Those are manipulations by some BTC market manipulators in China, start to spread FUD on Wiebo, dump some btc, get the price low enough, buy in, calm the panic, and then spread some abroad good news.
Within minutes these guys were making money on the panic sell of the thousands people. This is not the first time nor the last time this will happen, if certain market manipulators, such as some big V on weibo, have the means to manipulate price to make profits, they will do so again and again until the market stops paying attention. Good news is this time, the FUD has not affected the price much yet.