Seismic Activity in Europe

Every year, thousands of earthquakes hit Europe. However, the majority are too small to be felt otherwise they would cause greater damage to infrastructure and to people’s lives. 

The Irish Examiner¹ reports that – based on research by an international team of European seismologists, geologists, and engineers, along with the Swiss Seismological Service and ETH Zurich public university – Ireland is the least seismically active region in Europe. They revised the earthquake hazard model from 2013 and for the first time included the whole of Europe. The non-profit network European Facilities for Earthquake Hazard and Risk (EFEHR) reports that Turkey, Greece, Albania, Italy, and Romania are the countries with the highest hazard in Europe, followed by the following countries: Austria, Belgium, France, Germany, Iceland, Norway, Portugal, Slovenia, Spain, and Switzerland. They conclude that even in regions with low or moderate seismic hazards, earthquakes can still occur at any time and cause damage. They concluded that Europe has suffered more than 200,000 fatalities and more than €250 billion (£210 billion) in financial losses due to earthquakes in the last century.  

Picture 1: A M6.6 earthquake in the Aegean Sea, Kos Island, Greece.

According to the 2020 European Seismic Risk Model (ESRM20), European buildings constructed before the 1980s, urban areas, and high earthquake hazard estimates primarily determine earthquake risk². In recent years, many European countries have been putting more attention into completing the standards that ensure adequate protection from earthquakes. However, many infrastructures are still insufficiently reinforced against earthquakes, posing a great risk to people’s safety. Earthquakes pose the highest threat to densely populated urban areas. For example, the cities of Istanbul and Izmir in Turkey, Catania, and Naples in Italy, Bucharest in Romania, and Athens in Greece have suffered great losses due to earthquakes. In fact, these four countries alone experience almost 80% of the modeled average annual economic loss of €7 billion due to earthquakes².

Even though deadly seismic events are not as common in Europe as they are in other parts of the globe, powerful earthquakes do occur relatively frequently.

Picture 2: The European Seismic Hazard Map. Blue colors indicate comparatively low hazard areas, yellow to orange colors indicate moderate hazard areas and red colors indicate high hazard areas. © SHARE

Tectonic Fault Lines and Tectonic Plates

The largest earthquakes in Europe mostly occur on tectonic fault lines, which span from Iceland in the northwest of Europe, situated on the Mid-Atlantic-Ridge, to the North Anatolian Fault zone in Turkey in the southeast. The Balkan and Mediterranean countries, as well as Turkey, with their much denser populations living in regions at high risk, have a long history of destructive and deadly earthquakes. More remote areas, such as Iceland’s highly active and hazardous seismic zone, leave much smaller populations vulnerable to the danger. For example, a strong earthquake in Iceland in 1784 (an estimated magnitude of 7.2) caused severe damage to farmhouses and killed three people. In contrast, the first in a series of recent earthquakes in central Italy in August 2016 (magnitude 6.2) led to 299 deaths and caused severe damage to an entire town, leaving 4,500 people homeless. Other earthquakes in southern Europe and Turkey have cost thousands of lives in the past⁶.

Earthquakes in Europe are essentially a result of stress in the earth’s crust, the source of which is plate tectonics. Much of Europe’s mainland is encompassed by the Eurasian plate that moves mainly to the neighboring African plate to the south, the Anatolian microplate to the southeast, and the North-America plate to the west. There are several other microplates between Europe and Africa, which cause seismic activity, especially in the Mediterranean Sea region including the Alpine region. Because of the microplates, earthquakes in Europe occur across a large area, not only along a well-defined zone³.

Picture 3: World's tectonic plates.

You can read more about them here.

Tectonic plates also play a big role in mountain formation in Europe. For example, the Alps formed as a result of the collision of the Eurasian and African plates, two continental tectonic plates that were initially separated by ocean basins. The Himalayan Mountain range and Tibetan plateau have formed because of the collision between the Indian Plate and Eurasian Plate, which began 50 million years ago and continues today.

Europe's most destructive and largest earthquake

The most destructive earthquake in recorded European history hit the Straits of Messina in southern Italy in 1908, leveling the cities of Messina in Sicily and Reggio di Calabria on the Italian mainland. The magnitude 7.1 earthquake and tsunami caused an estimated 100,000 fatalities⁴. The economic damage was significant, as Messina was an important Mediterranean harbor. Losses have been estimated to be €88 million (US$116 million) at the time⁵.

The largest earthquake in recent years in wider Europe was a magnitude 7.6 earthquake that occurred on the 17th of August in 1999 in Derince, Turkey, less than 100 kilometers SE of Istanbul. It shook buildings, cut off electricity and telephone lines, and drove frightened residents to the streets. The earthquake caused more than 17,100 fatalities and injured more than 45,000 people. It also triggered a tsunami that killed 155 people.

Picture 4: Turkey's seismic map.

Just a few months after this earthquake, on November 12, 1999, one of the aftershocks shook Turkey again. This time the epicenter of the earthquake was about 100 kilometers east of the August earthquake. A magnitude 7.2 earthquake caused considerable damage in the Turkish city of Düzce and claimed between 850 and 900 lives⁷.

Picture 5: Saving lives after a devastating earthquake.

The earthquake that claimed the most lives in 2020 occurred on October 30^th in Samos, Greece. It claimed 119 lives, more than 100 people were injured, and many buildings were severely damaged. It also triggered a tsunami⁷.

One of the most surprising earthquakes in Europe in recent years was Zagreb’s magnitude 5.3 earthquake, which struck the capital of Croatia on the 22^nd of March 2020, and gained the reputation of being the biggest earthquake in Zagreb in the last 140 years. It caused widespread damage, including to the city’s cathedral, and caused the evacuation of hospitals. More than 1,900 buildings were reported to have been damaged to the point of becoming uninhabitable, one person was killed and 27 others were injured. It cost a total of €11.5 billion in economic loss⁸. 

Picture 6: Zagreb's earthquake consequences.

Solutions

A core team of researchers from different institutions across Europe, including GFZ, worked collaboratively to develop the first openly available Seismic Risk Model for Europe and to update Europe’s Seismic Hazard Model. They have been part of an effort that started more than 30 years ago and involved thousands of people from all over Europe. These efforts have been funded by several European projects and supported by national groups over the years².

GFZ is also chairing EFEHR (the European Facilities of Earthquake Hazard and Risk), which was created in 2020 for the purpose of ensuring the long-term accessibility and sustainability of open source and transparent European seismic hazard and risk models².

Sources:
1) Hoare, Padraig. 2022. Ireland One of the Least Likely Countries in Europe to be Impacted by Earthquakes. Accessed on 28-Jun-2022. Available at: https://www.irishexaminer.com/news/arid-40863605.html 
2) Ferman Research Centre of Geosciences. 2022. New Earthquake Assessments Available to Strengthen Preparedness in Europe. Accessed on 28-Jun-2022. Available at:https://www.gfz-potsdam.de/en/press/news/details/neue-erdbebenanalysen-staerken-die-katastrophenvorsorge-in-europa 
3) ETH Zurich. Causes of Earthquakes in Europe. Accessed on 28-Jun-2022. Available at: http://www.seismo.ethz.ch/en/knowledge/things-to-know/causes-of-earthquakes/europe/ 
4) History. Worst European Earthquake Ever Recorded. Accessed on 28-Jun-2022. Available at: https://www.history.com/this-day-in-history/worst-european-earthquake 
5) Geological Society of London. 2001. The Earth in Our Hands: How Geoscientists Serve and Protect the Public. Burlington House, London: April 2001.
6) Geographical. 2022. Danger Zones: Mapping Europe’s Earthquakes. Accessed on 28-Jun-2022. Available at: https://geographical.co.uk/science-environment/danger-zones-mapping-earthquakes-in-europe 
7) Potnik.si. 2021. Najhujši potresi v Evropi od leta 1995. Accessed on 29-Jun-2022. Available at: https://www.potnik.si/najhujsi-potresi-v-evropi/ 
8) The Guardian. 2020. Zagreb Hit by Earthquake While in Coronavirus Lockdown. Accessed on 29-Jun-2022. Available at: https://www.theguardian.com/world/2020/mar/22/croatia-earthquake-causes-widespread-damage-zagreb

All SHARE products, data, and results, are freely available and provided through the project website and the European Facility for Earthquake Hazard and Risk. The map shown in the figure can be ordered from the project website.