Cleft Segment

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 44.83°N
  • 130.3°W

  • -2140 m
    -7019 ft

  • 331030
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Cleft Segment.

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

Index of Monthly Reports

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

Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

09/1987 (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.

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.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1986 Aug (?) Unknown Confirmed 0 Historical Observations N Cleft Segment, S Juan de Fuca Ridge
1982 (in or before) Unknown Confirmed 0 Historical Observations N Cleft Segment, S Juan de Fuca Ridge
0270 BCE (?) Unknown Confirmed 0 Uranium-series S Cleft Segment, S Juan de Fuca Ridge

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.

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
"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 (

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

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 on 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.

Volcano Types

Fissure vent(s)

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Rock Types

Basalt / Picro-Basalt


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

Affiliated Databases

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).
WOVOdat 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.
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).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.