Earthquake Risks: Understanding the threat and preparedness

Positioned on the boundary of the Eurasian and African tectonic plates, this Iberian nation experiences seismic activity that has historically had some devastating effects.

Understanding the risks associated with earthquakes in Portugal, alongside the historical context, scientific assessments, and preparedness measures, is crucial for both residents and visitors alike in mitigating potential impacts.

Geological Background

Portugal's geological framework significantly contributes to its earthquake risk. The country is primarily situated on the Eurasian Plate; however, its western coastline is influenced by the presence of the Azores-Gibraltar Transform Fault and the Mid-Atlantic Ridge. The interaction between these tectonic plates creates an environment prone to earthquakes, both of shallow and deep focus. This geological makeup has led to various significant seismic events over the centuries.

Historical Context of Earthquakes

Portugal's history with earthquakes is marked by one of the most catastrophic events in European history - the Great Lisbon Earthquake of 1755. Occurring on November 1st, this earthquake, estimated at a magnitude of 8.5 to 9.0, devastated Lisbon and its surrounding regions. The repercussions included not just the tremors but also subsequent tsunamis and fires that led to the loss of approximately 30,000 to 100,000 lives as well as immense destruction of infrastructure. The event of 1755 profoundly influenced philosophical thought, leading to changes in building codes, urban planning, and emergency response mechanisms.

In the following centuries, Portugal has not been immune to other significant seismic events. In 1909, the city of Ribeira Grande in the Azores experienced a 7.2 magnitude earthquake, and in 1969, another quake measuring 7.9 struck the coast near the Algarve region. Each of these events has contributed to a growing awareness of seismic risks and the need for preparedness.

Current Seismic Risk Assessment

According to the European-Mediterranean Seismological Centre (EMSC) and the Instituto Português do Mar e da Atmosfera (IPMA), Portugal is categorized into different seismic risk zones. The Azores and parts of the mainland, especially the western and southern coasts, are classified as high-risk areas. Factors such as location, population density and the nature of infrastructure significantly affect the overall risk profile.

Urban centres like Lisbon and Porto, which are densely populated and host several historical buildings, are particularly vulnerable. Meanwhile, rural areas may face challenges related to older structures that are not adequately retrofitted to withstand seismic events. Modern building codes have improved the resilience of new constructions but many older buildings remain at risk.

Seismologists continue to diligently monitor the tectonic activity in the region. The IPMA and the Seismology Laboratory of the Faculty of Sciences of the University of Lisbon regularly conduct studies to track seismic activity and analyse historical data. The information gathered assists in formulating risk maps and understanding potential earthquake scenarios, helping communities better prepare for future events.

Impacts of earthquakes

The potential impacts of earthquakes in Portugal can be catastrophic, ranging from loss of life and injuries to widespread infrastructural damage and economic disruptions. The coastal regions are particularly susceptible to tsunamis generated by undersea earthquakes, posing additional risks to coastal communities and infrastructure.

The economic ramifications following an earthquake can also be profound. Reconstruction costs can exceed billions of euros, impacting national resources. The tourism sector, a significant contributor to Portugal's economy, could face declines following a major seismic event, especially in historically significant cities like Lisbon and Porto.

Furthermore, the psychological impacts on individuals and communities after experiencing an earthquake are significant. The trauma of such events often leads to long-term mental health issues that require attention and support from local healthcare systems.

Preparedness and response

Recognising the risks posed by earthquakes, Portugal has developed several measures to improve preparedness and response strategies. These initiatives involve both government bodies and community organisations focused on educating the public and enhancing infrastructure resilience.

1. Legislation and Urban Planning: Following historical earthquakes, Portugal implemented stringent building codes that address seismic safety. All new buildings, especially in high-risk areas, are required to adhere to these codes. Furthermore, urban planning now incorporates seismic risk assessments, ensuring that essential services are located in safer zones.

2. Public Awareness Campaigns: The government and NGOs engage in ongoing educational campaigns aimed at increasing public awareness about earthquake risks and safety measures. This includes information on how to prepare emergency kits, develop family communication plans, and respond during and after seismic events.

3. Emergency Preparedness Exercises: Regular drills and simulations are conducted to prepare local authorities and communities for potential earthquakes. These exercises involve emergency services, schools, and healthcare providers, ensuring that all parties understand their roles in response scenarios.

4. Research and Monitoring: Continuous research into seismic activity and advancements in geophysical technology have improved the understanding and modeling of earthquakes. The establishment of a network of seismic monitoring stations allows for real-time data collection and analysis, facilitating quicker response times and more accurate predictions.

5. Community Engagement: Local communities are encouraged to form emergency response teams and develop localised disaster response plans. These grassroots initiatives play a vital role in enhancing community resilience and ensuring that local knowledge and resources are utilised effectively during emergencies.

What can we all take from this?

While Portugal continually charms us with its natural beauty as well as a rich cultural and historical tapestry, it remains essential to keep informed about the ongoing risks associated with earthquakes. The country's geological characteristics, historical events and current seismic activity paint a complex yet sobering picture of potential vulnerability. However, through enhanced preparedness and community engagement, the impacts of potential seismic events can be substantially mitigated.

Education, legislation, and continuous research are key components in promoting a culture of resilience among residents and local authorities. With an ethos of preparedness and a proactive approach to disaster management, Portugal can better safeguard its citizens, it's infrastructure and its treasured cultural heritage from the inevitable seismic risks posed by our unique geographic location.

As Portugal navigates the challenges of potential natural disasters, the lessons learned from its past continue to serve as a guide for building a more resilient future.