Digital fundraising accounts for about two-thirds of donations to many charities that are made in response to emergencies, according to Maria Butera, head of digital at Save the Children Spain.
Butera told delegates at the International Fundraising Congress in the Netherlands that charities needed to embrace online fundraising tools in order to respond with greater speed to emergencies.
She was speaking at session called "What’s on your mind? New opportunities with Facebook", which explored the possibilities offered by the new fundraising tools available on the social network.
Facebook launched the tools in 16 countries including the UK in September, after they were launched in the US last year. They include a "donate" button that charities can add to Facebook posts and fundraising pages so people can raise money for their chosen causes.
Butera said the way in which Save the Children Spain raised money online had changed completely in recent years.
"In past emergencies, the first thing we usually did was to set up a web page, then send emails," she said. "Maybe after that you might put it on Facebook once or twice.
"For some organisations and for us, digital has come to be 60 to 70 per cent of emergency income because of the nature of digital. Speed is critical in an emergency, and digital tools can help you harness that because, particularly with natural disasters such as earthquakes or hurricanes, you get all the media attention in the first days.
"After a couple of weeks nobody else is talking about the emergency, but you’re still in the field helping those people.
"So you have to take the most advantage of that bunch of digital tools and start fundraising from the first day."
Tom D’Souza, global innovation manager at the Movember Foundation, said the Facebook tools, which the organisation tested in the US during last year’s Movember event, had been an "amazing success".
He said: "The most exciting thing for us was some of the statistics that showed fundraising behaviour change."
On average, he said, fundraisers using Facebook raised twice as much as those who did not.
He said the tools had also allowed the charity to reach millions of people.
"We didn’t spend a penny, so that is a natural marketing platform for us, and you’ll never be able to put a value on that," D’Souza said.
Anita Yuen, head of social good at Facebook, said another tool, which allows charities to include donate buttons on live streams and is currently available in the US, would be available in the UK soon but was unable to confirm when exactly that would be.