King County GIS Center
King Street Center
201 S. Jackson St.
Suite 706
Seattle, WA 98104

+ 47.59909 N
- 122.33136 W

+ 47°  35' 56.72"
- 122° 19' 52.90"


Seismic Hazards

Description | Contacts | Attribute Information | Constraints

Data layer thumbnail image


Layer name: SEISM
Subject category: enviro
Title: Seismic Hazards
Feature Count: 0
Feature Type: Polygon
Abstract: The King County Sensitive Areas Ordinance (SAO) defines significant seismic hazard areas as those areas of King County subject to severe risk of earthquake damage as a result of seismically induced settlement or soil liquefaction. These conditions occur in areas underlain by cohesionless soils of low density, usually in association with a shallow groundwater table.
Purpose: This is a SAO layer. SEISM is suitable for general reference and medium to small scale map displays; and generalized analyses.
Status: Complete
Updated: None planned
Time period of content: (single date,as YYYYMMDD):: 19900101
Time period of content: (date range, as YYYYMMDD):: -
Spatial reference: WA State Plane North
FGDC Documentation: Classic or FAQ
Open Data Availability: Yes
Place Keywords: Washington state, King County, WA, Pacific NW,
Theme Keywords: natural resoures, none, enviro,
Lineage: Available
Supplemental Information: When shaken by an earthquake, certain soils lose their ability to support a load. Some soils will actually flow like a fluid, a process called liquefaction. Loss of soil strength can also result in failure of the ground surface (e.g., surface settlement, surface cracking, landsliding) and damage to structures supported in or on the soil. Loose, water-saturated materials are the most susceptible to seismically induced ground failure. Such materials also tend to experience the most severe ground shaking during an earthquake. The geologic environment of Puget Sound commonly results in deposits of loose, lake and/or beach sedimentation proved conditions with the potential for seismically-induced liquefaction and ground failure. Likewise areas of artificial fill my also be subject to earthquake-induced settlement and loss of strength. When development is proposed on a seismic hazard area, the applicant must submit a study which demonstrates that: 1) evaluation of site-specific subsurface conditions shows that the site is not located in a seismic hazard areas; or 2) mitigation is implemented that renders the proposed development as safe as if it were not a seismic hazard area. Criteria for the design earthquake will be developed through administrative rules and will differ for critical facilities, as defined by the Uniform Building Code, and standard structures.


Maintained by:
King County GIS Center
Primary: Paul McCombs, Permitting GIS Program Manager, 206-263-4867
(How to e-mail a County contact)
Secondary: KCGIS Center; This mailbox is monitored during business hours.

Attribute Information

_HAZARD_Hazard Type
_EDIT_DATE_edit date


Access: None

Use: King County data are made available with the understanding that they shall be used exclusively by the obtainer or his/her authorized agents. Digital products may not be reproduced or redistributed in any form or by any means without the express written authorization of King County.