Question

The focus of the earthquake is also known as :

• A. The Epicentre
• B. The hypocentre
• C. Iso centre
• D. The principal centre

Answer 1

Answer:

B. The hypocentre

• Definition: The focus, technically known as the hypocenter, is the specific point within the Earth where an earthquake rupture begins.
• Key Distinction: It is located deep underground along a fault line, whereas the epicenter is the point on the Earth's surface directly above the focus.
• Seismic Waves: Seismic energy is released from the focus in the form of waves, specifically P-waves (primary) and S-waves (secondary), which propagate outward through the Earth's crust.
• Depth Classification: Earthquakes are categorized by their focal depth:
  • Shallow-focus: 0 to 70 km deep (most destructive and common).
  • Intermediate-focus: 70 to 300 km deep.
  • Deep-focus: 300 to 700 km deep.
• Technical Significance: The depth of the focus is a critical parameter in determining the intensity and potential impact of an earthquake at the surface level.