Partnerships for Reducing Landslide Risk Assessment of the National Landslide Hazards Mitigation Strategy (2004) / Chapter Skim
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3 Landslide Mapping and Monitoring
3 Landslide Mapping and Monitoring
Pages 31-50
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From page 31... ...
Most local governments do not have landslide hazard maps and do not have funding available for mapping activities, and such communities usually look to a higher level of government for mapping.
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From page 32... ...
It is important that the details of the cooperative mapping partnership be worked out carefully, in close consultation with state geologists, as the national strategy implementation plan is being developed. The principles and scope of the landslide hazard mapping, assessment, and delineation task contained within the USGS National Landslide Hazards Mitigation Strategy (Spiker and Gori, 2000)
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From page 34... ...
The fundamental importance of landslide hazard mapping, assessment, and delineation to the development of effective loss reduction strategies is discussed in section 3.3. It defines the role of landslide donation mapping in defining priorities for landslide investigations, monitoring activities, or mitigation programs within national, regional, or local landslide hazard mitigation plans.
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From page 35... ...
These document the locations and outlines of landslides that have occurred in an area during a single event or multiple events. Small-scale landslide inventory maps may show only landslide locations and general outlines of larger landslides, whereas large-scale maps may distinguish landslide sources from landslide deposits, classify different kinds of landslides, and show other pertinent data (Figure 3.1~.
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From page 37... ...
They allow variations in the safety factor to be approximated and, thus, yield information useful to design engineers. In an environment where choices must be made from a number of possible mapping approaches, the proposed National Landslide Hazards Mitigation Program can play a vital role in evaluating methods, setting standards, and ratifying procedures.
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From page 38... ...
Because landslides directly affect the ground surface, remote-sensing techniques are well suited to slope instability studies. Remote-sensing images can provide diagnostic information concerning the overall terrain conditions that often are critical for determining susceptibility to slope instability.
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From page 39... ...
The comparatively recent advent of commercial satellites capable of providing images with 1-m, and even submeter resolution suggests that such satellite imagery will form an important component of future landslide studies.
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From page 42... ...
These early maps show that high-resolution airborne LIDAR surveys can reveal previously unrecognized deep-seated landslides, can capture the sharp edges of small shallow landslide scarps and debris flow runout tracks, can show debris flow fans, and can greatly improve models for mapping shallow landslide potential. Much work lies ahead in learning how to exploit these data.
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From page 45... ...
A hazard mitigation clause is incorporated into FEMA-state agreements for disaster assistance, stipulating the identification of hazards and the evaluation of hazard mitigation opportunities as a requirement for federal assistance. In the case of state-declared disasters, some states also require the development of local hazard mitigation plans, and thus landslide zoning maps, as a prerequisite for receiving state emergency relief funds.
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From page 46... ...
46 PARTNERSHIPS FOR REDUCING LANDSLIDE RISK A national landslide inventory would form an important first step toward an appreciation of the true scope and distribution of landslide hazards. An accurate inventory would provide metrics for national policies and would greatly reduce the present uncertainty concerning the magnitude of economic loss and environmental damage caused by land
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From page 47... ...
3.4 LANDSLIDE MONITORING TECHNIQUES Monitoring existing landslides and sites of potential landslides plays an important role in landslide loss mitigation and landslide research. Monitoring serves several important purposes: · Identification of initiation of sliding or increased rates of sliding to provide a basis for alarms and warnings that can reduce landslide hazards · Determination of the depths and shapes of landslide masses as an adjunct to susceptibility and hazard mapping · Development of improved understanding of landslide processes and triggering mechanisms · Development of improved understanding of causative factors, such as earthquakes or high rainfall events · Evaluation of the effectiveness of control measures.
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From page 48... ...
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From page 49... ...
There is potential for broad application of such efforts to critical areas, with the likelihood that the involvement of FEMA in the partnership would assist emergency management. The USGS has taken the lead in applying the latest monitoring technologies in its volcano hazard program, and in its use of such technology for landslide monitoring at the Highway 50, Rio Nido, and Mission Peak landslides in California, it has worked with state agencies with the intention of ultimately transferring these capabilities to the state.
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From page 50... ...
Private firms in the electronic and telecommunication fields will play an essential role in developing new technologies and bringing them to market. Private firms in the geotechnical consulting field will make use of these technologies to improve the state of practice in landslide monitoring for their private and public sector clients.
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