VietNamNet Bridge – Many well-off families in Hanoi have spent their money on renovating old stilt houses from mountainous regions and relocating them to the city’s outskirts as weekend homes.  

After a family in Quoc Oai District, Hanoi, drilled a well, subsidence occurred in the neighborhood, unnerving locals. Geological experts say the phenomenon may have been caused by underground caverns and the weak soil or sand layers above them.