Please keep checking in.

People often complain about social media. Facebook is time-consuming and pointless and self-aggrandizing and there’s no real connection — yes, all right. Twitter is a constant, exhausting, too-cool-for-school barrage. And both of them leave you feeling a little more distant from everyone, at the price of keeping a line open to everyone you’ve ever met.

But when awful news hits like the explosions at the Boston Marathon, suddenly all of this feels less like a nuisance and more like a social network. Everyone I know has gone dashing to Facebook. The newsfeed, for once, is full of the bits of news that matter. I’m okay. Are you okay? 

These are days that remind you how many people you know. How many people you’re grateful to know. How many people there are to worry about. It’s a strange new ritual — the frantic phone call from Mom, multiplied and stretched over a thousand fainter connections.

Our social networks are where everyone goes to check in. In the wake of horror comes the flurry of wall posts. “Thanks for checking in. We’re okay” — each followed by a mushrooming number of Likes.

Like. “I’m Fine.” Like. Like. Twenty-seven Likes. It’s an odd response to have. It’s so impersonal. You really learn where you stand on the social pecking order when you post that It’s Okay Everyone, I’m Fine, and only two people like it, and neither one of them is your mother. Yet there’s a bizarre feeling of solidarity to it, too. This is where the huddle happens. All the people you would have wondered about and not known whom to ask — the fringes of your Facebook friends — they are there, huddling too.

Social media has its flaws. Twitter gets overrun with misinformation before the truth can get its 140-character shoes on — but, as Erik Wemple notes, it polices itself rapidly.

But when you want to know if everyone’s okay, it’s the first place to go.

Boston is a great city, “a tough and resilient town,” as President Obama said tonight in a brief statement. That goes without saying, and other people will say it much better, for people who grew up there or settled there for good, not just college friends of the city like myself.

When you leave a city after college, the city, like the people there, occupy a particular island in your memory where you assume nothing will change. You will always be college friends. That building will always be there. Those streets will always look the same. You might not speak for years but you wouldn’t unfriend each other on Facebook, and if you met five years from now you could pick up the conversation where you left off, in the very place you sat when you left off it.

And then something awful happens in a place that familiar, that insistently changeless, and suddenly you have to go reaching out for the people. Are you okay? Please be okay.

As the news continues to come in (there is a liveblog here) and rumors rise and fall, please keep checking in.

Say what you will about Facebook, it’s where the huddle is.

Alexandra Petri writes the ComPost blog, offering a lighter take on the news and opinions of the day. She is the author of "A Field Guide to Awkward Silences".