The Modified Mercalli, or Mike-Mike scale is used to standardize and make more efficient the reporting of earthquake damage. Instead of reporting damage by using general descriptions like "major" or "minor" or "heavy", a Mike-Mike value is reported. This value is quick and simple to communicate over the air and equates to a standard level of damage as defined in the scale below.
| | MM
12 | Catastrophic | |
| Damage total. Waves seen on ground surfaces. Lines of sight & level distorted. Objects thrown upward into the air. Few, if any, survivors. |
| | MM
11 | Extreme | |
| Few, if any, (masonry) structures remain standing. Bridges are destroyed. Broad fissures erupt in the ground. Underground pipelines are rendered completely out of service. Earth slumps & land slips in soft ground. Rails are bent greatly. |
| | MM
10 | Extreme | |
| Some well-built wooden structures destroyed; most masonry & frame structures destroyed with foundations. Rails bent. |
| | MM
9 | Violent | |
| Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. |
| | MM
8 | Severe | |
| Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great |
| | MM
7 | Very strong | |
| Damage negligible in buildings of good design & construction; slight to moderate in well-built ordinary structures; considerable damage |
| | MM
6 | Strong | |
| Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. |
| | MM
5 | Moderate | |
| Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop. |
| | MM
4 | Light | |
| Felt indoors by many, outdoors by few during the day. @night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing cars rocked noticeably. |
| | MM
3 | Weak | |
| Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. |
| | MM
2 | Weak | |
| Felt only by few at rest, especially on upper floors of buildings. |
| | MM
1 | Not felt | |
| Not felt except by very few under especially favorable conditions. |
