Cleft Segment

Photo of this volcano
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 44.83°N
  • 130.3°W

  • -2140 m
    -7019 ft

  • 331030
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

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 (see Caption) 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 (see Caption) 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:

Eruptive History


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


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1986 Aug 16 (?) ± 15 days Unknown Confirmed 0 Historical Observations N Cleft Segment, S Juan de Fuca Ridge
1982 Jul 2 (in or before) ± 182 days 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.

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).
See title for photo information.

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