Earthquakes – Tsunami

A Terra Treme Earthquake Awareness Exercise. 2023

All Saints Day 1st November 1755 was that date of the largest Earthquake in Portugal’s history measuring an estimated 8.5 to 9.0 on the Richter scale.

The following letter from a British nun at the time was discover some 2 years ago and describes the earthquake.

The article with it appeared in the Daily Mail in 2019  is an extremely interesting account of the event.

Download here with copies of the letter.

A Terra Treme Earthquake Awareness Exercise 2023

The National Emergency and Civil Protection Authority (ANEPC) promotes on Wednesday 14th of November 2023, at 11:14 am, the 10th edition of the national public awareness exercise for the seismic risk, called (A TERRA TREME) THE EARTH SHAKES. The date indicated for its completion coincides with the World Tsunami Risk Awareness Day, an event instituted by the UN.

This initiative is part of the activities that are part of the National Strategy for Civil Protection Preventive and aims to empower the population to know how to act before, during and after an earthquake, making citizens aware of the fact that they live in a risk society, and challenging them to get involved in the process of building communities that are safer and more resilient to disasters.

The exercise itself comprises the practice of 3 simple gestures that can make a difference to who practices them in the event of an earthquake. The action takes place for one (1) minute, in which the participants, individually or collectively, are invited to perform the 3 gestures of self-protection: DROP COVER HOLD.

In addition to the school-age population, whose adherence to the initiative has been significant over successive editions, ANEPC aims to successively broaden, year after year, the reflection and debate in around the topic of seismic risk and the participation in this exercise to other sectors of civil society.

To this end, we consider it important to involve organizations – public and private – in this collective purpose, seeking to join efforts and extract synergies from the whole of society, so that they are levels of resilience, both individual and collective, are achieved.

In this regard, the ANEPC would like to invite all Institutions to participate in this public initiative.

Participation in the Exercise can take multiple forms, namely:

  • Conducting an internal clarification session (for workers/employees) dedicated to explaining preventive measures and self-protection behaviour to adopt in our homes and workplaces;
  • The dissemination on the Institutional page and in other digital media, of involvement and participation of the Institution in the initiative;
  • Dissemination through internal email by all workers/collaborators information on preventive measures and self-protection behaviours to adopt in case of an earthquake/tsunami;
  • Individual and/or Institutional registration on the website;
  • Revisiting preventive and emergency procedures to deal with an event of earthquake and/or tsunami,
  • The carrying out of an evacuation test exercise on 14-11-2023, the date chosen for the realization of the Exercise “A TERRA TREME”, and wants to encourage other actions that may enrich the initiative’s agenda.

A TERRA TREME has a dedicated website (, which provides information about the Exercise.

Safe Communities Portugal announcement of the Exercise in English can be downloaded from Youtube here
The 1755 Lisbon earthquake, also known as the Great Lisbon earthquake, occurred on Saturday, 1 November, the holy day of All Saints’ Day, at around 09:40 local time. In combination with subsequent fires and a tsunami, the earthquake almost totally destroyed Lisbon and adjoining areas.
Seismologists today estimate the Lisbon earthquake had a magnitude in the range 8.5–9.0 on the moment magnitude scale, with its epicentre in the Atlantic Ocean about 200 km (120 mi) west-southwest of Cape St. Vincent. Estimates place the death toll in Lisbon alone between 10,000 and 100,000 people, making it one of the deadliest earthquakes in history.

Above picture 1755 Lisbon earthquake

According to historical records, most of the earthquakes affecting Portugal (mainland) have epicentre SW of the Iberian Peninsula (Gorringe bank) or in the Lower Tagus Valley. The most vulnerable areas are the Lisbon urban area and Algarve south. Major earthquakes: occoured in 1531, 1755, 1909 and 1969.

Preparation – Beforehand

  • Inquire about the possible causes and effects of an earthquake in your area. Discuss in a calm and serene way with your family and friends.
  • Make an emergency plan for your family.
  • Make sure everyone knows what to do in the event of an earthquake.
  • Identify and agree a meeting place in advance, in case the family members separate during the earthquake.
  • Prepare your home in order to facilitate the movements, clearing the corridors and passageways, arranging furniture and toys.
  • Organise your emergency kit:
    • Keep a flashlight, a portable dynamo radio (without batteries) as well as a fire extinguisher and a first aid kit.
    • Store water in plastic containers and dry food for two or three days (be careful: periodically check shelf life). Include a can opener.
    • Have the emergency services phone numbers in a handy location, the family / friends contact list, and copies of important documents.
    • Take your usual medication and personal hygiene products (including toilet paper, wet wipes and plastic bags for sanitary purposes), also include a change of clothes (do not forget a cap and waterproof);
    • Include also: money, a whistle, an anti-dust mask, and the mobile phone charger with an extra battery (common power-bank);
    • Extra food and water for pets.
  • Identify the safest places by distributing your family members through them: from interior doors, corners of master walls, under tables and beds.
  • Keep a safe distance from objects that may fall or splinter.
  • Know the most dangerous places: next to windows, mirrors, lamps, furniture and other objects. Elevators and exits to the street.
  • Secure the shelves, vases, and flower pots to the walls of your home.
  • Place heavy or large objects on the floor or on the lowest shelves.
  • Teach all family members how to turn off electricity and cut off water and gas.

Emergency telephone numbers are available in a handy location

During an earthquake

The accepted action to help protect yourself taught in countries at high risk of earthquakes, is to “drop, cover and hold” i.e. drop to the floor, take cover under a sturdy desk or table, and hold on to it firmly. More details can be downloaded here.

  • If you are inside a building, move no more than a few steps, drop, cover and hold. Stay indoors till the shaking stops and you are sure it is safe to exit. In most buildings you are safer if you stay where you are until the shaking stops.
  • If you are in an elevator, drop, cover and hold. When the shaking stops, try and get out at the nearest floor if you can safely do so.
  • If you are outdoors when the shaking starts, move no more than a few steps away from buildings, trees, streetlights, and power lines, then Drop, Cover and Hold.
  • If you are at the beach or near the coast, drop, cover and hold then move to higher ground immediately in case a tsunami follows the quake.
  • If you are driving, pull over to a clear location, stop and stay there with your seatbelt fastened until the shaking stops. Once the shaking stops, proceed with caution and avoid bridges or ramps that might have been damaged.
  • If you are in a mountainous area or near unstable slopes or cliffs, be alert for falling debris or landslides.

After an earthquake

  • Listen to your local radio stations as emergency management officials will be broadcasting the most appropriate advice for your community and situation.
  • Keep calm but expect to feel aftershocks.
  • Check yourself for injuries and get first aid if necessary. Help others if you can.
  • Be aware that electricity supply could be cut, and fire alarms and sprinkler systems can go off in buildings during an earthquake even if there is no fire. Check for, and extinguish, small fires.
  • IIf you are in a damaged building, try to get outside and find a safe, open place. Use the stairs, not the elevators.
  • Watch out for fallen power lines or broken gas lines, and stay out of damaged areas.
  • Only use the phone for short essential calls to keep the lines clear for emergency calls.
  • If you smell gas or hear a blowing or hissing noise, open a window, get everyone out quickly and turn off the gas if you can. If you see sparks, broken wires or evidence of electrical system damage, turn off the electricity at the main fuse box if it is safe to do so.
  • Keep your animals under your direct control as they can become disorientated. Take measures to protect your animals from hazards, and to protect other people from your animals.
  • If your property is damaged, take notes and photographs for insurance purposes. If you rent your property, contact your landlord and your contents insurance company as soon as possible.
  • Do not try and remove injured persons with fractures unless it is urgent to place out of danger – wait for medically trained personnel to arrive.

All prevention and protection information is from official sources.

“A Terra Treme” Earthquake exercise 2017 – Safe Communities Portugal together with Euroinesco participated in this exercise held on 13th October 2017, using “DROP, COVER, HOLD ON” . This can be viewed on YouTube here

Emergency planning

Under the emergency plans for earthquakes over 200 entities are involved covering First aid and medical assistance; Forensics / Mortuary; Law and order; Buildings and Structures; Logistics; Communications and Vital networks


Tsunamis are rare events, but can be extremely deadly. In the past 100 years, 58 of them have claimed more than 260,000 lives, or an average of 4,600 per disaster, surpassing any other natural hazard. The highest number of deaths in that period was in the Indian Ocean tsunami of December 2004. It caused an estimated 227,000 fatalities in 14 countries, with Indonesia, Sri Lanka, India and Thailand hardest-hit.

Over 700 million people live in low-lying coastal areas and Small Island Developing States exposed to extreme sea-level events including tsunamis (IPCC).

Investing in resilient infrastructure, early warning systems, and education is critical to saving people and protecting their assets against tsunami risk in the future.

Tsunami is a series of giant waves. In Japanese, tsunami means ‘Harbour Wave’. A wave is created when energy passes through water. Moving air or wind provides energy to water, forming regular waves.

While on the ocean floor, when a tectonic plate suddenly slides beneath the other, the resulting earthquake releases tremendous amount of energy. This energy spreads outward from the point of earthquake, triggering waves that can form tsunami. Initially, these waves are small in size but they travel at great speeds. However, when the waves approach the shore, the rising seabed obstructs the energy of waves. This slows down the speed of waves. But the energy flux must remain constant leading to an increase in height of the waves, thus resulting in tsunami.

Certain areas of Portugal’s coastline are at risk of a Tsunami. A very useful video about Tsunamis and what action you should take in the event of a Tsunami can be downloaded here.

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