Tornadoes swept across Oklahoma and the Midwest late Tuesday and into Wednesday, taking at least 15 more lives across the region. The storm system, which spawned over 50 tornadoes and hail as large as softballs, came only two days after one of the deadliest tornadoes on record destroyed much of Joplin, Missouri.

Tornado damage in Joplin, Missouri

The number of fatalities in Joplin continues to rise. At Freeman Hospital, where critically injured victims are being treated, workers said 11 people have died. City officials, who have not yet issued a revised death toll, report that 124 have died, and hundreds remain unaccounted for.

Missouri Governor Jay Dixon had declared that efforts would shift from searching for survivors to recovering the dead by Tuesday afternoon. Local emergency crews and volunteers were still conducting laborious house-by-house searches through thunderstorms Wednesday. “We are still in a search-and-rescue mode,” Joplin city manager Mark Rohr said at a press conference. “I want to emphasize that.”

The city of 50,000 suffered catastrophic damage from the tornado, which is now classified as the strongest category EF5. Rohr told reporters that 8,000 structures, including individual apartments in large complexes, were completely destroyed. The storm obliterated 1,800 acres, or about one-third of the city.

The city coroner’s office is struggling to identify some of the dead using DNA testing and dental records. Many victims were crushed under tons of rubble at a Wal-Mart Supercenter. (See “As more storms move in, death toll rises in Joplin, Missouri”)

Although still early in the tornado season, the country has seen major damage from over 1,000 tornadoes in 2011, and at least 505 people have died.

Five tornadoes struck suburbs of Oklahoma City Tuesday night, killing at least nine. Another four were killed in Arkansas, and two more in Kansas. Further storms were expected Wednesday night and into Thursday in Missouri, southern Illinois, southern Indiana and Kentucky.

Oklahoma City manager Nick Nazar told reporters that the death toll could have been far higher if not for a shelter in the Newcastle community, where 1,200 people found refuge ahead of the storm. In that area, 100 people lost their homes, several businesses were damaged, and a school was struck.

Across the state, 70 people were injured. Rapidly shifting tornadoes along Interstate 40 and US Highway 81 reportedly caught many motorists off guard, flinging vehicles before occupants had time to escape. Statewide, destruction of utility lines left 58,000 residences without power.

The National Weather Service’s Storm Prediction Center in Norman, Oklahoma and other meteorological facilities in the region were forced to evacuate.

Low-income communities southwest of Oklahoma City sustained the worst damage. In Piedmont, a three-year-old child remains missing after his family’s home was torn apart. According to relatives, the child, his mother and two siblings were forced to take shelter in a bathtub. The boy’s younger brother was killed and older sister and mother were seriously injured.

Other reports of survivors taking refuge in bathtubs or closets populate local news coverage. A trailer park was decimated in Chickasha, just south of Oklahoma City. Video at WNCT Channel 9 news shows mobile homes being flung into the air.

“The lights went out and we started praying out loud and screaming and you could hear the roar, the vibration of the tub, the house, the popping, the air sucking out of your ears, then it was gone,” a resident at the Watsons Mobile Home Estates told ABC television affiliate KSWO. She had crowded into a bathtub with seven others. They covered themselves with a mattress.

A young woman was killed, dozens were injured, and hundreds lost their homes, according to local police. “There’s nobody going to be living here,” a dazed resident told the local media. “I can’t live here, they’re standing around—they’re homeless. It’s shock. They don’t know what; we’re standing around. They [houses] are possessions, but there’s nothing we can do. It’s crazy.”

“I feel bad knowing that we still have our house and they lost theirs,” another resident, whose own trailer was intact, commented of his neighbors. “I was talking to a neighbor in the back. He was worried about his family instruments that had passed down from his grandpa… It’s just really bad.”

As the World Socialist Web Site has noted, the tornado fatality rate for those living in mobile homes mirrors the overall fatality rate of nearly a century ago, before warning systems and other basic social infrastructure were put in place. Such structures can be blown apart by wind gusts far less intense than even small tornadoes.

Residents of mobile homes are overwhelmingly poor. Many are renters, and lack even basic insurance. The Chickasha community is typical, with a poverty rate of 20 percent and per capita income of barely $15,000.

While there are many factors that underlie the level of destruction caused by storms, distressed social conditions and the lack of safety infrastructure play a major role. Millions of Americans live in or on the brink of destitution. Economic vulnerability begets a vulnerability to the rawest forces of nature, with masses of people forced to live in cheap housing built in areas prone to tornadoes, flooding, wildfires, and other hazards.

“I think we have to ask ourselves the tough questions now,” National Oceanic and Atmospheric Administration meteorological director Russell Schneider commented to the Associated Press after the Joplin disaster. “Why is this happening? The complexity of our society, the density of our populations in traditional tornado-prone regions of the world, community and family preparedness? Our science and technology—are we fully exploiting that to protect Americans?”

NOAA meteorologist Harold Brooks told the AP, “Tornado deaths require two things. You have to have the tornado and you have to have people in the right or wrong place… The biggest single demographic change that probably affects things is that the fraction of mobile homes in the United States has increased over the years.”

Some 20 million Americans live in mobile homes, according to federal Census data. Most trailer parks have no public shelter, even in tornado-prone areas, and many units lack foundations. Mobile homes are often simply tethered to concrete slabs with nylon cords.

Thousands of people who lost their homes will not be able to rebuild because they lack insurance or had insufficient insurance. Renters, who typically have fewer financial resources, have an insurance coverage rate less than half that of homeowners.