Understanding Seismic Risks in Western Washington

The Nisqually Earthquake: A Wake-Up Call

The 2001 Nisqually earthquake, with its 6.8 magnitude, served as a crucial reminder of the seismic risks that Western Washington faces. Since that time, extensive research has deepened our understanding of the region's vulnerability to more powerful earthquakes, making preparedness and proactive measures essential.
 

Technological Advancements Uncover Hidden Faults

The Nisqually earthquake could have caused far more destruction, according to scientists. Research over the past two decades has revealed that the region is susceptible to even stronger earthquakes. Marine geologist Chris Goldfinger from Oregon State University pointed out the increased likelihood of megaquakes in the Northwest, similar to the one that caused the devastating tsunami in Sumatra.

In 2001, only two active faults were known in the Puget Sound area; today, more than ten have been identified. Further studies have also shown that the ground beneath downtown Seattle is less stable than previously believed, increasing the area's seismic risk. USGS scientist Brian Sherrod emphasized that these findings represent a better understanding of the region's seismicity.

The Role of Earthquake Retrofitting in Protecting Homes

Technological innovations, particularly LIDAR, have played a significant role in these discoveries. By using airborne lasers to map the topography, LIDAR has exposed hidden faults previously concealed by vegetation. This technology has been instrumental in assessing seismic hazards more accurately.

Craig Weaver, the USGS' regional seismic-hazards chief, noted that these new insights are crucial for guiding building and emergency preparations. Over the last decade, what began as an exploratory phase has evolved into a more detailed understanding of the potential seismic events that could impact the region.

One particularly concerning scenario involves the Seattle Fault, which stretches from Bainbridge Island to Bellevue, running beneath critical infrastructure. A repeat of the last major quake on this fault 1,100 years ago would rank among the most destructive events in U.S. history. Additionally, the Southern Whidbey Island Fault poses an even greater threat, extending from Vancouver Island to Richland.

The Importance of Proactive Measures

Given these risks, earthquake retrofitting has become an essential strategy for mitigating damage. Retrofitting involves reinforcing structures, especially older buildings, to better withstand seismic forces. This is particularly critical for residential wood-framed homes in Seattle built before modern building codes were implemented.

The retrofitting process typically includes bolting the house to its foundation, bracing cripple walls, and securing heavy components like chimneys. For homeowners in Seattle and other earthquake-prone areas, retrofitting is not just a safeguard—it's a proactive step toward ensuring safety and peace of mind.

Ongoing research underscores the importance of retrofitting. Art Frankel from the USGS is developing advanced seismic-hazard maps that identify vulnerable areas in the Puget Sound region. These maps are vital for informing building codes and guiding retrofitting efforts, helping structures better withstand future earthquakes.

According to the USGS, there is an over 80% chance of another earthquake similar to the Nisqually quake occurring in the Puget Sound region within the next 50 years. The insights gained from the 2001 quake have led to more accurate models and predictions, which are crucial for preparing infrastructure and communities for inevitable seismic events.

In conclusion, the advancements in technology and research over the past two decades have provided a clearer picture of the seismic risks in Western Washington. Homeowners are strongly encouraged to invest in earthquake retrofitting as a proactive measure to protect their families and properties, ensuring they are prepared for the next significant seismic event.