It is estimated that 20,000 avalanches fall annually in Colorado. A small percentage

of these affect people, property,and highways. Every winter about60 people are reported caught byavalanches, six are injured and sixare killed. Additionally, avalanchescause about $100,000 in directproperty damage and cause indi-rect economic losses of $3Ð5million. (For example, a large

storm on a Saturday could triggeravalanches onto highways, pre-venting 10,000 skiers from reach-ing ski resorts and resulting in rev-enue loss of $500,000.) Another 300avalanches a year, many releasedwith explosives by ColoradoDepartment of Transportation(CDOT), hit state-managed highways.

Why an Avalanche Center?

Avalanches, therefore, pose a significant hazard to industry, resi-dents, recreationists, and travelers.An efficient and cost-effective pro-gram that monitors conditions andassesses the hazard is key to miti-gating the danger statewide.

OriginsThe seed that grew to be theColorado Avalanche Information

Center (CAIC) was sown in 1973.That year the U.S. Forest Serviceavalanche project in Fort Collins

formally launched a pilot forecastprogram for Colorado. It was thefirst avalanche forecast program inthe U.S., and it enjoyed 10 success-ful years.

However, in 1983 the projectlost its funding. In those years,avalanche research in the ForestService was a low priority and theAvalanche Warning Program wasabolished as a first step in disman-

tling the entire research project.But riding in like a white knightwas the Colorado Department ofNatural Resources to offer the pro-gram a new home in the ExecutiveDirectorÕs Office . . . as long as itcould raise its own money. It didso, but barely. The savior provedto be the Forest Service, whichprovided a lifesaving grant.

The CAIC: A New Name

and New MissionUpon entering state government,the program adopted a more ser-vice-oriented mission that stressednot only avalanche forecasting butalso public education. To reflect itsexpanded mission, the programwas renamed the ColoradoAvalanche Information Center.

COLORADO GEOLOGICAL SURVEY

V O L U M E O N E , N U M B E R F O U R O C T O B E R , 1 9 9 8

1

Colorado AvalancheInformation Center:

A Short History

FOCUS: COLORADOAVALANCHES

Field Notes from State Geologist.......2

Upcoming Events Involving CGS .......4

How to Order CGS Publications ........5

Geologic Hazards Conference Registration Form and Schedule........9

Inside this issue

Powder avalanche in motion

continued on page 4

The work of the CAIC is tiedto the seasonsÑspecifically,avalanche season. From

November through April, the Cen-ter is fully staffed for forecastingand educational services, andoperates seven days a week. FromMay through October, the Centercloses its forecast operations andmaintains a smaller staff that pro-vides management, fund-raising,data compilation and reporting,and other necessary services.

PurposesThe chief functions of the Centerare to:

¥ monitor changing snow andavalanche conditions,

¥ provide daily hazard evalua-tions and forecasts,

¥ warn of dangerous avalancheconditions,

¥ advise CDOT of avalanchepotential along state high-ways,

¥ provide avalanche safety education and outreach, and

¥ be the stateÕs focal point foravalanche information.

Forecast ServicesThe Denver office of the CAIC islocated at the National Weather

Field Notesfrom the

StateGeologist

The Colorado Department ofNatural Resources 1991Ð95Plan contained the follow-

ing statement as one of the goalsfor the Colorado Geological Sur-vey (CGS): ÒTo minimize or pre-vent environmental damage,loss of life, adverse financialimpacts or destruction ofresources as a result of geologichazards or energy and mineraldevelopment.Ó

The program within the CGSthat is concerned with the geo-logical hazard most deadly topeople in our state is the Colo-rado Avalanche InformationCenter. Avalanches pose a significant threat to people liv-ing and working in Colorado.Each winter, on average, ava-lanches kill six people and causeeconomic losses totaling mil-lions of dollars. Given the inher-ent risks taken by many back-country skiers, snowboarders,snowmobilers, and snowshoers,it is unrealistic to expect theCAIC to be able to eliminatefatal avalanches. Nevertheless,the number of victims can beminimized with a program thatinforms and educates the publicabout the potential hazard. Add-itionally, the possibility of anavalanche disaster along a Colo-rado highway or at a developedsite will always be present, butthe probability of it happening canbe reduced to near zero with astate-of-the-art avalanche center.

2

continued on page 3

The CAIC: Its People and Operations

Avalanches—The MostDangerous GeologicHazard in Colorado

HUERFANO

SUMMIT

M O F F A T

DEN.

25

160

25

133

70

50

50

9

135

82285

285

24

70

24

40

160

149

550

40

34

33

22

55

77

11

66

44

99

88

1010

12

50

A

A

A

A

A

Eisenhower Tunnel

Denver

Carbondale

Silverton

Pagosa Springs

Vail

GlennwoodSprings

GrandJunction

Telluride

Durango

Canon City

Pueblo

ColoradoSprings

Trinidad

Fort Collins

✪

Leadville

Gunnison

Buena Vista

Aspen

SteamboatSprings

SAGUACHE

GUNNISON

CONEJOS

RIO GRANDE

MINERAL

HINSDALE

ARCHULETALA PLATA

MONTEZUMA

DOLORES

SAN MIGUEL

SAN JUAN

OURAY

MONTROSE

DELTA

M E S APARK

CUSTER

FREMONTCHAFFEE

LAKE

COSTILLA

ALAMOSA

PITKIN

Ouray

Breckenridge

LARIMER

BOULDERG R A N D

JACKSON

EAGLE

G A R F I E L D

R I O B L A N C O

ROUTT

CrestedButte

GILPIN

CLEARCREEK

GrandMesaGrandMesa

West Elks &Ruby RangeWest Elks &Ruby Range

SawatchRangeSawatchRange

Sangre deCristos

Sangre deCristos

EasternSan JuansEasternSan Juans

WesternSan JuansWesternSan Juans

FrontRangeFrontRange

Park Range& Flat TopsPark Range& Flat Tops

Elk Mtns.Elk Mtns.

Gore Range &Summit Co.

Gore Range &Summit Co.

MAJOR AVALANCHEZONES OF COLORADO

and

CAIC Office LocationsA

Colorado avalanche zones and CAIC offices

Service. The staff includes KnoxWilliams, Nick Logan, Dale Atkins,and Scott Toepfer. Collectively, thisstaff has about 95 years ofavalanche experience. Throughoutthe winter season, this team sharesthe duties of lead forecaster who,on a daily basis, is responsible for:

¥ gathering, logging, and ana-lyzing data from about 40staffed sites (e.g., ski areas andhighway passes) or remoteweather stations,

¥ issuing snow stability evalua-tions and forecasts for 10mountain zones and fivehighway locations (see mapon page 2),

¥ disseminating those forecaststo the public and user groupsvia hotlines, fax, and e-mail,

¥ issuing formal Avalanche Warn-ing Bulletins, when warranted,

¥ responding to calls from thenews media, and

¥ handling special requestsfrom sponsors/clients.

Highway Forecast Offices

The CAIC staffs four mountainoffices to provide forecasting andtraining services to CDOT (see mapon page 2).

¥ Silverton: Andy Gleason andDoug Lewis forecast for U.S.550 from Coal Bank Hill toRed Mountain Pass, Colorado145 over Lizard Head Pass,and Colorado 110.

¥ Pagosa Springs: MarkMueller forecasts for U.S. 160over Wolf Creek Pass, U.S. 50over Monarch Pass, and Col-orado 17 over Cumbres andLa Manga Passes.

¥ Eisenhower Tunnel: Forecast-ers Lee Metzger and CathyFraser are responsible for theI-70 corridor from George-town to Vail, U.S. 6 overLoveland Pass, U.S. 40 overBerthoud Pass, and (in thespring) Colorado 82 overIndependence Pass.

¥ Western Slope: Based in Carbondale, Rob Hunker fore-casts for Colorado 133 overMcClure Pass, Colorado 65 onGrand Mesa, Colorado 139over Douglas Pass, and Colo-rado 24 on Battle Mountain.

Education,Publications and

Outreach ServicesThe CAIC provides avalanche

safety courses for citizens, tourists,

and avalanche practitionersstatewide. Annually the staff offersabout 70 classes to more than 3,000people. In recent years the CAIChas produced two educationalvideos and published a majorstudy of avalanche accidents enti-tled The Snowy Torrents. Every yearthe staff writes numerous articlesfor magazines and newsletters,and averages about 200 contactsseasonally to provide timely andaccurate information to broadcastand print media.

—Knox Williams

3

The CAIC has achieved muchwith very limited resources. Over-all revenues have increased thelast 10 years due to of a sizablecontract from the ColoradoDepartment of Transportation toprovide forecasting and trainingservices for CDOT employees.Cash funding in inflation-adjusteddollars, however, has actuallydecreased from 1987 to 1997, andthese are the dollars needed toprovide services to the public (i.e.,backcountry users), ski industry,and local and county govern-ments. At the same time, the CAIC

has seen demand for its serviceÑespecially educationÑincrease.

The CGS Advisory Committeerecently wrote, ÒThe CGSACbelieves that it is appropriate andtimely to begin supporting thestateÕs avalanche forecasting andoutreach efforts, even though theCAIC has not previously receivedSeverance Tax funding. Currently,the only funding support for thebackcountry avalanche forecastand education effort comes fromdonationsÑfrom individuals aswell as local governments andcompanies. In essence this pro-gram, which has a proven trackrecord in saving lives, exists onvolunteer donations. SeveranceTax funding will make the state a

partner in this life-saving endeav-or.Ó Likewise, the Colorado Min-ing Association and the Minerals,Energy and Geology Policy Advi-sory (MEGA) Board have bothendorsed providing funding to theCAIC backcountry avalanche fore-cast and education effort from thestate Severance Tax.

New funds for the backcoun-try forecast and education effortwill give the CAIC the opportuni-ty not to expand its mission butrather to fulfill it. With SeveranceTax funding, the CAIC is in aposition to provide a higher levelof service that will benefit every-one who lives in or travelsthrough ColoradoÕs avalanchecountry.

Field Notes from the StateGeologist—continued from page 2

How to contact the CAIC

MMaaiill:: Colorado Avalanche Information Center10230 Smith RoadDenver, CO 80239

PPhhoonnee:: 303-371-1080 (office)

303-371-5508 (fax)

EE--mmaaiill:: caic@rmi.net

WWeebb:: www.caic.state.co.us

4

The CAIC maintains hotlines inseven cities and towns (seebox below). Each hotline has a

local sponsor who shares the cost ofservice. The hotlines are updateddaily and contain the most recentlocal weather, snow and avalancheconditionsÑinformation valuablefor planning back-country trips. Lastseason the public made more than76,000 calls to these lines. Actualusage is certainly greater since somesystems do not count calls.

When you call one of the hot-lines, you will learn the present ava-lanche danger level. The danger rat-ing can vary from one mountainzone to another and is based onlocal weather, snow and avalanchedata. It can change from one day tothe next ... and often does. The Inter-national Avalanche Danger Scale (seetable) is used by all the avalanchecenters in the U.S. and Canada andis very close to that used in Europe.

—Knox Williams

Denver . . . . . . . . . . . . . . . . . . . . . .303-275-5360Colorado Springs. . . . . . . . . .719-520-0020Fort Collins . . . . . . . . . . . . . . . . .970-482-0457Summit County . . . . . . . . . . . .970-668-0600Durango . . . . . . . . . . . . . . . . . . . .970-247-8187USFS-Aspen . . . . . . . . . . . . . . . .970-920-1664USFS-Vail . . . . . . . . . . . . . . . . . . .970-827-5687

AvalancheHotlines andDanger Scale

Danger Level Avalanche Probability Extent of Instability

LOW Natural avalanches very Generally stable snow. Isolated unlikely. Human-triggered areas of instability.avalanches unlikely.

MODERATE Natural avalanches Unstable slabs possible on unlikely. Human-triggered steep terrain.avalanches possible.

CONSIDERABLE Natural avalanches Unstable slabs probable on possible. Human-triggered steep terrain.avalanches probable.

HIGH Natural and human- Unstable slabs likely on a vari-triggered avalanches likely. ety of aspects and slope angles.

EXTREME Widespread natural or Extremely unstable slabs human-triggered certain on most aspects and avalanches certain. slope angles. Large destructive

avalanches possible.

In 1983 the CAIC moved itsforecast operation into the NationalWeather Service office in Denver.And thus it began its first season(1983Ð84) with a shoestring budgetand a staff of four part-timers.

Three subsequent events haveshaped the CAIC: 1) in 1987, itmoved into the Colorado Geolog-ical Survey (CGS), a logical movesince avalanches are defined bystate statute as geologic hazards; 2)in 1992, it entered into a contrac-tual partnership with CDOT toprovide avalanche hazard fore-casts for all state and federal high-ways in Colorado; and 3) in 1995the Legislature passedÑand Gov-ernor Romer signedÑHB 1314 thatformally gave statutory authorityto the CAIC within the CGS.

The mission of the CAIC isstated formally as: ÒThe CAIC pro-motes safety by reducing theimpact of avalanches on recre-ation, industry, and transportationthrough a program of forecastingand education.Ó Less formally wesay, ÒThe CAIC doesnÕt makerules, enforce laws, collect fines, orreview, regulate, legislate, control,oversee, withhold, open, or closeanything. Instead, our purpose issimply to look out for the safety ofpeople living, working, playingand traveling through Colorado.Ó

To get the job done, the CAICrelies totally on funding by con-tracts, grants and donations. Lastyear more than 50 federal, state,and local government agencies;corporations; businesses; clubs;foundations; rescue teams; and arecently-founded grassrootsÒFriendsÓ association contributedto the cost-sharing of the CAIC.Additionally, the Center receivesfees for its avalanche courses, andit gets huge in-kind support fromthe National Weather Service inthe form of office space, access todata, use of forecast work stations,and access to NWS expertise.

—Knox Williams

CAIC: A Short History continued from page

Upcoming Events

Involving CGSOctober 10–11

Colorado SnowmobileExpo National WesternComplex, I-70 andBrighton Blvd., IndustrialExpositions, Inc., (303)892-6800

October 12–16Earth Science Week OpenHouse at the ColoradoGeological Survey, 1313Sherman Street, Room 715,Denver, (speakers, displayin the Capitol rotunda,handouts) Katie KellerLynn,(303) 866-2611

October 29–30Geologic Hazards andEngineering Practices inWestern ColoradoConference/Field Trip,sponsored by ColoradoGeological Survey, HotelColorado, GlenwoodSprings, (303) 866-2611for information and regis-tration (see p. 9 and 10)

5

While the CAIC cannot prevent all avalancheaccidents, it can reduce

injuries, deaths and economic loss-es due to avalanches. The key iseducation. An educated public andwork force will recognize andavoid (or mitigate) the threat ofavalanches during the most dan-gerous times, while the uneducat-ed will be unaware and vulnera-ble. Therefore, the CAIC offersextensive outreach to promoteavalanche safety.

¥ Avalanche seminars: CAICforecasters conduct 60Ð80 cours-es per year to teach avalancheawareness, safe travel and sur-vival skills. These range from2-hour introductory slide talksto multi-day on-snow semi-nars. (Call the Center thisNovember to get a list ofcourses available for 1998Ð99.)

¥ Safety brochure: A newavalanche awareness brochurewill be available this fall. Pro-duced by a donation from theEthan Gell Memorial Fund, itwill teach readers how to rec-ognize avalanche terrain, howto test for unstable snow, howto travel safely in avalancheterrain, and how to improvesurvival chances if caught inavalanches.

¥ Videos: CAIC staff has helpedwrite and produce three ava-lanche safety videos. Avalanche

Awareness: A Question of Balance(1987) teaches basic avalanchesafety, Avalanche Rescue: Not aSecond to Waste (1992) teachesorganized rescue techniques,and Avalanche Rescue Beacons: ARace Against Time (1995) (CGSIS 38) teaches the techniques ofbeacons and small-party rescue.

¥ Publications: The CAIC fore-casters writeand publisharticles formagazinesand newslet-ters. In 1996The SnowyTorrents (CGSSP 39) whichis an absorb-ing study ofavalanche

accidents, was published.¥ The Beacon: This is the CAICÕs

newsletter for its Friends asso-ciation. Published three times ayear, it covers current events,human interest stories, andavalanche science. Become aFriend and youÕll get it! (Seearticle below.)

Contact the CAIC for moreinformation about these education-al resources or see the sidebarÒHow to Order CGS PublicationsÓ.

—Knox Williams

Education Can Save Lives How to Order CGS

PublicationsBulletin 49Snow-Avalanche Hazard Analysisfor Land-Use Planning and Engineering $12.00Information Series 38Avalanche Rescue Beacons: A RaceAgainst Time (VHS video) $25.00Information Series 46Snow & Avalanche: Annual Report1997Ð98, Colorado Avalanche Infor-mation Center $5.00Miscellaneous 30The Avalanche Book (history, caus-es, terrains, weather, safety, sur-vival, rescue, control techniques,law, studies $17.00Special Publication 7Colorado Avalanche Area Studiesand Guidelines for Avalanche-Hazard Planning $8.00Special Publication 12NatureÕs Building CodesÑGeology and Construction in Colo-rado (includes building inavalanche prone areas) $4.00

Special Publication 39The Snowy TorrentsÑAvalancheAccidents in the U.S., 1980Ð86

$16.00

HOW TO ORDER PUBLICATIONSMail: Colorado Geological Survey,

1313 Sherman Street, Room 715, Denver, CO 80203

Phone: (303) 866-2611Fax: (303) 866-2461,

E-mail: katie.kellerlynn@state.co.us

Website: www.dnr.state.co.us/geosurvey

VISA¨ and MasterCard¨ areaccepted

SHIPPING AND HANDLINGShipping and handling

will be charged for all mailedorders. Please contact the CGS

for shipping and handling costs.

DISCOUNTSAvailable on bulk orders.

Call for a complete publication list

FRIENDS OF THE CAIC is the grassroots support group of theCenter. For a small annual donation that helps fund the back-country forecasting efforts of the CAIC and its hotlines, Friends

receive The Beacon newsletter, get the daily forecast via E-mail, if theywish, and get their avalanche questions answered by E-mail. This per-sonal service is a steal at $25 per year. ItÕs easy to join. Just send yourcheck for $25 (or more) payable to ÒFriends of the CAICÓ to CAIC,10230 Smith Road, Denver, CO 80239. Be sure to include your mailaddress, phone, and E-mail (if you have it), and youÕll receive a coolCAIC bumper sticker.

Be a Friend!

6

Types

Avalanches come in twotypes: loose-snow andslab. Loose-snow

avalanches (also called point-release) occur in a snow cover thathas little or no cohesion. Theystart at a point and fan out as theyslide downhill. Though numerous,

they are generally small and harm-less, but can become large, espe-cially in wet snowpacks.

Slab avalanches form andrelease in a snow cover that iscohesive. Each snow grain bondsto its neighbor, forming a slablayer. The slab can hold itself inplace until stress exceeds strength,causing the slab to fail and an

avalanche to release. Slabavalanches are far more dangerousthan loose-snow avalanchesbecause they move more snow athigher speeds and forces.

Both loose-snow and slabavalanches can form in dry, damp,or wet snowpacks.

IngredientsThere are four ingredients of a slabavalanche:

Slope: 90 percent of avalanch-es release on slopes of 30Ð45degrees. It is this range of slopeangles that produces the most crit-ical balance between stress andstrength.

Slab: A cohesive layer of snowthat is under stress as gravity triesto pull it downhill becomes thematerial for an avalanche.

Weak layer: For an avalancheto release, there must be a layerbeneath the slab that slips (shearfailure) or collapses, making itmuch easier for the slab to breakloose from its final anchors at thetop and sides.

An Avalanche Primer

Fifteen-foot crown of large slabavalanche

Loose-snow or point-release avalanche

Slab avalanche

Loose-snow avalanche in motion

LOW

MODERATE

HIGH

MODERATE

LOW

AvalancheRelease

Probability–vs–

Slope Angle

0°

25°30°

45°50°

Trigger: A trigger is the addi-tional load of new snow, fallingcornice, animal, person, or explo-sive charge that tips the balance ofstress to exceed strength.

Once the trigger causes theweak layer to fail (via shear or col-lapse), slab tensile stress suddenlyincreases, and tensile cracks shootthrough the slab. The slab starts toslide away and accelerates downthe track. The slab blocks breakinto chunks and particles, and thefaster avalanches throw a powdercloud into the air that movesahead of the denser snow flowingalong the ground.

Small avalanches may fracture1Ð2 feet deep and 50Ð100 feetwide, and travel at 30 mph; medi-um avalanches may break 3Ð6 feetdeep and 200Ð500 feet wide, andmove at 50Ð60 mph; largeavalanches can be 6Ð10 feet deep,thousands of feet wide, and roaralong at more than 100 mph. Largeavalanches may set more than500,000 cubic meters of snow inmotion, and have impact pressuresthat exceed 10 tons/m2, these

avalanches can snap or uprootmature trees and destroy buildings.

For victims caught in ava-lanches, it is hard to fight theforces of even small ones. Tum-bling downhill, fast and out ofcontrol, is never healthy. And ifburied, victims can seldom dig

themselves out of snow that oftensets up like concrete. Avalanchesare best viewed from a distance, ofcourse, so as to appreciate theirpower and beauty without beingso close as to be touched by theirmalevolence. —Knox Williams

7

Colorado Geological Survey1313 Sherman Street, Room 715

Denver, CO 80203Phone: (303) 866-2611Fax: (303) 866-2461

Website: www.dnr.state.co.us/geosurvey

Three-footcrown (fracture line) of slabavalanche

SLAB

BED SURFACE

Weak Layer

Possible Triggers

RECREATIONIST

EXPLOSION

NEW SNOW

CGS Advisory CommitteeBob Blakestad, Ed Church, John B. Curtis,

Martha Garcia, John M. Kaufman, Susan M. Landon, Forrest Luke,

Jan Rousselot, Robert Santistevan, Marian Smith, Darrell Speer, Susan Steele Weir

CGS StaffVicki Cowart, Director and State GeologistJames A. Cappa, Minerals, Mineral Fuels,

and Geologic MappingRandal C. Phillips, GIS and

Technical ServicesVickie B. Pierce, Administration

and OutreachMatt Sares, Environmental Geology Knox Williams, Colorado Avalanche

Information Center

AdministrationAnissa Olguin, Greg Richards

Avalanche Information CenterDale Atkins, Nick Logan, Scott Toepfer

Engineering Geology and Land Use

Celia Greenman, Dave Noe, Monica Pavlik, Roger Pihl, Jim Soule, Jon White

Environmental GeologyJeff Hynes, John Neubert, Ty Ortiz

Geologic MappingChris Carroll, Bob Kirkham, Randy Streufert

GIS and Technical ServicesCheryl Brchan, Matt Morgan, Larry Scott

Mineral FuelsWynn Eakins, Tom Hemborg

CAIC Advisory Committee,1997–98

Vicki Cowart, Colorado GeologicalSurvey; Lanny Grant, Colorado

Snowmobile Association; Scott Messina, Mountain RescueAspen; Marian Smith, Garfield

County Commissioner; Chuck Tolton, Copper Mountain

Patrol ; Ed Fink, ColoradoDepartment of Transportation;

Melanie Mills, Colorado SkiCountry USA; Dave Stark, U.S.

Forest Service; Mel Wolf, ColoradoSnowmobile Assoc.; Leigh Yule,

Summit Huts Association

8

Ayear ago the talk of El Ni�o had inflated near-ly everyoneÕs expectations for snow in Colo-rado. The CAIC forecasters had different

expectations. Review of snowfall records showed nostrong correlation between El Ni�o and winter weath-er, though there was a bias toward a drier winter. Onetrend that emerged was that the early and middlewinter (November through February) was frequentlydry, but the spring months of March and April weresnowy. This would mean a thin, unstable snow coverwith lots of depth hoar (weak faceted sugar-likesnow) for most of the winter to be followed by spring-time deep snows and a few big avalanches. ThatÕspretty much what happened.

HereÕs a month-by-month replay:October: ColoradoÕs

dry fall ended suddenlyin late October when amassive storm clobberedthe entire state and anextraordinary windstorm leveled 20,000acres of timber on Buffalo Pass near Steam-boat Springs.

November: Abun-dant snows fell in theSan Juan and Elk Moun-tains from subtropicalmoisture from Califor-nia, but much of thenorthern mountainswere rather dry.Avalanches were fre-quent but small.

December: Stormspassed either north orfar to the south of Col-orado, so snowfall withfew exceptions was wellbelow normal. The sea-sonÕs first fatalavalanche occurred onthe 30th, when a snow-shoer died in a smallhard-slab avalanche only a snowballÕs throw awayfrom his cabin on Guanella Pass.

January: The West Coast storms finally reachedColorado and brought above-normal snows to thenorth and central Colorado mountains, while in thesouthern mountains drier conditions prevailed. Januarywas an especially dangerous month as snow conditionsand peoplesÕ attitudes created a potentially lethal

combination. In January alone, avalanches caught 43people (about the same number of people caught inan average winter), but remarkably only one diedÑaback-country snowboarder near Lizard Head Pass.Conditions were building for big avalanches.

February: Avalanche workers anticipated a pun-ishing February, but it never came. There were no sig-nificant avalanche events. Storms split around Col-orado, and just enough moisture flowed in to fuelfrequent but light snowfalls. The mountain snowcover was a fragile house of cards waiting to be over-loaded by heavy spring snows.

March: In late March the big storm finally hit andsmothered the mountains. The San Juans caught thebrunt of it with heavy snowfall triggering the seasonÕs

only true cycle of largedestructive avalanches.In the western SanJuans some of thebiggest avalanches inmemory fell. Thesewiped out hundreds ofacres of timber anddestroyed a home nearSilverton. Avalanchesclaimed two additionallives in March. A back-country snowboarderdied on Berthoud Passand an out-of-areaskier died near Aspen.

April: A cool,snowy April meantfew avalanches due tothaw but continued theprospects for deepreleases. In fact twomore people died inavalanches: a climberon St. MaryÕs Glacierand a snowshoer onBerthoud Pass. Itwould be May beforethe snowpack startedto melt away.

When the numbers were tallied, seasonal snowfallranged from 87Ð106 percent of normal, and tempera-tures were warmer than normal. Observers reported2,958 avalanches, about 40 percent above average. Arecord number of people (101) were caught byavalanches. Six people were killed, which is the cur-rent average, and property losses were less than$200,000. —Dale Atkins

Winter of 1997–98 in Review

XX

Highland Pk(12,381)

Charges thrownfrom ridgeX

KesslerSnyder

Maroon Bells

Rescue routefrom lodge

Soddy

KesslerSnyder

SoddyPrimary release

Sympathetic release

(Old slide pathof 12/18/93)

Charge causing

XRupinski and Lembke

N

spotting activity

to ground

avalanche

of old snow layer

control routeSki Patrol

Drawing of avalanche accident at Aspen Highlands, March 31,1984 from The Snowy Torrents

9

GEOLOGIC HAZARDS ANDGEOLOGIC HAZARDS ANDGEOLOGIC HAZARDS ANDENGINEERING PRACTICESENGINEERING PRACTICESENGINEERING PRACTICES

IN WESTERN COLORADOIN WESTERN COLORADOIN WESTERN COLORADOSponsored by Colorado Geological Survey

Thursday, October 29, Friday Morning, October 30, 1998Hotel Colorado, Glenwood Springs, Colorado

Optional Half-Day Field Trip,Friday Afternoon,

October 30

Engineers, Geologists, Planners, Local Officials, and Builders . . .

To bring together the many stake-holders whoare living in, building on, and working within geologic-hazard areas in western Colorado;To clearly define the nature and impact of problems related to geologic hazards in thestate;

To encourage architects, engineers, geologists,homebuilders, planners, homeowners, andlocal and state government leaders to learnfrom each other and find practical, integratedsolutions to problems inherent to ColoradoÕscomplex geology.

Purpose of the Conference

Mastercard® or Visa® charges MC V

Name on card

Card no.

Expiration date Phone No.

Signature

Registrations will be taken by phone or FAX but must be paid withVISA or Mastercard or send a check to:

Colorado Geological Survey1313 Sherman St., Room 715Denver, CO 80203-2239(303) 866-2611 FAX (303) 866-2461

REGISTRATION FORMREGISTRATION FORMREGISTRATION FORMNumber of registrationsFor conference and Friday field trip_________x $150 = $_________

(includes Thursday lunch, Friday breakfast & lunch, plusconference packet and fieldtrip guidebook)

For conference only _________x $100 = $_________(includes Thursday lunch, Friday breakfast and lunch, plus conferencepacket.)

Call for student rates.

Names of people attending FIELD TRIP, Friday,Oct. 30 (12:30–6:30):

Name(s) of participant(s)

Affiliation

Street address

City State Zip Code

GEOLOGIC HAZARDS AND ENGINEERING PRACTICES IN WESTERN COLORADO

10

OCTOBER 29 SCHEDULE

CHECK IN (7:30–8:30 A.M.)

MORNING SESSION 1 (8:30–10:15 A.M.)JIM SOULE, MODERATOR

Opening RemarksVicki Cowart, Colorado Geological Survey

Local Government Needs and Problems in Achieving Smart Growth

Victoria Giannola, Garfield County Planning

Geologic Hazards, Land Use Laws and Professional Standards of Practice

David Noe, Colorado Geological Survey

DOLA Technical and Financial Assistance Available toLocal Governments for Smart Growth

Charles Unseld, Dept. of Local Affairs, Field Services Section

COFFEE BREAK (10:15–10:35 A.M.)

MORNING SESSION 2 (10:35 A.M–12:00 P.M.)JIM SOULE, MODERATOR

Programs and Services in Western ColoradoFred Sibley, Office of Emergency Management

CGS Multipurpose Geologic Mapping Program in Western Colorado Growth Areas: Direct and Spinoff Benefits DerivedBob Kirkham, Colorado Geological Survey

The GIS—Geology Connection—Making the Most ofMultipurpose Digital Geologic MapsRandy Phillips, Colorado Geological Survey

LUNCH (12:00–1:00 P.M.)

AFTERNOON SESSION 1 (1:00–3:00 P.M.)DAVE NOE, MODERATOR

Active Landsliding in Urban(izing) AreasMike West, Michael W. West and Assoc., Inc.

Western Colorado Earthquakes, Seismicity and Significance to Project Designs

Ivan Wong, Woodward-Clyde Consultants, Oakland, CA.

Prediction of Potential Sediment Yields Contributing toDebris or Hyperconcentrated Flows of Watersheds in

Burned AreasRobert C. Rasely, U.S. Dept. of Agriculture, Natural Resource

Conservation Service, Salt Lake City, UT.

COFFEE BREAK (3:00–3:20 P.M.)

AFTERNOON SESSION 2 (3:20–5:00 P.M.)DAVE NOE, MODERATOR

Geologic and Geomorphic Settings and Identification of Areas Prone to Collapsing Soil and

Evaporitic Bedrock HazardsJon White, Colorado Geological Survey

Evaluation, Design and Mitigation of Project Sites in Collapsible Soil Areas

Steven Pawlak, Hepworth-Pawlak Geotechnical, Inc.

Geological Setting and Hazard Evaluation for EvaporiteSinkholes and Related Underground VoidsRalph Mock, Hepworth-Pawlak Geotechnical, Inc.

OCTOBER 30 SCHEDULE

CONTINENTAL BREAKFAST (7:30–8:30 A.M.)

MORNING SESSION (8:30–11:30 A.M.)MARK BEAN, MODERATOR

Hydrologic Changes in a Wildfire Burn Area: BuffaloCreek, Colorado, a Continuing Case Study

Brian Hyde and Tom Browning, Colo. Water Conservation Board

ISDS Systems, Site Conditions, Design Options and Problem ConditionsEd Church, E.O. Church, Inc.

Advantages, Options and Economics of CentralWastewater Treatment Systems

John Kaufman, McLaughlin Water Engineers

COFFEE BREAK (10:25–10:45 A.M.)

Smart Growth Panel with Question and Comment Sessionfor Feedback from AttendeesDiscussion Leader: Vicki Cowart

Panelists: Marian Smith, Dave Noe, Steve Denney, Ron McOmber, Erin Johnson, Mike West

LUNCH (11:30 A.M.–12:30 P.M.)

(Registered Field Trippers Must be on Board Buses by 12:35 P.M.!!)

FIELD TRIP (12:30–6:30 P.M.)FIELD TRIP LEADERS: JON WHITE, LIV BOWDEN, RALPH MOCK, BOB KIRKHAM, SUE CANNON

The field trip will visit sites in Garfield, Eagle, andPitkin Counties that illustrate special geologic conditions,problems and mitigation options. Discussions at each site

will be led by geologists and engineers experienced inidentification and mitigation of geologic hazards.

Conference and field trip Program

11

All across the U.S., the num-ber of winter sports enthu-siasts are soaring, and so

are avalanche accidents anddeaths. U.S. avalanche deathshave risen 118 percent during the1990s, so that in an average winter24 people die in avalanches in theU.S., with six of these deathsoccurring in Colorado. Three rea-sons account for this trend: 1)more people participate in wintersports, 2) better equipmentenables enthusiasts to travel indeeper snow and onto steeperslopes, and 3) back-country travel-ers have increased their accep-tance of risk.

Though avalanche deaths inthe U.S. have soared the last 10years, those in Colorado areunchanged (at six a year) evenwhen winter recreation hasboomed. Graph 1 shows that inthe late 1980s avalanche deaths inColorado accounted for more thanhalf of all the U.S. avalanche fatal-ities, but in the 1990s the ratio hasdropped to one in four. This dropin number may be partially attrib-uted to greater public avalancheawareness and education.

Increasing avalanche aware-ness is key to saving lives. Sincemost avalanche victims triggertheir own avalanche, this meansmost accidents are preventable. Toincrease public avalanche aware-ness, the Center widely dessemi-nates its daily forecasts and a vari-ety of educational outreach (seeÒEducation Can Save LivesÓ).

Where the Accidents Occur

LetÕs look at where accidents arehappening by county. In Colorado48 people have died in avalanchessince 1990 (Graph 2). It should beno surprise that ColoradoÕs mostpopular mountain counties headthe list. It is important to note that

Graph 2: Avalanche fatalities by Colorado County since 1990

Trends in Avalanche Accidents: Good News for Colorado!

100

90

80

70

60

50

40

30

20

10

0

Year at End of Winter Season88 89 90 91 92 93 94 95 96 97 98

%%

%

%

%%

%

%

%

%

%

Pe

rce

nt

Graph 1: Colorado avalanche deaths as a percentage ofU.S. deaths

Summit

Pitkin

Eagle

Clear Creek

Chaffee

San Miguel

San Juan

Larimer

Gunnison

Boulder

Grand

La Plata

Garfield

El Paso0 1 2 3 4 5 6 7 8 9 10

Fatalities

400

350

300

250

200

150

100

50

0 93

Year at End of Winter Season94 95 96 97 98

Explosive triggered Natural

Graph 3: Avalanches hitting Colorado highways

all the avalanche deaths haveoccurred in the back-country orbeyond ski area boundaries(because the back-country snow-pack gets no stabilizing effect from explosive control or skiercompaction).

Impact of Avalanches onColorado’s Highways

Colorado has the most avalanche-prone highway system in the U.S..A total of 19 different state andfederal highways are affected byavalanches; the total is significant-ly greater when numerous countyroads are included. Graph 3 showsthe number of natural and pur-posely triggered avalanches hit-ting mountain highways the lastsix years. Since 1992 an average of115 avalanches release naturallyonto Colorado highways. And tosafeguard our highways, CDOTuses explosive control to releasean average of 179 additionalavalanches each winter. By trigger-ing more frequent but smalleravalanches, safety is increased and

delays are reduced. The programworks: the last avalanche death ofa motorist occurred back in 1963.

As ColoradoÕs populationgrows dramatically in the comingyears, so too will winter use andthe potential for more avalanche

accidents and deaths. If the bestdefense is a good offense, theCAICÕs forecasting and educationprogram is well prepared toreduce the impact of avalanchesupon the people who work andplay in Colorado. —Dale Atkins

12

COLORADO

GEO LO GI C AL SU RVEY

Colorado Geological Survey1313 Sherman Street, Room 715Denver, CO 80203

PIA 341100040

The CGS mission is to serve and inform the people of Colorado by providing soundgeologic information and evaluation and to educate the public about the important

role of earth sciences in everyday life in Colorado.

CGS Mission Statement

Avalanche debris blocking highway

Return Service Requested

FIRST CLASS MAILU.S. POSTAGE PAIDDenver, Colorado

Permit No. 738