Cotopaxi

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  • Ecuador
  • Ecuador
  • Stratovolcano
  • 1940 CE
  • Country
  • Subregion Name
  • Primary Volcano Type
  • Last Known Eruption
  • 0.677°S
  • 78.436°W

  • 5911 m
    19388 ft

  • 352050
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

7 September-13 September 2005

During 29 August to 4 September, the number of long-period and hybrid earthquakes at Cotopaxi decreased slightly, and the number of volcano-tectonic earthquakes increased, in comparison to the previous week. No changes in deformation were recorded, and no surficial changes were seen at the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)



 Available Weekly Reports


2005: August | September
2004: January
2003: November | December


7 September-13 September 2005

During 29 August to 4 September, the number of long-period and hybrid earthquakes at Cotopaxi decreased slightly, and the number of volcano-tectonic earthquakes increased, in comparison to the previous week. No changes in deformation were recorded, and no surficial changes were seen at the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


31 August-6 September 2005

During 22-28 August, a large number of long-period (LP) and hybrid earthquakes continued to be recorded at Cotopaxi. Increased seismicity was first recorded in late July. Most of the events recorded during the report period were small, and were recorded mainly at stations nearest to the crater. Also, several LP earthquakes correlated with increased activity at fumaroles in the crater. No deformation or surficial changes were observed at the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


17 August-23 August 2005

A seismic anomaly that began at Cotopaxi in late July continued through 14 August. During this period, there was an increase in the number of long-period earthquakes in comparison to previous months. The earthquakes were less than M 3 and occurred at depths between 1 and 2 km below the volcano. Several of the earthquakes correlated with increases in the volume of fumarole emissions in the crater. No carbon dioxide was detected when measurements were made during 8-14 August.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


7 January-13 January 2004

During 29 December to 4 January, the number of earthquakes at Cotopaxi slightly increased in comparison to the previous week. On 2 January a strong smell of sulfur was reported in the Yanasacha area.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


24 December-30 December 2003

During 15-21 December, there was a slight reduction in the level of seismicity at Cotopaxi in comparison to the previous week. The number of long-period earthquakes increased around 20 December. No volcano-tectonic earthquakes were recorded. Only fumarolic activity was observed at the volcano.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


17 December-23 December 2003

Seismicity at Cotopaxi during 8-14 December was above background levels, much like the previous week. During the report period, there was an increase in high-frequency tremor, but it remained within "normal" limits. A weak scent of sulfur was reported and steam columns rose to low levels.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


26 November-2 December 2003

During 10-16 November, seismicity at Cotopaxi was at moderate levels, although it had increased in comparison to previous weeks. During the report period, seismicity was dominated by long-period earthquakes. Since late October volcano-tectonic earthquakes occurred beneath the zone of Pita and beneath the volcano's edifice. These events were less than M 3 and were not felt by the local population.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)


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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
[ 1942 Feb 17 ] [ 1942 Feb 19 ] Uncertain 3  
1940 Unknown Confirmed 2 Historical Observations
1939 Feb 2 Unknown Confirmed 2 Historical Observations
1931 Unknown Confirmed 2 Historical Observations
1926 Unknown Confirmed 2 Historical Observations
1922 Unknown Confirmed 2 Historical Observations
1908 1914 Confirmed 1 Historical Observations
1907 Jun Unknown Confirmed 2 Historical Observations
1906 Aug 21 1906 Sep 19 Confirmed 2 Historical Observations
1905 Unknown Confirmed 2 Historical Observations
1903 Sep 26 1904 Dec Confirmed 3 Historical Observations
1895 Unknown Confirmed 2 Historical Observations
1886 Jan Unknown Confirmed 2 Historical Observations
1885 Jul 23 Unknown Confirmed 2 Historical Observations
1883 Dec Unknown Confirmed 2 Historical Observations
1883 Aug Unknown Confirmed 2 Historical Observations
1882 Jan 1882 Mar Confirmed 2 Historical Observations
1880 Feb 1880 Jul Confirmed 3 Historical Observations
1879 Feb 26 1879 Jun 19 Confirmed 2 Historical Observations
1878 Aug 23 1878 Aug 24 Confirmed 2 Historical Observations
1877 Jan 1877 Sep 2 Confirmed 4 Historical Observations
1870 1876 Confirmed 2 Historical Observations
1869 Jul 1869 Aug Confirmed 3 Historical Observations
1868 Aug 15 1868 Aug 16 Confirmed 2 Historical Observations
1867 Unknown Confirmed 2 Historical Observations
1866 Sep 21 1866 Sep 26 Confirmed 2 Historical Observations
1863 Unknown Confirmed 2 Historical Observations
1860 1862 Confirmed 2 Historical Observations
1859 Unknown Confirmed 2 Historical Observations
1858 Nov 1858 Dec Confirmed 2 Historical Observations
1857 Unknown Confirmed 2 Historical Observations
1856 Oct 1856 Dec Confirmed 2 Historical Observations
1856 May Unknown Confirmed 2 Historical Observations
1855 Nov Unknown Confirmed 2 Historical Observations
1854 Sep 14 Unknown Confirmed 2 Historical Observations
1854 Apr 3 Unknown Confirmed 2 Historical Observations
1853 Sep 13 1853 Sep 15 Confirmed 3 Historical Observations
1852 Unknown Confirmed 2 Historical Observations
1851 Jun Unknown Confirmed 2 Historical Observations
1850 Unknown Confirmed 2 Historical Observations
1845 Apr Unknown Confirmed 2 Historical Observations
1844 Unknown Confirmed 2 Historical Observations
1803 Jan 4 1803 Jan 5 Confirmed 3 Historical Observations
1768 Apr 4 Unknown Confirmed 4 Historical Observations
1766 Feb 10 1766 Dec Confirmed 3 Historical Observations
1750 Sep 2 ± 1 days 1750 Sep 4 ± 1 days Confirmed 2 Historical Observations
1747 1749 Confirmed 2 Historical Observations
1746 Feb Unknown Confirmed 2 Historical Observations
1744 May 1744 Dec Confirmed 4 Historical Observations
1743 Sep 27 1743 Oct 4 Confirmed 2 Historical Observations
1743 Apr Unknown Confirmed 3 Historical Observations
1742 Dec 9 Unknown Confirmed 3 Historical Observations
1742 Jun 15 1742 Jul Confirmed 3 Historical Observations
1740 1741 Confirmed 2 Historical Observations
1738 Unknown Confirmed 2 Historical Observations
1698 Unknown Confirmed 3 Historical Observations
1534 Jun 1534 Jul Confirmed 4 Historical Observations Tephra set MZ
1533 Oct 1533 Nov Confirmed 2 Historical Observations
1532 Nov 15 Unknown Confirmed 4 Historical Observations
1350 (?) Unknown Confirmed 4 Tephrochronology Tephra layer Y4
1260 ± 150 years Unknown Confirmed   Tephrochronology
1130 ± 75 years Unknown Confirmed 5 Radiocarbon (uncorrected) Tephra layer X
0950 (?) Unknown Confirmed 3 Tephrochronology Tephra layer L2
0770 ± 75 years Unknown Confirmed 4 Radiocarbon (uncorrected) Tephra layer L1
0740 ± 75 years Unknown Confirmed 4 Radiocarbon (uncorrected) Tephra layer Kb2
0550 ± 200 years Unknown Confirmed   Tephrochronology Tephra layer 10
0370 ± 200 years Unknown Confirmed   Tephrochronology Tephra layer 11
0180 ± 100 years Unknown Confirmed 4 Radiocarbon (uncorrected) Tephra layer Kb2
0150 (?) Unknown Confirmed 4 Tephrochronology Tephra layer Ka2
0070 ± 150 years Unknown Confirmed 4 Radiocarbon (uncorrected) Tephra layer Ka1
0050 BCE (?) Unknown Confirmed 3 Tephrochronology Tephra layer JK
0230 BCE ± 200 years Unknown Confirmed 4 Radiocarbon (uncorrected) Tephra layer JJ
0400 BCE (?) Unknown Confirmed 4 Tephrochronology Tephra layer J
1050 BCE (?) Unknown Confirmed 4 Tephrochronology Tephra layer I2
1510 BCE ± 150 years Unknown Confirmed   Radiocarbon (uncorrected)
2050 BCE (?) Unknown Confirmed 5 Tephrochronology Tephra layers I1
2220 BCE ± 100 years Unknown Confirmed   Radiocarbon (uncorrected) Tephra set H
2250 BCE Unknown Confirmed   Tephrochronology
2640 BCE ± 200 years Unknown Confirmed 5 Radiocarbon (uncorrected) Colorado Canyon tephra set
3280 BCE ± 500 years Unknown Confirmed 5 Tephrochronology Tephra set F-5
3880 BCE ± 75 years Unknown Confirmed 5 Radiocarbon (uncorrected) Tephra set F-4
4350 BCE ± 75 years Unknown Confirmed 5 Radiocarbon (uncorrected) Tephra set F-3
5820 BCE ± 75 years Unknown Confirmed 5 Radiocarbon (uncorrected) Tephra set F-2
7690 BCE ± 75 years Unknown Confirmed 2 Radiocarbon (uncorrected) Tephra set F-1

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. 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. Additional discussion of data sources can be found under Volcano Data Criteria.

Barberi F, Coltelli M, Frullani A, Rosi M, Almeida E, 1995. Chronology and dispersal characteristics of recently (last 5000 years) erupted tephra of Cotopaxi (Ecuador): implications for long-term eruptive forecasting. J Volc Geotherm Res, 69: 217-239.

Hall M L, 1977. El Volcanismo en El Ecuador. Quito: Biblioteca Ecuador, 120 p.

Hall M L, 1987. Peligros potenciales de las erupciones futuras del volcan Cotopaxi. Rev Politecnica, Quito, 12: 41-80.

Hall M L, 1992. . (pers. comm.).

Hall M, Mothes P, 2008. The rhyolitic-andesitic eruptive history of Cotopaxi volcano, Ecuador. Bull Volc, 70: 675-702.

Hantke G, Parodi I, 1966. Colombia, Ecuador and Peru. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 19: 1-73.

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

Miller C D, Mullineaux D R, Hall M L, 1978. Reconnaissance map of potential volcanic hazards from Cotopaxi volcano, Ecuador. U S Geol Surv Map, I-1072.

Mothes P A, Hall M L, Janda R J, 1998. The enormous Chillos Valley Lahar: an ash-flow-generated debris flow from Cotopaxi volcano, Ecuador. Bull Volc, 59: 233-244.

Mothes P, Hall M L, Andrade D, Samaniego P, Pierson T C, Ruiz A G, Yepes H, 2004. Character, stratigraphy and magnitude of historical lahars of Cotopaxi volcano (Ecuador). Acta Vulc, 16: 85-108.

Paulo A, Narebski W, Bakun-Czubarow N, Prochazka K, Wichrowoski Z, 1979. Geology, geochemistry and petrogenesis of volcanics of Cotopaxi (Ecuador). Prace Mineralalogiczne, 61: 1-62.

Symmetrical, glacier-clad Cotopaxi stratovolcano is Ecuador's most well-known volcano and one of its most active. The steep-sided cone is capped by nested summit craters, the largest of which is about 550 x 800 m in diameter. Deep valleys scoured by lahars radiate from the summit of the andesitic volcano, and large andesitic lava flows extend as far as the base of Cotopaxi. The modern conical volcano has been constructed since a major edifice collapse sometime prior to about 5000 years ago. Pyroclastic flows (often confused in historical accounts with lava flows) have accompanied many explosive eruptions of Cotopaxi, and lahars have frequently devastated adjacent valleys. The most violent historical eruptions took place in 1744, 1768, and 1877. Pyroclastic flows descended all sides of the volcano in 1877, and lahars traveled more than 100 km into the Pacific Ocean and western Amazon basin. The last significant eruption of Cotopaxi took place in 1904.