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Findings on Earthquake
Context:
New findings challenge traditional beliefs about the cause of earthquakes.
More on News:
- Researchers at Brown University adding a new insight to a long-held belief about what causes seismic quakes.
- The way fault networks are aligned plays a critical role in determining where an earthquake will happen and its strength.
As per the findings, described in the journal Nature:
- Traditional Notion of Earthquake:
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- When friction is stable, the plates then slide against each other slowly without causing an earthquake.
- This steady and smooth movement is also known as Creep.
- People used to measure the frictional properties, like whether the fault zone has unstable friction or stable friction.
- Based on laboratory measurements of fault zone stability, try to predict whether earthquakes will occur.
- When friction is stable, the plates then slide against each other slowly without causing an earthquake.
- New findings on the Earthquake:
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- Rapid slip and intense ground motions that follow are a result of unstable friction that can happen at the faults.
- Understanding the fault network geometry could improve predictions of where the most damaging earthquakes will occur, beyond just looking at the frictional properties at the fault boundaries.
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- The geometry to consider includes complexities in the underlying rock structures such as bends, gaps and stepovers.
- The geometry of fault lines, like the serrated teeth of a saw, determines whether earthquakes occur.
- Fewer, duller “teeth” allow smooth sliding.
- When rock structures in these faults are complex then rock structures catch on each other, build pressure, pull and push harder and suddenly break, causing earthquakes.
Bends: Refer to areas where the fault bends or curves, creating a change in the direction of the fault.
Gaps: Refer to segments of a fault that have not experienced significant seismic activity for an unusually long time compared to other parts of the same fault.
Stepovers: Areas where two or more faults intersect or overlap, creating a gap or a bend in the fault line.
About Earthquake:
- Earthquakes are the result of sudden movement along faults within the Earth.
- The movement releases stored-up ‘elastic strain’ energy in the form of seismic waves, which propagate through the Earth and cause the ground surface to shake.
- Epicentre: Location on the surface of the Earth directly above where the earthquake starts.
- Focus (Hypocenter): Location in the Earth where the earthquake starts.
Main Reason of earthquakes:
- Movement of Plate tectonics:
- The Earth’s outermost layer is fragmented into about 15 major slabs called tectonic plates.
- They move very slowly relative to each other, but this still causes a huge amount of deformation at the plate boundaries, which in turn results in earthquakes.
- During an earthquake, the rock on one side of the fault suddenly slips with respect to the other.
About Faults:
- Fault is a fracture or zone of fractures between two blocks of rock.
- Faults allow the blocks to move relative to each other.
- This movement may occur rapidly, in the form of an earthquake – or may occur slowly, in the form of creep.
