The northwestern portion of South America has been under observation from geological, tectonical and seismological standpoints; it has as well motivated multiple discussions and models to support the knowledge and understanding of the geodynamic of this zone, which is under the influence of Panama, Choco and Norandino plates, in the frame of Nasca, Sur America and Caribbean plates. Earthquakes from 192 17th and 18th October in the Atrato Medio region, (Choco and Antioqua), produced geological effects mainly over Murindo town and neighborhoods, as well as a region including municipalities from western Antioquia, Valle del Aburra (Medellín), Tolima, Valle del Cauca and Cauca, regions located as faraway as 390 km from the epicenter. Losses were estimated in US$ 15 million.

Key words: seismic hazard, earthquakes, northwestern Colombia, Chocó block, Panama block.