Since last Saturday's earthquake in Chile, tens of thousands of people have left messages on Google's Person Finder website. It first went online after January's earthquake in Haiti. There's another web resource - the International Committee of the Red Cross' Family Links site - that has been around a lot longer. Both sites have drawn tens of thousands messages.

Google’s Crisis Response Team, a division of the search engine giant that supplies aid organisations with free applications, created the Person Finder. "Aid organisations were already using Google Maps and another programme to create maps using spreadsheets, and the Person Finder was the next logical step," says Laura Scott of Google UK.

She says the demand for free programmes is enormous because many NGOs, especially the smaller ones, do not have the money to develop their own software.

Reliability
In the wake of the Chilean earthquake, 54,000 people have left messages on Person Finder, the vast majority of them concerning missing people. Some also left a photo and a last known address. Occasionally, a follow-up message is added, "Has made contact".

Google's disclaimer emphasises that the company does not verify the information left on the site, but leaves it up to the individual NGO. Ms Scott says, "I refuse to believe that someone would misuse the website, we're talking about a terrible tragedy here".

Satellite phone
The Google application is similar to the Family Links website run by the ICRC, which has been online since the 1992-1995 Bosnian War. However, the Red Cross site differs substantially.

"The Red Cross registers people at the site of the disaster," says Meike Groen. After the Haiti quake, she and a group of Haitian students went to the disaster area to gather information. People were also given the opportunity to borrow a satellite telephone for a few minutes to notify loved ones that they were safe.

Tight knit
Ms Groen says Family Links is perfect for informing large groups that a loved one has survived a disaster. "Immigrant communities are fairly tight-knit and when something terrible happens, they want to know right away if their loved ones in their home country are ok."

Ultimately, neither site is much more than a place to collect and display information. When it concerns vulnerable children and the elderly, the ICRC does try to locate family members, but others have to find their missing friends and family members themselves.

Updates
According to Marcel Izard at ICRC's headquarters in Geneva, precise information is essential, "If people contact us to say that someone has been found, then we update the database".

Mr Izard says that is one of the essential differences between the Red Cross site and Google's Person Finder or other sites started by media companies such as CNN and the New York Times. "We update our site, the database doesn't get clogged up," he says. It's one of the main reasons that the Red Cross does not want Google to copy its data."

Situation not ideal
However, Mr Izard is positive about co-operating in the future because four organisations are currently doing the same work. A workgroup is studying the options. Laura Scott says, "The situation is certainly not ideal at the moment".

"We're always happy to work with people but not committing to working with anyone specific, our aim is to connect people in the field with information they need."

Personal messages
It is difficult to measure the effectiveness of the various websites, says Marcel Izard, "We measure success through the number of personal messages we get. Last week we got an email from a man who had finally managed to locate his family, he did it through Family Links".