2111 ROSS AVE 2018-01-02 MF Import

using a handheld global positioning system (GPS) and are shown in Figure 2. Appendix A includes logs of the borings (Figures A-3 and A-4), logs of the test pits (Figures A-5 through r A-13), and details of the subsurface exploration program. �1 LABORATORY TESTING Soil samples obtained from the explorations were transported to GeoEngineers' laboratory in Redmond, Washington and examined to confirm or modify field classifications, as well as to _ evaluate engineering properties of the soil. Representative samples were selected for laboratory testing consisting of moisture content and sieve analyses. The tests were performed in general accordance with test methods of the American Society for Testing and Materials (ASTM) or other afplicable procedures. Appendix B includes a brief discussion of the laboratory tests and test results. I SITE CONDITIONS 1 GEOLOGY �. Geologic information for the project vicinity was obtained from the map entitled "Geologic Map of the Marysville Quadrangle, Snohomish County, Washington." Younger alluvial and estuarine deposits are mapped in the area. These deposits consist of stratified sediments laid down by the streams and rivers in the area. The sediment deposits consist of silt, sand and clay with organic matter. Peat deposits have been mapped in the area. SEISMICIW General Seismicity in the Puget Sound area is primarily driven by the Cascadia Subduction Zone, which is the zone where the westward advancing North American Plate is overriding the subducting Juan de Fuca Plate. Three potential seismic source zones are generally acknowledged for the Puget Sound area: (1) shallow crustal earthquakes associated with known and/or unknown faults; (2) Cascadia Subduction Zone interface earthquakes, which occur along the boundary located between the Juan de Fuca and North American plates; and (3) Cascadia Subduction Zone intraplate earthquakes, which occur within the subducting Juan de Fuca Plate. Shallow Crustal Earthquakes Shallow crustal earthquakes occur within the North American Plate to depths up to 15 miles. Shallow earthquakes in the Puget Sound region are expected to have durations ranging up to 1 60 seconds. Four magnitude 7 or greater known earthquakes have occurred in the last 1,100 years 1 in the Cascadia region, two of these occurred on Vancouver Island and two in Western Washington. The largest historic earthquake in Western Washington occurred in 1372 in the North Cascades and is estimated to have had a magnitude of 7.4. This earthquake is believed to have occurred at a depth of less than 10 miles. The other magnitude 7+ Western Washington earthquake occurred on the Seattle Fault approximately 1,100 years ago. IG e o E n g i n e c r s 4 File 3101-020-00\072502