וַתִּגְעַ֬שׁ וַתִּרְעַ֨שׁ ׀ הָאָ֗רֶץ וּמוֹסְדֵ֣י הָרִ֣ים יִרְגָּ֑זוּ וַ֝יִּתְגָּֽעֲשׁ֗וּ כִּי־חָ֥רָה לֽוֹ׃
Then the earth did shake and quake, the foundations also of the mountains did tremble; they were shaken, because He was wroth.
Read kabbalistic (mystical) interpretation of Psalms 18:8: and classical mystical sources.