Earthquake Flashcards
Focus and epicentre
The point where the energy is released
point on the surface directly above the focus is called epicentre
isoseismic line
line connecting all points on the surface where the intensity is the same is called an isoseismic line
Foreshocks and aftershocks
Major or even moderate earthquake of shallow focus is followed by many lesser-size earthquakes known as aftershocks.
A mild earthquake preceding the violent shaking movement of an earthquake is known as a foreshock.
3 cause of earthquake
Fault zones
Plate tectonics
Reservoir induced seismicity
Most powerful earthquake are associated with which boundary?
Convergent boundary
How Reservoir-induced seismicity can cause earthquake?
Loading and unloading of water can significantly change the stress.
Example: Koynanagar earthquake occurred near the Koyna Dam reservoir in Maharashtra
Type of earthquake based on depth of focus
Shallow earthquakes are 0 – 70 km deep.
- Intermediate earthquakes are 70 – 300 km deep.
- Deep earthquakes are 300 – 700 km deep.
Which is more frequent shallow, intermediate or deep?
Shallow
What are shallow earthquake
comparatively of low magnitude, shallow focus earthquakes can cause relatively greater damage at the surface (as the whole energy is directed towards a small area) compared to their deep-focus counterparts.
Deep-focus earthquake
deep-focus earthquakes” is applied to earthquakes deeper than 70 km, commonly occur in patterns called Benioff zones.
earthquakes alone may not cause much destruction as the foci of the quakes lie at great
depths and the energy of the quakes dissipates over a wide area.
What are Wadati–Benioff zone: Earthquakes along the Convergent boundary
Diagram
It is a zone of subduction along which earthquakes are common.
The most powerful earthquakes occur along this zone
Tsunami is a Japanese word for
Harbour wave
