Cobb Segment

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  • Country
  • Subregion Name
  • Primary Volcano Type
  • Last Known Eruption
  • 46.88°N
  • 129.33°W

  • -2100 m
    -6888 ft

  • 331011
  • Latitude
  • Longitude

  • Summit

  • Volcano

There are no activity reports for Cobb Segment.

 Available Weekly Reports

There are no Weekly Reports available for Cobb Segment.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1180 BCE (?) Unknown Confirmed 1 Uranium-series

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. 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. Additional discussion of data sources can be found under Volcano Data Criteria.

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.

Christeson G L, Purdy G M, Rohr K M M, 1993. Structure of the Northern Symmetrical Segment of the Juan de Fuca Ridge. Mar Geophys Res, 15: 219-240.

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.

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.

The Cobb Segment in the northern part of the Juan de Fuca Ridge, lies south of the Endeavour Ridge segment. Also known as the Northern Symmetrical or NSymm Segment, the 150-km-long Cobb Segment is the longest of the Juan de Fuca Ridge. It has a narrow, 1-2 km wide axial crest with a shallow graben that has a high point at a depth of about 2300 m. A prominent seamount with hydrothermal deposits at its summit lies just west of the axis high and was the source of a broad area of young, mostly sediment-free lava flows. As with other Juan de Fuca Ridge segments, a shallow magma chamber is thought to underlie the Cobb Segment, and a preliminary uranium-series date of Holocene age was obtained on a basaltic lava flow from the Cobb Segment.