How are earthquakes predicted?

Answer 1

Seismologists prefer to attempt to quantify the risk posed by a particular fault zone rather than state exactly when an earthquake will occur (as this is currently impossible).

In order to assess the risk of an earthquake posed by a given fault it is necessary to understand what causes earthquakes in the first place.

In simple terms they are caused by a build up of deformation in the Earth's crust which stores energy. When the stress becomes too large, exceeding the strength of the rock, the fault zone suddenly slips and all the energy is released in one instant in the form of an earthquake.

As such, seismologists will attempt to measure the movement of the crust around a fault zone to estimate the total strain that has accumulated. This measurement is often made using high precision GPS to measure relative positions of surface features around the fault zone. They may also use terrestrial laser scanning equipment which can measure changes in the ground shape (recording deformation) or by using a special form of radar and a technique called synthetic aperture radar interferometry (InSAR for short). This process essentially involves the use of a radar to create a series of very accurate relief maps of the ground surface over time and then to compare the maps to create a final plot showing the changes between them which is a record of the land surface deformation.

They may also use strain gauges and tilt metres within boreholes to observe ground deformations as well as a technology known as time domain reflectometry which is an electrical technique used to locate damage and deformation in electrical cables and which in turn can be used to measure subsurface deformations.

Using this information and an estimate of the strength of the rock mass, seismologists will attempt to quantify the likely risk of occurrence of an earthquake on that fault zone.

For example, seismologists had warned that a magnitude 7.0 or greater event was expected to occur on the Enriquillo-Plantain Garden fault system (which caused the very destructive earthquake which affected Haiti in January 2010) due to the accumulated strain that had built up, however they were not able to state exactly when it would occur.

Answer 2

Seismologists prefer to attempt to quantify the risk posed by a particular fault zone rather than state exactly when an earthquake will occur (as this is currently impossible).

In order to assess the risk of an earthquake posed by a given fault it is necessary to understand what causes earthquakes in the first place.

In simple terms they are caused by a build up of deformation in the Earth's crust which stores energy. When the stress becomes too large, exceeding the strength of the rock, the fault zone suddenly slips and all the energy is released in one instant in the form of an earthquake.

As such, seismologists will attempt to measure the movement of the crust around a fault zone to estimate the total strain that has accumulated. This measurement is often made using high precision GPS to measure relative positions of surface features around the fault zone. They may also use terrestrial laser scanning equipment which can measure changes in the ground shape (recording deformation) or by using a special form of radar and a technique called synthetic aperture radar interferometry (InSAR for short). This process essentially involves the use of a radar to create a series of very accurate relief maps of the ground surface over time and then to compare the maps to create a final plot showing the changes between them which is a record of the land surface deformation.

They may also use strain gauges and tilt metres within boreholes to observe ground deformations as well as a technology known as time domain reflectometry which is an electrical technique used to locate damage and deformation in electrical cables and which in turn can be used to measure subsurface deformations.

Using this information and an estimate of the strength of the rock mass, seismologists will attempt to quantify the likely risk of occurrence of an earthquake on that fault zone.

For example, seismologists had warned that a magnitude 7.0 or greater event was expected to occur on the Enriquillo-Plantain Garden fault system (which caused the very destructive earthquake which affected Haiti in January 2010) due to the accumulated strain that had built up, however they were not able to state exactly when it would occur.

Answer 3

Earthquakes cannot be predicted with certainty. Scientists use seismometers to monitor shifts in the Earth's crust and track historical seismic activity to estimate the likelihood of potential earthquakes in a specific region. However, the exact timing and location of an earthquake remain unpredictable.