On 7th July 2005, fifty two people were killed when four suicide bombers detonated home made explosives on the London Underground. During this time, there was panic, confusion, miscommunication and a number of issues relating to where to go and what was going on. Even law enforcement suffered making the situation even more fragile.
With experience of hindsight, with a number of events which social networking from ordinary members of the public ("citizen journalism") from the terrorist attacks in Mumbai, the Hudson river plane crash and the death of Michael Jackson; Twitter especially has been a key point of communication.
Mumbai was a perfect example of how Twitter dominated the intelligence gathering process, using real people and human intelligence but through an unconventional, insecure medium. Photos were being uploaded to Flickr and Twitpic, and tweets were dominating the blogosphere, and being used as part of commercial news channels as their own journalists simply couldn't be spread thinly enough.
However in the case of Mumbai, public and very widespread intelligence could have been used to the terrorists' advantages, also. Not so much the case of the London bombers, though.
How could it have helped London?
Twitter is instant and is accessible from anywhere with mobile signal. However the big issue with the London bombings is that the explosions were underground, some closer to Tube stations than others, but most had no signal while they were down there. Yet videos and texts were still sent to be delivered as soon as a trailing signal came into focus when they reached the surface.
Also, the 9/11 effect of so many people attempting to call and communicate with one another would cause the networks to become overloaded and flooded, meaning getting through to someone would be incredibly difficult. The Tube network would have had mobile phone signals in the deep underground levels, but has been heavily delayed citing security concerns, since mobiles can also become detonators.
But major events have had a toll on the networks for a while now. The networks are recovering and can now handle more communications especially in times of crisis.
Using tweets written and published by ordinary citizens, the latest and breaking news can be relayed through hashtags and retweeting. Through this, mashups can be quickly (and they often are, such as during the snow storms in the UK earlier this year) created and projected into a web service. Through everyone contributing as they do on Twitter, this collective information can be used to direct people away from certain areas and to organise the chaos.
Sending text messages is far better for the infrastructure than to make phone calls, and to tweet holds the same value except with a more public nature. You could text everyone in your phone book to tell them you are alive, or if all of your friends and family subscribed to Twitter, this would be one message to a service instead of dozens to multiple people through one service - easing the load.
Blogs can and have been used to document evidence after a terrorist attack, by taking eyewitness accounts of many people, assessing their validity from viewpoints and merging them together to get a general consensus.
But micro-blogging and services like Twitter and the status update feature on Facebook could be utilised as a far better way of communicating with people in a time of crisis. If it were me, and it nearly was as I was in London the week between the bombings and the second round of failed bombings, I would have Facebook'd and Twitter'd to the masses, and sent only a couple of text messages to those who weren't on either.