A week after the earthquake in Morocco, the country is beginning to accept the magnitude of the tragedy. As Moroccans mourn their dead and accept that they have lost everything, we ask the expert Geoffrey Abers about the keys to this earthquake. Abers, William & Katherine Snee Professor of Geological Sciences and chair of the Department of Earth and Atmospheric Sciences at Cornell University in Ithaca, New York, says that “many buildings in this part of the world are constructed of unreinforced masonry.” “, often stacked bricks or cement blocks without any wood or metal reinforcement. This type of structure is particularly vulnerable to failure in the event of an earthquake.”
Because that The earthquake was the strongest to hit the center of the country in more than a century?
Earthquakes in Morocco are rare and generally of lower magnitude. However, they occur because Morocco lies on the complicated plate boundary between Europe and Africa. Compared to other plate boundaries in the world, Africa collides with Europe very slowly, so tensions build more slowly here than elsewhere. The movements here are only a few millimeters per year, about six to eight times slower than those of the San Andreas fault in California. Furthermore, the movement occurs on a complex fault system in Morocco’s High Atlas Mountains, not on a single fault, so the buildup of stresses on any individual fault is small. The result is this Large earthquakes are rare, probably every few hundred years, but they do happen.
Earthquakes are not uncommon in this area, but should they be better prepared for earthquakes from now on?
This context probably helps answer the first two questions. Large earthquakes can be expected here from time to time, although less frequently than at most plate boundaries. For example, since 1990, nine magnitude 5.0 earthquakes have occurred within 500 km of the epicenter.
We know that ourselves too Minor earthquakes can cause extreme damage in this region. The 5.9 magnitude earthquake in Agadir, Morocco, not far from here, caused great devastation in 1960 and claimed between 12,000 and 15,000 lives. As with the current earthquake, much of the damage was due to building collapses. Many buildings in this part of the world are made of “unreinforced masonry,” often stacked bricks or cement blocks without any wood or metal reinforcement. This type of structure is particularly vulnerable to failure in the event of an earthquake., because the parts can be easily removed without holding and it is also heavy. Against this background, earthquake-resistant construction plays an obvious role.
Did the fact that the earthquake occurred at a relatively shallow depth make it even more destructive?
It is true that the earthquake was more destructive than other places due to its shallow depth. Regions where the main fault is dozens of kilometers deep and/or offshore, such as Chile or Japan, will experience less shaking at a given magnitude in populated areas. However, they carry the potential for much larger earthquakes, such as the M9.0 earthquake in Tohoku, Japan, in 2011. In addition, similar shallow earthquakes occur in many areas in continental collision zones, for example in the broad belt from Morocco to India, where India, Arabia and Africa collide with Eurasia. For example, Equally superficial was the sequence of deadly earthquakes last February in the Turkey-Syria region.