Where were you last August when a 5.8 magnitude earthquake hit the national capital region? Having originated in Virginia, it rattled Washington, DC, and sent waves all the way to New York. Many of us in the District thought a passing truck or some other commonplace occurrence was causing our buildings to shake and shudder. Others probably suspected something more sinister. When the media confirmed that an earthquake had struck, their worst suspicions turned out to be true. We have seen the cracks in the Washington Monument and the toppled spires and gargoyles on the National Cathedral. Headline-grabbing indeed. However, what about the damage to the ordinary buildings that PMA members manage? Why were they not newsworthy?

Photo 1: Masonry dislodged from a pitched roof truss.

ETC began receiving calls within a few hours of the event. Over the next few weeks, we visited about one hundred buildings and parking garages. The vast majority of the damage we saw was cosmetic cracking in drywall and plaster interior finishes. In many cases, building owners, managers, and occupants were not sure if the cracks were new—resulting from ground motion—or if they pre-dated the quake. In fact, some were new, but many contained dust, grime, spider webs, paint, and other signs of age.

We continue to receive calls from property managers worried that wall cracks in their buildings are the result of last summer’s earthquake. At the recent PMEXPO, many attendees asked about earthquake evaluations. They want to ensure that no serious structural damage occurred that could jeopardize occupant safety. This may or may not be a legitimate concern, but it is certainly worth discussing with a building engineer.

What About Those Cracks?

Cracks in buildings are neither uncommon nor necessarily a cause for concern. We pass by the same cracks so often that we fail to notice them. When the need arises to determine whether a crack is new or related to a specific event, evaluation can be difficult without a reference point. The more we know about what is new versus old, the easier it is to assess conditions. This is one reason why timely crack repair is important.

The 2011 earthquake caused sufficient damage to a number of buildings and parking garages to require structural repairs. In general, well-constructed buildings were left unscathed, while others revealed construction defects that had gone undetected for decades.

Earthquake shock propagates in waves radiating from the epicenter, often resulting in greater movement in the direction of the wave. One property we inspected had rows of three-story buildings both parallel and perpendicular to the wave direction. Only the perpendicular buildings sustained visible damage.

The most severe damage occurred in masonry gable walls between and at the ends of buildings. Large sections of masonry dislodged from roof trusses, crashing through roofs or leaning out of plumb by as much as four inches. These walls lacked proper structural ties above the roofline, leaving the CMU backup and brick façade acting as an unsupported cantilever approximately seven feet tall. While these buildings had withstood years of weather, the earthquake exposed a longstanding construction defect.

Photo 3: Cracks filled with spackle failed under earthquake movement; temporary supports were applied.

Raised Red Flags

The earthquake’s ground motion significantly worsened existing issues in all structures discussed. In some cases, no visible defects existed beforehand. When the ground shook, hidden problems became apparent. If you suspect wall cracks may indicate a larger issue, taking action early could save money, stress, and potentially lives.

One major takeaway from the earthquake is that inspections should not wait until after an event occurs. Proactive maintenance helps ensure buildings perform better and sustain less damage during future natural events.

In one parking structure, we found concrete that had fallen from the slab above—a clear life-safety hazard. Investigation revealed that corrosion from water infiltration had already weakened the reinforcing steel. The earthquake triggered failure, but it was not the root cause.

Photo 2: Masonry crashed through the roof following the earthquake.

Photo 4: Masonry columns pulled away from an end wall.

Photo 5: Stairwell towers cracked in shear due to lateral loads.

Delaminated concrete is often easy to detect with simple testing methods. If repairs had been made prior to the earthquake, falling debris—and the associated risks—could have been avoided.

FEMA Guidelines

The Federal Emergency Management Agency (FEMA) provides guidance to help identify common earthquake-related damage. Indicators include foundation movement, out-of-plumb walls, bulging basement walls, and cracking in drywall, stucco, or plaster.

However, these signs are not exclusive to earthquakes, making it difficult for untrained observers to determine the cause. Professional evaluation is necessary to distinguish between earthquake damage and preexisting conditions.

Our post-earthquake assessments suggest that most “earthquake damage” was actually the exposure of preexisting defects. Improper installation and long-term deterioration played a significant role. In that sense, the earthquake revealed hidden issues—arguably doing some property owners a favor.