San Jorge

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 38.65°N
  • 28.08°W

  • 1053 m
    3454 ft

  • 382030
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for San Jorge.

The Global Volcanism Program has no Weekly Reports available for San Jorge.

The Global Volcanism Program has no Bulletin Reports available for San Jorge.

The remarkably linear island of San Jorge (Sao Jorge) is 54 km long and only 5 km wide. It was formed by fissure-fed eruptions beginning in the eastern part of the island. The western two-thirds of dominantly basaltic San Jorge contains youthful, fissure-fed lava flows resembling those on neighboring Pico Island. Subaerial lava flows issued from three locations above the south-central coast during 1580, producing lava flows that reached the sea. In 1808 a series of explosions took place from vents along the south-central crest of the island; one of these fed a lava flow that also reached the southern coast. Submarine eruptions were reported on several occasions from vents off the southern and SW coasts.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
[ 1964 Feb 18 ] [ Unknown ] Uncertain 0   Off SW coast
1907 Unknown Confirmed 0 Historical Observations
1902 May 7 1902 May 8 Confirmed 0 Historical Observations Subm. vent ca. 20 km SW of Terceira
1808 May 1 1808 Jun 10 Confirmed 1 Historical Observations Sao Jorge
1800 Jun 24 1800 Jun 25 Confirmed 2 Historical Observations Subm. vent ca. 20 km SW of Terceira
1757 Jul 9 1757 Jul 10 Confirmed 0 Historical Observations Off south coast of Sao Jorge
1580 May 1 1580 Aug 30 (?) Confirmed 3 Historical Observations Sao Jorge (SW side)

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.



Synonyms
Sao Jorge
A Space Shuttle image with north to the upper left shows the remarkably linear island of San Jorge (Sao Jorge), which is 54 km long and only 5 km wide. The NW-SE-trending island was formed by fissure-fed eruptions. Historical eruptions in 1580 AD originated from three locations above and to the east of the coastal town of Velas, the small light-colored area along the SW coast (bottom left side), producing lava flows that reached the sea. Submarine eruptions were reported on several occasions from vents off the southern and SW coasts.

NASA Space Shuttle image ISS004-E-10891, 2002 (http://eol.jsc.nasa.gov/).
Pico da Velha is seen in this view of the interior of the island of San Jorge. The remarkably linear island (also known as Sao Jorge) is 54 km long and only 5 km wide. It was formed by fissure-fed eruptions beginning in the eastern part of the island, and the western two-thirds of the island contains youthful, fissure-fed lava flows resembling those on neighboring Pico Island. Historical eruptions have produced lava flows that reached the sea, and submarine eruptions were reported from vents off the southern and SW coasts.

Photo by Luís A. da Silveira, 2007 (Wikimedia Commons).

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.

Forjaz V H, Fernandes N S M, 1975. Geologic map of Ilha de San Jorge (Azores). Servicos Geologicos Portugal, 1:50,000 scale map with 32 p text (in Portuguese).

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Neumann van Padang M, Richards A F, Machado F, Bravo T, Baker P E, Le Maitre R W, 1967. Atlantic Ocean. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 21: 1-128.

Volcano Types

Fissure vent

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Rock Types

Major
Basalt / Picro-Basalt
Andesite / Basaltic Andesite
Minor
Trachyte / Trachyandesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
2,088
4,689
16,290
99,442

Affiliated Databases

Large Eruptions of San Jorge 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.