Hopson 2001 Potential Impact On Water Resources From Eruptions Near Mammoth Lakes Aeg Talk

POTENTIAL IMPACT ON POTENTIAL IMPACT ON WATER RESOURCES FROM WATER RESOURCES FROM

ERUPTIONS NEAR MAMMOTH ERUPTIONS NEAR MAMMOTH LAKES, MONO COUNTY, LAKES, MONO COUNTY,

CALIFORNIACALIFORNIAR. Forrest HopsonR. Forrest Hopson

Geological Information ServicesGeological Information Services

Reno, NevadaReno, Nevada

[email protected]@geoinfoservices.net

INTRODUCTIONINTRODUCTION

Concerns for renewed volcanism was Concerns for renewed volcanism was prompted byprompted by

Increased seismicity beneath the south Increased seismicity beneath the south moat of Long Valley calderamoat of Long Valley caldera

Uplift of the caldera floorUplift of the caldera floor Increased hot spring activityIncreased hot spring activity COCO22 emission near Lake Mary (early emission near Lake Mary (early

1990s) 1990s)

TOPICS OF DISCUSSIONTOPICS OF DISCUSSION

Explore possible scenarios for Explore possible scenarios for volcanic eruptions. volcanic eruptions.

Describe possible hazards from Describe possible hazards from these eruptions.these eruptions.

Explain why they can be expected.Explain why they can be expected. Discuss the impact on surface water, Discuss the impact on surface water,

including the Los Angeles-Owens including the Los Angeles-Owens River Aqueduct.River Aqueduct.

PURPOSEPURPOSE

Assess the potential impact of Assess the potential impact of eruptions on water resources near eruptions on water resources near Mammoth Lakes.Mammoth Lakes.

Specifically, the impact on surface Specifically, the impact on surface water quality and water distribution water quality and water distribution systems, including the Los Angeles-systems, including the Los Angeles-Owens River Aqueduct.Owens River Aqueduct.

PREVIOUS WORKPREVIOUS WORK

Impact on Water QualityImpact on Water Quality Blong 1984Blong 1984 Hopson 1991Hopson 1991 Hopson 2001Hopson 2001

Mammoth Lakes Geology Lakes Geology Bailey 1989Bailey 1989 Miller et al 1982Miller et al 1982 Ewert & Harpel 2000Ewert & Harpel 2000

Generalized map of the Mammoth Generalized map of the Mammoth Lakes region.Lakes region.

Long Valley Caldera from summit of White Long Valley Caldera from summit of White Mountain Peak.Mountain Peak.

Mammoth Mountain from Deer Mammoth Mountain from Deer Mountain.Mountain.

Inyo-Mono Craters Volcanic Chain Inyo-Mono Craters Volcanic Chain from the summit of Mammoth from the summit of Mammoth Mountain.Mountain.

Geologic OverviewGeologic Overview

Simplified geologic map of the Simplified geologic map of the Mammoth Lakes region. Mammoth Lakes region. Source: U.S. Source: U.S. Geological SurveyGeological Survey

Lake Crowley and south moat of Lake Crowley and south moat of Long Valley caldera.Long Valley caldera.

POSSIBLE ERUPTION POSSIBLE ERUPTION SCENARIOSSCENARIOS

Small- to moderate eruptions (0.1 to 1 Small- to moderate eruptions (0.1 to 1 kmkm33) of magma ) of magma

A.A. Phreatic phasePhreatic phase

B.B. Explosive magmatic phaseExplosive magmatic phase

C.C. Effusive phaseEffusive phase1.1. Dome-building eruptionsDome-building eruptions

2.2. Cinder cone eruptionsCinder cone eruptions

Inyo Craters from the summit of Deer Inyo Craters from the summit of Deer Mountain.Mountain.


Small- to moderate eruptions (0.1 to 1 Small- to moderate eruptions (0.1 to 1 km3) of magma km3) of magma





POSSIBLE ERUPTION POSSIBLE ERUPTION SCENARIOS SCENARIOS






Mono-Inyo Craters Volcanic Chain Mono-Inyo Craters Volcanic Chain from the summit of Deer Mountain.from the summit of Deer Mountain.

Cinder Cone and Butte Lake, Lassen Cinder Cone and Butte Lake, Lassen Volcanic National Park.Volcanic National Park.

Mono-Inyo Craters Volcanic Chain Mono-Inyo Craters Volcanic Chain from the summit of Mammoth from the summit of Mammoth Mountain.Mountain.

POTENTIALLY HAZARDOUS POTENTIALLY HAZARDOUS VOLCANIC EVENTSVOLCANIC EVENTS

A model showing the dike that triggered the A model showing the dike that triggered the eruptive events from the Mono-Inyo Craters eruptive events from the Mono-Inyo Craters chain 650–550 years ago. chain 650–550 years ago.

Illustration from J.H. Fink and modified by J. Illustration from J.H. Fink and modified by J. Johnson Photograph by S.R. Brantley on Johnson Photograph by S.R. Brantley on August 2, 1998.August 2, 1998.

POTENTIALLY POTENTIALLY HAZARDOUS VOLCANIC HAZARDOUS VOLCANIC

EVENTS EVENTS A.A. Lava Domes and FlowsLava Domes and Flows

B.B. Volcanic AshVolcanic Ash1.1. Airfall ashAirfall ash

2.2. Pyroclastic flows and surgesPyroclastic flows and surges

C.C. Lahars and FloodsLahars and Floods

D.D. Debris AvalanchesDebris Avalanches


EVENTSEVENTS

A.A. Lava Domes and FlowsLava Domes and Flows





Source: map from C. D. Miller, Source: map from C. D. Miller, modified by J. Johnson (U.S. modified by J. Johnson (U.S. Geological Survey).Geological Survey).

Ash and pumice layer from the May 18, Ash and pumice layer from the May 18, 1980 eruption of Mt. St. Helens. Layer 1980 eruption of Mt. St. Helens. Layer is about 15 cm thick.is about 15 cm thick.


EVENTSEVENTSA.A. Lava Domes and FlowsLava Domes and Flows





Source: map from C. D. Miller, Source: map from C. D. Miller, modified by J. Johnson (U.S. modified by J. Johnson (U.S. Geological Survey).Geological Survey).


EVENTSEVENTS






Smith Creek lahar from the May 18, Smith Creek lahar from the May 18, 1980 eruption of Mt. St. Helens.1980 eruption of Mt. St. Helens.


EVENTSEVENTS






ASSESSMENT OF POSSIBLE ASSESSMENT OF POSSIBLE IMPACT ON WATER IMPACT ON WATER

RESOURCESRESOURCES Lava Domes and FlowsLava Domes and Flows Volcanic AshVolcanic Ash Pyroclastic Flows and SurgesPyroclastic Flows and Surges Lahars, Floods, and Debris AvalanchesLahars, Floods, and Debris Avalanches

Lava Domes and FlowsLava Domes and Flows

Little impact on water quality Little impact on water quality Pipelines in path of advancing lava Pipelines in path of advancing lava

flows may be destroyedflows may be destroyed Lava flows may impede stream flow Lava flows may impede stream flow

and create large lakes and create large lakes Greatest danger would be from Greatest danger would be from

pyroclastic flows or debris pyroclastic flows or debris avalanches avalanches

Butte Lake and Fantastic Lava Beds Butte Lake and Fantastic Lava Beds from Cinder Cone, Lassen Volcanic from Cinder Cone, Lassen Volcanic National Park.National Park.

Volcanic AshVolcanic Ash

Increase in turbidityIncrease in turbidity Increase in acidity Increase in acidity Short-term chemical changes from Short-term chemical changes from

leaching of newly erupted ash leaching of newly erupted ash Change in ablation ratesChange in ablation rates

• Ash layers >24 mm would slow ablation Ash layers >24 mm would slow ablation rates rates

• Thin ash layers would increase ablation Thin ash layers would increase ablation

Pyroclastic Flows and Pyroclastic Flows and SurgesSurges

All of the aboveAll of the above Clog stream channels Clog stream channels Melt snow and ice that could trigger Melt snow and ice that could trigger

lahars, debris flows, and floods lahars, debris flows, and floods Clog filters, pumps, and pipes in Clog filters, pumps, and pipes in

water intakes and distribution water intakes and distribution systems along the LAORA systems along the LAORA

Damage turbines in power plants Damage turbines in power plants

Lahars, Floods, and Debris Lahars, Floods, and Debris Avalanches Avalanches

Lahars could block and change Lahars could block and change morphology of stream channels and morphology of stream channels and deposit massive volumes of sediment deposit massive volumes of sediment

Public water supply systems would Public water supply systems would be vulnerable to lahars and flood be vulnerable to lahars and flood

Changes in chemistry from the Changes in chemistry from the leaching of mud leaching of mud

Coldwater Lake debris dam, Mt. St. Coldwater Lake debris dam, Mt. St. Helens National Volcanic Monument.Helens National Volcanic Monument.

DISCUSSIONDISCUSSION

Lake Crowley from the summit of Lake Crowley from the summit of Glass MountainGlass Mountain

CONCLUSIONSCONCLUSIONS

1.1. Streams might be displaced from their Streams might be displaced from their channels by advancing flows or growing channels by advancing flows or growing domesdomes

2.2. Temporary increase in acidity and turbidity Temporary increase in acidity and turbidity from volcanic ash, lahars, or debris from volcanic ash, lahars, or debris avalanchesavalanches

3.3. Voluminous pyroclastic flows, lahars, and Voluminous pyroclastic flows, lahars, and debris avalanches might do two things:debris avalanches might do two things:

a.a. Impound streams channels, causing water to Impound streams channels, causing water to back up behind the debris dam. Failure of the back up behind the debris dam. Failure of the dam would cause massive flooding downstream.dam would cause massive flooding downstream.

b.b. Deposited in Lake Crowley or Mammoth Pool Deposited in Lake Crowley or Mammoth Pool Reservoir which could displace water causing it Reservoir which could displace water causing it to overtop and possibly damage the damto overtop and possibly damage the dam

CONCLUSIONS cont’dCONCLUSIONS cont’d

4.4. Temporary minor changes in water Temporary minor changes in water composition from leaching of volcanic composition from leaching of volcanic ash or sedimentash or sediment

5.5. Less snowmelt runoff if thick ash layers Less snowmelt runoff if thick ash layers were to accumulate over snow.were to accumulate over snow.

6.6. Water intake structures and conveyance Water intake structures and conveyance systems along the LAORA could get systems along the LAORA could get clogged and buried by large pyroclastic clogged and buried by large pyroclastic flows, lahars, and debris avalanchesflows, lahars, and debris avalanches

The EndThe End

Hopson 2001 Potential Impact On Water Resources From Eruptions Near Mammoth Lakes Aeg Talk

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