The web application - a kind of missing persons database - allows people to post and search for the status of loved ones affected by a disaster. It was built and first deployed in response to the 2010 Haiti earthquake.
As of 12.30pm on Monday, the tool reports that it is "tracking about 4,900 records".
Facebook chief Mark Zuckerberg said in a post on Saturday that the company had activated its Safety Check tool for people affected by the earthquake, so that they can let friends and family know that they are safe.
The 7.8-magnitude earthquake has killed more than 3,200 people.