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Sierra Negra

Negra, Sierra

Shield volcano · Ecuador · 1124m

An aerial view of the SW caldera floor of Sierra Negra volcano shows El Azufre fumarolic field and the trap-door fault to the left. This sinuous 14-km-long, N-S-trending ridge occupies the west part of the caldera floor, which lies only about 100 m below its rim. El Azufre, the largest fumarolic area in the Galápagos Islands, lies within a graben between this ridge and the west caldera wall. The broad shield volcano of Sierra Negra at the southern end of Isabela Island contains a shallow 7 x 10.5 km caldera that is the largest in the Galápagos Islands.
An aerial view of the SW caldera floor of Sierra Negra volcano shows El Azufre fumarolic field and the trap-door fault to the left. This sinuous 14-km-long, N-S-trending ridge occupies the west part of the caldera floor, which lies only about 100 m below its rim. El Azufre, the largest fumarolic area in the Galápagos Islands, lies within a graben between this ridge and the west caldera wall. The broad shield volcano of Sierra Negra at the southern end of Isabela Island contains a shallow 7 x 10.5 km caldera that is the largest in the Galápagos Islands. · Photo: Photo by Patricio Ramon, 2005 (Instituto Geofisca, Escuela Politecnica Nacional). · Wikimedia Commons
Type
Shield volcano
Country
Ecuador
Region
Eastern Pacific Volcanic Regions / Galapagos Hotspot Volcano Group
Elevation
1124m
Coordinates
-0.830, -91.170
Last eruption
2018
Tectonic setting
Rift zone / Oceanic crust (< 15 km)
Landform
Shield
Major rock type
Basalt / Picro-Basalt
Geological summary

The broad shield volcano of Sierra Negra at the southern end of Isabela Island contains a shallow 7 x 10.5 km caldera that is the largest in the Galápagos Islands. Flank vents abound, including cinder cones and spatter cones concentrated along an ENE-trending rift system and tuff cones along the coast and forming offshore islands. Although it is the largest of the five major Isabela volcanoes, it has the flattest slopes, averaging less than 5° and diminishing to 2° near the coast. A sinuous 14-km-long, N-S-trending ridge occupies the west part of the caldera floor, which lies only about 100 m below its rim. The Volcán de Azufre fumarolic area lies within a graben between this ridge and the west caldera wall. Lava flows from a major eruption in 1979 extend all the way to the north coast from circumferential fissure vents on the upper northern flank.

From Wikipedia

Sierra Negra is a large shield volcano at the southeastern end of Isabela Island in the Galapagos that rises to an altitude of 1124m. It coalesces with the volcanoes Cerro Azul to the west and Alcedo to the north. It is one of the most active of the Galapagos volcanoes with the most recent historic eruption beginning in June 2018 and continuing through the summer.

Wikipedia · CC BY-SA · Read full article →

Eruption history

Summary (VEI over time)
Click a bar to see individual eruptions
8250 BCE~7908 BCE · 1 eruptions · max VEI 01405 BCE~1062 BCE · 1 eruptions · max VEI 0307~649 · 1 eruptions · max VEI 0991~1333 · 1 eruptions · max VEI 01333~1676 · 1 eruptions · max VEI 01676~2018 · 13 eruptions · max VEI 38250 BCE5854 BCE3116 BCE720 BCE1676

Detailed timeline

  1. 2018VEI 2Observed
    2018-06-26 – 2018-08-23
    Summit crater and NNW flank, Volcan Chico fissure vent
  2. 2005VEI 3Observed
    2005-10-22 – 2005-10-30
    North caldera rim
  3. 1979VEI 3Observed
    1979-11-13 – 1980-01-14
    Upper NW and NE flanks (Volcán Chico)
  4. 1963VEI 2Observed
    1963-04-13 – 1963-05-16
    Volcán Chico area & NW caldera rim
  5. 1957VEI ?Geological estimate
    1957-07-02 – Ongoing
    Volcano Uncertain: Isabela Island
  6. 1954VEI 2Geological estimate
    1954-11-09 – Ongoing
    Volcano Uncertain: originally Alcedo
  7. 1953VEI 3Observed
    1953-08-27 – 1954-01-16
    Volcán Chico area & NW caldera rim
  8. 1948VEI 2Observed
    1948-08 – 1949-02
  9. 1911VEI ?Observed
    1911-12-31 – Ongoing
  10. 1860VEI 2Geological estimate
    1860 – Ongoing
    Volcano Uncertain: Isabela Island
  11. 1844VEI 0Geological estimate
    1844 – Ongoing
    Volcano Uncertain: Isabela Island
  12. 1817VEI ?Geological estimate
    1817 – Ongoing
    Volcano Uncertain: Isabela Island
  13. 1813VEI 2Geological estimate
    1813-07-13 – Ongoing
    Volcano Uncertain: South end of Isabela Island
  14. 1350 (±500 yrs)VEI 0Geological estimate
    1350 – Ongoing
  15. 1060 (±500 yrs)VEI 0Geological estimate
    1060 – Ongoing
  16. 370 (±1100 yrs)VEI 0Geological estimate
    370 – Ongoing
  17. 1250 BCE (±100 yrs)VEI 0Geological estimate
    BCE 1250 – Ongoing
    SE flank
  18. 8250 BCE (±1600 yrs)VEI 0Geological estimate
    BCE 8250 – Ongoing

External links

⚠ For reference only. Not for emergency response.