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Source: This post is created based on the article ‘Why the earthquake in Morocco has caused so much damage’, published in Indian Express on 12th September 2023.
Syllabus Topic: GS Paper 3 – Disaster Management
News: Morocco has been hit by its most powerful earthquake. It has resulted in casualties of more than 2500 people.
Morocco was hit by an earthquake of magnitude 6.8. Its epicenter was located in the Al-Haouz province, in the Atlas Mountains of the historic city of Marrakech.
It has resulted in heavy casualties and many survivors are left without food, electricity and phone services.
The earthquakes in the North Africa are the result of northward convergence of the African plate with the Eurasian plate along a complex plate boundary. The present earthquake was attributed by USGS to “oblique-reverse faulting at shallow depth within the Moroccan High Atlas Mountain range”.
| A fault is a crack between two rock blocks. If they move fast, a quake happens. Faults are classified by their angle and direction of movement. |
Why the Morocco earthquake was that dangerous?
Although the magnitude of the earthquake was 6.8, which in many other regions did not result in destruction and casualties. But in Morocco, it was a very shallow earthquake.
USGS reported the epicenter of earthquake roughly 18.5 km below the Earth’s surface. While Morocco’s own seismic agency pegged the depth at 11 km.
Shallow earthquakes carry a much higher amount of energy when they hit the surface. Whereas earthquakes with deep epicenters lose energy when they hit the surface. Although, deep epicenter earthquakes spread farther to great distances.
For example, the earthquakes, that hit Turkey and Syria were also shallow, originated 17.9 km below the Earth’s surface, with magnitude 7.8. it caused death of more than 50,000 people and destroyed about 1,60,000 buildings containing 5,20,000 apartments.
What are the measures of earthquake?
Apart from depth, magnitude is also an indicator of quake. Magnitude tells how big the seismic waves are. Each increasing number of magnitudes represents 32 times more energy release and 10 times more amplitude.
In simple terms, the seismic waves produced by a magnitude 6 earthquake have 10 times higher amplitude than the ones produced by a magnitude 5 earthquake.
What are the reasons behind heavy destruction in Morocco?
First, earthquakes are not very common in North Africa. Therefore, Morocco was not prepared for such a calamity.
Second, many changes were introduced to construction rules after Morocco faced the earthquake in 1960, but buildings in rural areas and older cities are not built to withstand the earthquake. Many houses collapsed in Marrakech, a UNESCO World Heritage Site.
What are the earthquake zones in India?
Western Himalayan region of the 2500-km stretch from the Hindu Kush mountains to the end of Arunachal Pradesh, is the most dangerous seismic zones in the world.
A huge amount of energy is stored along the fault lines there, due to the continuous interaction of different tectonic plates.
Energy can be released only in the form of massive earthquakes.
