Seismic disturbances (6)
I believe the answer is:
shocks
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">seismic disturbances</span>' is the definition.<br/ ><span class="explanation-format__explanation">('shock' can be a synonym of 'seismic disturbance')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for shocks that I've seen before include "Sudden upsetting or surprising events" , "Appals" , "Jolts, jars" , "Surprises, sometimes electrical" , "Effects of charges of electricity" .)