State study identifies local buildings at risk of collapse in earthquake

    412
    0
    One of two Mountlake Terrace buildings identified in the study is this brick structure at 5503 232nd St. S.W. (photo from Google Streetview)

    Earlier this year the State of Washington Department of Commerce completed an inventory of earthquake-vulnerable buildings in Washington. The bottom line: There are an awful lot of old unreinforced, brick or stone buildings that could be dangerous — and several of these are in our neighborhoods.

    The survey identified 15 suspected earthquake-vulnerable buildings in Edmonds, five in Lynnwood and two in Mountlake Terrace that would be in danger of potential collapse in an earthquake. The study used existing property and tax records as its data source.

    Several of the buildings identified have since been demolished (e.g., 202 Main St. in Edmonds, former home of Mar-Vel Marble, and the Olympic View Hotel, also in Edmonds).

    Among those buildings still standing in Edmonds are the 1910 Carnegie Library, present home of the Edmonds Historical Museum; the Doctors office at 110 4th Avenue, present home to Motto Mortgage; the Princess Theater, now the Edmonds Theater; 508 Main St., currently home to Mar-Ket; the Leyda Building at 5th and Main, home to Sound Styles, Pelindaba Lavender, Garden Gear and My Hearing Center; the Edmonds Bank Building, currently home to Interiors of Edmonds; the Yost Garage at 201 5th Ave. N., home to several businesses including Salish Sea Brewery, Otherworlds and the Cheesemonger’s Table; and the old Edmonds High School, 410 4th Ave. N. currently home to the Edmonds Center for the Arts.

    Vulnerable buildings in Lynnwood include the Keeler’s Korner Texaco at 16401 Highway 99 and the Wickers Building at 19921 Poplar Way, part of the Lynnwood’s Heritage Park.

    The two in Mountlake Terrace, near the intersection of 55th Avenue West and 232nd Street, are both classified industrial. The first, at 5503 232nd St. S.W., is being used for storage for the Jensen Hughes business located across the street. The second, at 23102 55th Ave. W., houses Specialty Door Service.

    This building, home to Specialty Door Service, was also identified in the state report. (Photo from Google Streetview)

    Accompanying the report is an interactive online database showing the locations of vulnerable buildings, and whether the construction style is known or merely suspected to be dangerous in an earthquake. While most of these are in Seattle, there are significant numbers in other cities across the state including in our area.

    This diagram shows the Cascade Fault subduction zone, major earthquake history, and the likelihood of additional quakes both on the fault itself and on the various crustal faults that branch out from it. (Source: Wikipedia)

    Seismologists say the Pacific Northwest has entered the broad time window for the next rupture of the offshore Cascadia fault zone, a 620-mile-long crack in the earth’s crust stretching from the northern end of Vancouver Island to Cape Mendocino, Calif., where tectonic forces are pushing the Juan de Fuca plate underneath the North American plate.

    But it’s not just the Cascadia fault: The next earthquake could just as easily come from one of the many shallow, crustal faults that run underneath nearly all of the Northwest’s larger cities, many in the Puget Sound basin. While these faults may be shallow, their proximity to the surface means that a smaller-magnitude quake will be felt more severely. Experts warn that slippage along them could set off quakes of magnitude 7 and above, resulting in significantly more damage than quakes of the same magnitude occurring deeper in the earth. A graphic example is shown in this 2009 video from the Washington State Department of Transportation simulating the effect of a quake on the Seattle Waterfront similar to the 6.8 magnitude 2001 Nisqually event. Warning: It is dramatic.

    The building survey considered commercial, government and apartment buildings (single-family homes were excluded) built prior to 1958, targeting unreinforced masonry (URM) structures particularly. URMs are constructed of brick and mortar with no internal skeleton or bracing to provide structural support. The survey identified nearly 4,500 confirmed or suspected URM buildings that would pose high risk of collapse in an earthquake, 70 of which are emergency facilities (e.g., fire stations, hospitals), and 219 of which are schools.

    Unreinforced masonry was a standard construction technique for load-bearing walls in brick buildings through the 19th and much of the 20th century. Bricks are simply stacked one on top of the other and held together with mortar, with no bracing, internal skeleton or other structural support. The structures are rigid, solid and the weight of the wall itself is what holds the building up.

    And, in the case of an earthquake, it’s exactly this weight and lack of structural integrity that brings it down as the mortar cracks, bricks fall, the building becomes unstable and collapses into a pile of rubble. (See diagrams and animations from the City of Seattle Department of Emergency Management here.)

    And you thought that the little pig who built his house of bricks was the smart one? The houses of his two compatriots built of straw and twigs would have a much better chance of surviving a temblor, a fact recognized in earthquake-prone Japan, where architects and engineers typically design buildings and other structures to be flexible, allowing them to sway in earthquakes without losing structural integrity.

    This diagram of the Cascade Fault shows how the Juan de Fuca plate is pushing under the North American Plate. Where the two plates rub together, slippage can occur resulting in earthquakes. (Source: Wikipedia)

    “URM buildings contribute to the unique, distinct character of the state’s cities and towns,” said Brian Bonlender, Director of Washingon State’s Department of Commerce in a letter to the State Legislature accompanying the report. “While historic and frequently majestic, URM buildings are prone to partial or complete collapse in the event of an earthquake. Washington’s URM buildings suffered extensive damage during earthquakes in 1945, 1969 and 2001. Similar earthquakes around the world have shown just how vulnerable URM building construction can be if left unmitigated. As the state with the second-highest earthquake risk in the country, Washington must identify and validate the number of URM buildings and where they are located to understand the scope of the problem and what may be needed to address it.”

    Earlier this year State Sen. Marko Liias, who represents part of Edmonds and Lynnwood in the 21st District, was among the sponsors of Senate Bill 5557. The bill would provide incentives for builders and owners of existing structures to build in or retrofit earthquake-resistance measures in new construction and existing buildings, authorize local governments to enact programs to encourage these, and create a state grant program for improving the earthquake resistance of unreinforced masonry buildings.

    Referred to the Ways and Means Committee, the bill did not move to the floor prior to the 2019 legislative session’s April 19 adjournment, but could return in 2020.

    When there is money to retrofit a vulnerable building, common fixes include strengthening exterior walls and reinforcing junctures between floors or ceilings and those walls. Another frequently recommended safety enhancement is to tie down parapets and cornices, which could otherwise rain down bricks or stones onto the heads of people passing below. In recognition of this, the Washington House of Representatives did authorize some capital budget investments for school seismic safety assessments.

    “Washington has both public and private buildings that would most likely not withstand an earthquake or tsunami,” said Rep. Strom Peterson, also from the 21st District. “We cannot ignore the devastation our state would face in the eventuality of this kind of natural disaster.

    “Last year’s capital budget got the ball rolling with funding to conduct seismic school assessments and create an inventory of unreinforced masonry buildings (URMs) in our state,” Peterson continued. “The 2019-21 capital budget builds upon that work with a $2.2 million investment to conduct seismic safety surveys of high-risk public-school facilities. These surveys will help schools adjust their safety plans in case of emergency and will provide estimates on how the state can best invest funds to retrofit these buildings, and protect the health and safety of our communities.”

    — Story and photos by Larry Vogel

    The building is currently being used for storage for the Jensen Hughes company, located across the street.

    LEAVE A REPLY

    Please enter your comment!