PARIS: The highly effective earthquake that struck Morocco, killing greater than 2,000 individuals, didn’t hit in essentially the most lively seismological area, stated one French skilled. However aftershocks will be anticipated, he warned.
Philippe Vernant — a specialist in lively tectonics, notably in Morocco, on the College of Montpellier — answered AFP’s query’s on the devastating quake.
Morocco is a type of international locations the place the query is just not whether or not there can be earthquakes.
The Agadir earthquake (magnitude 5.7 in 1960) destroyed the complete metropolis and killed nearly 15,000 individuals, and extra lately there was the Al Hoecima earthquake (magnitude 6.4 in 2004), additional out on the Mediterranean.
Trying additional again in historical past, there have been earthquakes within the 18th century, most likely round magnitude 7 within the Fez area.
The epicenter of the current quake is just not in essentially the most lively space of Morocco. However there are the Excessive Atlas mountains… Such a earthquake is what results in the rise of the Excessive Atlas vary.
In Turkiye, we had horizontal motion, as a result of Turkiye is shifting to the West, transferring towards Greece. There was a horizontal sliding of the (tectonic) plates.
Right here, we’re seeing extra of a convergence between Africa and Eurasia or Iberia, the Spanish half, and overlapping faults… However we’re nonetheless coping with plate boundaries.
We have to see what magnitude the earthquake can be. We’re speaking about 6.8 or 6.9, which is kind of sturdy.
This corresponds roughly to a median displacement on the fault line of round one meter in a number of seconds, over a number of kilometers.
Clearly, this shakes the area enormously.
Then there’s the depth: at first it was estimated to be at round 25-30 kilometers, however it appears to be going again up, nearer to 10 kilometers.
The nearer you get to the floor, the larger the impact of the rupture.
That is what occurred in France in 2019 within the Teil area within the (southern) Ardeche area. It was a “small” earthquake, however because it occurred at a depth of only one kilometer, it shook issues up rather a lot.
Aftershocks are sure to happen.
Even when they’re much less sturdy, they will result in the collapse of buildings already weakened by the earthquake.
Historically, we are inclined to say that aftershocks diminish in depth…
However in Turkiye, one earthquake triggered one other. The primary tear can result in the rupture of one other fault by way of a cascade impact, which is why there’s generally a threat of a stronger earthquake after the primary one.
Sadly, we are able to’t predict something.
We attempt to estimate recurrence durations in keeping with the completely different magnitudes of the earthquakes, however then the habits will be chaotic, with two sturdy earthquakes over a brief interval after which nothing for a really very long time.
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