Extended Strong's Greek Lexicon (Abbott-Smith based)
earthquake
Usage: σεισμός, -οῦ, ὁ (σείω), [in LXX chiefly for רַעַשׁ ;] a shaking, commotion, as a tempest at sea: Mat.8:24; esp. an earthquake: Mat.24:7 27:54 28:2, Mrk.13:8, Luk.21:11, Act.16:26, Rev.6:12 8:5 11:13, 19 16:18.† (AS)