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Eastern Oregon University December 2012 Page 3.1 Natural Hazard Mitigation Plan

Section 3: Risk Assessment

Introduction and Methodology ....................................................................... 1

Earthquake ...................................................................................................... 5

Wildfire ........................................................................................................... 11

Severe Weather: Winter and Wind Storms .................................................. 15

Flood .............................................................................................................. 17

Landslide ....................................................................................................... 21

Volcanic ......................................................................................................... 25

Drought .......................................................................................................... 27

Hazardous Materials ..................................................................................... 31

Introduction and Methodology As described in the Campus Profile, Eastern Oregon University functions as a complex network of physical and social systems. Disaster events often highlight the fragility of some of these systems. By looking at campus risk from a holistic perspective, we can identify which campus resources (e.g. buildings, roads, utilities, social services, etc.) are vulnerable and/or sensitive in certain events. This knowledge can then be used to help develop strategies that strengthen the University, reduce losses and increase resiliency for both short- and long-term disaster risk.

The purpose of Section 3- Risk Assessment is to identify and characterize the natural hazards that could impact this University and assess the risk those natural hazards pose. A risk assessment provides a snapshot of the University’s vulnerability relative to identified natural hazards. It becomes the factual basis for proposed activities that aim to mitigate damage to campus assets. By combining information from the natural hazard profile with an inventory of the existing campus characteristics, areas of vulnerability are exposed. The risk assessment process is characterized in Figure 3.1 below. From this information, “action items” or specific projects/activities are identified that will reduce potential losses and protect the integrity of the University.

This section identifies and profiles the location, extent, previous occurrences, and future probability of natural hazards that can impact the University.

2 December 2012 Eastern Oregon University Natural Hazard Mitigation Plan

Figure 3.1: Understanding Risk

What is a Risk Assessment? A risk assessment consists of three phases: hazard identification, vulnerability assessment, and risk analysis.

Hazard Identification The first phase, hazard identification, involves describing the causes and characteristics of each hazard, the history of that hazard on campus, the identification of the geographic extent of a hazard, its intensity, and its probability of future occurrence.

This level of assessment typically involves producing a map or maps. The outputs from this phase can also be used for planning, public awareness, and defining areas for further study.1

Vulnerability Assessment The second phase, vulnerability assessment, combines the information from the hazard identification with an inventory of the existing (or planned) property, population exposed to a hazard and attempts to predict how different types of property, population groups and functions will be affected by the hazard. This step can assist in justifying property acquisition programs, policies concerning critical and public facilities and outreach programs to members of the campus community at risk.2

In short, this section analyzes the vulnerability of the University by identifying assets that could be exposed to a hazard. Critical facilities are of particular concern because they provide essential services that are necessary to protect life and fulfill important public safety, emergency response, and/or disaster recovery functions.

1 Burby, R. 1998. Cooperating with Nature. Washington, DC: Joseph Henry Press. Pg. 126. 2 Burby, R. 1998. Cooperating with Nature. Washington DC: Joseph Henry Press. Pg. 133.

Eastern Oregon University December 2012 .3 Natural Hazard Mitigation Plan

Risk Analysis The third phase, risk analysis, involves estimating the damage, injuries, and costs likely to result from a natural hazard. Risk has two measurable components: (1) the magnitude of the harm that may result, defined through the vulnerability assessment, and (2) the likelihood or probability of the harm occurring.

An example of a product that can assist communities in completing the risk analysis phase is HAZUS, a risk assessment software program for analyzing potential losses from floods, hurricane winds and earthquakes. In HAZUS-MH current scientific and engineering knowledge is coupled with the latest geographic information systems (GIS) technology to produce estimates of hazard-related damage after a disaster occurs.

This three-phase approach to developing a risk assessment should be conducted sequentially because each phase builds upon data from prior phases. However, gathering data for a risk assessment need not occur sequentially.

Hazard Risk Assessments The Eastern Oregon University Steering Committee reviewed the Risk Assessment for Union County and the City of La Grande and also conducted a Hazard Risk Assessment to determine the relative risk incurred by Eastern Oregon University for a range of natural hazards.

Through this analysis the determined to include the following hazards in this NHMP Risk Assessment:

• Earthquake

• Severe Weather (Wind and Winter Storms)

• Wildfire

• Flood

• Landslide

• Volcanic

• Drought

• Hazardous Materials3

Each hazard addressed by the plan, the following information is provided:

• Hazard identification

• Vulnerability assessment

• Risk assessment

• Existing mitigation actions and successes 3 The steering committee elected to add this hazard to the Eastern Oregon University NHMP even though it was not included in the City or County NHMP.


Risk Assessment Methodology The Union County and La Grande Natural Hazard Mitigation Plans (NHMP) were updated in 2007 as part of a regional process. Additionally, the State NHMP was updated in 2012. These documents served as the primary sources for the Eastern Oregon University Risk Assessment.

To facilitate connections with the Union County NHMP and the State of Oregon’s NHMP, this plan uses the same rating scales as provided within Oregon Emergency Management’s Hazard Analysis Methodology template, and are listed below. Probability estimates are based on the frequency of previous events, and vulnerability estimates are based on potential impacts of the hazard.

Probability scores address the likelihood of a future major emergency or disaster within a specific period of time as follows:

• High = One incident likely within a 10-35 year period

• Moderate = One incident likely within a 35-75 year period

• Low = One incident likely within a 75-100 year period

Vulnerability scores address the percentage of population or region assets likely to be affected by a major emergency or disaster, as follows:

• High = More than 10% affected

• Moderate = 1-10% affected

• Low = Less than 1% affected

The probability and vulnerability scores in each hazard section were reviewed by the Eastern Oregon University Steering Committee members during the plan development process.

Table 3.1: Summary Risk Assessment Union County City of La Grande Eastern Oregon University Probability Vulnerability Probability Vulnerability Probability Vulnerability

Earthquake Low Moderate Low High Low Moderate Wildfire* High High High High High High

Severe Weather

High High High High High High

Flood High High High High High High Landslide Low Low Moderate Moderate Moderate High

Volcanic Low Low Low Low Low Low Drought High Low High Low High Low

Hazardous Material

High High


Earthquake Hazard Identification

Location and Extent of the Hazard Oregon and the Pacific Northwest in general are susceptible to earthquakes from three sources: 1) the off-shore Cascadia Subduction Zone; 2) deep intra-plate events within the subducting Juan de Fuca Plate; and 3) shallow crustal events within the North American Plate. All have some tie to the subducting or diving of the dense, oceanic Juan de Fuca Plate under the lighter, continental North America Plate.

• When crustal faults slip, they can produce earthquakes with magnitudes (M) up to 7.0 and can cause extensive damage, which tends to be localized in the vicinity of the area of slippage.

• Deep intraplate earthquakes occur at depths between 30 and 100 kilometers below the earth’s surface. They occur in the subducting oceanic plate and can approach M7.5. Subduction zone earthquakes pose the greatest hazard. They occur at the boundary between the descending oceanic Juan de Fuca Plate and the overriding North American Plate. This area of contact, which starts off the Oregon coast, is known as the Cascadia Subduction Zone (CSZ). The CSZ could produce a local earthquake up to 9.0 or greater.

Figure 3.2: Union County Earthquake and Fault Map 1841-20024

Additionally, as the State of Oregon NHMP indicates:

There are also a few identified faults in the region (Union County) that have been active in the last 20,000 years. The region has also been shaken historically by crustal earthquakes and prehistorically by subduction zone earthquakes centered outside the area.5

4 DOGAMI, Oregon statewide earthquake map showing earthquakes from 1841 to 2002 5 State of Oregon NHMP, Region 7: Central Oregon Regional Profile, 2012


Causes and Characteristics of the Hazard The severity of an earthquake depends on several factors, including the distance from the earthquake source, the ability of soil and rock to conduct seismic energy and the degree (angle) and composition of slope materials. The specific hazards associated with an earthquake include the following:

• Ground Shaking and Ground Shaking Amplification

• Surface Faulting

• Earthquake-Induced Landslides

• Liquefaction

The Union County NHMP contains more detailed description of the causes and characteristics of earthquakes.

Hazard History Historically, the region has been shaken by crustal and intraplate earthquakes and prehistorically by subduction zone earthquakes centered outside the area (Table 4). All considered, there is good reason to believe that the most devastating future earthquakes would probably originate along shallow crustal faults in the region.

Table 3.2 Significant Earthquakes in Eastern Oregon6 Date Location Magnitude Comments

9/1993 Klamath Falls 5.9 to 6.0 Two earthquakes causing two deaths and extensive damage. $7.5 million in damage to homes, commercial, and government buildings. Crustal event (FEMA-1004-DR-OR)

11 & 12 /1965 Halfway 4.3 & 4.2

8/1965 John Day 4.4

11/1962 Portland 5.2 to 5.5 Damage to many homes (chimneys, windows, etc.). Crustal event

1/1951 Hermiston V

6 & 4 /1942 Pine Valley – Cuddy Mtn V Minor Damage

7/1936 Milton-Freewater 6.1 This earthquake and the foreshocks and aftershocks caused $100,000 in damage (1936 dollars); Intense ground cracking

4/1927 Pine Valley – Cuddy Mtn

1/1924 Milton-Freewater

10/1913 Hells Canyon VI

3/1893 Umatilla VI or VII

1/1700 Offshore, CSZ Approx. 9.0 Generated a tsunami that struck Oregon, Washington, and Japan; destroyed Native American villages along the coast

Sources: 1: Wong, Ivan and Bolt, Jacqueline, November 1995, A Look Back at Oregon’s Earthquake History, 1841-1994, Oregon Geology, p.125-139. 2: The Pacific Northwest Seismograph Network, Notable Pacific Northwest Earthquakes Since 1993, www.pnsn.org/SEIS/EQ_Special/pnwtectonics.html, accessed July 30th, 2010. 3: Science Daily, “Unusual Earthquake Swarm Off Oregon Coast Puzzles Scientists,” April 14, 2008, www.sciencedaily.com/releases/2008/04/080413184801.htm, accessed July 30th, 2010.

6 State of Oregon NHMP, Region 7: Central Oregon Regional Profile, 2012


Probability of Future Occurrence The State of Oregon NHMP indicates that geologists predict a 10‐14 percent chance that a Cascadia subduction zone earthquake will occur within the next 50 years. This forecast comes from evidence for large but infrequent earthquakes and tsunamis that have occurred at the Oregon coast on average, every 500 years. However, as with any natural process, the average time between events can be misleading. Some of the earthquakes may have been 150 years apart with some closer to 1,000 years apart.7

Establishing a probability for crustal earthquakes is more difficult given the small number of historic events in the region. The State, County and City NHMPs all indicate that the probability of an earthquake is low.

Figure 3.3, below, depicts this hazard in terms of the intensity of ground shaking which has a 2% probability of being exceeded during a 50-year period. Depending on the epicenter of the earthquake, damage that campus could experience as a result of this hazard could be moderate to significant.

Figure 3.3: 2% 50-year earthquake Hazard

Source: United States Geological Survey. (2009). Earthquake Hazard Program: 2008 NSHM Figures. Retrieved from: http://earthquake.usgs.gov/hazards/products/conterminous/2008/maps/

7 7 State of Oregon NHMP, Region 7: Central Oregon Regional Profile, 2012

La Grande

http://earthquake.usgs.gov/hazards/products/conterminous/2008/maps/


Vulnerability Assessment The state of Oregon NHMP discusses the vulnerability in this way:

There is good reason to believe that the most devastating future earthquakes would probably originate along shallow crustal faults in the region.

Earthquake risk in (the) Region … is reflected in the Uniform Building Code’s (UBC) earthquake hazard maps (i.e., seismic zones 1‐4). The higher the numerical designation, the more stringent the building standards become. (The) Region is within UBC Seismic Zone 2b.8

Earthquakes will affect buildings and building occupants as a result of seismic waves traveling through the ground. These waves result in vibrations that cause motion within the structural system of each building. If the design does not allow the structure to respond safely and predictably to this motion, failure can occur and produce harm to occupants and damage to the building. This motion will also cause building contents to shift; unsecured items such as bookshelves, computers, and file cabinets could move significantly and threaten life and safety. Many spaces on campus contain expensive, rare, or hazardous items that can be damaged or lead to secondary hazards during an earthquake. In addition to buildings, infrastructure and transportation systems are vulnerable to ground motion and consequently threaten the University’s ability to operate.

The campus is composed of 9 academic buildings, 4 athletic buildings, 6 housing buildings, 10 student and support buildings, and 5 off-campus buildings. Campus buildings have several different construction systems. Building age, construction type and material, and soils all contribute to overall risk of building damage or collapse during an earthquake.

• 6 buildings are more than 70 years old

• 9 buildings are between 40 and 70 years old

• 12 buildings are between 10 and 40 years old

• 8 buildings are less than 10 years old

8 State of Oregon NHMP, Region 7: Central Oregon Regional Profile, 2012


Risk Analysis Though the location, duration, and magnitude of any earthquake is impossible to predict, Eastern Oregon University can reasonably expect tens of thousands if not millions of dollars in damage from even an earthquake of moderate magnitude. The losses may be attributable to damaged buildings, loss of life, loss of equipment, or loss of research assets or other intellectual property.

Based on the Structural Summary data provided in Section 2 Campus Profile, in 2010 the structural replacement cost for all of EOU’s buildings is more $329 million.

The Union County NHMP identified probability of and vulnerability to earthquakes for Union County and the City of La Grande. During development of Eastern Oregon University’s NHMP, the Steering Committee determined that the University experiences low probability (one incident likely within a 75-100 year period.) and moderate vulnerability (1-10% of the population affected). Union County City of La Grande Eastern Oregon

University Probability Low Low Low

Vulnerability Moderate High Moderate

Hazard Mitigation Successes • As a part of the Campus Master Plan development process, EOU

contracted with SERA architects to conduct a building and site assessment. This assessment included preliminary seismic information.

.


Wildfire Over the past decade, a number of wildfire specific hazard planning activities have been completed locally and regionally. Eastern Oregon University is within the jurisdiction of the La Grande Fire Department for fire related Risk Assessment, mitigation and response. Additionally, the Union County Community Wildfire Protection Plan (CWPP) was adopted in 2005. For the purposes of this Hazard Mitigation Plan, the Union County CWPP will serve as primary source document for wildfire Risk Assessment and is incorporated herein by reference.

Hazard Identification Location and Extent of the Hazard

Fire is an essential part of Oregon’s ecosystem, but it is also a serious threat to life and property, particularly within the state’s wildland-urban interface. Wildfires occur in areas having large areas of flammable vegetation that require a suppression response.

Causes and Characteristics of the Hazard Wildfire can be divided into three categories: interface, wildland, and firestorm.

• Interface Fires occur where wildland and developed areas come together with both vegetation and structural development combining to provide fuel.

• Wildland Fires main fuel source is natural vegetation. Often referred to as forest or rangeland fires, these fires occur in national forests and parks, private timberland, and on public and private rangeland. A wildland fire can become an interface fire if it encroaches on developed areas.

• Firestorms are events of such extreme intensity that effective suppression is virtually impossible. Firestorms often occur during dry, windy weather and generally burn until conditions change or the available fuel is consumed.


Hazard History Even though there is no history of direct impacts from wildfire on the Eastern Oregon University campus, wildfires have impacted Union County and the City of La Grande. These events include9:

• 1973 ‘Rooster Peak’: Lightning-caused; burned approximately 6,400 acres including six structures. Much of the fire was located near La Grande’s southwest city limits. Because structures were lost and the fire threatened the City of La Grande, this is the most significant fire in recent history.

• 1981 ‘Mt. Harris’: Human-caused fire resulting in significant timber loss; burned 850 acres. The fire was highly visible from La Grande, Summerville, Imbler and Cove.

• 1986 ‘Frizzel’: Lightning-caused; 250 acres burned. Took place in the Mt. Emily WUI.

• 1986 ‘Clear’: Baker, Grant, and Union Counties: Lightning-caused; 6,000 acres burned.

• 1988 ‘Turner’: Baker, Union, Grant Counties: 8,000 acres burned.

• 2001 ‘Boulevard’: Lightning-caused; 150 acres burned. The fire threatened the La Grande watershed, a rugged and road-less area of high environmental value. Much like the previous fires the potential for a catastrophic fire was high, but for different reasons. The watershed contains substantial fuel and has very limited access. Had conditions been less favorable, a major event could have occurred.

• 2003 ‘Craig Loop’: Human-caused; 43 acres burned. Took place in the Mt. Emily WUI

• 2005 ‘Clark Creek and Indian Creek’: 15 miles NE of La Grande. 450- 500 acres of grass, brush, agricultural fields, and timber burned in the vicinity of Mt. Harris.

• 2005 ‘Mule Peak’: Wallowa Whitman Forest, 20 miles SE of La Grande. 1,150 acres burned.

• 2007 ‘Gordon Creek’: Elgin: 17 acres burned

Probability of Future Occurrence The natural ignition of forest fires is largely a function of weather and fuel; human-caused fires add another dimension to probability. Dry and diseased forests can be mapped accurately and some statement can be made about the probability of lightning strikes. Each forest is different and consequently has different probability/recurrence estimates.

9 Union County Risk Assessment, 2007


Vulnerability Assessment Eastern Oregon University has some structures that are within the “Community At Risk” boundary for wildfire hazards. Additionally, significant wildlife locally or in the region has the potential to impact the campus community, indirectly. A wildfire of regional significance could restrict access to Eastern Oregon University’s campus via Highways I-84, 30, and 82 and decreased air quality in the region due to smoke could negatively impact overall health and safety.

Figure 3.4 depicts the “community at risk” boundaries for the community surrounding the Eastern Oregon University campus.

Figure 3.4: Wildfire Hazard – “Community At Risk” Boundary

Source: Oregon State University, Oregon Hazards Explorer, http://www.oregonexplorer.info/hazards/. Notes: (1) “Community Name and Rating” shows geographic areas that meet the population density requirements of the National Fire Plan (1 dwelling per 40 acre or 28 persons per square mile, minimum of 4 dwellings/8 people, or basic infrastructure present,), (2) “Community At Risk (CAR) Boundary” shows the area within and surrounding populated jurisdictions that meet Oregon's definition for Community at Risk. The boundaries reflect areas within and surrounding jurisdictional populated areas that are considered part of the community.

Eastern Oregon University Campus

http://www.oregonexplorer.info/hazards/


Risk Analysis The Union County NHMP identified probability of and vulnerability to wildfires for Union County and the City of La Grande. Eastern Oregon University’s Steering Committee used that information in assessing risk for the Eastern Oregon University campus and community and determined that the University experiences high probability (one incident likely within a 10 to 35 year period.) and high vulnerability (more than 10% of the population affected.). Union County City of La Grande Eastern Oregon

University Probability High High High

Vulnerability High High High


Severe Weather: Winter and Wind Storms

Hazard Identification Location, Extent, Causes and Characteristics of the Hazard

Winter storms affecting the Eastern Oregon University campus are characterized by a combination of heavy rains and high winds. Heavy rains can result in flooding, as well as debris slides and landslides. High winds commonly result in tree falls which primarily affect the electric power system, but which may also affect buildings and vehicles.

A windstorm is generally a short duration event involving straight-line winds and/or gusts in excess of 50 mph. Although windstorms can affect all of Union County, they are especially in developed areas with significant tree stands and major infrastructure, especially above ground utility lines. A windstorm will frequently knock down trees and power lines, damage homes, businesses, public facilities, and create tons of storm related debris.

The Union County NHMP contains more detailed description of the causes and characteristics of severe weather hazards.

Hazard History The following list describes the history of winter storms in Union County and the City of La Grande.

• 2011 – Strong wind storm topples a large pine tree on campus.

• Winter 1998-99 - One of the snowiest winters in Oregon history (Snowfall at Crater Lake: 586 inches).

• Mar. 1994 - Heavy snow throughout the Cascade Mountains.

• Nov. 1993 - Heavy snow throughout the Cascade Mountains.

• Feb. 1986 - Heavy snow in and around the Deschutes Basin. Traffic accidents; broken power lines.

• Jan. 1969 - Heavy snow throughout state.

• Jan. 1950 - Record snowfalls caused property damage throughout state.

• Jan. 1916 - Two storms over the state produce heavy snowfall, especially in mountainous areas.

Probability of Future Occurrence Winter storms and wind storm are considered chronic, seasonal hazards in Union County, occurring with some regularity and / or on an annual basis.


Vulnerability Assessment Eastern Oregon University’s campus vulnerability stems from unreinforced infrastructure and old or diseased trees.

• Tree limbs can fall during due to the weight of snow accumulation or from high wind speeds. Tree limbs falling on transportation routes, buildings, and other property can cause significant damage to both public and private assets.

• Trees can also fall when significant rain fall is followed or accompanied by strong winds. The rain will decrease the stability of the soil leaving the trees susceptible to the wind.

Risk Analysis The Union County NHMP identified probability of and vulnerability to winter storms for Union County and the City of La Grande. Eastern Oregon University’s Steering Committee used that information in assessing risk for the Eastern Oregon University campus and community and determined that the University experiences high probability (one incident likely within a 10 to 35 year period.) and high vulnerability (more than 10% of the population affected.). Union County City of La Grande Eastern Oregon




Flood Hazard Identification

Location and Extent of the Hazard The extent of the damage and risk to people caused by flood events is primarily dependent on the depth and velocity of floodwaters. Fast moving floodwaters can wash buildings off their foundations and sweep vehicles downstream. Roads, bridges, and other infrastructure and lifelines (pipelines, utility, water, sewer, communications systems, etc.) can be seriously damaged when high water combines with flood debris, mud and ice. Extensive flood damage to residences and other structures also results from basement flooding and landslide damage related to soil saturation. Surface water entering into crawlspaces, basements and daylight basements is common during flood events not only in or near flooded areas but also on hillsides and other areas far removed from floodplains. Most damage is caused by water saturating materials susceptible to loss (e.g., wood, insulation, wallboard, fabric, furnishings, floor coverings and appliances).

Figure 3.5: Waterways and floodplains in proximity to EOU

Source: Oregon HazVu: Statewide Geohazards Viewer, 2012

Causes and Characteristics of the Hazard Oregon has a detailed history of flooding with flood records dating back to the 1860s. There are over 250 flood-prone communities in Oregon. The principal types of flood that occur in the community include:

Riverine floods Riverine floods occur when water levels in rivers and streams overflow their banks. This type of flooding can be expected after spring rains, heavy



thunderstorms or rapid runoff from snow melt. Riverine floods can be slow or fast-rising, but usually develop over a period of days.

The danger of riverine flooding occurs mainly during the winter months, with the onset of persistent, heavy rainfall, and during the spring, and due to snow melt.

Flash floods Flash floods usually result from intense storms dropping large amounts of rain within a brief period. Flash floods usually occur in the summer during thunderstorm season, appear with little or no warning and can reach full peak in only a few minutes. They are most common in arid and semi-arid areas where there is steep topography, little vegetation and intense but short-duration rainfall. Flash floods can occur in both urban and rural settings, often along smaller rivers and drainage ways.

In flash flood situations, waters not only rise rapidly, but also generally move at high velocities and often carry large amounts of debris. In these instances a flash flood may arrive as a fast moving wall of debris, mud, water or ice. Such material can accumulate at a natural or man-made obstruction and restrict the flow of water. Water held back in such a manner can cause flooding both upstream and then later downstream if the obstruction is removed or breaks free.

Urban floods Urban flooding occurs in areas where the previous ability of water to filter into the ground is prevented by the extensive impervious surfaces associated with urban development (e.g. parking lots). This in turn results in more water quickly running off into watercourses which causes water levels to rise above pre-development levels. During periods of urban flooding streets can rapidly become swift moving rivers and basements and backyards can quickly fill with water. Storm drains often may back up with yard waste or other flood debris leading to further localized flooding. Another source of urban flooding is grading associated with development. In some cases, such grading can alter changes in drainage direction of water from one property to another.

Hazard History The most damaging floods for Union County have occurred during the winter and spring months, when warm rains from tropical latitudes melt mountain snow packs. Such conditions were especially noteworthy in February 1957, February 1963, December 1964 and January 1965. Somewhat lesser flooding has been associated with ice jams, normal spring run-off, and summer thunderstorms. Heavily vegetated stream banks, low stream gradients (e.g., Grande Ronde Valley), and breeched dikes have contributed to past flooding at considerable economic cost.

• December 1964-January 1965: Entire State: widespread destructive flooding from warm rain, melted snow, and runoff on frozen ground. Record snow depths and December rainfall led to hundreds of landslides. Bridges and roads washed out, homes were destroyed and thousands were evacuated. There were 47


deaths, 17 in Oregon. Damage statewide totaled $430 million. Regionally, property damage totaled $208,333.33.

• May 1998: Eastern and Central Oregon: persistent rains caused widespread damage. La Grande and Prineville reported 1-inch hail and Union received .75 inches of rain in 20 minutes. Prineville was declared a disaster area.

• June, 1998: City of La Grande: Up to 1.5 inches of rain fell in 20 minutes with ¼ inch in two minutes. Winds gusted up to 50 mph. Several inches of water flowed along La Grande streets. Eight thousand were without power and the storm stripped crops.

• July 22, 2004: La Grande: 70 mph winds wreaked havoc on trees, houses, cars and streets. Water flowed into the ground level floors of Ackerman Hall, Pierce Library, and Hoke Student Center at Eastern Oregon University.

Probability of Future Occurrence Oregon’s most severe flooding occurs between November and February and most are associated with a period of intense warm rain on a heavy mountain snow pack.

Localized flooding occurs annually due to high spring runoff, heavy rains, or ice blockages.

Vulnerability Assessment Eastern Oregon University’s campus vulnerability stems from Deal and Mill Creek. Both creeks run underground under the campus. Season flooding occurs that impacts the campus by flooding paths, walkways and streets, and cause building basements to flood due to in ability to drain to the creek. The basements hold equipment, supplies and infrastructure that has in the past sustained damage during these flood incidents.

Risk Analysis The Union County NHMP identified probability of and vulnerability to winter storms for Union County and the City of La Grande. Eastern Oregon University’s Steering Committee used that information in assessing risk for the Eastern Oregon University campus and community and determined that the University experiences high probability (one incident likely within a 10 to 35 year period.) and high vulnerability (more than 10% of the population affected.). Union County City of La Grande Eastern Oregon




Figure 3.6: City of La Grande Floodplain Map, 2009

Source: City of La Grande, 2009

Eastern Oregon University C


Landslide Hazard Identification

Location and Extent of the Hazard Landslides are a major geologic threat in almost every state in the United States. In Oregon, a significant number of locations are at risk from dangerous landslides and debris flows. While not all landslides result in property damage, many landslides do pose serious risk to people and property. Increasing population in Oregon and the resultant growth in home ownership has caused the siting of more development in or near landslide areas. Often these areas are highly desirable owing to their location along the coast, rivers and on hillsides.

Landslides are fairly common, naturally occurring events in various parts of Oregon. In simplest terms, a landslide is any detached mass of soil, rock, or debris that falls, slides or flows down a slope or a stream channel. Landslides are classified according to the type and rate of movement and the type of materials that are transported.

Figure 3.6: Landslide Hazard in proximity to EOU

Source: Oregon HazVu: Statewide Geohazards Viewer, 2012

Causes and Characteristics of the Hazard In understanding a landslide, two forces are at work: 1) the driving forces that cause the material to move down slope, and 2) the friction forces and strength of materials that act to retard the movement and stabilize the slope. When the driving forces exceed the resisting forces, a landslide occurs.



Landslides can be grouped as “on-site” and “off-site” hazards. An “on-site” slide is one that occurs on or near a development site and is slow moving. It is slow moving slides that cause the most property damage in urban areas. On-site landslide hazards include features called slumps, earth flows and block slides. “Off-site” slides typically are rapid moving and begin on steep slopes at a distance from homes and development. Landslides are classified based on causal factors and conditions and exist in three basic categories.

Falls This type of landslide involves the movement of rock and soil which detaches from a steep slope or cliff and falls through the air and/or bounces or rolls down slope. This type of slide is termed a rock fall and is very common along Oregon highways where they have been cut through bedrock in steep canyons and along the coast.

Slides This kind of landslide exists where the slide material moves in contact with the underlying surface. Here the slide moves along a plane and either slumps by moving along a curved surface (called a rotational slide) or along a flat surface (called a translational slide). While slow-moving slides can occur on relatively gentle slopes and are less likely to cause serious injuries or fatalities, they can result in very significant property damage.

Flows In this case the landslide is characterized as plastic or liquid in nature in which the slide material breaks up and flows during movement. This type of landslide occurs when a landslide moves down slope as a semi-fluid mass scouring or partially scouring rock and soils from the slope along its path. A flow landslide is typically rapid moving and tends to increase in volume as it moves down slope and scours out its channel.

Rapidly moving flow landslides are often referred to a debris flows. Other terms given to debris flows are mudslides, mudflows, or debris avalanches. Debris flows frequently take place during or following an intense rainfall on previously saturated soil. Debris flows usually start on steep hillsides as slumps or slides that liquefy, accelerate to speeds as high as 35 miles per hour or more, and travel down slopes and channels onto gentle sloping or flat ground. Most slopes steeper than 70 percent are at risk for debris flows.

In general, northeastern Oregon soil profiles are shallow and rainfall is less frequent and intense than the western portion of the state. Most landslides occur within the Interstate 84 corridor, and state highway 82.

Hazard History The Union County Risk Assessment cites no know instances of significant landslides. Relic landslides are known to have existed in the valley, and small, isolated events due to extremely heavy precipitation have occurred in mountainous regions, but there have been no documented injuries, death, or property damages associated with these events.


At Eastern Oregon University, ground shifting and settling has caused damage to the historic stairs along the northern edge of campus. The stairs are no longer in use due to the damage and risk of further sliding.

Probability of Future Occurrence Slides are more likely to happen during rain storms and earthquakes. The severity of a slide will vary depending on its location and magnitude.

Vulnerability Assessment Landslides have the potential to block streams and damage infrastructure. Channels at the mouths of both Mill Creek and Deal Creek are cut into Holocene mudflow deposits on the west side of the La Grande near Eastern Oregon University campus. Both channels contain remnants of younger mudflows.

Additionally, the ground shifting along the north edge of campus has the potential to impact Inlow Hall.

Risk Analysis The Union County NHMP identified probability of and vulnerability to volcanoes for Union County and the City of La Grande. Eastern Oregon University’s Steering Committee used that information in assessing risk for the Eastern Oregon University campus and community and determined that the University experiences moderate probability (one incident likely within a 35-75 year period) and high vulnerability (more than 10% of the population affected.).

Union County City of La Grande Eastern Oregon

University Probability Low Moderate Moderate

Vulnerability Low Moderate High


Volcanic Hazard Identification

Location and Extent of the Hazard Oregon’s vulnerability to volcanic events varies statewide. The Cascade Mountains, poses the greatest threat for volcanic activity. The Cascade Range of the Pacific Northwest has more than a dozen active volcanoes stretching from southern British Columbia to northern California.

Areas of concern in Oregon include: Mount Hood, which most recently erupted about 200 years ago, the Three Sisters, and Mt. Jefferson, which has not erupted for about 15,000 years, but is not considered to be extinct. Other Oregon volcanic areas include Crater Lake and Newberry Volcano.

Areas of concern in Washington State include Mount Adams, Mount Rainer and most notably Mount St. Helens.

Causes and Characteristics of the Hazard The existence, position and recurrent activity of Cascades volcanoes are related to the convergence of shifting crustal plates. Three main natural hazards occur as a result of Volcanic Eruption: ash fall, lava flows, and pyroclastic flows and surges.

Hazard History There have been seven eruptions in the Cascade Range in US History. The most recent events were Mt. St. Helens in Washington (1980-86) and Lassen Peak in California (1914-1917).

Probability of Future Occurrence Cascades volcanoes tend to erupt explosively, and have occurred at an average rate of 1-2 per century during the last 4,000 years. The Union County Risk Assessment states: “Future eruptions are certain.”

Vulnerability Assessment As population increases in the Pacific Northwest, areas near volcanoes are being developed and recreational usage is expanding. As a result more and more people and property are at risk from volcanic activity.

To identify the areas that are likely to be affected by future events, pre-historic rock deposits are mapped and studied to learn about the types and frequency of past eruptions at each volcano. This information helps scientists to better anticipate future activity at a volcano, and provides a basis for preparing for the effects of future eruptions through emergency planning.

The impacts to Eastern Oregon University will depend on the location, type, and intensity of the eruption. Eruptions to the north or south may result in some ash fall, while an eruption of Mount Hood, would significantly impact the infrastructure throughout northern Oregon,


including transportation and utilities. Additionally, communities outside of the blast zones may be called upon to provide support for response and recovery efforts.

Figure 3.7: Probability of Ash Fall, Cascade Range

Source: Scott et all, 1997, USGS 97-89

Risk Analysis The Union County NHMP identified probability of and vulnerability to volcanoes for Union County and the City of La Grande. Eastern Oregon University’s Steering Committee used that information in assessing risk for the Eastern Oregon University campus and community and determined that the University experiences low probability (one incident likely within a 75-100 year period) and low vulnerability (less than 1% affected). Union County City of La Grande Eastern Oregon University

Probability Low Low Low Vulnerability Low Low Low

Union County


Drought Hazard Identification

Location and Extent of the Hazard Central and southern Oregon as well as parts of the Willamette Valley experiences the greatest challenges with drought and water scarcity as rapidly growing populations place increasing demand on water resources

The terms “drought” and “water scarcity” are not necessarily synonymous. Water scarcity implies that demand is exceeding the supply. The combined effects of drought and water scarcity are far reaching and merit special consideration.

Causes and Characteristics of the Hazard Droughts are not just a summer‐time phenomenon; winter droughts can have a profound impact on the state's agricultural sector, particularly east of the Cascade Mountains. Below average snowfall in Oregon's higher elevations has a far-reaching effect on the entire state, especially in terms of hydroelectric power, irrigation, recreational opportunities and a variety of industrial uses.

There also are environmental consequences. A prolonged drought in Oregon's forests promotes an increase of insect pests, which in turn, damages trees already weakened by a lack of water. A moisture deficient forest constitutes a significant fire hazard, and drought and water scarcity also add stress to species listed pursuant to the Endangered Species Act (ESA) of 1973.

The Oregon Drought Severity Index is the drought measurement convention in Oregon. It incorporates precipitation, runoff, evaporation, and soil moisture as well as local conditions and snowpack. However, there are several different types of drought, all of which differ in the impact that water shortages can cause. The various types of drought include the following:

• Meteorological or climatological drought: the departure from a normal precipitation pattern, and the duration of this departure.

• Agricultural drought: Links the various characteristics of meteorological drought to agricultural impacts, focusing on precipitation shortages and soil-water deficits.

• Hydrological drought: the deficiencies in surface water and sub‐surface water supplies, measured in stream flow and as lake, reservoir and ground water levels.

• Socioeconomic drought: occurs when physical water shortage begins to affect people, individually and collectively. Most socioeconomic definitions of drought associate it with supply, demand, and economic factors.


Hazard History10 Oregon records, dating back to the late 1800s, clearly associate drought with a departure from expected rainfall. Concern for mountain snowpack, which feeds the streams and rivers, came later. Droughts were particularly noteworthy during the following years:

• 1904‐05: drought period of about 18 months

• 1917‐31: very dry period with brief rainy spells (1920, 1927)

• 1939‐41: three‐year intense drought

• 1965‐68: three‐year drought following the big regional floods of 1964‐65

• 1976‐77: brief, but very intense statewide drought

• 1985‐94: generally dry period, capped by statewide droughts in 1992 and 1994. In 1992, a drought emergency was declared for all of Oregon.

• 2001‐02: the second most intense drought in Oregon's history. This incident resulting in State and Federal Disaster declarations for several counties surrounding Union County.

• 2005: this drought affected at least eleven of Oregon’s thirty‐six counties

Probability of Future Occurrence Drought is a normal, recurrent feature of the North American climate but it is a temporary condition. Estimating drought probability and frequency continues to be difficult because of the many variables that contribute to weather behavior, climate change and the absence of long historic databases. Oregon weather patterns are driven by the impacts of El Nino and La Nina systems in the Pacific Ocean.

Once an El Niño or La Niña pattern is established, climatologists can project regional climatic behavior. The methodology consists of monitoring water temperatures, air temperatures, and relative humidity plus measuring sea‐surface elevations. Even so, all droughts are not associated with El Niño / La Niña events.

Vulnerability Assessment When a drought occurs, it may affect all aspects of a community. Urban areas usually fare better during a drought by encouraging or requiring water conservation measures during a drought and thereby reduce their demand for water.

Rural, less populated regions are much more dependent on water for irrigation to maintain and increase agricultural production.

10 The Oregon Weather Book, a State of Extremes (Corvallis, Oregon: Taylor, George H., and Hatton, Raymond R., 1999)


The State of Oregon Natural Hazard Mitigation Plan identifies Union County as an area with drought vulnerability.

Eastern Oregon University is located within the jurisdiction of the City of La Grande and the City provides water utilities for the campus. Water shortages and drought would impact the normal operations of the campus from residence life to facilities and maintenance

Risk Analysis The Union County NHMP identified probability of and vulnerability to drought for Union County and the City of La Grande. Eastern Oregon University’s Steering Committee used that information in assessing risk for the Eastern Oregon University campus and community and determined that the University experiences high probability (one incident likely within a 10 to 35 year period.) and low vulnerability (less than 1% affected). Union County City of La Grande Eastern Oregon


Vulnerability Low Low Low

Figure 3.8: Average Annual Precipitation in Oregon, 1971-2000

La Grande


Hazardous Materials Hazard Identification

Location and Extent of the Hazard Hazardous materials include chemicals used in manufacturing, household chemicals, crude oil and petroleum products, pesticides, herbicides, fertilizers, paints, medical wastes, radioactive materials and a host of other substances. Their manufacture, transport, storage, use and disposal may place public, property, and the environment at risk from their inadvertent or an intentional release.

There is one major transportation corridor, I-84, that passes through La Grande from east to west. The railroad also navigates along the east -west corridor of La Grande. The interstate highway and the rail line are rated to carry hazardous materials. An accident or sabotage of that material while it is in transit would impact the city of La Grande as well as Eastern Oregon University.

Causes and Characteristics of the Hazard Statistics show that nearly half of all hazardous materials incidents occur during transit. Hazardous materials incidents can happen at fixed sites or during transportation. Hazardous materials are transported by air, rail, truck, and ship.

Hazard History TBD

Probability of Future Occurrence Hazardous materials incidents may occur at any time and any place, when and where such materials are present under circumstances in which they may be released in sufficient volume and proximity to sensitive receptors and/or environments. The potential impact is dependent on the nature of the material, conditions of the release, and area involved. Releases may be small and easily handled with locally available emergency response resources or rise to the catastrophic level with immediate effect and long-term public health and environmental consequences.

Vulnerability Assessment Due to its proximity to both truck and rail transportation, Eastern Oregon University is vulnerable to hazardous materials accidents resulting in spills and leaks to the environment.

Airborne incidents would be problematic because La Grande is situated in a valley. The impact of the substance could be amplified if it cannot disperse fully and move outside of the valley.

Eastern Oregon University is located uphill from the I-84 and train corridors, so run-off would not directly impact the campus unless groundwater was also impacted. Additionally, if the interstate was closed


due to incident response, staff, faculty and students at Eastern Oregon University may not be able to access campus.

Risk Analysis Union County and City of La Grande did not include Hazardous Materials incidents in their NHMPs. Even so, Eastern Oregon University’s Steering Committee assessed risk for the Eastern Oregon University campus and community to hazardous materials incidents and determined that the University experiences high probability (one incident likely within a 10 to 35 year period.) and high vulnerability (more than 10% of the population affected.).

Union County City of La Grande Eastern Oregon

University Probability NA NA High

Vulnerability NA NA High

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