A series of small earthquakes rattled a Dallas-area city for two days and have left police overloaded with 911 calls about the shaking.
The US Geological Survey recorded the temblors in the Irving area, including three Wednesday. No major damage or injuries were reported in 11 earthquakes recorded since Tuesday, with magnitudes from 1.6 to 3.6.
Irving police on Wednesday asked people not to call 911 to report earthquakes unless they need medical or emergency help.
USGS geophysicist Carrieann Bedwell said scientists will look at the data from a seismic standpoint, investigating factors like depth, magnitude and location. The Irving area, with a population topping 250,000, has seen a swarm of mild earthquakes recently. Southern Methodist University researchers on Monday installed a seismometer to help determine what's behind the increase.
The U.S. Geological Service plotted the epicenters of four north Texas quakes to northeast Irving, a Dallas suburb.
The first quake at 3:10 p.m. measured 3.5 in magnitude. Another about 7 p.m. measured 3.6, while tremors at 8:11 p.m. and 8:12 p.m. measured less than 3.0.
All happened within an area near the Trinity River that's seen a swarm of mild temblors in recent months.
USGS geophysicist Jana Pursley says Tuesday's quakes were the "largest since the earthquakes started happening there in the last year."
Since the 1970s, 24 earthquakes of at least 3.0 magnitude happened within 75 miles of Irving.