Santa Ana - 2005 eruption |
Santa Ana experienced an eruption on October 1, 2005. This eruption was mainly phreatic and sent an ash plume to an altitude of ~14km. For detailed information see the Servicio Nacional de Estudios Territoriales (SNET) web site and the Bulletin of Global volcanism network (BGVN 30:9). A small lake quickly reappeared in the crater of the volcano. Late January, lake temperature started to rise and the lake is currently drying due to its small volume. |
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| Santa Ana lake in January 2000 (Photo A. Bernard) |
| Background: |
Santa Ana (also called Llamatepec) is the highest (2381 masl) and one of the most active volcanoes of El Salvador. Twelve historical eruptions have been recorded since the year 1500 with at least one eruption every century. The last eruption occurred in 1904. Two major cities are lying at ~ 20km from the volcano which represents a significant threat for one million people (Pullinger, 1998; Rose et al., 2004). |
A lake has been observed in the crater of Santa Ana since the 1904 eruption. Before the October 2005 eruption, the lake was almost circular with a diameter of ~ 200m, a maximum depth of 27m and a volume of 0.47 million m3. This lake has a typical acid-sulfate-chloride composition with a pH of 0.9-1.0 (Bernard et al. 2004). |
References: Bernard, A., Escobar, C. D., Mazot, A. and Guttierez, R. E. 2004. The acid volcanic lake of Santa Ana volcano, El Salvador. Geological Society of America, Special paper 375: 121-133. Pullinger, C. 1998. Evolution of the Santa Ana volcanic complex, El Salvador; [MS Thesis], Houghton, Michigan Technological University, 151p. Rose, W. I., Bommer, J. J. and Sandoval, C. A. 2004. Natural hazards and risk mitigation in El Salvador: An introduction. Geological Society of America, Special paper 375: 1-4. |
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| ASTER VNIR (simulated natural colors) of 6 March 2001 showing the volcanic complex of Santa Ana and Izalco volcanoes beside Coatepeque caldera. |
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| Geological sketch map from Meyer Abich (1956). |
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| Coatepeque caldera view from Santa Ana volcano (photo A. Bernard) |
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| Santa Ana lake in February 2002. Line A-B is the bathymetric traverse. |
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| A new lake quickly reappeared after the October 1, 2005 eruption. |
| 2006 satellite data: |
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ASTER TIR of 07 January 2006 processed with the split window (SW)algorithm. Maximum lake temperature is 43.3°C. |
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| Unprocessed ASTER TIR Band 13 image of January 16, 2006. A small thermal anomaly is always present on top of Izalco due to a feeble fumarolic activity. |
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| Maximum lake temperature increased to 65.2°C. |
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A significant reduction in lake area occurred between January 7 (79,000m2) and February 24, 2006 (27,000m2). |
Maximum lake temperature on Feb 24, 2006: 58.4°C. |
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| View of Izalco volcano from Cerro Verde (photo A. Bernard). |
ASTER satellite data courtesy of NASA, USA. Satellite images processing and page editor: Alain Bernard. |
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