When a disaster strikes a major city, millions of tweets, texts and Facebook posts will go out long before local authorities can give an official response. And as climate change makes natural disasters like floods and superstorms more common, two MIT researchers say Boston should look to Jakarta for clues about how to turn all that online chatter into useful information.

Jakarta is a crowded city of 10 million, built around 13 rivers in a tropical monsoon climate. Severe flooding is a fact of life. That may not sound much like Boston, but the two cities share a couple things. First, there’s a real potential for flooding in Boston as climate change brings sea level rise and more intense storms. And both cities have a tech-savvy population – Jakarta has one of the highest mobile phone adoption rates in the world, and its residents tweet more than any other city.

Dedi Setiawan lives along Jakarta’s main river, the Ciliwung. In 2013 his neighborhood was under three feet of water, and he had to retreat to the second floor of his house. When the water subsided, the flood had filled his home with polluted mud and trash. Since then he says he and his neighbors have set up group chats on WhatsApp and Facebook to organize during floods. Word spreads organically in Jakarta – people upriver might text friends a photo of flooding in their part of town so their neighbors downstream can prepare.

Setiawan says that social media is faster than waiting for official announcements. And he trusts that information more because it’s coming from a real person. Of course, you can’t believe everything you see online. Social media can spread false information that could make disasters worse, not better. After the Boston Marathon bombings, for example, Reddit users misidentified a missing Brown University student as one of the attackers. In the wake of a natural disaster, inaccurate reporting can lead people into more danger – so how do you sift the signal from the noise?

That’s where two MIT researchers come in. Etienne Turpin and Tomas Holderness, research associates at MIT’s Urban Risk Lab, founded PetaJakarta, an online flood map that gives Jakartans a real-time picture of what’s happening in their city.

“Maybe we don't have an official government report,” says Turpin, “but if you have four people with photos at different angles showing one event, that's a pretty difficult thing to stage.” 

Here’s how it works. When somebody in the city tweets the word banjir (Indonesian for flood) and tags PetaJakarta, the software adds the report to a flood map of the city. Their system automatically replies to those people, asking them to verify their location with a geotag. 

Say you’re at work in Jakarta and it’s raining. You might use PetaJakarta to look up the neighborhood where your kid is at daycare, to make a quick decision about whether the flood is bad enough that you need to pick him up. Before PetaJakarta, people had to wait hours to know what was really going on.

Flooding is common in Jakarta in a way it will never be in Boston. But when the big one hits, this kind of information could be invaluable. Earlier this year the U.S. Federal Communications Commission cited PetaJakarta as an example of how cities here should be embracing social media in their disaster response strategy.

“It doesn't matter how many more canals we build – eventually we will have to take a different approach to how to respond to extreme weather events,” says Turpin. “There is no amount of infrastructure that would prevent the situation of extreme weather events causing disasters in cities, and so our commitment is to develop digital infrastructure for climate adaptation that allows residents to coordinate.”

The reality is that people are a lot faster to report disasters from their homes and businesses than civil servants ever could be, which is why a lot of civil servants are getting on board. Anto Sugianto works for the city in a district in North Jakarta, which floods often. He says the city government doesn’t just give the public information anymore – now, they’re working together.

Sugianto says he actually turns to PetaJakarta during floods, to find out where his constituents are reporting dangerous situations. He remembers a mighty flood in April, when he logged onto PetaJakarta to learn how high the water was in different parts of his district. That information helped him figure out a response, he said. In this case, they deployed pumps to suck water away from important streets, and closed roads where rising waters threatened to trap people in their cars.

Sugianto says PetaJakarta may be the best way to ensure that people get the best possible information after a disaster strikes, but people still need the government’s help with disaster management. 

And when it comes to preparing for climate change, an online map won’t replace the need for seawalls, barriers and other physical flood defenses. 

That’s as true in Boston as it is on the other side of the world, in Jakarta.

This story is part of WGBH’s collaborative series with The GroundTruth Project, called Rising Tide: Boston Underwater, looking at how the Bay State is preparing for climate change.

Chris is a freelance writer, photographer, editor and producer based in Boston.