Page 1 - Lesson notes- Terms related to Earthquake

SAI INTERNTIONAL SCHOOL
Class 8
Lesson notes
Subject- Physics
Ch- Some Natural Phenomena
Subtopic- Terms related to earthquake

Terms related to earthquake:
• Seismic zone: The boundaries of tectonic plates are weak zones which
are prone to earthquake. These weak zones are called seismic zone or
fault zone.
o Fault zones in India: Western and central Himalayas
o Whole North-East region
o Rann of kutch
o Rajasthan
o Indo-Gangetic Plane.
• Richter scale: It is a scale in which power of Earthquake is expressed as a
number. It is a logarithmic scale. The earthquake with value more than 7 is
destructive in nature.
• Seismograph or seismometer: It is an instrument used to detect and
record earthquakes. It measures the intensity of an Earthquake.
• Seismic waves: It is the wave produced due to disturbance below the
Earth’s surface, which travels to the earth and give rise to tremors.
• Mercalli scale: It is another scale used to measure an earthquake. It is
based on observed effect of any earthquake.
• Focus (Hypocentre): It is the point below the Earth’s crust where
earthquake originates.
• Epicentre: It is the point just above the focus, on Earth’s Surface.