Global Volcanism Program

Most Recent Bulletin Report: September 1987 (Ref 1989)

New lava mounds along ridge

[Comparison of September 1987 SeaBeam data with a single 1983 SeaBeam pass and a more detailed 1981 survey revealed a series of new lava mounds along a segment of the Juan de Fuca Ridge from about 45.01°N to 45.15°N, 130.15°W (figure 1). No seismic data are available and no eruption time(s) can be definitively established. However, large hydrothermal "megaplumes" that may have occurred during the same rifting episode were detected by research vessels in mid-August 1986 and mid-September 1987 (Baker and others, 1989).]

Figure 1. SeaBeam bathymetric map of the southern Juan de Fuca Ridge (uncorrected for sound velocity), from Embley and others, 1991. Contour interval, 100 m. Temperature anomaly contours (°C) of megaplumes I (August 1986) and II (September 1987) are from Baker and others, 1989. Pillow mounds are shown in black, the zone of young sheet-flows is indicated by diagonal shading, and high-temperature vents are marked by stars.

References. Baker, E.T., Lavelle, J.W., Feely, R.A., Massoth, G.J., and Walker, S.L., 1989, Episodic venting of hydrothermal fluids from the Juan de Fuca Ridge: JGR, v. 94, p. 9237-9250.

Embley, R.W., Chadwick, W., Perfit, M.R., and Baker, E.T., 1991, Geology of the Northern Cleft Segment, Juan de Fuca Ridge: recent lava flows, sea-floor spreading, and the formation of megaplumes: Geology, v. 19, p. 771-775.

Information Contacts:

The Global Volcanism Program has no Weekly Reports available for Cleft Segment.

Bulletin Reports - Index

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

09/1987 (Ref 1989) New lava mounds along ridge

Information is preliminary and subject to change. All times are local (unless otherwise noted)

September 1987 (Ref 1989)

New lava mounds along ridge

[Comparison of September 1987 SeaBeam data with a single 1983 SeaBeam pass and a more detailed 1981 survey revealed a series of new lava mounds along a segment of the Juan de Fuca Ridge from about 45.01°N to 45.15°N, 130.15°W (figure 1). No seismic data are available and no eruption time(s) can be definitively established. However, large hydrothermal "megaplumes" that may have occurred during the same rifting episode were detected by research vessels in mid-August 1986 and mid-September 1987 (Baker and others, 1989).]

Figure 1. SeaBeam bathymetric map of the southern Juan de Fuca Ridge (uncorrected for sound velocity), from Embley and others, 1991. Contour interval, 100 m. Temperature anomaly contours (°C) of megaplumes I (August 1986) and II (September 1987) are from Baker and others, 1989. Pillow mounds are shown in black, the zone of young sheet-flows is indicated by diagonal shading, and high-temperature vents are marked by stars.

References. Baker, E.T., Lavelle, J.W., Feely, R.A., Massoth, G.J., and Walker, S.L., 1989, Episodic venting of hydrothermal fluids from the Juan de Fuca Ridge: JGR, v. 94, p. 9237-9250.

Embley, R.W., Chadwick, W., Perfit, M.R., and Baker, E.T., 1991, Geology of the Northern Cleft Segment, Juan de Fuca Ridge: recent lava flows, sea-floor spreading, and the formation of megaplumes: Geology, v. 19, p. 771-775.

Information Contacts:

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Thermal

Feature Name

Feature Type

Elevation

Latitude

Longitude

Fountain Vent

Thermal

45° 0' 0" N

130° 12' 0" W

Monolith Vent

Thermal

44° 59' 0" N

130° 12' 0" W

Pipe Organ Vent

Thermal

44° 58' 0" N

130° 13' 0" W

Table Vent

Thermal

44° 59' 0" N

130° 12' 0" W

Basic Data

Volcano Number

Last Known Eruption

Elevation

Latitude
Longitude

331030

1986 CE

-2140 m / -7019 ft

44.83°N
130.3°W

Volcano Types

Submarine
Fissure vent(s)

Rock Types

Major
Basalt / Picro-Basalt

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km

0
0
0
0

Geological Summary

The Cleft Segment, the southernmost of the Juan de Fuca Ridge, lies immediately north of the Blanco Fracture Zone. The 80-km-long segment is named for a nearly continuous 10-km-long, 30-50 m wide cleft at its southern end. Two episodes of sea-floor spreading have been documented along the northern part of the Cleft Segment in the 1980's. Bathymetric surveys indicated that a series of discontinuous pillow-lava mounds were extruded along a 17-km-long fissure between 1981 and 1987. The eruption possibly took place at the time of emission of a large plume of hot mineral-laden water in 1986. The location is at a depth of about 2300 m near the northern edge of the Cleft segment and the southern end of the Vance segment of the Juan de Fuca Ridge, about 500 km west of the central Oregon coast. Youthful sheet-lava flows immediately south of the pillow lavas were estimated to be only a few years older.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Baker E T, 1991. Megaplumes. Oceanus, 34: 84-91.

Carbotte S M, Detrick R S, Harding A, Canales J P, Babcock J, Kent G, Van Ark E, Nedimovic M, Diebold J, 2006. Rift topography linked to magmatism at the intermediate spreading Juan de Fuca Ridge. Geology, 34: 299-212.

Chadwick W W Jr, Embley R W, 1994. Lava flows from a mid-1980s submarine eruption of the Cleft segment, Juan de Fuca Ridge. J Geophys Res, 99: 4761-4776.

Chadwick W W Jr, Embley R W, Fox C G, 1991. Evidence for volcanic eruption on the southern Juan de Fuca ridge between 1981 and 1987. Nature, 350: 416-418.

Embley R W, Chadwick W W Jr, Perfit M R, Baker E T, 1991. Geology of the northern Cleft Segment, Juan de Fuca Ridge: recent lava flows, sea-floor spreading, and the formation of megplumes. Geology, 19: 771-775.

Goldstein S J, Murrell M T, Janecky D R, Delaney J R, Clague D A, 1992. Geochronology and petrogenesis of MORB from the Juan de Fuca and Gorda ridges by 238U-230Th disequilibrium. Earth Planet Sci Lett, 109: 255-272.

Koski R A, Jonasson I R, Kadko D C, Smith V K, Wong F L, 1994. Compositions, growth mechanisms, and temporal relations of hydrothermal sulfide-sulfate-silica chimneys at the northern Cleft Segment, Juan de Fuca Ridge. J Geophys Res, 99: 4813-4832.

Perfit M R, Chadwick W W Jr, 1998. Magmatism at Mid-Ocean ridges: constraints from volcanological and geochemical investigations. In: Buck W R, Delaney P T, Karson J A, Lagabrielle Y (eds) Faulting and Magmatism at Mid-Ocean Ridges {Amer Geophys Union Geophys Monograph} 106: 59-115.

Smith M C, Perfit M R, Jonasson I R, 1994. Petrology and geochemistry of basalts from the southern Juan de Fuca: controls on the spatial and temporal evolution of mid-ocean ridge basalt. J Geophys Res, 99: 4787-4812.

Volpe A M, Goldstein S J, 1993. 236Ra-230Th disequilibrium in axial and off-axis mid-oecan ridge basalts. Geochim Cosmochim Acta, 57: 1233-1241.

Eruptive History

There is data available for 3 Holocene eruptive periods.

Start Date	Stop Date	Eruption Certainty	Evidence	Activity Area or Unit
1986 Aug 16 (?) ± 15 days	Unknown	Confirmed	Historical Observations	N Cleft Segment, S Juan de Fuca Ridge
1982 Jul 2 (in or before) ± 182 days	Unknown	Confirmed	Historical Observations	N Cleft Segment, S Juan de Fuca Ridge
0270 BCE (?)	Unknown	Confirmed	Uranium-series	S Cleft Segment, S Juan de Fuca Ridge

Deformation History

There is no Deformation History data available for Cleft Segment.

Emission History

There is no Emissions History data available for Cleft Segment.

Photo Gallery

"Black Smoker" vents are active along the Cleft Segment, the southernmost of the Juan de Fuca Ridge. These sustained high-temperature vents were photographed along fissures that fed an older lava flow adjacent to a sea-floor lava flow that was emplaced in 1986 during the second of two documented submarine eruptions in the 1980s. The 80-km-long Cleft Segment is located immediately north of the Blanco Fracture Zone about 500 km off the Oregon coast.

Image courtesy of National Oceanic and Atmospheric Administration (http://www.pmel.noaa.gov/vents/home.html).

Smithsonian Sample Collections Database

There are no samples for Cleft Segment in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites

WOVOdat
   Single Volcano View
   Temporal Evolution of Unrest
   Side by Side Volcanoes

WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.

Large Eruptions of Cleft Segment

Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).

MIROVA

Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.

MODVOLC Thermal Alerts

Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.

EarthChem

EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).