Satellite image of San Salvador

Image of the month, processed with Sentinel-2 imagery

When I look at that satellite image of San Salvador, capital city of El Salvador, here is what strikes me most: why this city which is a capital city, i.e. the administrative and political center of the country, has spread on the slopes of a volcano?

Quetzaltepec volcano or mountain of quetzal birds

Let’s set the scene first. The volcano is called Quetzaltepec, meaning mountain of quetzal birds. It is also known as San Salvador volcano or El Boquerón. The city is San Salvador with a population of 1.5 million for the whole metropolitan area. The country is El Salvador. Out of the 20 volcanoes that are located across the country, only two of them are still active. Fortunately, Quetzaltepec volcano is not on the list!

San Salvador is sandwiched between Quetzaltepec volcano to the west and Lake Ilopango to the east which is a crater lake, interestingly enough. I told you this is a volcanic area! The region is called « Valle de Las Hamacas » which means Valley of the Hammocks because of the many earthquakes reported over the centuries.

What about the history of the area?

The capital San Salvador was destroyed or partially damaged many times over the years. It was due to different Quetzaltepec eruptions or severe earthquakes caused by the local intensive seismic activity.

The last eruption was in 1917. It produced lavas flowing down the northwest flank of the volcano that are still visible on the satellite image. Shown here are archival photographs of the event.

The last earthquake struck San Salvador in 2001. It caused around 1500 deaths and many landslides in the San Salvador area.


Under the volcano

San Salvador is just one of the many cities that has expanded at the foot of a volcano. Despite all the dangers of potential eruptions or earthquakes, men have always settled close to volcanoes. “Right now, 500 million people across the world live close to an active volcano”, says French volcanologist Jacques-Marie Bardintzeff.

Why do people live in such a dangerous environment? A number of reasons can be listed: fertility of the volcanic soil favourable for agricultural development, lava contains minerals that can be mined, and the benefits of geothermal energy. Tourism is another reason. Volcanoes, active or not, attract millions of visitors around the world every year, just to discover usually amazing places and sceneries.

At PlanetObserver, we know what volcano attractiveness is about. Just west to Clermont-Ferrand, the city where we are based, you find the alignment of the Chaîne des Puys volcanoes. This is a chain of 80 volcanoes that stretch over 45 kilometers. None is active though. I just wish to point that out in case some of you might want to visit us! The city has not expanded on the slopes of the Puy de Dôme (1465 m), the highest point of the volcanic chain. However, the local black lava stone has been largely used over the centuries for all types of buildings. Clermont-Ferrand Cathedral has been entirely built in this black lava stone, which makes it highly distinctive.

For El Salvador National Day, 15 September.

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