Simplify the following text for a Grade 11 native English-speaking person.
Original: Seismic activity in this eruption caused the eastern flanks of the volcano to slip by up to two metres , and many houses on the flanks of the volcano experienced structural damage .
Simplified: Seismic activity in this eruption caused the eastern flanks of the volcano to slip by up to two metres , and many houses on the flanks of the volcano got structural damage .