seis·mic 
/ˈsaɪzmɪk/ adjective
always used before a noun /ˈsaɪzmɪk/ adjective 1 technical : of, relating to, or caused by an earthquake
▪ seismic activity/data/waves/zones 2 [more seismic; most seismic] : very great or important
▪ Seismic social changes have occurred. ▪ The discovery caused a seismic shift [=a great change] in public attitudes.
▪ seismic activity/data/waves/zones
▪ Seismic social changes have occurred. ▪ The discovery caused a seismic shift [=a great change] in public attitudes.
— seis·mi·cal·ly /ˈsaɪzmɪkli/ adverb
▪ a seismically active region [=a region where many earthquakes occur]
/ˈsaɪzmɪkli/ adverb ▪ a seismically active region [=a region where many earthquakes occur]
