Offshore Earthquakes Rattle Sierra Leone’s Capital

Two powerful earthquakes struck the central Mid-Atlantic Ridge on Tuesday, sending tremors through Freetown, the capital of Sierra Leone, more than 1,100 kilometers away.

The U.S. Geological Survey recorded a magnitude 6.7 quake at 5:44 a.m. GMT and a magnitude 6.9 quake at 12:23 p.m. GMT. Both were shallow, at a depth of 10 kilometers, along the underwater ridge where the African and American tectonic plates separate.

Residents across central Freetown reported feeling their buildings shake around 12:30 p.m. local time, just minutes after the second quake. Workers at offices including the Africell headquarters and the Youyi Building were among those who felt it.

Sierra Leone’s National Disaster Management Agency launched a full investigation with the Sierra Leone Institution of Geoscientists, forming a technical working group to determine whether the offshore quakes caused the shaking.

Inspectors visited the sites where tremors were reported and found no major structural damage, property destruction or fatalities, the agency said.

The USGS issued a green alert for both quakes, signaling a low likelihood of casualties or economic losses, and authorities confirmed there was no tsunami threat to Caribbean or West African coasts.

Major earthquakes are extremely rare in Sierra Leone, which sits far from active fault zones. Seismologists say a strong enough ocean quake can send waves over very long distances, felt most inside multistory buildings.

Philadelphia is home to one of the largest Sierra Leonean and West African communities in the country, concentrated in Southwest Philadelphia, where families spent Tuesday checking in on relatives back home.