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Table 1. --Landslides in the Puget Sound area, January 1997

[locations keyed to Plate 1]


Location number Landslide type Estimated volume (m3) Source material Damage Comments
1 Debris slide or flow ? Sand House deck footings exposed; yard partially removed Occurred January 2, 1997. Pictured in Tacoma News Tribune, January 26, 1997
2 Debris flows <100 each Sand & silt Southbound lane of Schuster Parkway temporarily blocked Small, shallow failures; some <30 cm thick
3 Debris flows <100 Outwash sand and gravel Street blocked; house slightly damaged Same house damaged 1996 by flow that pushed nearby house into Puget Sound
4 Earth slide 150 ? House deck undermined  
5 Rapid debris slide or flow 1500 Sandy gravel (outwash?) Part of north-bound lane of highway removed Slide debris excavated and replaced with rock fill
6 Earth slide ? ? Slide broke pavement Vegetation obscured most of slide. Slide still active in April 1997
7 Debris flows 100 to 200 Sand and silt Building pushed from foundation  
8 Debris slides and flows <100 Sand and silt Buildings struck; house yards filled with debris  
9 Debris slide and flow 500 (?) Sand and silt Street intersection blocked Street blocked near same place 1996

Table 1. (cont.)

Location number Landslide type Estimated volume (m3) Source material Damage Comments
10 Rapid earth slide and flow >2000 Sand and silt House foundation 3/4 undermined Slide may be source of debris that impacted buildings at north end of Alki Avenue
11 Earth slide 1000 Clay or silt and fill Retaining wall broken and overturned; enclosed porch of house crushed Occurred 6:00 a.m., January 1, 1997
12 Earth slide and flow 9000 Sand and silt, fill(?) Secondary supports of bridge broken; house partially undermined; parts of house yards destroyed Occurred January 2, 1997
13 Debris slide 100,000 Glacial till, silt(?) Street and utilities destroyed; houses deformed and tilted Deep, slow-moving slide; large graben at head
14 Debris flows <100 Sand Road blocked; mud in yards City crews removed trees that might have fallen onto road
15 Debris flows <100 Glacial till House partially filled with debris; street temporarily blocked Occurred about January 1, 1997
16 Debris slides and flows <100 Sand and silt Lane temporarily blocked; old building damaged  
17 Earth slide and flow 1500-2500 ? Road blocked; power lines down Occurred early evening, January 20, 1997
18 Earth slide 3000-6000 Outwash sand and gravel Road impassable Deep slide, head scarp 1 to 2 m high. Remedial work already in progress late January 1997


Table 1. (cont.)

Location number Landslide type Estimated volume (m3) Source material Damage Comments
19 Earth slide 1000-2000 Artificial fill, silt and clay Road impassable Chronic slide aggravated by 1996-1997 storms. Slide excavated and road rebuilt
20 Debris flow 500-1000 Outwash sand & gravel Four people killed; house collapsed; top story pushed into Puget Sound Occurred between 7:30 and 8:00 a.m., January 19, 1997
21 Earth slide 3000 ? House undermined; yards destroyed; culvert blocked  
22 Debris slides and flows 200 (largest) Colluvium derived from glacial sand and silt Trail temporarily blocked by debris Small, shallow slides
23 Rotational earth slump 200 Outwash sand and gravel About 6 m of westbound lane destroyed 1-m-high scarp
24 Earth slide 100,000 Sand and silt Several homes deformed; roads impassable Shallow debris flows from north flank of slide area covered railroad tracks
25 Earth slide ? ? Collapsed garage 2- to 3-m-high scarp
26 Debris flows 200-400 Sand and silt Road temporarily blocked; field covered with debris Several smaller debris flows on nearby slopes
27 Earth slide 75,000-150,000 Esperance Sand, Lawton Clay Train derailed; tracks blocked; part of convent yard destroyed Main slide Janaury 15 1997, about 10:30 p.m. Second slide January 16, 5:30 a.m. Remaining unstable blocks could move and block railroad tracks

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