San Jorge

Photo of this volcano
Google Earth icon
  Google Earth Placemark
  • 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.

Basic Data

Volcano Number

Last Known Eruption

Elevation

Latitude
Longitude
382030

1907 CE

1053 m / 3454 ft

38.65°N
28.08°W

Volcano Types

Fissure vent

Rock Types

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

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Population

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

Geological Summary

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.

References

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

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.

Eruptive History


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

Photo Gallery


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).

Smithsonian Sample Collections Database


A listing of samples from the Smithsonian collections will be available soon.

Affiliated Sites

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).
MODVOLC - HIGP MODIS Thermal Alert System 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.
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.