An alert telling residents to flee an imminent tsunami reached 52,614 phones along Portugal’s Algarve coast on Saturday evening, prompting a rush from waterfront streets in Faro, Olhão and Tavira. The warning was false: no earthquake or sea surge had been recorded, officials said. At least 3,200 people moved towards higher ground before the volunteer-built app was shut down.
The first message arrived at 18:42 on 31 October and said a wave would reach the coast in 12 minutes. The Algarve Civil Safety Office said it had issued no warning, while its monitoring stations showed no unusual sea movement. The app’s operators disabled alerts at 19:07 and told users to check official channels for emergency information.
A local alert network
The app, Maré Clara, was built by the volunteer group Litoral Link and had been running for 18 months. It began as a way for residents to share flood and beach-condition reports, then added emergency push alerts. Coordinator Hugo Carvalho said 26 volunteers maintained the service for users across 14 Algarve municipalities.
Carvalho said the team was reviewing how a tsunami drill message could have reached the live system. The app’s security contractor found that an account used by a volunteer had been accessed from an unrecognised device; the source of that access has not been identified. The group said its alert channel was separate from government emergency networks.
Local officials counted 3,200 people moving uphill or away from the waterfront, using transport data and reports from municipal crews. Several bus routes paused for up to 19 minutes, two ferry services waited at their terminals, and businesses along Faro’s waterfront closed their doors. No injuries were reported, and the civil safety office said there was no need for an evacuation.
“We built a helpful neighbourhood tool and discovered it could sound like the state speaking,” Carvalho said. He apologised to residents and said Litoral Link had stopped all push alerts while it checked the system. The group had not asked the government to approve its emergency messages before launching them.
Who can send a warning
Sofia Magalhães-Reis, a cybersecurity researcher in Lisbon, said the incident showed how a small volunteer service could be mistaken for an official warning channel. “The danger is not only a false message; it is that people may stop believing the next one,” she said. She urged residents to confirm urgent alerts through more than one source.
Carvalho said the app had no formal review of who could send a live alert, and that the group was now removing old accounts and requiring two-person approval for every emergency message. A technical audit and a review by the Algarve Civil Safety Office are due by 16 November. The app will remain online for ordinary beach reports, but its alert feature is suspended.
The regional transport consortium estimated that the disruption cost about €180,000 (about $207,000), including staff overtime and delayed services. Litoral Link said it had less than €9,000 in its account and was seeking help to cover an independent security review. The civil safety office said it would publish revised guidance on verifying local digital alerts this week.
Residents interviewed near Faro’s harbour said some had followed the message because it arrived with a countdown and a map. Amália Molnárová, who was walking home when her phone sounded, said she first checked on neighbours before heading uphill. “The map looked official, but the sender was unfamiliar,” she said. “Next time, I’ll check the city channel first.”
