| H1 - generally safe for people, vehicles and buildings |
| H2 - unsafe for small vehicles |
| H3 - unsafe for vehicles, children and the elderly |
| H4 - unsafe for people and vehicles |
| H5 - unsafe for vehicles and people. All buildings vulnerable to structural damage. Some les robust building types vulnerable to failure |
| H6 - unsafe for vehicles and people. All building types considered vulnerable to failure |