A South Korean passenger watches TV showing Japan's Fukushima No. 1 atomic plant spewing fumes amid reports that a meltdown is feared after a massive quake, at a railway station in Seoul on March 12. Searching the Internet on sites such as Google, Twitter and their local variants has become more effective in finding loved ones than sifting through wreckage following Japan's devastating tsunami.

Searching the Internet on sites such as Google, Twitter and their local variants has become more effective in finding loved ones than sifting through wreckage following Japan's devastating tsunami.

Frantic friends and relatives leapt onto their computers to find information about people who had not been heard from since the mighty wave crashed ashore Friday.

Global web giant Google's person finder service had notched up over 45,000 records of people leaving messages seeking information on friends and family, or providing information about people in the , by 1130 GMT.

The site was updating, in English and Japanese, by the hundred every few minutes.

A random search for the common Japanese surname "Sato" brought up hundreds of results, many of them for people living in Sendai -- the city that faced the brunt of the thunderous body of rolling water.

Gunduzhan posted a message seeking Aki Sato, a dentist from Sendai who studied at Ohu University in Koriyama. A photo of the young woman was also posted on the site.

"Looking for Aki Sato," the post read. "Last heard from after earthquake but before tsunami."

Another post seeking Fatima Sato had some good news -- "Mom is ok. She is on her way home."

The international and Japanese also set up a similar site.

People in and abroad can register names on the website or consult the list, while those in Japan can inform family and friends that they are safe and provide contact details.

And micro-blogging site Twitter was updating every second with messages of good will, of condolences and offering aid.

Hashtags, or labels that allow people to share and locate messages around a specific subject, #prayforjapan and #tsunami were soon joined by one named #radiation.

People used the new hashtag to update information on fears of meltdown following an explosion at the Fukushima .

"Radiation's growing, they are collecting iodine. If wind blows too much may move it all to Russia, China, Phillipines & over the Pacific. But come on! It's not Chernobyl yet," wrote fabrykamagazine.

A service was also being shared on Twitter enabling people to donate to the Red Cross via text message, the donation being added to phone bills.

Some tweets were posted by international celebrities such as the American singer Lady Gaga, who launched a bracelet campaign to support the relief effort.

She asked her legion of fans -- whom she calls "Little Monsters" -- to buy a bracelet on her website with the message, "We Pray for Japan". All proceeds will go to relief efforts, she said.

Other pop stars offered condolences. R&B icon Alicia Keys wrote on her account: "My heart breaks for Japan."

And Canadian teen idol Justin Bieber called Japan "one of my favorite places on Earth".

On Facebook, the largest Japan Tsunami 2011 page had over 2,600 people saying they "liked" the page and scores of messages, plus links to some of the astonishing videos of when the tsunami hit.

But US computer security authorities warned that online scammers may seek to exploit the quake.

The US Computer Emergency Readiness Team (US-CERT) told computer users to be wary of "potential email scams, fake antivirus and phishing attacks regarding the Japan and the tsunami disasters".

"Email scams may contain links or attachments which may direct users to phishing or malware-laden websites," US-CERT said in a statement.

"Fake antivirus attacks may come in the form of pop-ups which flash security warnings and ask the user for credit card information," it said.

"Phishing emails and websites requesting donations for bogus charitable organisations commonly appear after these types of natural disasters."

Phishing refers to attempts to steal user names, passwords and other personal information from unsuspecting victims, mostly through email or instant messages.

Useful links:

The English version of the Red Cross website was being set up at www.icrc.org/eng/familylinks-japan

The English version of the friend finder service can be found here: japan.person-finder.appspot.com/?lang=en

Facebook's Japan tsunami page can be found here: www.facebook.com/#!/japan.tsunami.2011