Following Jonathan’s act of faith, the Lord caused the ground to shake.1 Presumably the ground shook particularly violently in those areas where the Philistines were encamped and patrolling.2 In a time where people did not have knowledge of tectonic plates, the shaking of the ground would have been attributed to the actions of a deity, in this case the Lord. The Philistines were thus driven to panic because they realized that the Lord, the God of Israel, was against them and they knew from past experience (see 1 Samuel 5:1 – 6:21) that no one can stand against him. The panic which the Lord sent among them was consistent with what he promised in the past (cf. Exodus 23:27; Deuteronomy 7:23).3
15 And there was a panic in the camp, in the field, and among all the people. The garrison and even the raiders trembled, the earth quaked, and it became a very great panic.