As in a number of other recent humanitarian disasters, social networking sites were inundated with eyewitness reports from Haiti as well as expressions of support from people outside the country.
With telephone lines down, local people turned to Facebook and Twitter to alert the world to the earthquake and to attempt to reach family and friends who were missing.
Shortly after the earthquake hit at about 4.53pm local time (9.53pm Irish time), locals began tweeting about the damage to buildings in the Haitian capital Port-au-Prince.
Among them was Troy Livesay country director for the non-profit organisation World Wide Village. Minutes after the earthquake hit he tweeted, "just experienced a MAJOR earthquake here in Port au Prince - walls were falling down. - we are ALL fine - pray for those in the slums..."
In an update a short time later he added that a friend had managed to make it out to them who had seen "many dead bodies and injured along the way."
Still later he tweeted: "the sun went down shortly after the big quake. It is up now. It is eerily quiet."
Another person tweeting from the Haitian capital was a Richard Auguste Morse, a Puerto Rican-born Haitian-American musician and hotel manager.
"Just about all the lights are out in Port au Prince.. people still screaming but the noise is dying as darkness sets," he tweeted just moments after the incident."
He later added: "Another aftershock..a little longer..much screaming downtown..this is going to be a long night."
The twitter updates highlighted the fear that Haitian felt over the aftershocks which continued to occur long after the initial tremor.
"Was in the streets during that last aftershock. people were terrified, screaming and running in every possible direction," said sound engineeer Frederic Dupoux.
He later tweeted "Everybody camping in the streets of Port-au-Prince sleeping under stars to wake up from an awful nightmare."
Elsewhere, local radio and tv host Carel Pedre encouraged people from outside Haiti to contact him if they wanted information on friends and colleagues.
Meanwhile former Fugees singer Wyclef Jean, a Haitian who was born in Croix-des-Bouquets, was among those living outside the country who tweeted about the earthquake, calling on twitter users to donate money to charities helping to allieviate the suffering of people in the country.
Many of those humanitarian organisations also used social networking sites to make appeals for donations while updating users as to the situation on the ground.
