The magnitude 5.1 La Habra earthquake that shook Southern California isn't going into the seismic history books for its modest size and small damage totals.
But it was an event on social media, which transmitted stories and images of the quake and its many aftershocks with a speed and breadth that left seismologists and emergency personnel taking notice.
The first signs of damage came not from authorities but from residents posting photos on Facebook of broken dishes and fallen cabinets. The public learned that Disneyland rides were closed from scores of photos tweeted by park visitors. In 15 words and a photo on Twitter, Brea police announced that the quake caused a significant rockslide that flipped a car, resulting in the only injuries from the quake.
By Saturday, U.S. Geological Survey seismologist Lucy Jones had become a trending topic on Twitter and finally created an account. (After some playful debate, she used @DrLucyJones as her account name rather than her nickname, the Earthquake Lady). In her first tweet, she assured those on social media that the large aftershocks still rattling across Orange and Los Angeles counties were normal.
The real-time reporting of a quake provides many opportunities but also some pitfalls. Officials can use the stream of data to determine where damage has occurred and allocate resources. The challenge is sorting between the valuable facts and the misinformation and speculation.
"This is sort of the evolution where 30 years ago, we'd have an earthquake and we'd all listen to KFWB, and people called in to talk about what they felt," Jones said, "and there'd be no information for another hour until we found out the magnitude and more information on the actual earthquake."
With social media, it's the same principle, but the timing has accelerated, Jones said.
"People need to talk to other people when they're scared. And if we don't communicate quickly, it doesn't stop people from talking, it just means they don't have factual information to share," she said.
Indeed, as aftershocks continued through the weekend, some people said they went to Twitter to see if what they were feeling was a quake or nothing but a truck rolling by.
The USGS was a pioneer in digital crowdsourcing by creating a system for people to report whenever they felt a quake. More than 16,000 reports were sent to the Did You Feel It? system after Friday's earthquake. Based on the surveys, the USGS produces maps showing where the quakes were felt the most.
But in an era of second screens and the mobile Web, some experts say seismologists need a larger presence in social media.
"Places like Caltech and the USGS need to get on Twitter," USC social media professor Karen North said, "so that when the torrent of tweets go out talking about this earthquake's implications for future earthquakes, they can go into that communication channel and correct false information and lead people to facts."
Scott Horvath, Web and social media chief for the USGS, agreed that there is an expectation for instant feedback on what happened.
"We try to send out as much as we can, the basic information that we know that everyone is going to need," he said. "It's not efficient to wait for someone to respond hours after an earthquake happens ... and in between that time, if you don't hear what's going on, people can start coming up with their own stories."
When a earthquake occurs, the USGS Twitter account helps direct people to the agency's Did You Feel It? site.
An estimated 17 million people felt the magnitude 5.1 quake, said USGS seismologist David Wald, and the USGS received valuable information from 16,000 reports by individuals who used Did You Feel It?
"About 1 in 1,000 are actually reporting.... That's a pretty good [data] sample. If you're polling for political responses, that would be a huge sample," said Wald, who co-created and operates the Did You Feel It? system.
Before the system was created in 1999 as part of an undergraduate project at Caltech, the USGS sent postal questionnaires to ZIP Codes in an area that experienced an earthquake. People filled them out and it would take months to compile the information that now can be done automatically through a computer.
Wald said that unlike the torrents of information posted on Twitter and Facebook after an earthquake, the questions people respond to for Did You Feel It? are well-tuned inquiries that seismologists have asked for decades — streamlining the information that comes in and giving scientists usable, sortable data that helps determine such things as intensity and how far the shaking traveled.
The real-time reporting aspect of social media, however, can offer snapshots of an earthquake's effect that first responders say they cannot ignore.
"I was at home when this earthquake hit and the first thing I did was turn over my iPad and go to Facebook," Brea Police Capt. Gregg Hayden said. "People were already talking about it.'
Within a few minutes, dispatches were pouring in from across Southern California. Near the epicenter, people tweeted photos of damaged homes and broken water mains. Others wrote about the surreal experience of rolling through a quake while watching the new movie "Noah."
Hayden said the struggle is to use the information that is essential to emergency personnel while ignoring the rest.
After the La Habra earthquake, more than a few people referred to the shaker as "huge," when in fact the quake's size falls under the category of moderate.
"Generally, the human tendency we see on Twitter and social media is to amplify and spread rumors without any filter," said Jeffrey I. Cole, director and chief executive of USC's Center for the Digital Future. "You just get to see everyone's version of the truth."
What Twitter is very good at is showing the scope of one event, like an earthquake, Cole said.
"That part is reliable," he said. "But to really understand it, that's where a Lucy Jones plays an important role."
But there are drawbacks to a society that is so wired. Friday's quake was big enough to be felt across the region, but small enough not to interrupt the digital infrastructure.
Experts have long warned that a massive quake could cut off Internet lines and cause major power outages. Twitter, Facebook and other social media may be inaccessible to hard-hit communities for days.
And that would leave people with their old-fashioned means of getting information, like sitting by their portable radios.