prediction and forecasting of hazards Flashcards
hazard prediction
-knowing when/where a hazard will strike on a spacial and temporal scale
hazard forecasting
-provides a % of a hazard occuring
earthquake prediction (key points)
-cannot be validly predicted
-areas at high risk can be identified by looking at frequency patterns from previous earthquakes
-seismic gaps are used
-can only calculate the probability not deterministic
what are seismic gaps
-areas that have not experienced an earthquake for some time and are “overdue” can lead to high risk
tsunami prediction (key points)
-partially predictable as they are a secondary impact of seismic activity but eq cant be predicted
-the DART system is example that can detect a tsunami as small as a cm high
how does the dart system work
-seismometers can detect when a eq has occurred
-open ocean monitoring equipment e.g. sensors that sit on sea floor detect tsunami passing overhead
-buoy relays message to shore via satellite
what is the DART system
-deep ocean assessment and reporting of tsunamis
Volcano eruption prediction (key points)
-are predictable to an extent
-prediction is expensive and difficult to pinpoint
what helps prediction of volcano eruption
-seismographs/ seismometers to track eq’s and the length/strength
-satellites to monitor temp and deformation
-gas spectrometers to analyse gas emissions from vents
-history of volcanic activity- time span between eruptions and how long since last eruptions
what makes prediction, monitoring, forecasting difficult for volcanos
-expensive
-difficult to pinpoint exactly when it will happen
-temporal extent and magnitude hard to pin down
what does prediction of tsunami depend on
-the technology in place
what can scientists use to predict tsunami’s
-computer-simulated tsunami at digital representation of coastline
-predict when, how far inland, and how high
-predict when to evacuate
what are forecasts made on and how do they vary- eq
-long term forecast more reliable than short term
-made on seismic monitoring networks, historical data, high density local monitoring
what is the main reason why its we cant predict earthquakes
-cant identify a diagnostic precursor e.g. characteristic, change, etc
why are earthquakes difficult to predict
-crust response to changing stress non-linear
-eq’s originate kilometres beneath ground, so data gathering depends on effects at surface as hard to drill into ground
-there’s no definitive pattern of earthquake activity- small eq’s don’t mean a large one- can be swarms of small eq’s
