What is a Risk Assessment?
Risk assessment is the process of estimating or calculating the potential losses (in terms of life, injuries, and property and economic damage) resulting from a natural hazard event. To conduct this analysis, it is necessary to identify and understand the hazards that can impact the community (hazard identification and hazard profiling), assess the vulnerability of the people, buildings and infrastructure that can be impacted by each hazard identified (vulnerability assessment and asset inventory), and estimate the potential losses (risk analysis). Each of these tasks, as it pertains to the city of Glendale, is described further below:
1) Hazard Identification
This is the description of the geographic extent, potential intensity and the probability of occurrence of a given hazard. Maps are frequently used to display hazard identification data. The city of Glendale and its residents can be impacted by earthquakes (and secondary hazards triggered by earthquakes), storm flooding and debris flows, urban and wildland fires, landslides, dam and water reservoir failures, strong winds (such as Santa Ana winds), tornadoes, and dangerous vectors, plants and animals. Man-made hazards that could impact the area include terrorist attacks using weapons of mass destruction, accidental releases of hazardous materials, aviation accidents, and civil unrest events. However, the City has chosen to discuss only natural hazards in this document, and specifically the hazards of earthquakes, wildland fires, floods (storm flooding, debris flows and inundation due to catastrophic failure of dams and water reservoirs), and landslides. These are the hazards with the potential to cause the most damage, in terms of losses, at the city. Each of these hazards will be described in detail in the following sections. The geographic extent of each of the identified hazards has been identified in the City's Safety Element of the General Plan using the most current data available, and the maps that accompany that document have been included herein, throughout the text of the report, and in Appendix H (see list on Table 3.1 below).
2) Profiling Hazard Events
This process describes the causes and characteristics of each hazard, how it has affected the city of Glendale in the past, and what part of Glendale's population, infrastructure, and environment has historically been vulnerable to each specific hazard. A profile of each hazard discussed in this Plan is provided in Sections 6 through 9. Therefore, for a description of the history of hazard-specific events, please see the appropriate hazard section.
3) Vulnerability Assessment/Inventorying Assets
This is a combination of hazard identification with an inventory of the existing (or planned) property development(s) and population(s) exposed to a hazard. Critical facilities are of particular concern because these entities provide essential products and services to the general public that are necessary to preserve the welfare and quality of life in Glendale and fulfill important public safety, emergency response, and/or disaster recovery functions.
Table 3.1: List of Maps that are Part of this Local Natural Hazards Mitigation Plan
| Map/Plate |
Type of Map |
Section of the Plan |
| 1.1 |
City of Glendale (boundaries and major roads) |
Section 1: Introduction |
| 2.1 |
Freeways and Major Arterials in the Glendale Area |
Section 2: Community Profile |
| 2.2 |
Regional Active and Potentially Active Faults |
Section 2: Community Profile |
| 3.1 |
Critical Facilities in and Near Glendale |
Section 3: Risk Assessment |
| 6.1 |
Faults in and Near Glendale |
Section 6: Earthquakes |
| 6.2 |
Ground Shaking Zones in California |
Section 6: Earthquakes |
| 6.3 |
Earthquake Scenario for the 1857 San Andreas Fault Rupture |
Section 6: Earthquakes |
| 6.4 |
Scenario for a M6.7 Earthquake on the Verdugo Fault |
Section 6: Earthquakes |
| 6.5 |
Scenario for a M6.5 Earthquake on the Raymond Fault |
Section 6: Earthquakes |
| 6.6 |
Distribution and Severity of Damaged Residential Buildings in Glendale as a Result of Three Different Earthquake Scenarios |
Section 6: Earthquakes |
| 6.7 |
Distribution and Severity of Damaged Commercial Buildings in Glendale as a Result of Three Different Earthquake Scenarios |
Section 6: Earthquakes |
| 6.8 |
Distribution and Severity of Damaged Schools in Glendale as a Result of Three Different Earthquake Scenarios |
Section 6: Earthquakes |
| 6.9 |
Distribution of Damaged Bridges in Glendale as a Result of Three Different Earthquake Scenarios |
Section 6: Earthquakes |
| 7.1 |
Historical Wildfires in the Glendale Area |
Section 7, same as H-6 |
| 7.2 |
Fire Hazard Areas in Glendale |
Section 7, same as H-7 |
| 8.1 |
Geomorphic Map of Glendale Showing the Canyons Referred to in the Text |
Section 8, same as H-1 |
| 8.2 |
Effects of the 1934 Flood in Glendale |
Section 8, same as H-9 |
| 8.3 |
Dam Inundation Areas in Glendale |
Section 8, same as H-10 |
| 9.1 |
Geologic Map of Glendale |
Section 9, same as H-2 |
| 9.2 |
Slope Instability Map of the Glendale Area |
Section 9, same as H-11 |
| H-1 |
Geomorphic Map of Glendale |
Sections 1, 2, 6 - 9, Appendix H |
| H-2 |
Geologic Map of Glendale |
Sections 1, 2, 6, 8, 9, Appendix H |
| H-3 |
Historical Seismicity in Glendale |
Section 6, Appendix H |
| H-4 |
Fault Map of Glendale |
Section 6, Appendix H |
| H-5 |
Seismic Hazards Map of Glendale |
Section 6, 7, 9, Appendix H |
| H-6 |
Historical Wildfires in Glendale |
Section 7, Appendix H |
| H-7 |
Fire Hazard Areas in Glendale |
Section 7, Appendix H |
| H-8 |
Non-Compliant Roads in Glendale |
Section 7, Appendix H |
| H-9 |
Damage Resulting from 1934 Floods in Glendale |
Section 8, Appendix H |
| H-10 |
Dam Inundation Pathways in Glendale |
Section 8, Appendix H |
| H-11 |
Slope Instability Map |
Section 9, Appendix H |
| H-12 |
Critical Facilities in Glendale |
Sections 2, 3 |
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Note: These maps were derived from data provided by the City and/or publicly available sources. Care was taken in the creation of these maps, but the maps are provided "as is." The City of Glendale cannot accept any responsibility for errors, omissions or positional accuracy, and therefore, there are no warranties that accompany these maps. Although information from land surveys may have been used in the creation of these maps, this does not mean that the maps represent or constitute a land survey. Users are cautioned to field verify the information on these products before making any decisions.
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The critical facilities in Glendale have been identified and are illustrated in Map 3.1 and in Plate H-12 (Appendix H). In addition, this Plan includes a community issues summary in each hazard section to identify the most vulnerable and problematic areas in the city, including critical facilities, and other public and private properties.
4) Risk Analysis
The purpose of this task is to estimate the potential losses in a geographic area over a given period of time by assessing the damage, injuries, and financial costs likely to be sustained. This level of analysis involves using mathematical models. The two measurable components of risk analysis are magnitude of the harm that may result and the likelihood of the harm occurring. Describing vulnerability in terms of dollar losses provides the community and the State with a common framework by which to measure the potential effects of a given hazard on the assets of the area.
5) Assessing Vulnerability/ Analyzing Development Trends
This task provides a general description of land uses and development trends within the community so that mitigation options can be considered in land use planning and future land use decisions. This Plan provides comprehensive description of the character of Glendale in the Community Profile section (see Section 2). This description includes the geography and environment, population and demographics, land use and development, housing and community development, employment and industry, and transportation and commuting patterns. Analyzing these components of Glendale can help in identifying potential problem areas, and can serve as a guide for incorporating the goals and ideas contained in this Mitigation Plan into other community development plans.
Hazard assessments are subject to the availability of hazard-specific data. Gathering data for a hazard assessment requires a commitment of resources on the part of participating organizations and agencies. Each hazard-specific section of the Plan includes a section on hazard identification using data and information from City, County or State agency sources.
A loss estimate for the city of Glendale was conducted for the hazard of earthquakes. This estimate was done using HazUS, a standardized methodology for earthquake loss estimation based on a geographic information system (GIS). HazUS was created as a project of the National Institute of Building Sciences, funded by the Federal Emergency Management Agency (FEMA), and it is based on guidelines and procedures developed to make standardized loss estimates at a regional scale (allowing estimates to be compared from region to region). HazUS is designed for use by State, regional and local governments in planning for loss mitigation, emergency preparedness, response and recovery. HazUS addresses nearly all aspects of the built environment, and many different types of losses, and newer components of the program allow loss estimates for hurricanes, and floods in addition to earthquakes. The earthquake component has been tested against the experience of several past earthquakes, and against the judgment of experts. Vulnerability assessments and risk analyses for the other hazards addressed in the Plan, including floods, wildfires, and landslides, were not conducted, although qualitative assessments are included in the appropriate chapter for each hazard.
Regardless of the data available for hazard assessments, there are numerous strategies Glendale can take to reduce risk. These strategies are described in the action items detailed in each hazard section of this Plan. Mitigation strategies can further reduce disruption to critical services, reduce the risk to human life, and alleviate damage to personal and public property and infrastructure. Action items throughout the hazard sections provide recommendations to collect further data to map hazard locations and conduct hazard assessments.
Federal Requirements for Risk Assessment
Recent federal regulations for hazard mitigation plans outlined in 44 CFR Part 201 include a requirement for risk assessment. This requirement is intended to provide information that will help communities identify and prioritize mitigation activities that will reduce losses from the identified hazards. There are four natural hazards profiled in this Mitigation Plan, including earthquakes, wildfires, floods, and landslides. The Federal criteria for risk assessment and information on how the Glendale's Natural Hazard Mitigation Plan meets those criteria is outlined in the table below:
Critical Facilities and Infrastructure
Critical facilities are those parts of a community's infrastructure that must remain operational after a disaster. Critical facilities include schools, hospitals, fire and police stations, emergency operation centers, and communication centers. A vulnerability assessment for these facilities involves comparing the locations of these facilities to the hazardous areas identified in the city.
Other important facilities often considered in risk assessments include:
- High-risk facilities, if severely damaged, may result in a disaster far beyond the facilities themselves. Examples include power plants, dams and flood control structures, freeway interchanges, bridges, and industrial plants that use or store explosives, toxic materials or petroleum products.
- High-occupancy facilities have the potential of resulting in a large number of casualties or crowd-control problems. This category includes high-rise buildings, large assembly facilities, and large multifamily residential complexes.
- Dependent-care facilities, such as preschools and schools, rehabilitation centers, prisons, group care homes, and nursing homes, house populations with special evacuation considerations.
- Economic facilities are those facilities that should remain operational to avoid severe economic impacts. These facilities include banks, archiving and vital record-keeping facilities, airports, and large industrial or commercial centers.
Facilities critical to government response and recovery activities (i.e., life safety and property and environmental protection) include: 911 centers, emergency operations centers, police and fire stations, public works facilities, communications centers, sewer and water facilities, hospitals, bridges and roads, and shelters. Facilities that if damaged could cause serious secondary impacts may also be considered "critical."
Lifelines are those services that are critical to the health, safety and functioning of the community. They are particularly essential for emergency response and recovery after a disaster. Furthermore, certain critical facilities designed to remain functional during and immediately after a disaster, such as an earthquake, may be able to provide only limited services if the lifelines they depend on are disrupted. Lifeline systems include water, sewage, electrical power, communication, transportation (highways, bridges, railroads, and airports), natural gas, and liquid fuel systems.
Some of the critical facilities in the city of Glendale are shown on Map 3.1 and in Plate H-12.
Summary
Natural hazard mitigation strategies can reduce the impacts concentrated at large employment and industrial centers, public infrastructure, and critical facilities. Natural hazard mitigation for industries and employers may include developing relationships with emergency management services and their employees before disaster strikes, and establishing mitigation strategies together. Collaboration among the public and private sector to create mitigation plans and actions can reduce the impacts of natural hazards.
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