LisbonWave26: Lisbon to Test Tsunami Warning Sirens on Tuesday, March 24

If you hear air-raid-style sirens across central Lisbon on Tuesday morning, there is no need to panic. The city's Civil Protection authority will conduct "LisbonWave26," a full-scale test of the municipal tsunami warning and alert system, between 10:30 AM and 12:00 PM on March 24.

The drill will activate all four of Lisbon's tsunami sirens simultaneously, simulating the warning that would sound in the event of a real seismic-triggered wave approaching the capital. Residents and visitors in the affected zones are encouraged to participate by practising the designated evacuation routes.

Where the Sirens Are

Lisbon currently has four tsunami warning sirens installed along the waterfront, positioned at the areas most vulnerable to wave impact:

• Passeio Carlos do Carmo
• Doca de Alcantara
• Praca do Imperio (Belem)
• Terreiro do Paco (Praca do Comercio)

All four will be activated during the exercise. The sirens produce a distinctive rising-and-falling tone designed to be distinguishable from other emergency signals. During the test, residents should listen for the tone and familiarise themselves with its sound.

Why Lisbon Tests for Tsunamis

Portugal sits at the junction of the Eurasian and African tectonic plates, making it one of the most seismically active countries in Western Europe. The catastrophic earthquake and tsunami of November 1, 1755, remains the defining natural disaster in Portuguese history. Waves estimated at five to six metres high struck the Lisbon waterfront, reaching 250 to 350 metres inland in some areas. In the Algarve, waves may have been even higher, and the impact was recorded as far away as North Africa and the Caribbean.

While a repeat of the 1755 event is statistically unlikely in any given year, seismologists consider the risk real enough to warrant preparedness. The Azores-Gibraltar fault zone, which runs from the mid-Atlantic to the Strait of Gibraltar, remains capable of generating significant seismic events. A 2024 study published in the journal Tectonics identified active submarine faults southwest of Portugal that could produce earthquakes of magnitude 7.0 or greater.

What You Should Do

The exercise is purely a drill and requires no emergency action. However, the Camara Municipal de Lisboa encourages everyone in the waterfront zones to use the opportunity to:

• Learn the sound of the tsunami siren so you recognise it in a real emergency
• Identify your nearest evacuation route -- generally, move uphill and away from the river
• Locate the nearest designated meeting point
• Check that your mobile phone is set to receive emergency alerts (most Portuguese carriers participate in the EU-Alert system)

For Residents Outside Lisbon

The LisbonWave26 drill is specific to the capital. However, other Portuguese coastal cities -- including Porto, Faro, Setubal, and several Algarve municipalities -- have their own emergency preparedness programmes. The national Civil Protection authority (ANEPC) periodically conducts broader exercises along the Atlantic coast.

Residents of the Algarve, which faces the open Atlantic and would be among the first areas affected by a tsunami originating from the southwest, should familiarise themselves with local evacuation signage. Many coastal municipalities in the region have installed blue evacuation route signs indicating the direction to higher ground.

The drill is part of activities connected to the International Day of Civil Protection, observed on March 1. It represents a step in Lisbon's ongoing investment in disaster preparedness infrastructure, following the installation of the four-siren network in recent years.