After a powerful earthquake rocked the northern Philippines on July 27, a video of strong waves washing away small boats was viewed more than a million times in Facebook posts that falsely claimed it showed a tsunami in the archipelago's northern province of La Union. The head of the Philippine seismology agency, however, told AFP the video did not show a tsunami. No tsunami alert was issued following the earthquake that was the strongest recorded in the Philippines in recent years.
"Tsunami in La Union due to the earthquake," reads the Tagalog-language caption to the video shared on Facebook on July 27.
It was also overlaid with text that states: "Tsunami La Union".
The four-minute 56-second clip circulated online within hours after a 7.0-magnitude quake struck the lightly populated province of Abra.
The powerful quake rippled across the mountainous region, toppling buildings, triggering landslides and shaking high-rise towers hundreds of kilometres away in the capital Manila.
As of July 28, five people were killed and more than 150 were injured, according to authorities.
La Union is a coastal province close to Abra.
Screenshot of the false post taken on July 28, 2022
Comments to the posts indicate people believed the video showed a tsunami following the earthquake.
"Oh no, there's a tsunami, why are people just watching? They should leave that area," one wrote.
"OH MY GOD PLEASE PROTECT YOUR CHILDREN," said another.
But responding to the posts, Renato Solidum Jr, director of the Philippine Institute of Volcanology and Seismology (Phivolcs), told AFP: "That is not a tsunami and will not be life-threatening."
'No tsunami threat'
Solidum said that the strong waves seen in the video could be from ground movement.
"There can be seawater oscillation on coastal areas near the epicenter as the ground is shaking," he said.
According to a Phivolcs tsunami advisory on July 27, the country has "no tsunami threat" from the earthquake.
It reads in part: "There is no tsunami threat to the Philippines from this earthquake.
"However, earthquakes of this size may generate unusual sea level disturbances that may be observed along coasts near earthquake epicenter of Abra province."
In a press briefing following the earthquake, Solidum explained the agency has not raised a tsunami warning since the "fault is inland".
"It will not raise the seafloor to cause any life-threatening tsunami," he said.
The US Geological Survey (USGS) defines a tsunami as a series of waves triggered by "large-scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands".
No injury from waves
Keyword searches found the clip was taken from a Facebook livestream published on July 27 by user Fati Ong Cabangcla.
At the clip's 39-second mark, someone could be heard shouting: "Tsunami, tsunami!"
But when AFP reached out to Cabangcla, she said: "waves did not cause any injury although they were strong."
The footage was filmed in the municipality of Luna in La Union province.
The location can be seen here on Google Street View.