Geologists are well aware of the faults that will produce major earthquakes, but they can’t determine when. These are chaotic dynamic phenomena and therefore very difficult to predict.
Two earthquakes measuring 7.8 and 7.5 on the Richter scale rocked Turkey and Syria on Monday, February 6. The earthquakes have left more than 3,000 dead and thousands injured. Faced with such a catastrophe, it would be worth asking again why, given the technology we have today, these kinds of phenomena continue to overwhelm us.
Unfortunately, not everything in science is predictable. In general, the future is not predictable. You cannot accurately predict the weather after a week, nor can you predict earthquakes. And this is not the fault of meteorologists or geologists. Let’s keep in mind Heisemberg’s uncertainty principle: either we know the speed of an electron or we know its position. You cannot do both things at the same time.
Geologists have done a great job of mapping the fault lines—breaks in the Earth’s crust caused by displacement between two boulders—that will produce major earthquakes.
The maximum earthquake magnitude a fault can generate depends on its length. In Europe and the Mediterranean basin, the North Anatolian Fault is the longest notable fault line, comparable to the San Andreas Fault in California. The North and East Anatolian, along with the Jordanian, are strike errors (tears).
In the Aegean Sea, seismic activity is very notable and associated with normal (extensive) faults, while earthquakes of greatest magnitude should occur in subduction zones (Crete-Cyprus, Calabria) or protosubduction, such as in the Tell Mountains in the north. , where in 1980 a magnitude 7.3 earthquake occurred in the city of El Asnam.
Each country has its seismic monitoring network, although in Switzerland there is a Euro-Mediterranean level service called the Euro-Mediterranean Seismological Center (CSEM). In Spain, the responsible body is the National Geographical Institute. These systems locate earthquakes in real time and, for those of greater magnitude, get to see how the associated fault moves.
Map showing the earthquakes that occurred on February 6, 2023 marked with red and purple dots.
We know that earthquakes will occur in these areas, but we cannot determine when. Attempts to predict earthquakes using geodetic methods do not work. They can determine where voltages build up, but not when a breakdown occurs.
The rate at which earthquakes occur is not periodic. In Sumatra, there have been tsunamis every 80 years for the last 800 years, but before that there was a 1000 year period without one.
Weather and earthquake occurrence are the product of chaotic dynamical systems and therefore the degree of predictability is low or very low. It’s not about having more powerful computers or better algorithms. Chaotic dynamical systems are very unpredictable.
In the southwest of the Iberian Peninsula, there was a massive earthquake and tsunami in 1755, when the great Lisbon earthquake occurred. Will it happen again? Certainly. When? Tomorrow or in 1000 years. The only possible approximation is probabilistic.
For example, there is a 50% chance that there will be another tsunami that will devastate Matalascañas. But what does that mean? Well, it’s like saying that in a football match between Real Madrid and Leganés, the odds of the former winning are 60%, the former drawing 20% and losing 20%. No one can get rich off that kind of analysis. Leganés has won on occasion.
But let’s go to Turkey. We geologists know why it happened. The African, Arabian and Indian plates approach, in a north-south direction, that of Eurasia. The result is the formation of the Himalayas, the Caucasus Mountains, the Zagros and the subduction zone south of Crete.
This shortening causes the tectonic “breakaway” of the Turkish block to the west, in favor of two major strike faults: the North Anatolian Fault, lateral to the right (the block limiting the fault moves to the right), and the Eastern Fault. from Anatolia, left lateral (the block limiting the error moves to the left).
The tectonic breakout is like the “pimple effect.” If we pinch it with our fingers in a direction parallel to a mirror, the inside shoots perpendicular to the mirror. In this case, the “fingers” are Eurasia and Arabia, and the “shin” is the Turkish block (Anatolian plate), which shoots west towards Greece towards the subduction zone of Crete and Cyprus.
In this case, and given the strength of the quake, the entire eastern Anatolian fault line ruptured, pushing Turkey westward.
And then what can we do? For me, the most sensible thing is to build buildings and infrastructure that can withstand earthquakes. It’s not that expensive. Not as many as the thousands who have died in Turkey and Syria, or in Lisbon, Huelva or Granada. When? Well, maybe tomorrow.
This article was published in ‘The Conversation’.
Source: La Verdad
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