OKLAHOMA CITY — Storms shuffled through parts of the south-central United States again Tuesday, bringing more heavy rain and thunder so loud some people in Oklahoma mistook it for an earthquake.

Forecasters said the slow-moving storm system that socked the region Monday could cause more flash floods, hail, strong winds and possibly tornadoes in a corridor stretching from Texas east to Louisiana and as far north as Missouri.

The National Weather Service issued tornado watches for parts of Louisiana, Texas and Arkansas. Two tornadoes in the San Antonio area injured at least eight people and damaged about 30 buildings Monday. A twister injured four people and damaged homes near North Platte, Neb., on Sunday.

Heavy downpours were expected again Tuesday, the first day of spring. Residents and emergency workers were already reeling from the rain after what was an unusually dry winter in many places.

Officials in southeast Kansas closed several bridges, and workers in Missouri shut down a rural roadway after rain sparked flash flooding there. In Arkansas and Oklahoma, the Forest Service closed campsites in low-lying areas to avoid another catastrophe like the flash flood that killed 20 people at a remote campground in 2010.

Meanwhile, storms rattled Tulsa, Okla., early Tuesday morning with thunder so strong that it registered on seismic equipment. Meteorologist Pete Snyder felt his home shake and several concerned residents called the National Weather Service to ask if there had been an earthquake.

“We have seen quite a bit of thunder on all of our seismic stations across the state,” said Austin Holland, a research seismologist with the Oklahoma Geological Survey. “We can confidently say there were no earthquakes large enough to be widely felt.”

Forecasters in Tulsa said the storms have dropped between 3 and 5 inches of rain in parts of eastern Oklahoma since the storms began late Sunday night. More rain is expected there and in neighboring Arkansas.

The storms are expected to stick around for the next few days and then peter out as they meander east, said Jared Guyer, a meteorologist with the weather service’s Storm Prediction Center in Norman, Okla.

“It’s typical March-type severe weather,” he said.