February 27, 2002

Nisqually quake reinforced some vital lessons

CREDIT Photo courtesy of ABS Consulting The Nisqually quake reminded us that we're in earthquake country. The control tower at the Sea-Tac International Airport sustained heavy damage.

It's been one year since the Nisqually earthquake and it's important to reflect on the lessons learned and what preventive steps are needed to be better prepared the next time.

For many, the earthquake was a non-event with relatively modest impact on family and workplace. However, for many of us, the tremor left a lasting imprint of gaping cracks in walls around us and unsightly scaffolds around significant landmark structures. When the shaking stopped, we wondered if our workplace, home and classrooms would be safe in the event of future quakes.

Is the region really ready for a major earthquake? The answer is: probably not yet.

The 6.8-magnitude earthquake served as an important reminder that the Pacific Northwest is earthquake country. Not only are we subject to great earthquakes every few hundred years (the last was in January 1700), but also, that much more frequent moderate events, such as the Nisqually earthquake, are capable of inflicting significant damage. On average, the Puget Sound region has experienced such an earthquake every 25 years. Businesses big and small have felt their impact.

4 basic lessons

The basic lessons from the Nisqually earthquake experience, though not new, are still vital:

1. Outdated construction types founded on poor soils can be a devastating combination. Good examples of this are the many unreinforced brick structures and tilt-up concrete buildings located on the reclaimed land south of downtown, which experienced significant structural failure and liquefaction. Many businesses in the area are still recovering from the earthquake.

2. Simple preventive upgrades (such as tying walls and floors together) do work, even for challenging structures on seismically questionable sites.

3. Unrestrained non-structural elements (piping, gas-fired equipment, pallet racks, and computers) can cause millions of dollars of preventable damage and prolonged interruption of operations.

Water damage to valuable building contents and finishes is certainly preventable. Adequately braced equipment success stories are well documented in recent earthquakes. The Boeing facilities in Seattle and other major employers have suffered significant damage from broken water mains, while buildings have remained relatively intact. Inadequately braced sprinkler lines pose similar concerns.

Many Puget Sound organizations have recognized these issues and have embarked on a systematic risk reduction program. Our neighbors in British Columbia have developed a matching funds program for schools, hospitals, and universities to specifically address non-structural seismic issues.

4. Simple, yet workable emergency response plans that recognize where a building's earthquake damage is likely to occur can have a significant impact on quick restoration of occupancy and operations, as well as preventing injury with safer egress routes.

Recipes for success

Seismic risk remains a threat worth preparing for through preventative engineering and planning. So, what is the recipe for success in the next earthquake?

• Understand your seismic risk

• Implement easy fixes and upgrades before it happens

• Plan for response and resumption following the event

• Understand your property insurance needs

Facility owners and tenants often want to know the following:

• Are their structures basically sound?

• How do they compare to similar facilities?

• Will the occupants be safe?

• Is gas-fired equipment property restrained?

• Will egress routes be clear?

• Are heavy suspended objects going to stay suspended?

• How much earthquake insurance should I purchase?

A seismic risk audit performed by experienced structural engineers is one logical way to answer these questions. Risk audit provides an understanding of potential seismic risks (areas of damage) and associated financial losses, and permits owners to develop a game plan for addressing the risks through engineering improvements, transferring the risk to others (insurers) and planning an effective post-event response.

The Nisqually earthquake has served notice to local property holders that the Pacific Northwest is seismically vulnerable. The lessons from this event are not new. The increased property insurance rates have further limited owners' options in dealing with seismic risks. Engineering solutions exist to manage that risk and keep our communities safe and economically healthy in the event of the big one.

Other Stories:

• Welding practices reconsidered
  
• Will your building stand up to the Big One?
  
• Three earthquakes, one tough building
  
• Earthquake aftermath: a tale of two buildings