Behind the earthquake in Morocco

Sawsan Samy Elawady , Sunday 17 Sep 2023

A look into the geological factors behind the powerful earthquake that struck southern Morocco last week

Behind the earthquake in Morocco
photo: AFP


A 6.8 magnitude earthquake struck the Al-Haouz Province of Morocco on 9 September, with the numbers of victims reaching 2,122 deaths and 2,421 injured, according to the Moroccan Ministry of the Interior as Al-Ahram Weekly went to press.

The US Geological Survey said the earthquake was caused by the movement of the African tectonic plate at its meeting point with the Eurasian plate. Increased seismic activity has been seen in the region due to the northward convergence of the African plate and the Eurasian plate that began about 50 million years ago and is linked to the closure of the ancient Tethys Sea that once existed in the region.

The current Mediterranean Sea is what remains of the Tethys Sea, which was an ocean in prehistoric times.

“It is surprising to see such a large earthquake in this region,” said seismologist at the Institute of Geosciences at the University of Grenoble in France Florent Bringier. In a statement to the UK network Sky News, Bringier said that although the large faults in the region have developed over hundreds of thousands of years, the epicentre of last week’s Morocco earthquake does not lie in the area separating tectonic plates.

“This is why the area is not accustomed to facing such strong earthquakes. The vast majority of earthquakes in Morocco have occurred 500 km north of this region. Usually, the strength of an earthquake within the plate is less.”

Bringier said that “a recent earthquake of this magnitude will change the way scientists look at tectonic activity on the northern front of the Atlas Mountain Range.”

However, “Morocco as a whole is considered an earthquake zone. In general, the entire Mediterranean region is likely to suffer from large earthquakes, especially around the boundaries of the African and European plates in the north of the country, where the majority of tectonic movements are concentrated,” he said.

An earthquake that took place in the Moroccan coastal city of Agadir killed 12,000 people and destroyed almost the whole of the city in 1960. The US Geological Survey said that the earthquake last week was “unusually strong” for this region of Morocco. “Earthquakes of this size in the region are uncommon, but not unexpected,” it said.

“Since 1900, there have been no earthquakes with a magnitude of 6 on the Richter Scale and larger within 500 km of this earthquake. Also, only 9 earthquakes with a magnitude of 5 and larger have occurred” during the same period.

Outside Morocco, another devastating earthquake struck the Middle East region in February this year and affected both Syria and Turkey, resulting in the deaths of thousands, hundreds of thousands of displaced people, and the destruction of large urban areas.

The question now is whether there will be aftershocks to the Moroccan earthquake and whether it will trigger other seismic events in neighbouring areas. Some also fear warnings of tsunamis in the Mediterranean Sea or the Atlantic Ocean and further danger to North Africa.

The epicentre of the Moroccan earthquake was located near the town of Ighil about 70 km south of Marrakesh. According to the US Geological Survey, many people in the area reside in buildings that are “severely threatened by seismic vibrations.”

The magnitude of the earthquake reached 6.8, with a tremor that lasted several seconds, suggesting that the epicentre was at a depth of 18 km below the surface. The Moroccan Seismic Agency said the epicentre was at a depth of eight km. Surface earthquakes are more dangerous.

“It is known that large earthquakes throughout the Mediterranean region produce large and destructive tsunamis, and one of the most prominent historical earthquakes within the area was the 1755 Lisbon earthquake, which was estimated from non-instrumental data to have a magnitude of 8,” the US Survey said.


EGYPTIAN REACTION: Gad Al-Qadi, head of the National Institute for Astronomical and Geophysical Research in Egypt, denied the existence of warnings of a possible tsunami, given that “the earthquake occurred on land in a mountainous area 300 km away from the sea, so there is no indication of any kind for this unlikely possibility.”

“The Marrakesh region of Morocco is characterised by buildings not built according to the seismic code that regulates modern construction methods. This is especially the case in the countryside, where many buildings are made of mud bricks, increasing the number of buildings that collapsed after the earthquake.”

“The region of the epicentre of the earthquake is adjacent to a mountainous area, and this exacerbated the number of victims as a result of landslides that caused great damage to lives and property,” Al-Qadi said.

Sherif Al-Hadi, also a professor at the National Institute for Astronomical and Geophysical Research, described the area where the earthquake occurred as a “seismically emerging region,” as the geological fault is located on the edge of the continent of Africa and separates it from Europe. He said that there was no danger to neighbouring regions of North Africa.

Al-Hadi said that “seismic activities are concentrated in their areas of occurrence and do not usually spread to other places,” denying fears on social media of earthquakes moving to other places in the region. However, he said that in rare circumstances “a seismic focus can cause excitement” elsewhere, as happened in the Turkey earthquake earlier this year.

On the risk of earthquakes in the Arab region, Moroccan geological researcher Kamal Agroud said that there was discussion about the geodynamic movements taking place on the African and Eurasian continents, especially since the Arab world contains areas susceptible to earthquakes, such as northern Morocco and the Atlas Mountains and southern Morocco.

Northern Algeria and northern Tunisia are also vulnerable to a lesser extent, as are parts of the Horn of Africa and the Red Sea, along with parts of Anatolia. It was necessary to research the risks more thoroughly in order to protect countries as much as possible and mitigate the repercussions of such natural disasters, Agroud said.

Strong earthquakes are also often followed by successive aftershocks, but these are usually smaller in size. They occur because the tectonic plates near the epicentre of the earthquake continue to move until they eventually stabilise. Such aftershocks may also cause serious damage, because they can lead to the collapse of buildings that were damaged during the original earthquake.

This is what happened during the earthquake in Syria and Turkey earlier this year.

Haluk Ozner, director of the Kandilli Observatory and Earthquake Research Institute in Turkey, said that the 7.4-magnitude earthquake that struck southern Anatolia and northern Syria earlier this year could have caused a tsunami in the Mediterranean Sea.

In a previous interview with the US CNN network, Ozner said that “we are facing the greatest damage caused by an earthquake in this region since 1999,” adding that “it is expected that the aftershocks will continue for months, and perhaps up to a year, and we may face the risk of the earthquake causing tsunami waves in the Mediterranean region. We have informed 14 countries of this, including Morocco.”

At the end of 2022, the UN cultural agency UNESCO announced the need to prepare for the risks of a new tsunami that might strike some coastal cities on the Mediterranean Sea, among them Istanbul, Marseille, and Alexandria. Such a tsunami could reach more than a metre in height during the next 30 years, it said.

Tsunamis are powerful waves that arise from the movement of a large area of ​​water and can result from earthquakes and other movements, whether on or under the surface of the water and including volcanic eruptions and eruptions under the surface. As a result of the huge amount of water and energy generated by such movements, the effects of tsunamis can be devastating.


MORE DISASTERS: The Morocco earthquake comes a few months after the Turkey earthquake, which left 50,000 people dead and occurred on the border between the Anatolian plate and the Arabian plate.

The Turkish earthquake was more predictable because the region lies on the boundaries of two major plates. However, in the Moroccan case things are more surprising because it is rare for such large earthquakes to occur within plates.

Despite the similar strength of the two earthquakes, the length of the fault in the Turkish case played a role in mitigating losses, as it is about 300 km long, while the fault is 30 km long in Morocco, or ten times less. Therefore, the energy transmitted underground is less important and the earthquake is more local in its effects.

A World Bank report on natural disasters in the Arab region indicates that earthquakes are on the rise. Earthquakes come in second place among the most widespread natural disasters in the region, and they are equal to floods in the size of the damage they cause.

While the number of natural disasters around the world has nearly doubled since 1980, it has nearly tripled in the Arab region, according to the report. Rapid urbanisation, water scarcity, and climate change have all exacerbated the effects of natural disasters in the region and created new challenges to development.

“Disasters leave strong impacts on cities, especially in informal settlements, which are often the most vulnerable to danger. 62 per cent of the region’s total population lives in cities, and this number is expected to double by 2040,” the report said.

“Informal settlements will increase and grow side by side” with cities, “which will leave more and more people vulnerable to the devastating effects of natural disasters.”


The writer is an environmental and climate change expert who works with local and international bodies and has represented Egypt at conferences on the environment and climate abroad.

* A version of this article appears in print in the 14 September, 2023 edition of Al-Ahram Weekly

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