There are at least two dozen buildings at risk of collapse, according to a new report highlighting the earthquake risk to San Francisco’s city buildings.

Seismic Hazard Ratings (SHRs) were first developed in San Francisco in 1992 and are used to assess risk and prioritize seismic-strengthening capital improvements for over 200 public buildings.

Seismic retrofit projects are typically bundled with other building improvements.

Buildings are rated on a scale from SHR1 (best) to SHR4 (worst).

There are more than 3,700 publicly and privately owned older concrete buildings that were constructed before modern city building codes, some of which have the potential to fail and collapse in an earthquake, according to San Francisco’s Earthquake Safety Implementation Program.

The city’s mayor has issued a directive to add voluntary retrofit standards for concrete buildings in the San Francisco Existing Building Code, offering owners of vulnerable concrete buildings a clear pathway to improve their buildings’ safety.