS, NOAA and Williamson and Associates aboard.
		The cruise (D1-96-NC), with Robert Embley (NOAA, Newport, Oregon) and Kim Klitgord (USGS, Menlo Park, California) as co-chief scientists, successfully completed sidescan sonar studies of the Co-Axial segment of the Juan de Fuca Ridge (NOAA VENTS Program) and the Escanaba Trough on the southern Gorda Ridge.
		The AMS-60SI (98 kb) sidescan sonar system and 4.5 kHz sub-bottom profiler system leased and operated by Williamson and Associates were used for both surveys.
	walrus.wr.usgs.gov /gordaridge/disco.html (505 words)

	Tufts Submarine Fan: Turbidity-Current Gateway to Escanaba Trough (Site not responding. Last check: 2007-10-22)
		For this study, available 3.5-kHz high-resolution and airgun seismic-reflection data, long-range side-scan sonar images, and sediment core data are used to define the growth pattern of the fan.
		Tufts fan deposits have smoothed and filled in the linear ridge-and-valley relief over an area exceeding 23,000 km2 on the west flank of the Gorda Ridge.
		The southernmost part of the fan is represented by a thick (as much as 500 m) sequence of turbidite deposits ponded along more than 100 km of the northern flank of the Mendocino Fracture Zone.
	geopubs.wr.usgs.gov /bulletin/b2216 (360 words)

	USGS Fact Sheet: The Escanaba Trough of Gorda Ridge: A Laboratory for Mineral-forming Processes
		USGS Fact Sheet: The Escanaba Trough of Gorda Ridge: A Laboratory for Mineral-forming Processes
		Right: Location of Gorda Ridge and other ocean ridges (indicated by double lines) in the northeast Pacific Ocean.
		Photograph taken from submersible Alvin, courtesy of Bruce Taylor.
	marine.usgs.gov /fact-sheets/gorda (1065 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations (Site not responding. Last check: 2007-10-22)
		Geologic controls of hydrothermal discharge on the northern Gorda Ridge
		Hydrothermal activity at the TAG hydrothermal field, Mid-Atlantic ridge crest at 26/sup 0/N
		Intense CH{sub 4} plumes generated by serpentinization of ultramafic rocks at the intersection of the 15{degree}20[minutes]N fracture zone and the Mid-Atlantic Ridge
	www.osti.gov /energycitations/searchresults.jsp?Author=Rona,+P.A. (247 words)

	REFERENCES
		Chemistry of hydrothermal fluids from the Escanaba Trough, Gorda Ridge.
		Formation and transformation of clay minerals in the sedimentary sequence of Middle Valley, Juan de Fuca Ridge, ODP Leg 169.
		Sediment alteration associated with massive sulfide formation in Escanaba Trough, Gorda Ridge: the importance of seawater mixing and magnesium metasomatism.
	www-odp.tamu.edu /publications/169_SR/chap_06/c6_10.htm (767 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		Energy Citations Database (ECD) Document #6739797 - Sonobuoy array measurements of active faulting on the Gorda Ridge
		Availability information may be found in the Availability, Publisher, Research Organization, Resource Relation and/or Author (affiliation information) fields and/or via the "Full-text Availability" link.
		Sonobuoy array measurements of active faulting on the Gorda Ridge
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=6739797 (94 words)

	Amazon.com: Gorda Ridge: A Seafloor Spreading Center in the United States' Exclusive Economic Zone : Proceedings of the ... (Site not responding. Last check: 2007-10-22)
		Amazon.com: Gorda Ridge: A Seafloor Spreading Center in the United States' Exclusive Economic Zone : Proceedings of the Gorda Ridge Symposium May 11-13, 1987, Po: Books
		This item is not eligible for Amazon Prime, but over a million other items are.
		Gorda Ridge: A Seafloor Spreading Center in the United States' Exclusive Economic Zone : Proceedings of the Gorda Ridge Symposium May 11-13, 1987, Po (Hardcover)
	www.amazon.com /exec/obidos/tg/detail/-/0387970347?v=glance (252 words)

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