Waiting for the Earthquake to Decide

Unreinforced masonry (URM) buildings — constructed with brick, stone, or concrete block without steel reinforcement — are the deadliest building type in earthquakes worldwide. An estimated 1.7 million URM buildings exist in high-seismic zones in the U.S. alone, with far larger numbers in Turkey, Iran, Italy, Nepal, and Central Asia. Seismic retrofit technologies are well established (steel bracing, fiber-reinforced polymer wraps, shotcrete walls), but building codes in most jurisdictions only apply seismic requirements to new construction or major renovations. No retrofit trigger exists for the vast majority of URM buildings: owners face no requirement to evaluate or upgrade their buildings unless they voluntarily undertake a renovation exceeding a threshold (typically 50% of building value). The result is a growing inventory of known-dangerous buildings with no mechanism to drive their improvement.

URM building collapses caused >75% of the 50,000 deaths in the 2023 Turkey-Syria earthquake, >80% of the 87,000 deaths in the 2005 Kashmir earthquake, and the majority of deaths in every significant earthquake in URM-prevalent regions. In the U.S., the "Big One" scenario for the Hayward Fault estimates 800+ deaths, predominantly in URM buildings. Portland, OR has 1,600+ URM buildings; Seattle has 1,100+; Salt Lake City has 700+. Only Los Angeles and a handful of California cities have mandatory retrofit ordinances. FEMA estimates that the nationwide cost of URM retrofits would be $12–20 billion — a fraction of the projected earthquake losses.

Los Angeles's mandatory URM retrofit ordinance (2015) demonstrates that policy mechanisms work: 13,000+ buildings are being assessed and retrofitted on a 25-year timeline. However, most cities cannot replicate this approach because: (1) retrofit costs ($15–$150/sq ft) fall entirely on building owners, many of whom own small commercial or residential properties with tight margins; (2) cities lack political will to impose unfunded mandates on property owners; (3) no federal or state program provides retrofit financing at the scale needed; (4) building inventories are incomplete — many cities don't know which buildings are URM. The technical solutions exist. The barrier is a feedback loop between incomplete inventory data, absent policy triggers, and unfunded mandates.

Two parallel advances: (1) rapid, low-cost building inventory methods that can identify URM buildings from street-level imagery, satellite data, or tax records without individual site inspections — enabling cities to quantify their risk; and (2) financial mechanisms (seismic improvement districts, resilience bonds, insurance-linked incentives) that distribute retrofit costs beyond individual building owners. The adjacent success of energy retrofit programs (PACE financing, energy improvement districts) provides a financial model, though seismic retrofit lacks the ongoing energy cost savings that make those programs self-financing.

A team could develop a machine learning classifier to identify URM buildings from Google Street View imagery in a target city, producing a probabilistic inventory map. Alternatively, a team could design and analyze a financial mechanism (resilience bond, special assessment district) for URM retrofit funding in a specific city, modeling costs, participation rates, and risk reduction. A structural engineering team could prototype a low-cost retrofit technique (e.g., near-surface-mounted FRP strips) and test it on a masonry wall specimen under cyclic loading. Relevant disciplines: structural engineering, urban planning, public policy, machine learning, finance.