A powerful magnitude 7.4 earthquake hit near Puerto Madero in southern Mexico on Friday, triggering a tsunami threat warning from the US Tsunami Warning System for parts of the Pacific coast.The US Tsunami Warning System said hazardous tsunami waves are possible along coastlines within 300 km of the earthquake’s epicentre in the Mexico region, as cited by Reuters.The earthquake struck near the Mexican city of Puerto Madero at a shallow depth of 10 km (6 miles), USGS said. The tremor shook buildings in Guatemala City and was also felt in neighbouring El Salvador, according to Reuters.(This is a developing story)