Doğa ve Deprem Bilimi: Prof. Dr. Ali Osman Öncel Anlatıyor: Earthquake in Greece: Unraveling Its Impact and Reach

Monday, November 4, 2024

Earthquake in Greece: Unraveling Its Impact and Reach

On November 3, 2024, a 5.3-magnitude earthquake struck southeastern Greece, near Thessaloníki, sending tremors across vast distances—even reaching Istanbul, Turkey, over 500 kilometers away. This event, though moderate in magnitude, demonstrates the complex interplay between seismic forces and urban environments, showcasing how even smaller-scale quakes can have significant impacts on populated regions. Understanding these dynamics provides valuable insights for future seismic preparedness.

Earthquake Details and Geographical Context

The earthquake occurred at 17:03 UTC, with an epicenter located approximately 13 km south of Néa Moudhaniá, at a depth between 8 and 12 kilometers, depending on varying agency reports. Classified as a normal fault earthquake, this event resulted from vertical stress along Greece’s active fault systems, located at the convergence of the African and Eurasian tectonic plates

(Papazachos & Papazachou, 2024). Such earthquakes are frequent in this region, where tectonic plate interactions create conditions for seismic activity.

This earthquake, although relatively shallow, released energy that propagated across diverse geological landscapes, amplifying its effects in certain regions and affecting structural integrity across cities with differing building codes and designs.

Variations in Intensity and Factors Influencing Impact

The earthquake’s intensity reached level VII on the Modified Mercalli Intensity (MMI) scale near the epicenter, resulting in noticeable shaking and some structural disruptions. However, the effects varied significantly depending on distance from the epicenter and local structural resilience:

Within 30 km of the epicenter, intensity dropped sharply from VII to around III.
Between 30 km and 50 km, there were observed fluctuations, with intensity briefly rising to level IV due to variations in soil and structural stability.
Beyond 50 km, intensity steadily declined from IV to III, though it unexpectedly rose back to level IV at distances over 300 km, likely due to specific geological formations that amplified the seismic waves.

These intensity fluctuations reveal that local ground composition and infrastructure quality played a crucial role in how the quake was experienced. In regions with weaker soils or less stringent building standards, seismic waves tended to amplify, leading to varied impacts even at similar distances.

The Reach and Influence: A 500-km Radius

This earthquake was felt across an unusually large area, with tremors reaching Istanbul. This broad reach is due to the complex geological structures in Greece and the dense urban centers that effectively conducted the seismic energy. Reports from thousands of residents in distant cities underscored how the shaking was intensified in regions with high population density and diverse building structures (Global Disaster Alert and Coordination System [GDACS], 2024). These reports further emphasize the importance of understanding the interactions between natural forces and human-made environments.

Conclusion

The November 3 earthquake in Greece illustrates the nuanced and often unpredictable nature of seismic activity, especially in regions with intricate geological and urban landscapes. Variations in experienced intensity underscore the need for continued research into earthquake-resistant building practices and preparedness strategies in seismically active areas. As cities grow and infrastructures age, understanding these dynamics is essential to mitigate risks associated with future quakes.

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