The damages in El Galpón
During our fieldwork we had the chance to visit the village El Galpón, which was mainly affected by the earthquake in October 2015. To give a visible expression how much shaking can be generated by a 5.7 Mw earthquake watch this video of a security camera in the city of Metán, approximately 50 km away from the epicenter.
El Galpón is quite small and only has some hundreds inhabitants. When we first arrived we thought the people removed the damages really quick or nothing really happened. When we got closer to the center we investigated the latter was true. The newer buildings in the outer part had no obvious damage. But in the central part most of the buildings were stabilized by wooden planks.
These are mainly older buildings with a different type of construction. In the pictures you can see some buildings with a big D tagged on the wall. These are not from some bored youths, instead they were marked from local authorities for buildings which have to be teared down and will be rebuild. We went there 5 months after the event, but the number of empty and damaged houses was still remarkable. Although construction workers were working all over the village building new houses.
I’m not an engineer but I had the feeling that the ‘new’ way of build the houses is still not perfect for even stronger earthquakes (the strongest in the region was the Esteco earthquake in 1692, Magnitude 7). They are just building up walls with bricks and strengthen the structure with reinforced concrete in all corners of the house where walls converge.
Anyway, beside some normal houses the municipality also needed to to rebuild the school building completely. The old school was one of the most damaged buildings as you can see below.
Luckily, the earthquake took place on a Saturday morning and no one was in the building. The rooms where the wall collapsed were the classrooms of the first and second year pupils. While wandering through the village we couldn’t imagine how there was only one fatality. It was an old lady who was still in the bed. Her house you can see below.
When we arrived at this house from the right hand side we didn’t saw any damage at all, only the big D painted on the wall. The western outer wall you can see above was the only damage of this building. This pattern that only western outer walls collapsed towards the west was somehow very common over the whole village. Our locals told us this observation, too. One possible explanation could be that the strongest horizontal ground acceleration was towards the west; all streets are perpendicular and nearly N-S or E-W oriented. When you look closer you will see some destabilized, not collapsed walls which were slightly tilted. Also the perpendicular oriented partition walls were ripped off the corners.
For me it was the first time I’ve seen buildings damaged by an earthquake with my own eyes. Although I’ve never felt an earthquake by myself I would call myself a seismologist, at least that’s what I’ve studied the most of the time in the university. But it was very striking how I could apply my knowledge about the mechanics and the effects of earthquakes to understand what I saw. I could explain to myself what I was seeing. That’s cool.