- The type of earthquake hazard faced by a population varies in different parts of the world.
- In Utah our primary hazard is—BRICKS. But not all bricks—specifically, unreinforced brick buildings. Unreinforced masonry buildings (URMs) can be built of brick, adobe, stone, cinder block, concrete block, or other earth materials, but in Utah most are built of bricks or cinder blocks.
- Models show that most deaths and serious injuries (up to 98% under some scenarios) in a major earthquake will result from shaking-induced collapse or damage of URMs.
- Utah has over 200,000 URMs—approximately 20% of our occupied buildings—a higher percentage than in nearly any other earthquake-prone metropolitan region in the western U.S.
- Even though California has a higher risk of earthquakes, Utah probably has a higher risk of deaths and serious injuries from earthquakes in the 6.0-7.5 magnitude range due to our much higher percentage of URMs.
- Every person should act now to protect themselves and their families.
What is an Unreinforced Masonry Building (URM)?
- A URM is a building in which the primary supporting walls are brick, blocks, stone, adobe, or concrete (masonry) that does not have adequate steel or wood structural support to properly withstand shaking associated with a severe earthquake.
- Properly engineered buildings have a steel or wood frame that provides the structural strength, and any bricks or stone are securely tied to the building frame. While the bricks and mortar may crack in a severe earthquake, and in a few cases, may fall off the outside of the building, the wood or steel framework should prevent the building from collapsing onto its occupants.
- In Utah most brick or block URMs were built from the 1860s to the mid-1970s when earthquake building codes were first enacted. There is not an exact date after which codes were enforced (it took a few years); we use 1980 as an approximate starting date for when most construction followed earthquake building codes.
The Problems with Unreinforced Masonry Buildings (URMs):
- Most URMs in Utah have brick bearing (supporting) walls. Early Utah pioneers quickly discovered ideal brick-making clay and rock in the hills. Wanting to build buildings that would last, they preferred to put in the extra initial labor to use bricks—and brick buildings do hold up well against the weather, but … they generally do not hold up well in an earthquake.
- While brick or block walls are very good at supporting the static load of a roof or multiple floors, they generally perform very poorly in the side-to-side shaking caused by earthquakes. The shaking often causes walls to buckle or crumble, allowing roofs to collapse onto occupants. In addition, outside walls, parapets, and chimneys often fall onto people fleeing buildings or on sidewalks and streets.
- Collapsing URMs have caused by far the greatest number of deaths and serious injuries in earthquakes around the world during the last few hundred years (excluding tsunamis in coastal areas).
- Failure of an unreinforced masonry building in an earthquake generally happens quite quickly—often within the first few seconds after shaking starts, seldom allowing time for anyone to escape the building.
- This is not to say that every unreinforced building will perform poorly and every reinforced building will perform well in an earthquake—the real world is not that simple. But, we can say that being inside or near a URM in an earthquake greatly increases the risk of injury or death in an earthquake compared to nearly any other place you or a family member is likely to be.
You may want to ask yourself the following questions before you buy, rent, or occupy a building:
- Is this building a URM? By following guidelines and descriptions on this and other websites you can make a good estimate [see How to Recognize a URM]; 100% certainty often requires careful evaluation by an experienced structural engineer or other professional.
- Do I really want to buy, rent, or occupy a URM?
- Maybe a URM is cheaper, but is your family’s safety—and your peace-of-mind—worth it?
- Have I considered the higher risk of injury or death in a URM?
- Have I considered the higher financial risks of owning or renting a URM?
- Am I willing to sell or rent my URM to someone without informing them of the risks?
- Would I worry less if I knew that my building meets modern earthquake building codes?
- If the location is so ideal that I won’t consider going anywhere else, then have I considered retrofitting or replacing the URM to meet modern earthquake building codes?
- Before making a binding financial agreement, have I hired a trained structural engineer or builder to evaluate the earthquake safety properties of the building?
- Have I evaluated the earthquake risk of ANY building I intend to occupy? Even newer buildings that should meet modern seismic codes can have increased earthquake risks due to faulty construction or modifications that didn’t follow code; improvements in codes after they were built; addition of heavy objects that exceed load recommendations; poorly anchored tall furniture and electronics; high and/or precarious shelves, lamps, or other objects; weakly attached mirrors, chandeliers, and other wall or ceiling hangings; and many other reasons. Look around—and think.
- We are not aware of any real estate or rental companies that routinely provide information or disclosure statements regarding URMs or other earthquake risks; in general, it is “buyer or renter beware.”
- Being in a non-URM does not guarantee your safety, but it does significantly improve your odds of surviving an earthquake compared to being in a similar-size URM. Non-URMs may also have issues that need to be addressed, such as improperly attached brick, stone, or adobe veneer or facing; tall chimneys; non-anchored shelves, appliances, electronics, and other decorations and furnishings; a “soft story” (a weak level—often a ground-level garage or offices); inadequate steel; design flaws; etc.
Yes, we know it is expensive and inconvenient, but how much is your life, the life of a family member, and your financial investment, worth to you?