Some regions of the world are much more prone to earthquakes than others. This is explained by the fact that they are located on the faults of tectonic plates. The Earth’s surface consists of 53 relatively large tectonic platforms that are in constant motion. At the same time, the plates deform, accumulating elastic energy – they behave like a tightly compressed spring. And when the resistance threshold is reached, a huge amount of energy is released in the contact zone, allowing the plates to move freely and causing earthquakes on the surface.
Countries and regions located on tectonic plate fault zones are most at risk of earthquakes. Earthquakes are especially strong in places along faults in subduction zones, where one lithospheric plate dives under another. According to statistics, 80% of all seismic activity on the planet occurs in the Pacific Ring of Fire, which includes the Antilles. The central surface of plates between fault is much less prone to earthquakes. Statistics show that even though earthquakes occur in these areas, in most cases, the population doesn’t feel the seismic activity.
Which countries have the lowest risk of earthquakes
Countries located in the central part of the tectonic plates are the least susceptible to seismic risk. These include:
- Great Britain and Ireland are islands located on the surface of the ancient Precambrian shield with a thickness of 75 to 125 km, and are at a distance from fault zones. Several hundred earthquakes occur there annually, most of which are weak and cause no damage;
- Portugal is a more seismically active country and has experienced several major earthquakes. It is believed that the earthquake and tsunami of 1755, which ruined Lisbon, could have been caused by a fault that initiated the formation of a new subduction zone.
- the territory of Spain is occasionally prone to small earthquakes due to the ongoing deformation of the platform in the Pyrenees zone;
- the French Alps are still partially tectonically active and capable of generating earthquakes, although not as intense as the Apennines in Italy;
- North Africa experiences infrequent earthquakes, mainly in the ancient mountain ranges of the seismically inactive Atlas;
- Eastern North America, unlike the active western coast, is located in the center of the plate. Earthquakes of magnitude 3-3.5 occur here, but scientists associate them with the formation of karst caves and underground seas;
- Eastern part of South America is located in the center of the plate and, unlike the coasts of Peru and Chile, is less susceptible to earthquakes;
- Iceland experiences frequent minor earthquakes with magnitudes up to 3.0, but most of them are of magmatic origin, as in Hawaii.
Australia, Greenland, Belarus, the Czech Republic, and Poland, as well as Antarctica, are considered to be relatively quiet seismic zones.
Intraplate earthquakes
Unlike regular earthquakes that occur along fault zones, seismic activity in areas located above tectonic plates is more dangerous and unexpected. The earthquake in Morocco on September 8, 2023 is one example of such seismic events. Tremors of magnitude 7.0 occurred in the relatively stable region of the Atlas Mountains. The unexpected earthquake caused more than 600 deaths and destruction in the Oukaimeden ski resort, near Marrakech.
Scientists consider the causes of intraplate earthquakes to be:
- deformation of the Earth’s crust that occur over tens of thousands of years and can weaken the structure of plates from the inside;
- existence of ancient, partially overgrown faults that are located deep inside and have not been noticed by scientists;
- hydraulic fracturing of rock layers (fracking) when injecting water and sand during oil production. Fracking is linked to a series of earthquakes that occurred in Ohio in 2015.
It is important for seismologists to understand the nature and causes of intraplate earthquakes. These events pose a significant risk to people living in relatively seismically safe regions, since no one expects earthquakes here and prepares for them.