These impulses or elastic waves are generally induced by blasting charges of dynamite in shot-holes drilled into the ground or by weight dropping .

• 首先是挖一个爆破井，将炸药放人井中，引爆炸药后便会产生所需的弹性波或脉冲。也可以利用一重物自由落体所产生的冲击得到弹性波。