Earthquakes

सारांश

An earthquake is the sudden release of elastic strain energy along a fault, producing seismic waves.

मूल विचार

प्रणाली को समझें

An earthquake is the sudden release of elastic strain energy along a fault, producing seismic waves.

क्यों और कैसे होता है

कारण और संदर्भ

Earthquakes occur when tectonic stress overcomes frictional resistance on a fault. Elastic strain accumulates during locked motion, rupture releases that strain suddenly, and the resulting seismic waves transmit energy through the crust and across the surface.

यह कैसे काम करता है

First, stress deforms rocks around a locked or slipping fault. When resistance is exceeded, rupture starts at the focus and propagates. P, S and surface waves then travel outward; shaking, rupture, liquefaction and secondary hazards vary with distance and ground conditions.

मुख्य तथ्य

• Focus is the underground origin; epicentre is its surface projection.
• P-waves are fastest; S-waves cannot pass through liquids.
• Magnitude measures released energy, whereas intensity describes observed effects at a place.

ज़रूरी शब्द

• focus
• epicentre
• fault
• magnitude
• intensity

उदाहरण और केस स्टडी

• The 2015 Nepal earthquake illustrates how Himalayan convergence creates seismic risk.

कारण और घटक

• Elastic strain accumulates as fault-block motion is temporarily locked by friction.
• Rupture begins when shear stress exceeds fault resistance.
• Tectonic loading, volcanic activity, collapse or human activity can trigger seismic events.

प्रभाव और महत्व

• Seismic shaking damages buildings, roads, bridges and lifelines.
• Surface rupture, liquefaction, landslides and fires create secondary losses.
• Undersea displacement can generate a tsunami.

भूगोल से जुड़ाव

The 2015 Nepal earthquake illustrates how Himalayan convergence creates seismic risk. This illustrates how earthquakes varies by location, scale or environmental context.

बांग्लादेश से जुड़ाव

Bangladesh faces earthquake risk from the Dauki Fault, Madhupur Fault and active tectonic systems toward the Indo-Burma ranges.

BCS प्रारंभिक के तथ्य

• Focus is the underground origin; epicentre is its surface projection.
• P-waves are fastest; S-waves cannot pass through liquids.
• Magnitude measures released energy, whereas intensity describes observed effects at a place.

BCS लिखित विश्लेषण

एक विश्लेषणात्मक उत्तर बनाएँ

• Explain elastic rebound from stress accumulation to fault rupture and wave propagation.
• Distinguish magnitude as source energy from intensity as observed effect at a site.
• Discuss Bangladesh preparedness through seismic codes, land-use planning, public awareness and resilient lifelines.

आम गलतफ़हमियाँ

• Magnitude and intensity are not interchangeable.
• The epicentre is not the underground point where rupture begins.

झटपट दोहराव

• Earthquakes
• Focus is the underground origin; epicentre is its surface projection.
• P-waves are fastest; S-waves cannot pass through liquids.
• focus / epicentre
• Definition → process → spatial example