This paper presents a conceptual discussion on structural response to ground shocks. Nonlinear finite element analyses on a 2-storey RC frame subjected to explosion-induced ground shocks are carried out to investigate structural response to explosions . This study shows that maximum response to explosion generally occurs after the major ground shock has ceased. It is found that the response in the forced-vibration phase includes high frequency vibration modes characterised by small displacement but large acceleration, which induce high inertial shear force. On the other hand, the free-vibration response is dominated by lower frequency oscillations with large displacement which may soften the structure. Hence, a structure subjected to explosion may have to face two probable hazards . Firstly, it may experience a large shear force that may cause a sudden shear failure within the major shock period. Secondly, if its shear resistance is large enough to overcome the induced shear force, it may undergo large flexural deformation that may induce severe damage after the major ground shock has ceased. The possibility and extent of these two damage mechanisms depend on the scale of explosion, the distance of the structure from the explosion source and the toughness of the structure.