A magnitude-7.7 earthquake struck near Pitaloza Arriba in Panama, producing strong surface shaking. The rupture occurred on land and involved rocks sliding horizontally past one another. A tsunami alert was later lifted. Around 4.6 million people experienced moderate to severe shaking, while casualty statistics were still unavailable when the initial scientific assessment appeared.
Science··Midday
A shallow rupture shakes Panama
A magnitude-7.7 earthquake struck Panama on 9 October. Shaking from the shallow rupture was felt across a wide area, including the capital, Panama City.[1], [2]
The epicentre was southwest of Pitaloza Arriba, a settlement in Panama’s Herrera Province. USGS initially measured the earthquake at magnitude 8.0 before revising it to 7.7. Its assessment estimated that around 4.6 million people experienced moderate to severe shaking. Fatality and injury statistics were not yet available when the initial scientific assessment appeared.[1]
Horizontal movement occurred on land
USGS seismologist Susan Hough described strike-slip faulting: blocks of rock moved mainly horizontally past each other. The rupture occurred on land at a relatively shallow depth. Such a shallow rupture can produce strong shaking at the surface. Panama sits near the Cocos, Nazca, Caribbean and South American tectonic plates, whose junction contains a complicated network of faults. The earthquake occurred on one of those faults.[1]
The tsunami alert was lifted
An initial tsunami alert was later lifted. Hough explained that this rupture did not directly move the seafloor beneath the water column, an important mechanism in tsunami formation. President José Raúl Mulino said he had ordered personnel, resources and aid mobilized to the area. USGS estimates of possible casualties and economic damage were based on modelling. Strong aftershocks remained a possibility.[1]
