Seismic Intensity : Ten (X+) - Very Destructive

Ten (X+) : Very destructive levels of shaking. The USGS scale extends to Level Ten (X+), while some scales extend to Level Twelve (XII). The following description include all observations at Level Ten (X) and higher. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.

Perceived Shaking

Very Violent

Potential Damage

Very Heavy

Peak Ground Motion Acceleration

greater than 124 (%g)

Peak Ground Motion Velocity

greater than 116 (cm/sec)

Video Example

Intensity Ten (X+)

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