Six miners and three rescuers were killed in a collapse at the Crandall Canyon coal mine in Utah in August 2007.

• 如果地面站配有地震传感器和电脑就有两种方法寻找生生存者。但是现在，作为一种潜在的廉价的报警和定位系统，引来许多研究人员的研究。