School Seismic Safety
   

The School Seismic Safety Project (SSSP) is a statewide effort to evaluate how Washington public school buildings could be affected by earthquake shaking.

Project Overview

Many of Washington’s K–12 students attend schools that may not withstand earthquake shaking. Washington State ranks second in the nation for earthquake risk, but most of Washington’s public school buildings were built before the adoption of modern building codes.

The School Seismic Safety Project (SSSP) is the first phase of a statewide effort to systematically evaluate Washington school buildings for seismic performance. The SSSP is a 2017–2019 Capital Budget-funded project led by the Washington Geological Survey (WGS), a division of the Department of Natural Resources (DNR), in cooperation with the Office of Superintendent of Public Instruction (OSPI).

The project involves both geological and engineering assessments. Over the summer and fall of 2018, WGS scientists collected seismic data to measure the soil conditions at almost 100 school campuses, usually on playing fields. This seismic data greatly improves our estimates of potential ground shaking by more accurately evaluating site-specific soil conditions under the school buildings. In addition to this, a group of licensed professional structural engineers collected building data at the school campuses. They evaluated the structural and nonstructural adequacy of the school buildings.

Based on limited funding, only 222 school buildings across the State were selected for this initial phase of the project. We hope that funding will be reallocated this biennium to continue assessing Washington’s public school buildings.

The results of the SSSP will inform schools, districts, and public officials of the policy and funding needs for improving the seismic safety of our state’s K–12 public school buildings. In October 2018, a preliminary progress report for the SSSP was submitted to state legislators and the governor. Currently, the project is on schedule to be completed by June 2019.

Schools Assessed in this Study

For this project, 222 school buildings were selected based on seismic hazard (expected amount of earthquake shaking at a given location), building construction type, year built, geographic location, and student capacity.

Seismic Hazard

Schools were selected in areas with low to high seismic hazard, with a greater emphasis on high seismic hazard areas. We also prioritized campuses that were located near active faults.

Simplified map of seismic hazard. Colors represent shaking hazard, with darker colors indicating higher hazard areas. Major active faults are shown as black lines.

Building Type

We selected schools of all building types (such as wood frame, concrete, steel, masonry, and unreinforced masonry). Only educational facilities and permanent structures were assessed in this study; portables and secondary buildings such as greenhouses and bus depots were excluded.

Year Built

Building age is one of the most significant factors affecting the seismic vulnerability of a structure. Most (88%) of permanent public K–12 school buildings in Washington were constructed prior to 2005, which means they do not incorporate expected shaking from a Cascadia subduction zone or Seattle Fault earthquake into their building design. Buildings constructed before 1998 are especially at risk, as this is the first year when buildings began to be constructed to “modern” seismic standards. We therefore focused on older buildings as they are more likely to be at a higher seismic risk than newer structures.

Geography

School buildings were selected from rural and urban school districts across the State. School districts in large metropolitan areas such as Seattle and Bellevue were not part of this initial study—the Seattle school district has already seismically upgraded many of its schools.

Capacity and Enrollment

We looked at buildings ranging in size from 400 square feet to more than 120,000 square feet, and schools with all levels of enrollment (16–1,752 students), with an emphasis on school buildings with larger enrollments (>250 students).

Grade

Only public K–12 school buildings are included in this initial study.

From the 222 school buildings studied, we selected 15 buildings for further analysis. This included estimating how much it would cost to upgrade the building to meet seismic code. We mostly selected schools in high seismic risk areas, but included a few in moderate to lower risk areas. We also focused on main school buildings and gymnasiums because these large public facilities often serve as community emergency shelters. We selected school buildings of varying age, type, and construction materials. Assessing such a broad range of school buildings allows us to determine the cost to seismically upgrade school buildings across the State.

Map showing the locations of all 222 school buildings studied as part of this project. The 15 school buildings selected for further analysis are shown as darker circles.

Click here to download a table with the names of all 222 school buildings studied.

Project Timeline

The School Seismic Safety Project began in June 2018 with geologic field assessments and engineering building surveys. In the fall and winter of 2018 through the spring of 2019, scientists and engineers are assessing the data collected in the field and writing up their results for each school. The final report for the project will be finished by the end of June 2019. Once the individual reports for each school are finished and the final project report is submitted, this website will be updated with links to the new information. Pending capital budget funding, this project may continue into the next biennium.

Project Activities

Funding allowed for initial seismic screening evaluations at 222 school buildings across the State. Geological site classifications were performed at each of the selected school campuses. In addition to this, we were able to perform more detailed analyses (known as concept-level seismic upgrade designs) for 15 school buildings and five fire stations located within one mile of a school campus.

An initial seismic screening evaluation (conducted at 222 schools) includes:

  • An on-site assessment of the seismic site class of the soils. Seismic site class is related to soil type and determines the level of earthquake shaking expected at the site.
  • An on-site investigation of the school buildings to screen for potential seismic hazards. Licensed structural engineers evaluated building type, age, configuration, condition, and other features in order to determine how the building would react to an earthquake.
  • Creation of a seismic screening report to document the findings from each school building. These reports will be distributed to each school and district to support further seismic improvement work.
  • Input of this seismic screening information into the Office of Superintendent of Public Instruction’s (OSPI) Information and Condition of Schools (ICOS) database so that results and reports are available to OSPI and are captured in the statewide database of school information.

A concept-level seismic upgrade design (conducted at 15 schools and five fire stations) includes the initial seismic screening evaluation plus the following:

  • Drawings that show how seismic upgrades could be made, as well as a review of how the proposed upgrades would affect the architecture of the school. Changes in architecture would affect whether the building would keep people safe during an earthquake and whether the building could be used again immediately following the earthquake.
  • Creation of a design report for each facility.
  • Additional screenings and calculations to determine a cost-effective way to seismically upgrade the school building, including a final estimated cost to upgrade.

The concept-level seismic upgrade designs provide: (1) more detailed information about the structural and nonstructural seismic deficiencies of each building; (2) design solutions for how to lessen the impact of these seismic deficiencies; and (3) an estimate of how much it would cost to bring the building up to seismic code. Based on this information we can extrapolate our findings to other buildings in the State. This will help us better understand the scope of seismic risk and the cost of seismic upgrade for all schools across Washington State.

Seismic Site Class Assessments

At each school campus a team of DNR geology personnel conducted a seismic survey to determine the National Earthquake Hazard Reduction Program (NEHRP) soil site class at that school. Site class categories inform scientists and engineers about whether the soils under a school might amplify ground motion during an earthquake. We determine site class for a school by measuring how fast shear waves move in the upper 30 meters (98 feet) of the ground. Shear waves are the earthquake waves that create the strongest horizontal shaking and are the most damaging to buildings during an earthquake. This measurement, known as Vs30, is correlated with site class using the table shown below. Different types of soil and rock can make earthquake shaking stronger at the surface. Site class therefore tells us about the potential for strong ground shaking in a particular area during an earthquake. Engineers use the site class information for a school to ensure that the building upgrades will be able to withstand the expected amount of shaking at that location.

NEHRP site class categories. By measuring Vs30 we can use this table to identify the composition of the soils beneath a structure. Softer soils typically make ground shaking stronger.

  NEHRP site class Description Vs30 (meters/second) Ground shaking potential
A Hard rock greater than 1,500 Low
B Rock 760–1,500  
C Soft rock/very dense soil 360–760 Moderate
D Stiff soil 180–360  
E Soft soil less than 180 High

Progress To Date

Phase 1 of the SSSP (the 2017–2019 biennium) is complete.
  • We assessed the NEHRP seismic site class at 94 school campuses and five fire stations across the State.
  • We performed seismic evaluations of 222 public school buildings across the State.
  • We performed more detailed seismic analyses for 15 of these 222 buildings in order to evaluate seismic upgrade strategies and determine how much it may cost to bring each building up to current seismic building codes.
  • We submitted a preliminary progress report to the legislature and the governor on October 1, 2018. You can find it here.
  • We submitted a final report to the governor, the legislature, school districts who were a part of this study, and schools where assessments were performed, on June 28, 2019. You can find it here.

Phase 1 Findings

  • One goal of the SSSP is to provide site-specific information about how the soils underlying each school building will amplify seismic waves. Nearly a quarter of the school campuses have a measured site class that differed from previous estimates of site class made based on broad-scale geologic maps. These differences can significantly affect building upgrade cost estimates and building designs.
  • About half of the school buildings were built before 1963, well before the adoption of modern seismic codes. Building age and material is a key indicator of the need for a seismic upgrade. Older unreinforced masonry buildings and non-ductile concrete buildings are especially at risk. Buildings constructed prior to 1975, when the statewide building code was adopted, are particularly vulnerable.
  • The Earthquake Performance Assessment Tool (EPAT) estimates that the median building is expected to be 43 percent damaged by a design-level earthquake (a modeled earthquake that could be similar to a Cascadia subduction zone earthquake in some parts of Washington).
  • The EPAT tool estimates that the majority of buildings in this project are expected to receive a “Red—Unsafe” post-earthquake building safety placard following a design-level earthquake, meaning that the buildings may be unsafe to occupy.
  • The EPAT tool estimates that approximately one-fourth of buildings studied may not be repairable following a design-level earthquake, and will require demolition.
  • Many of the schools with the highest estimate of damage following a design-level earthquake are located in areas of highest earthquake hazard.
  • The results of the more detailed seismic analyses indicate that the cost to seismically upgrade a vulnerable structure is less or much less than the damage costs the building would incur in an earthquake. For less vulnerable structures, especially structures in low seismicity areas, however, it may not be financially worth conducting seismic upgrades.
  • Based on the limited number of buildings (15) where seismic upgrade cost estimates were made, the average cost to upgrade to the Life Safety standard (meaning the building will keep people safe and provide exits, but won’t necessarily be useable after the earthquake) is $42 per square foot. The average cost to upgrade to the Immediate Occupancy standard (meaning the structure is built to be useable after the earthquake) is $69 per square foot.
  • Estimated costs to seismically upgrade a school building range from $63,000 per building to $5,010,000 per building.

Download Reports

This section provides links to reports on SSSP methods and findings.

  • The initial progress report submitted to the legislature on September 28, 2018 can be found here.
  • The final Phase 1 report submitted to the legislature on June 28, 2019 can be found here.
  • Four engineering reports outline the results of the seismic screenings:
  • A publication detailing the methods and results of the site class assessments, including an appendix containing the reports for each of the school campuses, can be found here.

The map below allows you to download the Tier 1 engineering seismic screening reports for each of the school districts. Click on each district to access a link to the report.

Tier 1 engineering seismic screening reports are also available for each of the five fire stations:

The concept-level seismic upgrade design reports are available bundled as Volume 4 above, or individually for each school building by clicking on the names below:

Next Steps

The Washington State legislature has elected to continue funding the SSSP in the 2019–2021 biennium at a level of $2,200,000 from the capital budget (Phase 2). The funding will cover site class assessments, seismic screenings, and concept-level seismic upgrade designs for many more schools across the State. This continued funding is important for progressing our understanding of seismic risk in Washington schools.

Information for School Districts

The goal of this project is to provide each school district that participated in the study with the information and seismic safety advocacy needed to make improvements to the earthquake safety of their school buildings.

The results of Phase 1 of the SSSP are available for download in the ‘Download Reports’ section. There you can find site class assessment reports for your school campuses, and seismic screening reports for your school buildings.

If you have any questions or would like more information about your school building(s) that is not covered in the published reports, please reach out to us—we can get you the information you need.