Lecture 7: Data for monitoring natural hazards: Disaster risk reduction Flashcards
Large spatial and temporal range
of such hazards
…Need a range of different techniques to monitor them
Remote sensing: satellite & aircraft
Ground observations: direct sensors
Remote sensing: satellite and aircraft
Can see large areas
Lower resolution
Gaps in coverage
Ground observations: direct sensors
Can see limited area
Higher resolution
Volcano hazards
Pyroclastic flow Lahars / mud flow Noxious gasses (CO2) Earthquakes Eruption plumes
Climate impacts
Sulphate aerosols
Ground observations for volcanos
Surface deformation
Tiltmeters (changes in slope)
GPS
Seismicity
Seismographs
Gas emissions
Collected from vents and fumaroles
Volcano detections
Gas emissions
Increase in gas emissions may indicate potential eruption
Volcano detections
Ground based remote sensing
Perform transects beneath the plume to sum overhead concentrations across profile and find total emission.
Provides fine spatial resolution
But poor spatial coverage
To get better spatial coverage need to get higher
Volcano detections
Volcano surface deformation
Stage 1: Inflation begins as magma moves into the volcano or as pressure increases in the magma chamber
Stage 2: As magma chamber inflates the sound surface above it is displaced
Stage 3: After an eruption, the magma chamber deflates.
Ground surface subsides with potential formation of crater.
Volcano detections
Seismicity
Magma fractures cooler rock causing earthquakes
An increase in the number of earthquakes may indicate an imminent eruption
What do crater lakes on volcanoes act like?
Calorimeters, absorbing heat given off by intruding magma
Approximately 12% of the world’s 700 or so active volcanoes have crater lakes.
Remote sensing: satellite and aircraft
What is it?
Defines as ‘study of Earth and its environment from a distance via emitted or reflected electromagnetic energy”
-i.e not in contact with the object under study
Remote sensing
Can be:
Ground based (tower, handheld device)
Airborne
Spaceborne
Advantages of space borne remote sensing
Obtain data over large areas (e.g global)
Provide a time series of consistent data
Acquire data in inaccessible and remote areas
Potential to provide data at a high temporal frequency compared to ground observations
Thermal observations useful for monitoring:
1) Volcanic monitoring
Ash (contaminates water, respiratory hazard, danger to aircraft)
Lava and pyroclastic flows (cause fatalities, destroy property)
2) Wildfire
Respiratory hazard, cause fatalities, destroy property, contaminates water
InSAR
Interferometric Synthetic Aperture Radar
Maps ground deformation
Comparison of two or more radar images
Managing hazards
Speed of onset (slow = drought; fast = earthquake)
Magnitude (strength/force) (e.g. wind speed, height of tide)
Frequency (return period, e.g. 1 in 100 years)
Intensity (severity/impacts) = disaster potential scales
Hazard + Vulnerability =
Risk
- Long term planning (mitigation)
Aim: To eliminate or reduce the probability of a disaster, or reduce the effects of unavoidable disasters.
E.g.: undertake vulnerability analyses; active public education; implement tax incentives and disincentives to change public behaviour towards risk; re-allocate resources; introduce preventive health care.
E.g. to facilitate recovery: strengthen building codes and regulations; reconsider zoning and land-use management; disaster unemployment insurance and risk assessment studies.
Other forms of Long Term Mitigation
Structural measures
e.g. engineering technologies to make infrastructure more robust to hazards.
Other forms of Long Term Mitigation
Non-Structural measures
e.g. land-use planning and regulation + information dissemination + economic incentives to reduce deliberate or accidental exposure.
Other forms of Long Term Mitigation
Risk-spreading measures
Risk-spreading measures e.g. economic measures to encourage higher long term preparedness, such as loss insurance.
- Prepare
Aim: Activities taken prior to a disaster, to save lives, minimize disaster damage, and enhance response operations.
E.g.: preparedness plans; emergency exercises/training; early warning systems; emergency communications systems; evacuation plans and training; mutual aid agreements; and public information/education.
- Respond
Aim: Activities immediately before, during and following a disaster to provide emergency assistance for casualties, reduce the probability of secondary damage, and speed recovery operations.
E.g.: public warning systems; notifying public authorities; mobilizing emergency personnel/equipment; emergency medical assistance; manning emergency operations centres; declaring disasters and evacuating; mobilizing security forces; search and rescue; and emergency suspension of laws.
- Recovery
Aim: Activities following a disaster, which continue until all systems return to normal or better.
E.g.: Returning life-support systems to minimum operating standards; damage insurance/loans and grants; temporary housing; long-term medical care; public information; health and safety education; reconstruction; counselling programs; and economic impact studies.
