San Salvador: living under the volcano

Dominating the landscape to the west of El Salvador’s capital of San Salvador is the massive volcano that shares the city’s name. San Salvador volcano last erupted in 1917, the beginning of the eruption being marked by an earthquake estimated to have been magnitude 5.6 which left up to 90% of the capital’s housing stock damaged or destroyed according to contemporary reports (see today’s Daily Volcano Quote). The 1917 eruption, the seat of which was El Boquerón, the main summit of San Salvador, lasted from June to November and produced extensive lava flows and ashfall, damaging crops and causing some fatalities in the surrounding region.

Today the city of San Salvador has a population estimated at 2.2 million and its suburbs encroach upon the lower slopes of San Salvador volcano. A fresh eruption of San Salvador on almost any scale would have serious consequences for the city of San Salvador. Even without any eruptive activity, the volcano’s unstable slopes pose a significant landslide hazard for the surrounding areas.

The authorities in El Salvador are very conscious of the hazard San Salvador poses. Yesterday the Salvadorean newspaper El Diario Co Latino reported that the Salvadorean environment ministry, the Ministerio de Medio Ambiente  y Recursos Naturales (MARN) has been working with geologists and non-governmental organizations from across the world to assess the potential threat of San Salvador and plan hazard mitigation and response strategies. Taking into account San Salvador’s 3000-year history of frequent activity, ‘The likelihood that a phenomenon such as that of 1917 will occur within the next 100 years is high, but it is not possible to give an exact time range’, says volcanologist Dolores Ferrés, author of the study Estratigrafía, geología y evolución del volcán de San Salvador: Aplicación en la evaluación de peligros volcánicos y su posible impacto, which was presented to the media at a congress held by MARN on 21 September.

Ferrés’s study is described in a news release from El Salvador’s Servicio Nacional de Estudios Territoriales (SNET) as ‘a breakthrough in the generation of knowledge about volcanic risk in the country and providing vital information to decision-makers in various sectors’. The intention is to carry out a comprehensive hazard assessment programme for San Salvador volcano and the surrounding area. ‘Although the volcano currently shows only very week activity (fumaroles in Cerro La Hoya and very sporadic volcanic-tectonic seismicity) it is considered one of the most dangerous volcanoes in Central America because of its proximity to large urban areas and its eruptive history’, is the SNET’s current verdict on San Salvador volcano.

News
Presentación Estudio volcán de San Salvador – SNET news release, 21 September 2010
Volcán de San Salvador: un gigante activo – Diario Co Latino, 27 September 2010

Information
Global Volcanism Program: San Salvador – summary information for San Salvador (1403-05=)
Volcano Hazards in the San Salvador Region – USGS report, 2001, available at the CVO website