§ ¨ ¦ 5 § ¨ ¦ 5 § ¨ ¦ 5 § ¨ ¦ 105 ¬ « 126 ¬ « 99 ¬ « 126 ¬ « 99 ¬ « 569 ¬ « 569 ¬ « 126 ¬ « 99 ¬ « 126 ¬ « 58 W all ac e C r e ek M c K e n z i e Ri ver M c K e n z i e R i v e r M c K e n z i e R i v er M i d d l e F o r k W i l l a m e t t e R i v e r Wild Ho g C r ee k A m a z o n Cre e k A m a z o n C r e e k A m a z o n Cr e e k S p e n c e r C r e e k S p e n c e r C r e e k Fla t C r e e k W i l l a m e t t e R i v e r W il l a m e tt e R iver W i l l o w Cr e e k S o u t h For k S p e n c e r C r e e k A m a z o n C r e e k D i v e r s i o n C h a n n e l C o a s t F o r k W il l am e t t e R i v e r Walterville Reservoir C e d a r C r e e k Camp Creek Moh a w k R i v e r S p ri ng C r e e k Bail ey H i l C rabtree H i l F i r Bute G i l esp ie Bute Kel y Bute Murray H i l Mount P isgah Sho rt Mountain Ski nner Bute S pencer Bute V i tus Bute Briggs H i l Oak H i l Spo res Po int Mohaw k Val ey Cantrel H i l Mon Mountain L o ra n e H wy Lo r a n e H wy S pen cer C reek R d Bailey Hill Rd B a il e y Hill Rd River Rd River Rd W i ll a m e t t e S t Green Hill Rd Clear Lake Rd Willamette Hwy Royal Ave G i m p l Hill R d 29Th Ave Marcola Rd J a s pe r Rd Prairie Rd Pine Grove Rd B o b S t r a ub P k w y Crow Rd Ca mp Creek R d Ca mp C r e ek Rd Green Hill Rd ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! S hal ow Landsl i de S uscep t i bi l ity Map o f Eugene and Sp ri ngfiel d, Lane County, Oregon 2018 § ¨ ¦ 5 § ¨ ¦ 5 § ¨ ¦ 5 § ¨ ¦ 105 ¬ « 126 ¬ « 99 ¬ « 126 ¬ « 99 ¬ « 569 ¬ « 569 ¬ « 126 ¬ « 99 ¬ « 126 ¬ « 58 Lane County Eugene South Eugene North Eugene West Springfield West Springfield East Coburg Eugene Southwest Lane County Walterville Goshen ! ! Study Area Communit ies Map W i l l a m e t t e Valley C a s c a d e Ra n g e Spencer Butte Mount Pisgah W i l l a m e t t e River River McKenzie Fern Ridge Lake Fall Creek Lake OREGON Study Area Lo cat i on Map Source Data: Oregon Lidar Consortium, 2008-2009 and 2013-2015, 3-foot bare earth lidar digital elevation model for Coburg (44123-B1), Creswell (43123-H1), Crow (43123-H3), Eugene East (44123-A1), Eugene West (44123-A2), Fox Hollow (43123-H2), Jasper (43122-H8), Junction City (44123-B2), Springfield (44122- A8), Walterville (44122-A7). Water features are from the USGS National Hydrography Dataset (2015). Highways and signed routes are from the Oregon Department of Transportation (2013). Additional physical and cultural locations are from the Geographic Names Information System (GNIS), U.S. Geological Survey (2013). Eugene and Springfield community boundaries and building footprints are from Lane Council of Governments (2017). Projection: Oregon Statewide Lambert Conformal Conic, Unit: International Feet. Horizontal Datum: NAD 1983 HARN. UTM Coordinates: Zone 10N, NAD83. Software: Esri® ArcMap® 10.6 Cartography: Jon J. Franczyk Lane County Eugene South Eugene North Eugene West Springfield West Springfield East Coburg Eugene Southwest General i z ed S urfici al Engi neeri ng Geo l ogy Map ( S ee Study Area Com munit ies Map fo r mo re detai l ) O R E G O N D E P A R T M E N T O F G E O L O G Y A N D M I N E R A L I N D U S T R I E S 1 9 3 7 STATE OF OREGON DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES BRAD AVY , STAT E GEOLOG I ST www. OregonGeo l ogy. o rg Elevation Change Feet above sea level 4984 272 16.5 TRUE NORTH MAGNETIC NORTH APPROXIMATE MEAN DECLINATION, 2014 0 5 10 2.5 Miles 0 5 10 2.5 Kilometers 1 : 290 , 000 S CALE 16.5 TRUE NORTH MAGNETIC NORTH APPROXIMATE MEAN DECLINATION, 2014 SCALE 1:34,000 0 1 2 3 4 0.5 Miles 0 1 2 3 4 0.5 Kilometers T his shal ow l andsli de suscep t ibi li ty m ap ident ifi es l andsl ide- p rone areas that are defi ned fo l owi ng the p ro to co l o f Burns and o thers ( 2012 ) . On the basi s o f several facto rs and past studi es ( descri bed in detail by Burns and Madin [2009 ]) , a dep th o f 15 ft ( 4 . 5 m) i s used to di vide shal ow from deep l andsl i des. W e p repared thi s shal ow suscep t i bil i ty m ap by combini ng three facto rs: 1 ) cal cul ated facto r o f safety ( FOS) , 2 ) l andsl ide i nvento ry data, and 3 ) bufers, as described bel ow. W e cal culated the FOS by usi ng conservat i ve val ues such as havi ng the w ater tabl e at the ground surface. W e used l andsl ide i nvento ry data from the co rrespondi ng invento ry m ap ( P l ate 1 ) . T he combi nat i ons o f these facto rs comp ri se the rel at i ve suscep t i bil i ty haz ard zones: hi gh, moderate, and l ow, as shown by the S uscep t ibil i ty Hazard Zone Matrix bel ow. T he l andsl ide suscep t ibil i ty data are di sp l ay ed on top o f a base m ap that consi sts o f the l i dar- deri ved digital el evat ion model . EXPLANATION Each l andsl i de suscep t i bi l ity haz ard zone shown on thi s m ap has been devel oped acco rdi ng to a num ber o f specifi c facto rs. T he cl assi fi cat ion schem e w as devel oped by the Oregon Departm ent o f Geo logy and Mineral I ndustries ( Burns and o thers, 2012 ) . T he sym bo l ogy used to di sp l ay these haz ard zones i s exp l ai ned bel ow. Shallow Landslide Susceptibility Zones: T his m ap uses co l o r to show the rel at i ve degree o f haz ard. Each zone i s a combi nat ion o f several facto rs ( see Hazard Zone Matri x, bel ow) . SHALLOW LANDSLIDE SUSCEPTIBILITY CLASSIFICATION Shallow Landslide Susceptibility Hazard Zone Matrix T he m echanics o f slope stabi li ty can be di vided into two fo rces: dri vi ng fo rces and resist ing fo rces. T hese fo rces are a funct i on o f the materi al p ropert i es and the geometry o f the sl ope. T hese two fo rces oppo se each o ther , and sl ope stabil i ty can be thought o f as their rat i o . A sl ope wi th a FOS > 1 i s theo ret i cal y a stabl e sl ope because the shear strength i s greater than the shear stress. A sl ope wi th a FOS < 1 i s theo ret ical y an unstabl e sl ope because the shear stress i s greater than the shear strength. A cri t i cal y stabl e sl ope has a FOS = 1 . Because o f the inabi l i ty to know al the condi t i ons p resent w ithi n a sl ope, mo st geo techni cal engi neers and engi neering geo l ogists recommend that sl opes with a FOS < 1 . 5 be considered po tent ial y unstabl e ( T urner and S chuster , 1996 ; Co rnfo rth, 2005 ) . W e calcul ated the FOS by usi ng the i nfi ni te slope equat ion wi th conservat i ve param eters. S aturated condit i ons w ere used so that a wo rst case scenario coul d be eval uated. Because o f l imi tat i ons rel ated to a grid type anal y si s, we removed iso l ated areas wi th sm al ( l ess than 4 ft [1 . 2 m] high) el evat ion An i nvento ry o f al exi st i ng l andsl i des in thi s area i s shown on P l ate 1 . W e p repared thi s invento ry m ap by comp il i ng al p revi ousl y mapped l andsl i des from publi shed and unpubl i shed geo l ogic and l andsl ide mapp i ng, anal y zing l i dar- based geomo rpho l ogy, and revi ew ing aeri al pho tographs. W e also atributed each l andsli de wi th cl assi fi cat ions fo r act i vi ty, dep th o f fai lure, movement type, and confi dence o f i nterp retat ion. W e created the i nvento ry by usi ng the p ro to co l devel oped by Burns and Madin ( 209 ) . W e extracted the shalow landsl i des from the invento ry and used these to create this shal ow l andsli de suscep t i bil i ty m ap . Buffer for Factor of Safety Less Than 1.5: T his bufer w as app l i ed to al areas with a calcul ated FOS l ess than 1 . 5 . T he bufer consi sts o f a 2 : 1 ho ri zontal to vert i cal distance ( 2H : 1V ) . Fo r exam p l e, i f the m axi m um dep th fo r shalow l andsl i des i s 15 ft ( 4 . 5 m) , then the 2H : 1V bufer woul d equal 30 ft ( 9 m) . Buffer for Head Scarps: T his bufer w as ap l ied to al head scarp s from the l andsl ide invento ry . T he bufer consi sts o f a 2 : 1 ho ri zontal to vert i cal di stance ( 2H : 1V) . T hi s bufer is diferent fo r each head scarp and i s dependent on head scarp hei ght . Fo r exam p le, a head scarp hei ght o f 6 ft ( 2 m) has a 2H : 1V bufer equal to 12 ft ( 4 m) . Head Scarp Height (V) 2H:1V Head Scarp Buffer (orange) 2H:1V Head Scarp Buffer 2 times V = 2H Horizontal (H) Vertical (V) 2H:1V Factor of Safety Buffer = 9 m (30 ft) 2H:1V Diagram Block Diagram Cross-Section (profile) Cross-Section (profile) Head Scarp Height (V) Maximum depth z = 4.5 (15 ft) L i mi tat ions i ncl ude the fo l owi ng. 1 ) Every efo rt has been m ade to ensure the accuracy o f the G I S and tabul ar database, but it is no t feasi bl e to comp l etel y veri fy al o f the o ri gi nal i nput data. 2 ) T he shal ow l andsl i de suscep t ibil i ty m ap s are based on three p ri mary components: a) cal cul ated facto r o f safety , b) l andsli de i nvento ry , and c) bufers. Facto rs that can afect the l evel o f detai l and accuracy o f the fi nal suscep t i bi l ity m ap i nclude the fo l owi ng: a) Facto r o f safety cal cul at i ons are strongl y infl uenced by the accuracy and reso l ut i on o f the i nput data fo r materi al p ropert i es, dep th to fai lure surface, dep th to groundw ater , and sl ope angl e. T he fi rst three o f these i nputs are usual yest imates ( m ateri al p ropert i es) o r conservat i ve li mi t ing cases ( dep th to fail ure surface and groundw ater) , and l o cal condi t i ons may vary substant i al y from the est i mated val ues used to m ak e these m ap s. b) L i m itat ions o f the l andsl ide i nvento ry are di scussed by Burns and Madi n ( 2009 ) . c) I nfini te sl ope facto r o f safety cal cul at i ons are done on one gri d cel at a t ime w ithout regard to adjacent gri ds. T he resul ts m ay underest i mate o r overest imate the l evel o f stabi l ity fo r a certai n area. W e devel oped bufers fo r areas wi th l ow facto rs o f safety to counter the tendency to underest i mate suscep t ibil i ty. W e devel oped the fo cal rel ief method to reduce the p robl em o f overest i m at iono f suscep t i bil i ty due to steep sl opes w ithlow rel i ef . However , overest im at i on and underest i m at i on o f suscep t i bl e areas are st i l l i k el y in some iso lated areas. 3 ) T his suscep t i bil i ty m ap is based on the topographi c and l andsl ide invento ry data avai l abl e as o f the date o f publ i cat i on. Future new l andsli des m ay render thi s m ap l o cal y i naccurate. 4 ) T he l i dar- based di gi tal el evat i on model does no t di st i nguish el evat i on changes that may be due to the construct ion o f structures li ke retaini ng w al s. Because i t woul d requi re extensi ve G I S and fiel d wo rk to l o cate al exist i ng structures and remove them o r adjust the m ateri al p ropert i es i n the model , such features have been i ncluded as a conservat i ve app roach and m ust be exam i ned on a si te- specifi c basis. 5 ) Some l andsl ides in the invento ry m ay have been mi t i gated, thereby reducing their l evel o f suscep t i bil i ty. Because i t is no t feasibl e to co l ect detail ed site- specific info rm at i on on every l andsl ide, LIMITATIONS Burns, W. J. , and Madi n, I . P . , 2009 , P ro to co l fo r i nvento ry m ap ing o f l andsl i de depo sits from l ight detect ion and ranging ( li dar) i m agery: Oregon Departm ent o f Geo l ogy and Mi neral I ndustries Speci al Paper 42 , 30 p . , geodatabase temp l ate. Burns, W. J. , Madi n, I . P . , and Mi ck el son, K . A . , 2012 , Pro to co l fo r shal ow- landsl i de suscep t i bil i ty mapp i ng: Oregon Departm ent o f Geo l ogy and Mineral I ndustries Special Paper 45 , 32 p . Co rnfo rth, D . H . , 2005 , Landsl ides in p ract ice: I nvest i gat ion, anal y si s, and rem edial / p reventat i ve op t i ons in so i l s: Hoboken, N . J. , John W i l ey and Sons, I nc. , 596 p . T urner , A . K . , and S chuster , R . L . , eds. , 1996 , Landsl i des: invest i gat ion and mit igat i on: W ashi ngton, D . C . , Nat i onal Research Council , T ranspo rtat i on Research Board Speci al Repo rt 247 , 673 p . REFERENCES SHALLOW LANDSLIDE SUSCEPTIBILITY CLASSIFICATION 1:130,000 SCALE 16.5 TRUE NORTH MAGNETIC NORTH APPROXIMATE MEAN DECLINATION, 2014 0 2.5 5 1.25 Miles 0 2.5 5 1.25 Kilometers 123°0'0"W 123°0'0"W General Features 123°0'0"W 123°0'0"W 44°0'0"N 123°0'0"W 44°0'0"N LOW: Low suscep t ibil i ty to shal ow MODERATE: Moderate suscep t i bi l ity to shal ow l andsl ides. HIGH: H igh suscep t i bi l ity to shal ow Factor of Safety (FOS) 1 F acto r o f S afety Resist i ng Fo rces Dri ving Fo rces = Landslide Inventory 2 3 Buffers for Head Scarps and Factor of Safety Less Than 1.5 44°0'0"N 44°0'0"N 44°0'0"N 44°0'0"N 123°0'0"W Contributing Factors Final Hazard Zone Factor of Safety (FOS) Landslide Deposits and Head Scarps Buffer High Moderate Low < 1.25 2H:1V (head scarps) 2H:1V (FOS < 1.5) 1.25 - 1.50 > 1.50 included 44°0'0"N 123°0'0"W 44°0'0"N 123°0'0"W 16.5 TRUE NORTH MAGNETIC NORTH APPROXIMATE MEAN DECLINATION, 2014 0 5 10 2.5 Miles 0 5 10 2.5 Kilometers 1 : 122 , 000 S CALE I MS - 60 By Nancy C . Cal houn, W i l i am J. Burns, Jon J. F ranczy k , and Gustavo Monteverde PLATE 2 Landslide Hazard and Risk Study of Eugene-Springfield and Lane County, Oregon Fundi ng fo r this p ro ject w as part ial y p rovided by the F ederal Emergency Managem ent Agency ( EMW - 2015 - CA - 00106 ) . INTERPRETIVE MAP SERIES Community Boundaries Eugene North Eugene West Eugene South Eugene South West Coburg Springfield East Springfield West T hi s p roduct i s fo r info rm at ional purpo ses and may no t have been p repared fo r o r be suitabl e fo r l egal , engineering, o r survey ing purpo ses. Users o f this info rm at ion shoul d revi ew o r consul t the p rim arydata and info rm at ion sources to ascertain the usabi l ityo f the info rm at ion. T his publ i cat ion canno t subst itute fo r sit e- specific i nvest igat ions by qual ified p ract it ioners. S ite- specific dat a may gi ve resul ts that difer from t he resul ts shown in t he publ icat ion. S ee the accompanying t ext repo rt fo r mo re detai l s on the l im it at ions o f the methods and data used t o p repare this publ i cat ion. NOTICE T he east ern po rt ion o f Lane County contains the ci t ies o f Eugene, Sp ringfiel d, and Coburg. Because l andsl ides are one o f the mo st w idesp read and dam agi ng natural haz ards in the state, i t is i mpo rtant to m ap and assess the risk in the st udy area. T he purpo se o f this study i s to assist the cit ies and county in understanding the l andsl ide haz ard bet er and thus i ncrease their abi l it y t o reduce future risk . T he study publ icat ion consists o f a t ext repo rt , three m ap p l at es, and G I S data. ABOUT THIS PUBLICATION 123°14'57"W 43°57'14"N 123°14'56"W 44°08'56"N 123°14'56"W 44°08'56"N 123°14'57"W 43°57'14"N Explanation of Symbols River Study Area City / County Boundary Study Extent Highway River / Lake Lane County (Outside Study Area) Lane County (Within Study Area) Explanation of Symbols D Stream Summit Road Waterbody Study Area Buildings The unit names listed below in generally increasing strength (weaker to stronger) Landslides (deep) deposits Recent alluvial deposits Older alluvium Residual soil on sedimentary rocks Residual soil on volcaniclastic rocks Residual soil on tuff Residual soil on mafic rocks Bedrock at surface Man-made fill