I don't use Twitter or Facebook, and I don't know how they work.
(snip)
how do you use them without giving up your personal info to the cloud?
Here are the two shortest possible answers to your core questions, then I'll go into why Twitter and Facebook are important tools for emergency communications.
First, I'll answer your last question.
You can't use the internet without your real identity being discoverable. It's just a matter of the effort that needs to expended, and that ranges from "none" to "quite a bit" - but the end state is one where if you're using the internet, you can be connected to what you're using it for. Unless you were born in and lived in a tent your whole life, only ride a bike and pay only with cash, you have no possible way to avoid having your personal information recorded in a database somewhere that can be accessed by someone for some reason.
In terms of "what they are" -
Twitter is a service that gathers and distributes short messages using two communications infrastructures. The Short Message Service (SMS) global telecommunications infrastucture is one and the global Internet is the other. It is the use of the SMS infrastructure that gives Twitter an important capability: it reaches everywhere there is any level of mobile phone service, no internet connection required.
You do not need to join Twitter to get messages from Twitter users. To use it, all you need to do is text “follow [username]” to Twitter’s shortcode of 40404.
For example, you can follow the Los Angeles Fire Department if you send "follow lafd" to the number 40404. You do need to join the service in order to send messages.
While often derided as a tool that does little more than tell you what people you don't care about are having for lunch, in terms of emergency communications, it's quite powerful and useful. First of all, the very short messages (140 characters or less, due to limitations in the SMS infrastructure) make for concise communications. Secondly, the ability for people to immediately create ad-hoc "categories" via the use of a "hashtag" allows for a simple and effective way to distribute and gather information about an event or topic.
A hashtag is simply a word preceded by the "#" symbol, and included in the message. Thus, a fire in San Bernadino might be tagged with #sanbernadino and people posting messages about it would just start to include that hashtag. There's no central planning or coordination of hashtags, they just happen, and they work.
In my own experience, while on vacation recently, knowing that there was a risk of hurricane activity, I located the Delaware Office of Emergency Management on Twitter, and "followed" them. As a result, I was among the first to know that an evacuation order had been issued for my area. I was then able to monitor the hashtags #irene and #delawareshore for things like traffic reports.
As an Emergency Management Coordinator, I found that Twitter was a good way to monitor the overall level of impact of the storms and such that led to flooding and road closures and power failures - by searching for "Bucks County" and related terms, I was able to ascertain the scope and impact of road closures (lots) by people complaining on Twitter. Additionally, I used Twitter to connect with news media outlets by "mentioning" them in my messages from Emergency Management. That meant that people subscribing to new media twitter accounts also would see my messages from time to time.
Facebook is a service that people use to find and connect with people and companies that they interact with on a regular basis both in the real world and online only. People sign up for Facebook using their real names and real information, and then search the 500,000,000 Facebook user database to find and connect with people they know. Once connected, Facebook users can post messages, much like here on the ETS forums, but they can also easily post pictures (Facebook is the largest photo-sharing site on the planet), videos and more, all of which are shared with all or some of the people on their "friends" list.
The typical Facebook user has 140 "friends" - so, for example, when I post a message on my Facebook page, all 140 of my friends will see that message on their Facebook. The key thing to understand about this is that it is possible to very quickly propagate information to self-organizing communities of interest. What I share on my Facebook page reaches, at first, the friends on my list (assume 140) and in turn, depending on how my friends have set up their accounts and/or if they decide to leave their own facebook page viewable to some or all of their friends - or even the public at large - I can quickly reach 140x140 or so people (19,600) and so on (using the 140 people with 140 friends model for the math).
In the context of emergency management, Facebook offers a more "conversational" tone with the constituents of the community, and it also allows for the participation with field reports from the community.
For example, on the Bridgeton Township EMA page, as the incident progressed, we heard rumors of a dam break in the community across the river from us. One of our "fans" on the Facebook page posted a video from the scene.
See
https://www.facebook.com/bridgetonema and scroll down a ways to see not only the video, but also photos of various flooding conditions.
These field reports not only helped me, they helped the community by giving them the access to the information that showed them exactly what was going on and where.
In addition, we were able to use the Facebook page to help people understand how to go directly to the right source for information, rather than just picking up on what they "heard" about a bridge or road closure.
In larger emergencies (including the Nuclear emergency in Fukashima) Facebook was the only communications tool that was able to provide us with "safe and well" information about a friend's son who lived not far from the nuclear plant. Like Twitter, Facebook has integration with both the internet and with mobile networks - it is possible to post a Facebook status message of "I am OK" via an SMS message to your own account.
In general, my opinion on communications tools in an emergency is "use everything you can". Our tiny community used Email, Web Sites, Facebook, Twitters, A Recorded message Hotline, SMS and Mass Media. In my opinion, the SMS and recorded message hotline were very important because the power was out, but the Facebook page was a close second.
Finally, the digital media agency where I work is currently in the process of creating new digital user experiences for the American Red Cross, and I had the privilege of being exposed to pertinent information about their efforts in social media - Facebook and Twitter included, of course, and I can confidently say that these tools are a valuable and important component of any emergency management mass communications plan.
I would be very happy to take anyone who wants on a tour of these tools, and I would encourage anyone with a mobile phone to at least consider using Twitter as a means of connecting with emergency agencies.