On the afternoon of 23 August 2011, a rumbling in the ductwork was heard overhead in a chemistry classroom on the fourth floor of a brand-new building at Montgomery College in Maryland. As a laboratory safety class was getting ready to begin, the noise quickly transitioned to a swaying of the building – a motion that was soon recognized as an earthquake. The view from the window showed no ripples in the pond below, but dozens of students, faculty, and staff were evacuating multiple buildings. Although the consequences of an earthquake affecting the college would typically be low, the need to more formally address the risk than it had been in the past became apparent. By early in the Fall semester, the college developed a set of practical procedures and protocols to address the actual hazards that present themselves in a region of low earthquake risk, while considering the potential need to quickly assess damages and hazards that an earthquake might present.
Every year, thousands of people die around the world due to earthquakes. Almost all are killed by building collapses. In the United States, though, such collapses are much less likely to occur. The vast majority of injuries due to earthquakes in the United States are caused by nonstructural building materials falling on people. It is for this reason that the United States Geological Survey (USGS), the Federal Emergency Management Agency (FEMA), and the American Red Cross (ARC) all urge people not to evacuate buildings during an earthquake.
2010 Potomac-Shenandoah Region Earthquake
The 2011 earthquake, known as the Virginia Region Earthquake (Magnitude [M] 5.8), was not the first that Montgomery College had experienced in recent history. On 16 July 2010, the college experienced a magnitude 3.4 earthquake, with its epicenter just over a mile south of the Germantown Campus. That earthquake was much closer than that of the future 2011 earthquake (about 80 miles), but it provoked little interest, for two reasons. First, the intensity of the shaking at the campuses and in the region was weak, due to the quake’s low magnitude. Second, it occurred at 5:04 a.m., when few people were at work or school. The shaking did awaken some, though.
Despite the limited nature of hazards that earthquakes pose in that area, a significant (and easy) step of downloading ShakeCast to particular emergency management computers improved preparedness shortly after this earthquake. ShakeCast is a free application that automatically retrieves shaking data from USGS’s ShakeMap system, and provides almost instantaneous structure damage estimates for locations chosen by the user. Applying ShakeCast to the 2010 earthquake about two weeks after the event – and including data for the three campuses, two offsite facilities, and a significant dam that the college owned – the program correctly predicted (again, after the fact) damage at all locations to be “unlikely.”
In 2010, it was necessary to download the entire ShakeCast application, which was not very user friendly. Currently, the system is available as Standalone ShakeCast, ShakeCast Lite, or ShakeCastCloud, depending on information needs and capabilities. At Montgomery College, ShakeCast continued to be monitored and location information improved after the 2010 earthquake, despite the low likelihood of a similar event occurring at the college.
Local Seismicity & the ShakeCast-Driven Investigation
Most earthquakes occur along tectonic plate boundaries. Quakes that occur in other areas are sometimes referred to as the product of “intraplate seismicity.” Such activity, generally less severe than that along plate boundaries, is uncommon but not rare in the Washington, D.C. metropolitan area. Subsurface faults, leftover from significant geologic events like the formation of the Appalachian Mountains, can be found all around the Eastern United States. Occasionally, they are “reactivated,” and create a little jolt.
The earthquake that hit Montgomery College in 2011 was one of these reactivations, centered beneath the town of Mineral in Central Virginia. At a magnitude of 5.8 and a depth of less than four miles, it caused significant shaking throughout the region. Substantial damage occurred to the National Cathedral, the Mormon Temple, and the Smithsonian Castle. The Washington Monument was so severely damaged that it was closed for repair for most of the subsequent eight years.
At Montgomery College, there were three campuses and 55 buildings, but only one college architect who could assess damage. Efficiently assessing buildings for safety with such limited resources was a challenge that ShakeCast overcame by providing instantaneous damage forecast data for all three campuses, the dam, and two major offsite facilities. ShakeCast suggested focusing initial inspections on the Rockville campus, which the software identified as most likely to have suffered damage as significant as broken windows. The software accurately predicted that none of the locations would have experienced structural damage.
Upon inspection, led by the college architect, the Rockville Campus was confirmed to have been the most impacted by the earthquake. Buildings on campus suffered cracks in interior walls and floors, fallen light fixtures, and cracks in brick facades. The other campuses and facilities had significantly less damage. By prioritizing inspection locations based on predicted damage, the focus was put on areas expected to have been most severely impacted and quickly confirmed that all buildings were safe to continue to occupy.
Montgomery College’s Preparedness Actions
It was still critical to ensure the college was addressing the building shaking threat, whatever the cause, adequately. In October 2011, the Metropolitan Washington Council of Governments (MWCOG) hosted a one-day Earthquake Preparedness for Schools Training. Representatives of the Los Angeles Unified School District and the Southern California Earthquake Center led the seminar. Representatives of Montgomery College, other local colleges, public school systems, and local governments were in attendance. Along with the emphasis on mitigating nonstructural damage, the biggest takeaway from this training was learning about ATC-20.
In 1987, FEMA and the State of California awarded the Applied Technology Council (ATC) a contract to develop “procedures for postearthquake safety evaluation of buildings.” The result of that project was the September 1989 Procedures for Postearthquake Safety Evaluation of Buildings, also known as ATC-20.
ATC-20 explains the simple three-level evaluation procedure that may be employed immediately after an earthquake. It is written for volunteer inspectors, assuming the availability of professional building inspectors and other competent local government employees might be too limited after widespread shaking to make fast decisions regarding occupancy of damaged buildings.
Subsurface faults, leftover from significant geologic events, can be “reactivated,” and create a jolt in areas that are typically unprepared for earthquakes.
In October 1989, the Loma Prieta Earthquake, also known as the World Series Earthquake, caused extensive damage and loss of life in Northern California, and required hundreds of safety evaluation inspections. ATC-20 was widely used following that earthquake, immediately leading to the identification of some gaps in coverage that the document did not anticipate. In particular, the Loma Prieta quake caused many gas leaks, hazardous materials releases, and building closures due to the release of asbestos-containing materials (ACM). ATC-20 had not addressed hazardous materials at all.
ATC was brought back, with funding by USGS, and produced the 1995 Addendum to the ATC-20 Postearthquake Building Safety Evaluation Procedures (ATC-20-2). ATC-20-2 adds guidance to ATC-20 on how to address possible hazardous materials releases during rapid building assessments. Together, ATC-20 and ATC-20-2 allow for the development of simple and effective procedures for assessing building damage after an earthquake.
Protocols & Procedures
At Montgomery College, the ATC documents facilitated development of a half-page Rapid Evaluation Inspection checklist to be used by the college’s security officers after an earthquake. It allowed for the rapid designation of a building, portion of a building, or an area as INSPECTED (apparently safe), UNSAFE, or RESTRICTED USE. All evaluations could be performed from outside the structures. Along with ShakeCast data, the Rapid Evaluations could be used to focus the efforts of the college architect or a structural engineer after basic conservative safety decisions had already been made. The college also developed Earthquake Procedures, to be followed by students, faculty, and staff during and after an earthquake. The emphasis was on not evacuating during strong shaking.
In October 2012, Montgomery College went on to be the largest organization participating in the Great Southeast Shakeout earthquake drill. The drill, along with a month of emergency preparedness fairs and educational articles, promoted general safety and preparedness among community members.
For any organization in the United States, it makes sense to develop a simple approach to earthquake preparedness.
- First, recognize that the greatest threats are nonstructural: bookcases falling over, pictures falling off walls and their glass breaking, roof tiles or parapet walls falling, ductwork or pendant lights falling from ceilings, etc. All of this can be quite dangerous, and people should be educated to limit exposure to these hazards by following the simple rule: Drop! Cover! Hold On!
- Second, write a simple rapid building assessment protocol based on ATC-20 and ATC-20-2. These documents help to tailor procedures to an organization’s capabilities and resources. Remember, this is a rapid assessment that should err on the side of safety. A building or portion of a building can always be closed off until a structural assessment can be arranged. Also, the assessment procedure can be used to rapidly assess a building for damage, no matter the cause.
- Third, consider using ShakeCast to guide the initial stages of any assessment. Download it now and begin adding location information. Alternatively, simply refer to the USGS website immediately after an earthquake and look at the ShakeMap data. When taking this route, it is important to become familiar with the online products ahead of time.
Hazards associated with earthquakes in much of the United States can be expected to be relatively minor in their severity. Even so, safety and emergency management professionals should prepare for earthquakes, particularly when given the fact that preparedness is as straightforward as writing some simple procedures and protocols, driven by the ATC documents and ShakeCast or the USGS website. The Occupational Safety and Health Administration (OSHA) provides recommendations for preparing a workplace for earthquakes. Compare your current emergency plans with the OSHA guidance, and make any necessary changes. If you choose to use products like ShakeCast, learn and drill on those tools.