September 11, 2023

expert reaction to Morocco earthquake

Scientists respond to news that Morocco has been struck by an earthquake.

Ziggy Lubkowski, Associate Director and seismic design expert at Arup, said:

“Our thoughts are with the families impacted by this tragic event.

“This is the most devastating earthquake in the region since the 1960 Agadir event which resulted in 12,000 to 15,000 fatalities.

“The epicentre was located between Agadir and Marrakesh at the southern end of the Atlas Mountains therefore both cities were spared the full impact of ground shaking.

“The use of brick and adobe as a building material for residential properties will probably lead to a number of collapses. Unfortunately brick and adobe structures are very susceptible to earthquake shaking, due to their brittle nature.”

Prof Colin Taylor, Emeritus Professor of Earthquake Engineering at the University of Bristol, said:

“The tragic photos of collapses of buildings in Morocco are not unexpected and show the challenges of applying good earthquake engineering principles in countries that have expanding economies and populations as well as an extensive stock of old, traditional, and seismically brittle buildings.

“We know how to approach this problem, but it is a huge, long term, economic and political demand to apply the knowhow. Morocco doesn’t have big earthquakes that often – perhaps once in a generation – so the public consciousness and conscience wanes, and other, more immediate, life challenges capture their attention and drive political agendas.

“Nevertheless, the government of Morocco sets disaster risk management and emergency response as high priorities.

“The relatively shallow earthquake, located in the High Atlas Mountains, will probably have led to localised intense shaking, which would be bad for old masonry.  Landslides or rockslides are to be expected that will impede rescue efforts.

“It is also likely that some newer reinforced concrete buildings might have collapsed due to poor design and construction not adhering to building codes.

“A big challenge for the government and authorities will be to quickly find out what has happened and where so that they can design and implement their response plans effectively and efficiently, including knowing where to prioritise limited resources.”

Dr Brian Baptie, Head of Seismology, British Geological Survey, said:

“A magnitude 6.8 earthquake occurred in the High Atlas Mountain range, near the town of Adassil in the Marrakesh-Safi region of Morocco and approximately 75 km from the city of Marrakech. The focus was relatively shallow and nearby towns are likely to have experienced very strong or severe shaking.

“Earthquakes are relatively uncommon in this region of Morocco, with most seismic activity to the northeast, closer to the plate boundary between Africa and Europe. However, earthquakes have occurred nearby in the past and earthquakes remain a significant hazard in this region of Morocco.

“For example the last major earthquake to strike Morocco was the magnitude 6.3 Al Hoceima earthquake in 2004, that struck near the coast of northern Morocco and killed over 600 people. However, earthquakes have occurred nearby in the past and earthquakes remain a significant hazard in this region of Morocco. In 1960 a magnitude 5.9 earthquake struck the city of Agadir in Morocco causing between 12,000 and 15,000 deaths, making it deadliest earthquake in Moroccan history.

“Aftershocks will affect the region for the weeks to come but their number will rapidly decrease with time after few days.”

Prof David Rothery, Professor of Planetary Geosciences at the Open University, said:

“This earthquake was in the mountains about halfway between Agadir and Marrakech. It was about 500 km south of the boundary between the African tectonic plate and the Eurasian plate, but nevertheless it was a consequence of the northward collision of Africa into Eurasia in a place where the High Atlas mountains are being thrust upwards.  This earthquake was magnitude 6.8, and there has been nothing bigger than 6.0 within 500 km of the epicentre since before 1900.

“Neither people nor civil authorities are likely to have been well prepared for this, and I would be surprised if even modern buildings were built to be resilient to major ground shaking. We wait to learn whether landslides have taken many lives, in addition to buildings that were shaken down.”

Prof Bill McGuire, Professor Emeritus of Geophysical & Climate Hazards at UCL, said:

“Morocco is not the first place that comes to mind when people think of earthquakes, but they do happen. This one, however, is especially large for the region – the biggest in more than 120 years – and, as the climbing death toll indicates, deadly. The problem is that where destructive earthquakes are rare, buildings are simply not constructed robustly enough to cope with strong ground shaking, so many collapse resulting in high casualties. I would expect the final death toll to climb into the thousands once more is known. As with any big quake, aftershocks are likely, which will lead to further casualties and hinder search and rescue.”

Dr Carmen Solana, a volcanologist from the University of Portsmouth:

“Earthquakes in Morocco are not unusual, but this one is larger and close to the large city of Marrakesh. As with many other cities in the region, old buildings would not have any anti-seismic design, hence are very dangerous.

“There is no connection with the recent Turkey earthquake.

“The mountains where the earthquake occurred were a result of the African and the European plates crashing into each other and these forces produce earthquakes.”

Dr Mohammad Kashani, Associate Professor of Structural and Earthquake Engineering at the University of Southampton, said:

“The earthquake was magnitude 6.8 with 18.5 km depth, which is quite shallow. The shallow earthquakes are normally more destructive. The location is at the boundary of the Eurasian and African plates. Almost all earthquakes occur at the boundary of tectonic plates due to their movement.

“It is too early to see the extent of damage. However, from what I’ve seen in photos and videos this very similar to the earthquake that occurred in February in Turkey. The area is full of old and historical buildings, which are mainly masonry. The collapsed reinforced concrete structures that I saw in the photos were either old or substandard.”

Prof Joanna Faure Walker, Professor of Earthquake Geology and Head of the UCL Institute of Disaster Risk Reduction, said:

“Morocco lies in the north of the African plate that has been converging obliquely with the European plate for millions of years. Movement associated with the plate boundary can cause damaging earthquakes. There have been other magnitude 6 earthquakes in Morocco in the past few hundred years, and Morocco has also experienced shaking from earthquakes with epicentres outside the country including in Portugal.

“When an earthquake occurs at night, people can be particularly vulnerable as getting out of their homes and navigating rubbles and debris in the dark adds to risk of injury and getting trapped.

“The early death toll figures are likely to increase significantly as early information is limited and rescue efforts are ongoing.

“Residents should be cautious returning into damaged buildings as some damage may not be visible and aftershocks of magnitude 5-6 should be expected. Large earthquakes can trigger other earthquakes along the same or neighbouring faults as stress transfer can bring other faults closer to failure. In an area already experiencing damage and reduced capacity for emergency services, vulnerability to aftershocks and triggered events can be higher than before the first event.”

https://www.bbc.co.uk/news/live/world-africa-66771590

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