Azul, Cerro (Ecuador): Recorded Eruptions and Historical Activity

Cerro Azul is a shield volcano located in Ecuador, standing at an elevation of 1,640 meters within a rift zone and oceanic crust setting (< 15 km). According to the Smithsonian Global Volcanism Program's official record, the volcano has a confirmed total of 14 eruptions spanning from ancient history up to the 21st century. The historical record includes documented events utilizing both modern observational reporting and scientific dating methods such as cosmic ray exposure.

Eruption History and Chronology

The confirmed eruption record for Cerro Azul dates back to 950 BCE (with a start year uncertainty of 900 years) and extends through 2008 CE. Across the full collection of 14 confirmed eruptions, activity has been distributed unevenly across centuries, with the highest concentration of recorded events occurring during the 20th century CE.

The distribution of confirmed eruptions by century includes:

• 6th century BCE: 1 eruption
• 10th century BCE: 1 eruption
• 13th century CE: 1 eruption
• 19th century CE: 1 eruption
• 20th century CE: 9 eruptions
• 21st century CE: 1 eruption

Notable Recorded Eruptions

Eruptions at Cerro Azul have varied in style, location, and magnitude. Out of the 14 total confirmed events, 12 have assigned Volcanic Explosivity Index (VEI) values, with the largest recorded VEI reaching 3.0.

Selected examples from the official eruption record illustrate the variety of documented activity:

• 950 BCE: An early confirmed eruption identified via isotopic cosmic ray exposure methods (eruption number 11714, VEI 0.0).
• 1850 CE: A confirmed eruption starting around July 2, 1850, noted with a start year modifier indicating an approximate or open-ended initial timeframe.
• 1943 CE: An explosive event along the caldera ring fracture lasting from April 13, 1943, to May 11, 1943, with a recorded VEI of 3.0.
• 1959 CE: An eruption originating from the east flank, spanning from June 29, 1959, to July 31, 1959, with a recorded VEI of 2.0.
• 2008 CE: The latest recorded eruption in the official database, taking place at the summit and southeast flank from May 29, 2008, to June 17, 2008, with a recorded VEI of 1.0.

None of the historical eruption records are marked as continuing; all documented events concluded within their respective observation periods. The last known eruption year listed in the profile is 2008.