The epicentre of Morocco’s devastating earthquake on 8 September was in the High Atlas Mountains, about 71km south-west of Marrakesh. Moina Spooner, from The Conversation Africa, asked Jesús Galindo-Zaldivar, who has been carrying out research on the formation of the Atlas mountains and the geology of the area, about the factors which led to this situation.
What research have you been doing in Morocco’s Atlas mountains?
The Atlas Mountains are a fascinating range in north-west Africa, spanning Morocco, Algeria and Tunisia. They’re situated south of the main Eurasia and Africa (Nubia) tectonic plate boundary.
This area doesn’t usually have a lot of earthquakes compared to other places near the edges of tectonic plates, where the movements of plates will cause intense seismic activity. But in 1960 the Agadir earthquake caused a lot of damage and loss of life.
I’m part of a team of geologists, geophysicists and geodesists from various Moroccan universities and Spanish institutions carrying out research in the area. We want to understand this mountain range’s development and its position at the edge of a continental plate boundary. Studies of seismic activity, gravity and other geophysical phenomena allow us to understand the Earth’s deep structure, down to depths exceeding 100km.
Through field geological research, we can detect and analyse faults – fractures or cracks in the Earth’s crust along which there has been movement. These movements can be horizontal, vertical or diagonal, and they occur due to the immense forces acting on the Earth’s tectonic plates.
Finally, using geodetic techniques (GPS recordings) we are able to determine how tectonic plates are moving. This is done by regularly measuring benchmark sites with millimetre accuracy.
What has your research found?
Our research shows that the Atlas Mountains were formed during the break-up of the Pangea supercontinent. It is now a mountain range that is actively rising, as evidenced by its high peaks and steep slopes.
The steep slopes of the mountains and the straight lines where the Earth’s crust has cracked suggest that there has been recent movement in the Earth beneath this area. It’s surprising that there aren’t more earthquakes here.
The Atlas Mountains are getting pushed together at a rate of about 1 millimetre each year. This happens because the Eurasian and African plates are moving closer to each other. This squeezing action is responsible for creating the tallest mountains in the area, the southern edge of where these two big plates meet.
