Seismic Intensity : Four (IV) - Largely Observed

Four (IV) : Felt indoors by many to all people, and outdoors by few people. Some awakened. Dishes, windows, and doors disturbed, and walls make cracking sounds. Chandeliers and indoor objects shake noticeably. The sensation is more like a heavy truck striking building. Standing automobiles rock noticeably. Dishes and windows rattle alarmingly.

Perceived Shaking


Potential Damage


Peak Ground Motion Acceleration

1.4 to 3.9 (%g)

Peak Ground Motion Velocity

1.1 - 3.4 (cm/sec)

Video Example

Intensity Four (IV)

Reference: Modified Mercalli Intensity Scale (Adapted from Sieberg's Mercalli—Cancani scale, modified and condensed)