Earthquakes: Hundreds of people take to the streets for fear of earthquakes in Granada
The testimonies. The testimonies during the Granada earthquake: "Fear has brought us out to the streets"
Analysis: What is happening in Granada so that there have been more than 280 earthquakes since December?
The earthquakes that are occurring in Granada are a "normal" phenomenon in the area, amplified by the proximity to the surface.
In recent years, there have been major earthquakes that the population has not felt when they occur in greater depth. Here are the 10 questions that give answers to the why of the earthquakes that occur in the province of Granada.
How intense have the earthquakes reached?
The maximum magnitude observed by the National Geographic Institute (IGN) has reached 4,
5 on the seismological scale and was recorded this Tuesday at 10:54 p.m., with its epicenter in the towns of
Santa Fe
,
Atarfe
and
Cullar Vega
, all of them in the Vega de Granada region.
A few minutes before, there had been two other earthquakes of similar intensity, at 10:36 p.m. and 10:44 p.m., both of 4.2 degrees.
How many tremors have been recorded?
Only on Tuesday night there were more than 30 earthquakes, which were noticed in more than 40 municipalities in the provinces of
Pomegranate
,
Almeria
,
Cordova
,
Jaen
,
Malaga
and
Seville
.
As indicated by the Andalusian Institute of Geophysics, the Atarfe and Santa Fe area, the most affected, has been registering "relevant" seismic activity since December 2, 2020. In total, and since that time, about 200 aftershocks of varying magnitude, according to the National Geographic Institute.
How do the tremors compare to the Lorca tragedy?
On May 11, 2011, the city of
Lorca
(
Murcia
) suffered
an earthquake
that reached 5.1 degrees of magnitude, not much higher than the 4.5 of Granada, but enough to place the first in the category of "moderate", more dangerous than that of "light" in which, According to the Richter scale, the tremors of Tuesday are framed. In Lorca there were nine fatalities and more than 300 injured.
The reason that this earthquake was so
devastating
According to the analysis carried out in 2019 by researchers from the Higher Technical School of Roads, Canals and Ports of the Polytechnic University of Madrid, it was accompanied by a "directivity effect", rare in earthquakes of these magnitudes, which multiplied its potential destructive.
Fortunately, nothing similar has been observed in Granada.
Have these earthquakes been an anomaly?
Despite the material damage and the logical fear that the earthquake has caused, it is a normal phenomenon in the area, according to experts.
Manuel Regueiro
, president of the Illustrious Official College of Geologists (ICOG), considers that "it is not unusual" for earthquakes to occur in the province of Granada, located on a seismic zone of moderate risk, on the border between the Eurasian and African plates.
"There are documentary records of earthquakes in the area from the time before the Catholic Monarchs," Regueiro recalls.
Ana Crespo Blanc
, Professor of Geodynamics at the University of Granada, explains that "we are at a limit of plates that move five millimeters per year, and that deformation is what makes it normal for earthquakes to repeat themselves, no matter how scary they generate," he reports.
Efe
.
For this expert, earthquakes like those of the last few days are "something totally normal."
Why have earthquakes been so felt in various municipalities?
The tremors suffered by the population on Tuesday night were greater than the maximum magnitude of the earthquake (4.5 degrees) could suggest.
The reason is that, on the one hand, the latest earthquakes have occurred very close to the surface, at depths of between three and zero kilometers, according to the National Geological Institute, to which we must add the properties of the soil in the affected localities.
In the words of Crespo Blanc: "It is not the same to have a house on rock than on sediment, and in La Vega we have unconsolidated sediments that generate a wave amplification phenomenon".
Are there seismic precedents in the area?
Yes, and of immense gravity.
"The last major earthquake occurred in 1884 in the Granada municipality of Arenas del Rey and caused damage to 106 towns, 39 of which were very serious, leaving Arenas del Rey and Ventas de Zafarraya completely destroyed, which had to be rebuilt" Regueiro details. "It produced more than 1,200 fatalities and some 1,500 injured, totally destroyed some 4,400 houses, caused serious damage - they were semi-destroyed - in another 6,300 and suffered more than 20,000," he adds.
What is the relationship between the earthquake on Saturday and the one on Tuesday?
The Andalusian Research Institute for Geophysics and Seismic Disaster Prevention, attached to the University of Granada, has explained that the earthquake on Tuesday night was a "rebound" in the activity observed since the end of last year, reports
Europa Press
The first earthquake of intensity was registered on December 2, with a magnitude of 3.6 degrees.
The two highlights have occurred on Saturday and Tuesday.
No other aftershocks greater than 3.3 degrees have been recorded.
Could new earthquakes of greater intensity occur?
The magnitude of the earthquakes depends on the length of the fault and that of Granada is only 20 kilometers, which makes it difficult for tremors to occur stronger than those already suffered. "We cannot fear a large earthquake like the ones in San Francisco, which it has a fault, that of San Andrés, of 1,500 kilometers ", contrasts Crespo Blanc, who considers that Granada has already" reached its maximum magnitude. "
The largest earthquake recorded in recent years exceeded six degrees, but the population did not feel it, as it occurred at a depth of 620 kilometers.
Is it possible to foresee this kind of earthquake?
Experts can determine which areas are most at risk of earthquakes, but not when the next will occur.
"We know where they will be produced thanks to the risk maps, hazard studies and the historical series, but we do not know when they will be produced," says Regueiro.
What to do in case of new tremors?
The National Geological Institute advises, in general, to have a first aid kit, dynamo flashlights, bottled water and non-perishable food, a whistle, battery-operated radio and a fire extinguisher, and recommends that drills be held and spoken in family of what to do in the event of an earthquake, as well as to securely attach furniture that could become detached to the wall and not to place heavy objects on the shelves.More specifically, Crespo Blanc has issued the following recommendation to the citizens of Granada and its surroundings: "You understand fear, but if you put rationality on it, the failures are short and the best we can do is find a table, stick to the wall and not go out on the street like so many people did."
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