can we expect another eruption? o r e g o n ’ s active

his Spring hasb rought us tworeminders that geo -

logic change is an everydaypart of life in Oregon. Thefirst reminder was the 21stanniversary of the last erup -tion of Mount St. Helens; thesecond, satellite photos thatshow a small uplift aroundthe ancient volcanoes of theSisters near Bend.

In fact, the land wedefine as Oregon is verymuch a creation of volcanism.From the headlands along theCoast, to the mighty Cascades, the Columbia River Gorge and the mesas of easternOregon, our state reflects a violent, eruptive geologic past. The devastation wroughtby Mount St. Helens shows us the process of volcanism continues today.But despite Mount St. Helens, and the ongoing concerns about Mount Rainier andMount Hood, the Pacific Northwest is not a seething cauldron of hot lava ready toexplode. Scientific research has given us a clear idea of our current volcanic hazards.Enhanced monitoring abilities and technical resources give us a much better idea ofwhat may happen in the future. For unlike earthquakes, scientists have begun to pre -dict volcanic eruptions. That makes knowing what to expect an important part of liv -ing with active volcanoes in Oregon.

ruptions in the Cascades haveoccurred at an average rate of1-2 per century during the last

4,000 years, and future eruptions arecertain. Seven volcanoes in theCascades have erupted since the firstU.S. Independence Day a little morethan 200 years ago. Four of thoseeruptions would have caused consid-erable property damage and loss oflife if they had occurred today with-out warning. As population increasesin the Pacific Northwest, areas nearactive volcanoes are being developedand recreational usage is expanding.As a result, more and more peopleand property are at risk from volcanica c t i v i t y. The next eruption in theCascades could affect hundreds ofthousands of people.

Turn the page to learn more aboutOregon’s active volcanoes.

V o l u m e 1 , N u m b e r 2 w w w . O r e g o n G e o l o g y . c o m S p r i n g 2 0 0 1V o l u m e 1 , N u m b e r 2 w w w . O r e g o n G e o l o g y . c o m S p r i n g 2 0 0 1

A quarterly publication of the Oregon Department of Geology & Mineral Industries

In this issue:

Mount Hood hazards - page 2

Pro te cting our co m m u n i t i e sf rom vo l cano hazards - page 4

En e rgy from rocks - page 5

Field note s :d i s cove ry of a ct i ve fault under Po rtland - page 6

South Si s ter surprise! - page 6

Can we expect another eruption?

O r e g o n ’s active volcanoesBy James Rod d ey

T

E

Ca s cade vo l cano hazards ( Graphic co u rte s ty USGS)

The eruption of Mo u nt St. Helens in 1980 killed 57 people and caused over $1.1 billion in damage

and rebuilding co s t s. (USGS photo )

areas on its flanks and the major rivervalleys that head up to the volcano. Alook at the hazards gives us an idea ofwhat we might expect during the nexteruption.Pyroclastic Flows

The collapse of a growing lavadome or the front of a thick lava flowgenerates landslides of hot rock calledp y roclastic flows. Pyroclastic flowsare fluid mixtures of hot rock frag-ments, ash, and gases that sweepdown the flanks of volcanoes atspeeds of 30 to 90 miles per hour,d e s t roying virtually everything intheir paths. Most are confined to val-ley bottoms, but pyroclastic surges—overriding clouds of hot ash andgases, are more mobile and can over-whelm even high ridge tops.

At Mount Hood, past pyroclasticflows have traveled at least 7 milesf rom lava domes and pyro c l a s t i csurges probably traveled even farther.Pyroclastic flows and surges also pro-duce ash clouds that can rise tens ofthousands of feet into the atmosphereand drift downwind for hundreds ofmiles.Lahars

Pyroclastic flows and surges canalso melt snow and ice and generatelahars (also called volcanic mud flowsor debris flows). Lahars are rapidlyflowing, water-saturated mixtures ofmud and rock fragments that range in

now-clad Mount Hood domi-nates the Cascade skyline fromthe Portland metropolitan areato the wheat fields of Wasco and

Sherman Counties. The mountaincontributes valuable water, scenic,and recreational resources that helpsustain the agricultural and touristsegments of the economies of sur-rounding cities and counties. MountHood is also one of the major volca-noes of the Cascade Range, havingerupted repeatedly for hundreds ofthousands of years—most re c e n t l yjust before the arrival of Lewis andClark in 1805. When Mount Hooderupts again, it could severely affect

ituated on the Ring of Fire thats u r rounds the Pacific Ocean,Oregon has its share of volca-

noes in its older geology and cappingits more recent landscape. As sub-duction moves the once Pacific seafloor to greater depths below Oregon,the water bearing material of thatlower slab is melted to give magma,which rises to give us the volcanoes ofthe Cascade Range. This dynamicprocess that continues to shape thelandscape of our state is also respon-sible for the earthquake hazards wecontinue to prepare for as well.

Geologists have studied the pastbehavior of many Cascade volcanoesto define, in general terms, whatmight happen in future eru p t i o n s .Such information is basic to properlyc o n s t ructed long-term hazard riskreduction strategies, which includelong-term plans for hazardresponse.Those who remember the1980 eruption of Mount St. Helens arealso aware that the intensive monitor-ing of volcanoes at critical times canpresent us with much more preciseinformation about specific eruptionsas they occur. This information can bethe basis for daily responses in termsof travel, evacuation, and event man-agement.

Recent breakthroughs now alsomake it possible to detect broad areasof bulging using satellite radarimagery long before an eruption (ifthat is the case) or as an indicator ofother deformation that may not leadto eruption. Such is the situation thisyear in the area west of South Sister.

Volcanoes are a mixed blessing,providing us with minerals, parent

material for rich soils, elevated terrainto prompt and capture rainwater,scenery to enhance tourism, highquality rock for road construction andonce in awhile, an eruption.

Although the excitement of erup-tions may gain our attention, in thelarger view, eruptions often are sec-ondary to the benefits of a volcano'spresence longer term. If an eruption oft ruly hazardous nature is in ourimmediate future at South Sister, geol-ogists will give us ample warning andperspective to manage our aff a i r sintelligently. Until then, we have thebenefits of volcanism to appreciate.

Through the eyes of the StateG e o l o g i s tby John D. Beaulieu, O regon State Geologist

S

S

Mount HoodH a z a r d sHow dangerous is the sleeping giant?

w w w. O re g o n Ge o l ogy. co m

f rom the Oregon Department of Geology and Mineral Industries

2

If Mount Hood erupted today, it couldaffect hundreds of thousands of

people across the Northwest. (Photoby Dave Weiprecht, USGS)

warranted, understanding the worst-case scenario is still prudent. A sdemonstrated by Mount St. Helens’c a t a s t rophic eruption on May 18,1980, two types of large-scale haz-ardous events can occur at volcanoeslike Mount Hood—a larg e - v o l u m edebris avalanche and lahar, and alarge directed blast (a type of highlymobile pyroclastic flow). Smallerevents are more likely to occur, but

even a smalldebris avalancheor lahar couldhave very dam-aging conse-quences.

(Excerpts fro mUSGS Open File

Report 97-89 -Volcano Hazards in theMount Hood Region, Oregon, 1997)

Learn more by logging on t ohttp://vulcan.wr.usgs.gov/Volcanoes/Hood/Hazards/OFR97-89/

consistency from mixtures resemblingfreshly mixed concrete to very muddywater. Lahars can travel more than160 miles down valleys. They move asfast as 50 miles per hour in steepchannels close to a volcano, but slowdown to about 10-20 miles per houron gently sloping valley floors fartheraway.

Past lahars at Mount Hood com-pletely buried valley floors in theSandy and HoodRiver drainagesall the way to theColumbia Riverand in the WhiteRiver drainage allthe way to theDeschutes River.How Likely?

The largest magnitude event inany 30-year period is less than 1 in10,000, but it could have very seriousconsequences. Although pre p a r i n gfor such a rare event is probably not

Past lahars at Mount Hoodcompletely buried valley

floors in the Sandy and HoodRiver drainages all the way to

the Columbia River...



3

Cascadia is published quarterly by theOregon Department of Geology

and Mineral Industries800 NE Oregon Street, #28,

Suite 965, Portland, Oregon 97232 (503) 731-4100 Fax (503) 731-4066

Governing Board Donald W. Ch ri s te n s e n , Chair - Sa l e m

Ve ra E. Si m o nton - Pe n d l e to nBa r b a ra Seymour - Sa l e m

State Geologist - John D. Be a u l i e uDeputy State. Geologist -

Dennis Ol m s tead Cascadia Editor - James Rod d ey

Mined Land Reclamation Program:229 Broadalbin St. ,S E, Al b a ny 97321,(541) 967-2039, FAX (541) 967-2075.

Ga ry W. Ly n c h , Su pe rv i s o r.

Baker City Field Office:1510 Ca m p bell St. , Ba ker Ci ty 97814,(541) 523-3133, FAX (541) 523-5992.

Ma rk L. Fe rn s, Regional Ge o l og i s t.

Coastal Field Office:313 SW 2nd St re e t, Su i te D,

New po rt 97365,(541) 574-6642, FAX (541) 265-5241.

Ge o rge R. Pri e s t, Coastal Team Le a d e r.

Grants Pass Field Office:5375 Mo n u m e nt Dri ve,

Gra nts Pass 97526,(541) 476-2496, FAX (541) 474-3158.Thomas J. Wi l ey, Regional Ge o l og i s t.

The Nature of the Northwest Information Center:

Su i te 177, 800 NE Oregon St. # 5,Po rt l a n d, OR 97232-2162,

(503) 872-2750, FAX (503) 731-4066,Donald J. Ha i n e s, Ma n a g e r.

I nte rn e t : h t t p : / / w w w . n a t u r e n w . o r g

For a free subscription to Cascadia, log onto www.OregonGeology.com

or call (503) 731-4100

Oregon’s Cascade volcanoes, likeMount Hood, can produce a wide

variety of natural hazards that can kill people and destroy

property. Some hazards, such as lahars and landslides, can

occur even when a volcano is not erupting.

Original Graphic bySusan Mayfield andSara Boore and used

courtesy of USGS.

ith today’s sophisticatedtechnology, scientists canrecognize the signs ofimpending volcanic erup-

tions. The upward movement ofmagma into a volcano prior to aneruption causes changes that canusually be detected by geophysicalinstruments and visual observation.Swarms of small earthquakes can bedetected as rocks break to makeroom for rising magma or as theheating of fluids causes undergroundpressures to increase. The composi-tion of gases emitted by fumarolescan be monitored for changes asmagma nears the surface. Injectionsof magma into the volcano can causesurface deformation that can bedetected by satellites or aerial surveys.

Although outstanding advanceshave been made in volcano monitor-ing and eruption forecasting over thepast few decades, scientists are oftenable to make only very general state-ments about the probability, type,and scale of an impending eruption.The public must realize the limita-tions in forecasting eruptions and beprepared for such uncertainty.

Le a rn more about fo rca s t i n ge ruptions at ht t p : / / v u l ca n . w r. u s g s. g ov /Vo l ca n oe s / Hood / Ha z a rd s /

O F R 9 7 - 8 9 / f ra m ewo rk . ht m l

ommunities, businesses, andcitizens need to plan ahead tomitigate the effects of futureeruptions, debris avalanches,

and lahars. Long-term mitigationincludes knowing about volcano haz-ards when making decisions aboutland use and the siting of critical facil-ities. Development should avoidareas judged to have an unacceptablyhigh risk or it should be planned toreduce the level of risk.

Because an eruption can occurwithin days to months of the first pre-cursory activity and because somehazardous events can occur withoutwarning, emergency response plansshould already be in place and publicofficials should have an understand-ing of what to expect. Other issues,like public education, communica-tions, and evacuation plans need to be

considered. Mount Hood has a settle-ment (Government Camp), majorhighways (US 26 and OR 35), andpopular tourist and recreation areas(Timberline Lodge and Mount HoodMeadows Ski A rea) on its flanks.Several thousand people live withinabout 20 miles of the volcano alongthe channels and flood plains of riversthat drain it. These areas are at great-est risk from lahars and debris ava-lanches and could be inundated with-

in an hour of one of these eventsbeginning. Emergency plans alreadydeveloped for floods may apply, withmodifications, to hazards from lahars.

Businesses and individualsshould also make plans to respond tovolcano emergencies. Planning is pru-dent because once an emerg e n c ybegins, public resources can often beoverwhelmed, and citizens may needto provide for themselves and makeinformed decisions. The Red Crossrecommends numerous items thatshould be kept in homes, cars, andbusinesses for many types of emer-gencies that are much more probablethan a volcanic eruption. Becauselahars pose the biggest threat to peo-ple living in valleys that drain MountHood, a map showing the shortestroute to high ground will also behelpful.

T h e re are manyplaces to turn for helpin putting mitigationand emerg e n c yresponse plans inplace, but the first stepis learning about theh a z a rds. The USGSCascades Vo l c a n oObservatory inVancouver, WA is anincredible resource onall things volcanic andthe place to start yourplanning proces -(360)993-8900 or

h t t p : / / v u l c a n . w r. u s g s . g o v. You canalso look on the DOGAMI web site (seebelow) for a general introduction to vol-cano hazards in Ore g o n .

(Excerpts of both articles from USGSOpen File Report 97-89 -Volcano Hazardsin the Mount Hood Region, Oregon byW.E. Scott, et. al., 1997)

Mo re vo l cano hazard re s o u rces can be found at ht t p : / / w w w. O re g o n g e o l ogy. com/ e a rt h q u a ke s / vo l ca n oe s. ht m

Mo n i to ring gas emissions at fumaroles isone way to help pre d i ct eru p t i o n s.

( Ph o to by Thomas J. Ca s a d evall)



4

Hazard forecastsand warnings

Protecting our communitiesfrom volcano hazardsC

W

Fast moving lahars from the 1980 Mo u nt St. Helens e ruption destroyed hundreds of homes.

( p h o to by Lyn To p i n ka ,U S G S )

here are about 500 geothermalwells throughout KlamathFalls, which happens to sit

atop a hot water reservoir warmed bythe same torrid Earth that fuels theNorthwest's volcanoes. The wells heathomes, buildings, swimming pools,sidewalks and roads, and now thathigher power prices have Westernersthinking twice about turning on thelights, many more people are thinkingabout pulling geothermal energ yfrom the Earth.

O regon and the Northwest lieatop a volcanic province with some ofthe nation's highest potential for geot-hermal energy production, whichdraws energy from the ground anduses it to heat buildings or drive tur-bines that generate electricity forcities near or far. Some estimate that ifOregon's geothermal energy reserveswere developed to their full potential,they could produce 2,000 megawattsof electricity, the equivalent of twonuclear power plants. By comparison,the four federal dams on the lowerSnake River combined generate about1,200 megawatts at their peak.

Power companies are drawingup plans to probe the flanks ofNewberry Crater, a volcano east ofBend that ranks as probably the mostpromising Northwest site for geother-mal development. "It definitely is themajor point of geothermal interest inthe Pacific Northwest," said LarryChitwood, a geologist for theDeschutes National Forest, whichoversees Newberry. Although thevolcano forms the core of a protectednational monument, geothermaldrilling is permitted outside the mon-ument's boundaries on the flank ofthe 8,000-foot caldera, which lastspewed lava 1,300 years ago. DOGA-MI is the lead agency in the regulationof geothermal development outsidethe national monument.

A l re a d y, geothermal powert h roughout the United States pro-duces energy equivalent to 10.3 mil-lion barrels of fuel oil annually. Atleast 62 countries have developedgeothermal energy reserves, some to amuch greater degree than the UnitedStates, which pulls little more than 1p e rcent of its electricity from hotground.

As a power source, geothermale n e rgy is everything the curre n tpower market is not - reliable, clean,moderately priced and unaffected byd rought or concerns about endan-gered species. The biggest trick togeothermal power, however, is find-ing it. The rock overlying most geo-thermal reservoirs is very hard and adrill hole must directly intersect acrevice or fissure that carries the pres-surized water. Past drilling as deep as10,000 feet at Newberry Crater has hitextremely hot ground but missed thecritical fissures thought to exist on thevolcano's west flank.

E n v i ronmental concerns aboutgeo- thermal power at NewberryCrater apply mainly to the possiblevisual intrusion of a power plant andthe diversion of underground flowsfrom natural hot springs.

(Excerpts from an Oregonian article byMichael Milstein, We d n e s d a y, June 13,2001.)

Learn more about the Oil, Gas and Geothermal Program by logging on to:www.OregonGeology.com



5

Energy fromhot rocks

T

DOGAMI Governing Boardto expand to five

n January, 2002, the DOGAMIGoverning Board will expandfrom its current 3 board members

to 5. A search for possible new boardmembers is currently underway andinterested individuals are encouragedto contact the department for moreinformation.

Many agencies in Oregon stategovernment have a Board orCommission overseeing agency activ-ities and Oregon prides itself in hav-ing citizen involvement and publicinput through this process. By statute,certain decisions are made by Boards;for example approval of an agencybudget before it goes to the Governor,approval of bills an agency wants toi n t roduce before the legislature ,approval of a strategic plan whichguides areas of work to be pursued bythe agency. Agencies also report their

activities to their Boards for feedback.Board members are appointed by

the Governor and are confirmed bythe Senate. Their term is 4 years andmembers may serve additional terms.

Governing Board meetings, opento the public, are at least quarterly,located around the state. Costs of trav-el, meals and lodging to these meet-ings are covered for members, as wellas expenses for attending other neces-sary meetings representing the Board.DOGAMI strives for geographicdiversity on the Board. We specifical-ly would like new members fro msouthern Oregon and the Portlandm e t ropolitan area. Board membersmust be citizens of Oregon. Call theGovernor’s office for more informa-tion - (503) 378-4582.

Le a rn more about the DOGAMIGove rning Bo a rd by logging on to : w w w. O re g o n Ge o l ogy. co m

I

Ge o t h e rmal well ve nting steam

eologists at DOGAMI have discovered the first direct evi-dence that the Portland Hills

Fault is capable of producing a futureearthquake.

Mapping Team Leader Ian P.Madin spotted the evidence of a pastearthquake—deformed soil layers—as he peered into a shallow construc-tion trench at Rowe Middle School inMilwaukie in May. A closer examina-tion with other scientists verified thatan earthquake caused the disruptedlayers.

State Geologist and DOGAMIDirector John Beaulieu said the dis-covery was significant, but moreresearch needs to be done. He said thefindings reinforced his agency's warn-ings that the Portland area and therest of Oregon needs to be preparedfor destructive earthquakes.

DOGAMI geologists re p o r t e dtheir findings at a May 29th PressC o n f e rence. Of particular intere s twere soil deposits in the trench thathad slipped about 5 or 6 feet, suggest-

n May, USGS scientists announced they had detected a slight swell- ing, or uplift, of the ground over a

broad area centered 3 miles west ofSouth Sister volcano near Bend. Theuplift, which occurred between 1996and 2000, covers an area about 9 to 12miles in diameter and the maximumamount of uplift at its center is about4 inches.

The specific cause of the uplift isuncertain. Because the Three Sistersregion is a volcanic area, the upliftmay reflect intrusion of a small vol-ume of magma (molten rock) deepunder the surface-probably at a depthof about 4 miles. Such a pro c e s s ,which keeps volcanic areas "alive"and prepares them for future erup-tions, is a common occurrence undervolcanoes, but until the use of satellitetechnology, it has been difficult todetect. If intrusion of magma were tocontinue, it could eventually lead to avolcanic eruption; however, an erup-tion is unlikely without significantp recursory activity. In addition tocontinued or accelerating uplift, pre-cursors to an eruption would includeearthquakes and large emissions ofvolcanic gases. So far, several closeaerial inspections of the area haverevealed no unusual surface features.

In order to be prepared to moreaccurately detect possible precursorsand to better understand this upliftphenomenon, the USGS has installedadditional seismometers and a GlobalPositioning System (GPS) re c e i v e r,and will resurvey existing bench-marks and install new ones. The lasteruption in the Three Sisters regionwas about 2,000 years ago.

(photo credit Lyn Topinka)Learn more at: http://vulcan.wr.usgs.gov/Volcanoes/Sisters. Thanks to the USGS Cascades Volcano Observatory for use of publications and graphics in this issue of Cascadia.

ing the earthquake measured aboutmagnitude 6.5—a moderate quakethat could cause substantial damage.Madin and others estimate the earth-quake appears to have occurred about10,000 years ago - recent enough forthe fault to be labeled "active."

The fracture, which runs throughdowntown Portland, runs in a north-west-southeast direction for about 20miles and is one of three large faultsthat underlie the city.

Madin and the DOGAMI earth-quake team along with URS-Greiner(a major engineering firm) and BoiseState University began their investi-gation last year in North ClackamasPark. The study, funded by the U.S.Geological Survey through theNational Earthquake HazardReduction Program (NEHRP), seeksto determine whether the fault isactive, and therefore poses an earth-quake threat to the region. In this caseactive means that it has moved duringthe last 10,000 to 15,000 years. Workwill continue in the area.

(Excerpts from an Oregonian articleby Richard Hill, May 29th. Used with per-mission.)

Learn more by logging on towww.OregonGeology.com.



F i e l dn o t e s

6

( Cl oc kwise from bo t tom ri g ht) DOGAMI Mapping Team Leader Ian Ma d i n , co n s u l t-ing geologist Ma rk He m p h i l l - Ha i l ey, and DOGAMI g e o l ogists Je rry Black and Jo n

Ho f m e i s ter discuss the phys i cal ev i d e n ce of past eart h q u a ke act i v i ty at the co n s t ru ction site at Rowe Middle School in Mi l wa u ki e.

South S i s t e r

S u r p r i s e !

South S i s t e r

S u r p r i s e !G I

USGS - Vo l cano Ha z a rds at New be rryVo l ca n o, O R , Sh e rrod & others, U S G SOFR 97-513 1997 $10.00

USGS - Vo l cano and eart h q u a ke haz-a rds in the Crater La ke re g i o n ,O re g o n ,USGS OFR 97-487, 1997 $10

USGS - Ge o l ogic histo ry of Mo u nt HoodVo l cano-a field trip guide, O re g o n ,USGS OFR 97-263, 1997 $6

USGS - Vo l cano hazards in the Mo u ntHood re g i o n ,O re g o n , USGS OFR 97-89,1 9 9 7 $ 1 0

USGS - Vo l ca n i c - h a z a rds zo n at i o nMo u nt St. He l e n s, Wa s h i n g to n ,U S G SOFR 95-497, 1998 $20

USGS publications can be accessed viathe web at : ht t p : / / v u l ca n . w r. u s g s. g ov /

A co m p l e te list of DOGAMIp u b l i cations can be found online at :w w w. O re g o n Ge o l ogy. co m .

Use the order fo rm be l ow or log on tow w w. Nat u re N W. o rg to ord e r.

S P - 3 2 . Ge o l ogic hazard s :reducing Ore g o n’s losses,by J.D. Beaulieu & D. L .Ol m s te a d, 2 0 0 0 , 27 p. $ 1 0This manual summari zes the geolog i ch a z a rds of Oregon and lists seve ra lg e n e ral strategies that might be pur-sued in the re d u ction of risks from haz-a rd s. This manual is a summary ofSpecial Pa per 31.

S P - 3 1 . Mi t i g ating geologic hazards inO R : A te c h n i cal re fe re n ce manual, byJ . D. Beaulieu & D. L . Ol m s te a d, 2 0 0 0 ,6 0p. $20

This manual is designed for re fe re n ceby a va ri e ty of audiences va rying fro mg e n e ral to te c h n i cal and from po l i cy -o ri e nted to re s e a rc h - o ri e nte d. It is notn e ce s s a ry to read the ent i re manual.I n s te a d, it is designed so users ca nl ocate facts or specific discussions inwhich they are inte re s te d.

USGS - Vo l cano hazards in the Th re eSi s ters region , O re g o n , USGS OFR 99-4 3 7 , 1998 $20

USGS - Vo l cano hazards from Mo u ntRa i n i e r, Wa s h i n g to n , USGS OFR 98-428,1998 $10

These and many other vo l cano hazard sp u b l i cations can be purchased onlineat :w w w. Nat u re N W. o rg.

The only single volume to pre s e nt aco m p re h e n s i ve survey of all the We s t ' svo l canic ce nters that are po te ntial dan-ger spo t s, Fi re Mo u ntains of the West byStephen Ha rris is non-te c h n i cal andi ntended for the general reader whowa nts to learn more about the geolog i cfo rces that shaped our we s te rn moun-t a i n s ca pe. It also adds dire ctions onh ow one can enjoy a particular moun-tain by ca r, by foo t, or by climbing to itss u m m i t. 379 pages. Published byMo u ntain Pre s s. $ 1 3



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Newberry Crater, heart of the Newberry National Volcanic Monument, Deschutes County

The “crater” is, strictly speaking, a caldera - the remnant of a large shield volcano that collapsed during its eruptive lifebetween about 500,000 and less than 2,000 years ago. With many eruptions continuing after the collapse, a great diversityof volcanic landforms and rock types were created. This view to the south shows the central pumice cone that separatesEast and Paulina Lakes, with the Big Obsidian Flow stretching behind to the caldera rim. A related story on the potentialfor geothermal energy production at Newberry Crater can be found on page 5.

Learn more about Oregon’s geology by going online at www.OregonGeology.com.

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can we expect another eruption? o r e g o n ’ s active

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