BOCA CHICA, Texas – As the most powerful rocket ever built blasted from its launchpad in Boca Chica, Texas, on Thursday, the liftoff rocked the earth and kicked up a billowing cloud of dust and debris, shaking homes and raining down brown grime for miles.

In Port Isabel, a city about 10km north-west where at least one window shattered, residents were alarmed.

“It was truly terrifying,” said Ms Sharon Almaguer, who, at the time of the launch, was at home with her 80-year-old mother. During previous launches, Ms Almaguer said she had experienced some shaking inside the brick house, but “this was on a completely different level.”

Meanwhile, SpaceX’s Starship exploded minutes after liftoff and before reaching orbit. Near the launch site, the residents of Port Isabel, known for its towering lighthouse and less than 16km from the border with Mexico, were left to deal with the mess.

Virtually everywhere in the city “ended up with a covering of a rather thick, granular, sand grain that just landed on everything”, Ms Valerie Bates, a Port Isabel spokesman, said in an interview.

Images posted to social media showed residents’ cars covered in brown debris.

A window shattered at a fitness gym, its owner, Mr Luis Alanis, said. Mr Alanis, who was at home at the time of the launch, said he felt “rumbling, kind of like a mini earthquake”. He estimated that the window would cost about US$300 (S$400) to fix.

Closer to the launch site, large pieces of debris were recorded flying through the air and smashing into an unoccupied car.

Mr Louis Balderas, the founder of LabPadre, which films SpaceX’s launches, said that while it was common to see some debris, smoke and dust, the impact of Thursday’s liftoff was unlike anything he had ever seen.

“There were bowling ball-sized pieces of concrete that came flying out of the launchpad area,” Mr Balderas said.

The blast, he added, created a crater that he estimated was around 7.6m deep.

In a statement posted to Facebook, the city of Port Isabel said the emergency management division of Cameron County confirmed the dust “was sand and soil from near the SpaceX launch site that was lofted into the air by the force of liftoff”.

A spokesman for the county’s emergency management division said all questions regarding the dust from the explosion should be directed to SpaceX.

On Thursday, Cameron County Judge Eddie Treviño Jr ordered the closure of Boca Chica Beach and a section of State Highway 4 until 2pm on Friday “for the purpose of protecting public health and safety during anomaly cleanup efforts”.

Ms Bates, the Port Isabel spokeswoman, said based on current information, there was no “immediate concern for people’s health.”

Mr Eric Roesch, an expert in environmental compliance and risk assessment who has been tracking SpaceX’s rocket launches, said in an interview that he and others had long warned of the environmental risks to the surrounding region.

But without a chemical analysis of the dust and debris, he added, it was difficult to say whether or not they were harmful to human health.

But, Mr Roesch said, “the presence of that dust kind of indicates to me that the impact modelling was inadequate because this was not really disclosed as a possible impact”.

In June, an environmental assessment by the Federal Aviation Administration concluded that SpaceX’s plans for orbital launches would have “no significant impact” on the region along the Gulf Coast.

Mr Roesch, who runs the environmental policy blog ESG Hound, said he believed the dust and debris came largely from a giant crater formed during the rocket’s liftoff.

Normally, major launch sites are engineered with a trench or water system that helps to divert the rocket’s flame away from the ground and to dampen the impact, he said.

“They didn’t do that,” he said. “It appears they just went ahead and just launched this thing.”

Neither SpaceX nor the FAA immediately responded to questions about the dust and debris Thursday evening.

Ms Almaguer, the Port Isabel resident, said while Mr Elon Musk’s venture has brought jobs to an economically distressed region, the brown muck covering her city is a reminder of the environmental downsides and a sign that things had gotten out of hand.

“The locals here are just being sacrificed,” she said.

“He just wanted to get this thing up in the air,” Ms Almaguer said of Mr Musk. “Everybody else sort of be damned.” NYTIMES