By Avi Selk

They weren't the Big Ones -- but a couple of the earthquakes that hit Tuesday were the biggest in a cluster that's been rocking North Texas since last fall. And by the end of the day, eight had been reported.

They rattled people all over the Dallas area, with reports pouring in from Arlington to McKinney and Lewisville to Rowlett.

"It felt like the whole building was moving sideways," said Juanita Gonzalez, in downtown Dallas. "I thought I was feeling things."

She wasn't. People across North Texas rushed to swap stories after the first quake hit about 3 p.m. -- about 3 miles beneath State Highway 183, just east of the former Texas Stadium site in Irving. That one registered 3.5 on the Richter scale.

The second, which hit shortly before 7 p.m., registered 3.6 and was centered near the Elm Fork of the Trinity River, also close to the old stadium site.

A pair -- measuring 2.9 and 2.7 and not far from the others -- hit in rapid succession after 8 p.m. The fifth and sixth, which were weaker, happened around 10 p.m., according to the U.S. Geological Survey. The seventh hit just after 11 p.m.

Early Wednesday, officials added a quake earlier Tuesday -- at 7:37 a.m. -- to the list, making the total eight.

After the first quake, Texas Rangers pitcher Derek Holland, perhaps jokingly, tweeted that he fell in the shower of his Irving home.

"This earthquake crap needs to stop," he wrote. "#imfine."

Another jokester tweeted a photo of a T-shirt with the slogan "I survived the 3.5."

More than 20 small quakes have hit in or near Irving since October, most of them within a few miles of the stadium site. But Tuesday's rumbling was more than twice as strong as the previous record-setter, a 3.3-magnitude quake in November.

"I'm used to the rock and rolling we've had in the last few months," said longtime resident Linda Andujar, preparing to restraighten all the pictures on her wall after the earlier temblor. "This one was big."

No injuries or damage had been reported to Irving police late Tuesday, but many people called 911 inquiring about the rattling. Likewise in other cities, though Texas Department of Transportation crews were keeping an eye out for damage.

Several water mains broke in Dallas on Tuesday, but city officials said there was no definitive link with the earthquakes.

The quakes made national headlines, showing up on the Drudge Report. And researchers at Southern Methodist University held a last-minute news conference to share what they knew about them.

Which wasn't much.

Seismologist Brian Stump told reporters he didn't know what's causing Irving's quakes -- some of more than a hundred that have rattled the once-quiet Fort Worth basin since 2008.

"Even this part of Texas has old faults, and those old faults have stored stress," said Stump, a professor of earth sciences at SMU. "The disposal of fluids [wastewater] in some cases can trigger small quakes." But, he said, that remains an "open question."

Craig Pearson, a seismologist with the Texas Railroad Commission, said in a statement sent to The Dallas Morning News that "there are no oil and gas disposal wells in Dallas County. And I see no linkage between oil and gas activity and these recent earthquakes in Irving."

Stump's team installed an extra earthquake detector in the city on Monday to learn more about the spate of shakes, though they're more interested in pinpointing their locations than the cause. And Stump didn't know if gas drilling could be a factor, or if even stronger quakes are in store.

"We cannot predict the size of the largest events, and that motivates a need to study these events," he said.

Not everyone shared in Tuesday's earthquake experience. In some offices, a worker would leap to her feet while another in the next cubicle felt nothing. The SMU researchers chalked that up to perception -- sitting turns out to improve human earthquake detection.

In Cedar Hill, 20 miles from the epicenter of the first earthquake, Olivia Lira was watching TV when she felt the telltale vibrations through her sofa.

"I know what an earthquake feels like," she said. "I lived in California."

When the TV news confirmed her suspicions, she felt a rush of excitement.

But it was excitement tempered by experience. Tuesday's Slightly Bigger Ones wouldn't have rated a mention by California earthquake standards.

"This is nothing," Lira said. "We wouldn't even pay attention to it."

Sharon Barbosa-Crain of Irving was sorting through mail when the first earthquake hit, and in a restaurant for the second.

"The whole restaurant -- all sides of it -- shook," she said late Tuesday.

She said she suspects gas drilling is the cause -- not coincidence.

"I'm most concerned that it appears to be increasing in intensity," she said. "Little by little it seems to be increasing."

Staff writers Brandon Formby, Claire Z. Cardona and Robert Wilonsky contributed to this report.

(c)2015 The Dallas Morning News