Isla San Luis

Photo of this volcano
Google Earth icon
  Google Earth Placemark
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 29.97°N
  • 114.4°W

  • 180 m
    590 ft

  • 341003
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for Isla San Luis.

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

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

Isla San Luis is the largest of the seven Encantada islands at the NW end of the Guaymas lineament in the northern part of the Gulf of California. The roughly 180-m-high island (also known as La Encantada Mayor, or Salvatierra) is located 3 km off the eastern shore of Baja California north of Punta Bufeo. The small 4.5 sq km island has an irregular shoreline with a narrow peninsula forming its SW tip. Initial basaltic-andesite and andesitic submarine surtseyan eruptions producing palagonite tuffs were followed by the effusion of subaerial dacitic lava flows and the formation of dacitic tuff rings. The latest eruptions formed two rhyolitic obsidian domes, the younger in a tuff cone at the center of the island and at the older at the NW tip of the island. Although the age of the domes is not known precisely, Medina et al. (1989) suggested that they could be less than a century old.

The Global Volcanism Program is not aware of any Holocene eruptions from Isla San Luis. If this volcano has had large eruptions (VEI >= 4) prior to 10,000 years ago, information might be found on the Isla San Luis page in the LaMEVE (Large Magnitude Explosive Volcanic Eruptions) database, a part of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).

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

Encantada Mayor, La | Salvatierra

Cones

Feature Name Feature Type Elevation Latitude Longitude
Plaza de Toros Tuff ring 50 m 29° 58' 0" N 114° 24' 0" W
Poma, Isla Tuff ring 29° 59' 0" N 114° 23' 0" W
Isla San Luis, viewed here from the SW with a large rhyolitic lava dome at the left center, is the largest of the seven Encantada islands in the northern part of the Gulf of California. The roughly 180-m-high island lies 3 km off the eastern shore of Baja California. An older lava dome forms the NE tip of the island, and a dissected tuff ring lies at the SE tip. The lava dome seen here in the center of the island was constructed within a tuff cone and is the youngest volcanic product of Isla San Luis.

Photo by Brian Hausback, 1997 (California State University, Sacramento).
Isla San Luis is seen here from the south with a 2-km-long spit (at low tide) at the lower left. Three major vents, a rhyolitic lava dome forming the NW tip of the island, the central rhyolitic obsidian dome, and a dissected dacitic tuff ring at the SE tip of the island, were erupted along a trend parallel to a transform fault in the Gulf of California. Another tuff ring, Isla Poma, lies 1 km NE of Isla San Luis and is visible at the upper right.

Photo by Brian Hausback, 2000 (California State University, Sacramento).
Isla San Luis lies across a narrow channel from the NE coast of Baja California (visible in the background). The center of the small island is dominated by a dramatic dark-colored rhyolitic obsidian dome. An older dome, partially mantled by ash and pumice from the central dome, forms the northern part of the island (foreground). A dissected tuff ring, Plaza de Toros, occupies the SE end of the island. A sequence of rocks ranging from initial basaltic-andesite and andesitic palagonite tuffs to rhyolitic lava domes was erupted during a short time interval.

Photo by Keith Sutter, 2000.
The Plaza de Toros tuff ring on the SE side of Isla San Luis, seen here from the east, has been partially dissected by wave erosion. Remnants of dacitic lava flows are visible in the upper walls of the crater. Only a third of the tuff ring is still standing; the remainder subsided along normal faults or was removed by wave erosion. Longshore currents have redistributed friable volcanic ejecta from the cone to produce the dramatic tombolo at the upper right that forms the SW tip of the island and is 2 km long at low tide.

Photo by Keith Sutter, 2000.
A dramatic youthful obsidian dome occupies the center of Isla San Luis off the NE coast of Baja California. The dome was constructed within a tuff cone whose rim is visible immediately in front of the dome. As growth of the dome continued in the central vent (left foreground), a thick coulee advanced to the south and overflowed the SE rim of the tuff cone, forming the broad lobe behind it. The age of the extremely youthful rhyolitic dome is not known. The dissected Plaza de Toros tuff ring in the left background forms the SE tip of the island.

Photo by Keith Sutter, 2000.

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.

Gastil R G, Phillips R P, Allison E C, 1975. Reconnaissance geology of the State of Baja California. Geol Soc Amer Mem, 140: 1-170.

Medina F, Suarez F, Espindola J M, 1989. Historic and Holocene volcanic centers in NW Mexico. Bull Volc Eruptions, 26: 91-93.

Paz Moreno F A, Demant A, 1999. The Recent Isla San Luis volcanic centre: petrology of a rift-related volcanic suite in the northern Gulf of California, Mexico. J Volc Geotherm Res, 93: 31-52.

Volcano Types

Tuff cone
Lava dome(s)
Tuff ring(s)

Tectonic Setting

Rift zone
Continental crust (> 25 km)

Rock Types

Major
Rhyolite
Dacite
Andesite / Basaltic Andesite
Basalt / Picro-Basalt
Minor
Trachyandesite / Basaltic trachy-andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
0
1
606
18,532

Affiliated Databases

Large Eruptions of Isla San Luis 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.