What caused the Miami building collapse?
A 12-STORY apartment block partially collapsed near Miami beach on June 24, leaving one person dead and tens more unaccounted for. The incident has left lots of unanswered questions about what may have caused the 136-unit building to inexplicably crumble. Here we explain the latest. Miami authorities are conducting an investigation into the Champlain Towers South Condo collapse, though an official cause behind the devastation has yet to be determined. After the incident, Mayor Daniella Levine Cava said there were "structural" issues and said engineers are determining the risk after the collapse and what caused it. "There will probably be federal resources involved in the investigation also," Cava said. One licensed general contractor told WNYT that "subterranean currents" or a "sinkhole" may be responsible for the collapse. He echoed comments from Surfside Mayor Charles Burkett that it hard to imagine that could have been the impetus for a catastrophic collapse" other than by a possible sinkhole from rising sands and rising sea levels. Theres no reason for this building to go down like that, Burkett said, unless someone literally pulls out the supports from underneath, or they get washed out, or theres a sinkhole or something like that, because it just went down.  The building was built in 1981 and it was undergoing roof work for about 30 days before the disaster struck in the early hours of June, 24. Following the deadly partial collapse, state Sen. Annette Taddeo called for changes to building inspection rules. "Buildings need to be inspected much sooner than 40 years, especially in a county where sea-level rise can affect a foundation," she tweeted. The shifting sands in Miami refer to the constantly changing formations of the coastline. Wind, waves, tides and human activity such as development and recreation can change the beach landscape. It can coincide with the formation of sinkholes which are caused by a collapse of the Earths surface layer. Heavy localised rainfall or large areas of concreted ground can change the natural water flow. Speaking to CNN, Shimon Wdowinski, a professor with Florida International Universitys Institute of Environment, suggested he conducted a study last year that the Champlain Towers South condo showed signs of sinking in the 1990s. Although Wdowinski said that this sinking alone would likely not cause the condos collapse, he said it could be a contributing factor. Specific details of the buildings composition is unknown although experts in the field believe the building was predominantly supported by steel frameworks. Gary Slossberg, founder of the South Florida construction company National Home Building & Remodeling Corp, suggested that many Miami-area buildings are built with concrete balconies that are "back-pitched," meaning they don't allow water to escape properly after it rains. There's a lot of concrete restoration going on, and this is where you see a lot of that rust and rebar coming through the slab between the water sitting there and the salt air  it's just not a good combination," he said. "But again, I don't know if that would take down the whole building. We just don't know what happened." With uncertainty surrounding the nature of the buildings collapse, many experts have put forward their theories forward. Mr Slossberg, suggested that salt in Miami's coastal air could have potentially facilitated the erosion of the steel framework that was supporting the structure. "It's like a cancer," Slossberg told Fox News. "By the time you see it, it could be too late." The expert also theorised that if the building were constructed with a "post-tension slab filled with cables," and one of those cables came loose, that could have led to its destruction. "It could take down a whole building," he said.