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Intensity Lab

Modified Mercalli Intensity VII MMI VII: Very strong shaking

MMI VII is very strong shaking. Difficult to stand. Noticed by drivers. Damage negligible in well-built structures; considerable in poorly built ones. Typical peak ground acceleration is 18–34% of gravity, and the damage potential is moderate.

What MMI VII does

Perceived shaking
Very strong
Damage potential
Moderate
Peak acceleration
18–34% g
Peak velocity
31–60 cm/s

What people feel

  • Difficult to stand; movement hard to control
  • Noticed by drivers of motor vehicles
  • General alarm; many people run outdoors

What objects do

  • Large church bells ring
  • Heavy furniture overturned
  • Waves on ponds; water turbid with mud

What happens to buildings

  • Chimneys cracked considerably
  • Plaster falls in large amounts
  • Trees and bushes shaken moderately to strongly
  • Considerable damage in poorly built structures

Also at this level, in other versions of the scale

Sources: the USGS Modified Mercalli Intensity scale (Wood and Neumann, 1931; Richter, 1958); ground-motion ranges from the USGS ShakeMap documentation (Worden et al., 2012), approximate and overlapping between neighbouring levels. See instrumental intensity. An older example: MMI VII on YouTube.

Seen on camera: 7 clips rated MMI VII

Each clip is rated from the effects it shows. A rating describes one camera at one place, not a whole town.

All clips at VII →

Showing 5 clips: Homes, MMI VII. Wanted at this level: Pools, Warehouse, Skyscraper.

VII Interior of home with falling objects M7.7 12 km WSW of Pitaloza Arriba, Panama · 0:05 Seen: heavy furniture overturned. VII Exterior home and yard. M5.6 11 km N of Redwood Valley, CA · 0:22 Seen: trees and bushes shaken moderately to strongly. VII Exterior driveway in Willits M5.6 11 km N of Redwood Valley, CA · Willitis, CA · 0:30 Seen: trees and bushes shaken moderately to strongly. VII Driveway with two vehicles and pedestrian M7.1 Ridgecrest Earthquake Sequence · Ridgecrest, California · 0:27 Seen: trees and bushes shaken moderately to strongly. VII Exterior of house and yard in Cerritos, CA M6.4 Ridgecrest Earthquake Sequence · 0:14 Seen: trees and bushes shaken moderately to strongly.

Simulated at MMI VII

Our animations of named places where the estimated shaking reached this level, driven by simulated or recorded ground motion.

How the animations work →
VII Kitchen: Redwood Valley M5.6 11 km N of Redwood Valley, CA VII Kitchen: Willits M5.6 11 km N of Redwood Valley, CA VII Kitchen: Cape Town M6.4 15km WSW of Ferndale, CA VII Kitchen: Ferndale M6.4 15km WSW of Ferndale, CA

Recently at MMI VII in our region

Earthquakes in the western United States and northern Mexico whose strongest shaking at a named place reached this level.

Recent earthquakes →

How MMI VII is estimated

From instruments

USGS ShakeMap converts peak ground acceleration and velocity recorded at seismic stations into intensity. About 18–34% g of acceleration corresponds to MMI VII.

From people's reports

USGS Did You Feel It? turns answers from thousands of people into a community intensity for each place. If you felt an earthquake, report it there.

From footage

We rate each clip with questions built from the scale's own statements: what people, objects and buildings do on camera. A rating describes one camera at one place.

Common questions

What magnitude causes MMI VII?

It depends on distance and ground conditions, not magnitude alone. In our region, MMI VII has come from earthquakes such as M5.6 near Redwood Valley, CA (2026); M7.1 Ridgecrest Earthquake Sequence (2019); M6.4 Ridgecrest Earthquake Sequence (2019).

What does MMI VII feel like?

Difficult to stand; movement hard to control. Noticed by drivers of motor vehicles. General alarm; many people run outdoors.

How strong is the ground motion at MMI VII?

Peak ground acceleration is typically 18–34% g and peak velocity 31–60 cm/s.

How is intensity different from magnitude?

Magnitude measures the energy an earthquake releases and is one number per earthquake. Intensity describes the shaking at one place, so a single earthquake produces many intensities, strongest near the fault and weaker with distance.