The Team reconnaissance included surveys in Olympia, Seattle, Tumwater, Burien, Maplewood, Tacoma and Nisqually. Investigations were conducted March 2nd, 3rd and 4th. Damage types observed included: structural, nonstructural, contents, lifelines, landslides, liquefaction, lateral spreading, sand boils, and settlement.

Infrastructure damage observed included: bridges, roads, unreinforced masonry buildings (URMs), concrete frames, tilt ups, mobile homes, RVs, parapets, facing, windows. In places, liquefaction, lateral spreading, settlement and landslides significantly contributed to the earthquake-related damage.

Listed below are sites of observed damage arranged by buildings, lifelines, landslides and liquefaction. Nineteen photographs are included at the end of this report to highlight some of the more prominent damage locations.

Buildings:

• Seattle Pioneer Place numerous structures, Fenix

• Seattle industrial area numerous structures

•Seattle Chocolate

•Starbucks HQ

• Capitol, Olympia and nearby structures

• Olympia downtown numerous structures, including Ramada Hotel

•Old Olympian Hotel apartments

• Nisqually mobile home park

Lifelines:

• SeaTac Airport (Control tower windows and minor terminal damage)

• Boeing Field (runway extensive liquefaction and settlement up to 9 inches)

• Harbor Island Port Terminals (water pipe breaks, liquefaction, lateral spreading, settlement)

• Alaskan Way Viaduct (structural, tie rods, corbels, vertical cracks in columns)

• Spokane Viaduct (minor damage)

• Seattle terminal area (water pipe breaks, liquefaction, lateral spreading up to 500 ft.)

Landslides:

• Salmon Beach Landslide near Pt. Defiance (minor breakage of electrical, sewer, staircase, home

and trees down) in Tacoma

• Two Cedar River mud slides and flooding in Maplewood (near Renton)

• West Seattle on 36th affecting 10 homes, 1 yellow tagged home

• Burien, 8 red-tagged homes

• Highway 101 NW of Olympia

Liquefaction:

• Seattle waterfront (Ferry terminals and cracks in pier)

• Olympia Capitol Lake (liquefaction and lateral spreading)

• Seattle Harbor Island (ferry terminal, ports, marina)(liquefaction, lateral spreading, settlement)

• Trosper Sunset Lake Mobile Home Park in Tumwater (home slid off foundation, liquefaction, lateral spreading, numerous sand boils)

Damage was observed in structures and areas that, for the most part, could be predicted to be vulnerable. These include: old buildings (such as URMs), old lifelines (such as 4th Ave bridge in Olympia), areas of poor soil conditions (such as at Harbor Island and Sunset Lake), and steep slopes (Salmon Beach, Burien).

The level of damages for the M6.8 Nisqually quake was considerably lower than would be expected for a shallower, crustal M6.8 quake. Two key factors help to explain the lower levels of overall damage. First, the Nisqually quake, with a focus of 52 km, is considered to be a deep earthquake. As the seismic waves propagate up towards the ground surface, they attenuate with greater distance. Because of this depth factor, the ground shaking levels were dampened and produced less damage than a shallower earthquake would induce. Second, the 2000-2001 rainfall season has also been unusually dry. If the region experienced average precipitation, the slopes would be more saturated and vulnerable to landsliding. Significantly more landslide and liquefaction failures would be expected if the event occurred during wet slope conditions. For example, the January 13, 2001 M7.6 El Salvador intraplate earthquake had a reported 491 landslides.

The City of Seattle has been FEMA Project Impact community for three years. Because of regional coordination and public education efforts associated with Project Impact, Seattle’s level of preparation and awareness was heightened. Consequently, the emergency response efforts were made more efficient. Note, however, that only limited seismic structural improvements were conducted as part of Project Impact; consequently, Project Impact may not have significantly lower the structural damage.

Past intraplate earthquakes in the Juan de Fuca plate, including the 1949 M7.1, 1965 M6.5, 1999 M5.9, produced either no felt aftershocks or only small aftershocks. However, it is possible that large aftershocks may occur. This is illustrated by the El Salvador sequence. The January 13, 2001 M7.6 El Salvador intraplate earthquake has triggered two large aftershocks. On February 13th and 28th, a M6.6 crustal and a M5.4 intraplate earthquake were triggered, respectively.

Oregon Needs:

• Detailed studies and analyses on damages

• Studies on faults and data development targeting geohazards (good hazard info guides cost-

effective mitigation)

• Studies on infrastructure (roads, bridges, ports, airports, etc.) vulnerability in communities

• Inventory and risk assessment of state-owned inventory

• Actions to provide improved public safety (e.g., brace parapets on URMs)

• Develop regional preparedness and improve public awareness

• Inventory, assess and retrofit critical and important facilities (e.g., schools, hospitals, fire stations)

Team members:

Yumei Wang- DOGAMI, R. Jon Hofmeister- DOGAMI, Greg Graham- DOGAMI, Lou Clark- DOGAMI, Neva Beck- DOGAMI, Tova Peltz- GRI, Mark Darienzo- Oregon Emergency Management, William Elliott- Elliott Consulting, LLC, Carol Hasenberg-Portland State University Civil Engineering Department

Acknowledgements:

The Team gratefully acknowledges the many unnamed persons who have provided information, access and other assistance to our efforts. We would like to generally thank personnel at the Washington Emergency Management Division, the University of Washington, the Earthquake Engineering Research Institute, the U.S. Geological Survey, and the Washington Department of Natural Resources.

This summary report provides a quick overview of the Nisqually earthquake and our reconnaissance efforts. It has not been subjected to the Agency’s standard review process.