Disaster Management · M2 · revision
Earthquakes, floods and cyclones
Last-day M2 revision
Short revision after the complete lessons
| Topic | Recall |
|---|---|
| Earthquake cause | Fault slip releases stored strain; waves transmit energy. |
| Focus / epicentre | Origin within Earth / surface point above it. |
| Waves | P parallel compression; S transverse shear; Love/Rayleigh surface waves. |
| Magnitude / intensity | Source size / local observed effects. |
| Magnitude +1 | Amplitude ×10; approximate energy ×31.6. |
| Flood mechanisms | Too much water for available storage/conveyance; exposure and vulnerability determine losses. |
| Urban flood | Impervious cover, blocked/constrained drainage and loss of natural storage. |
| Cyclone | Warm ocean, moisture, rotation and suitable atmospheric conditions; eye, eyewall and rainbands. |
| Cyclone hazards | Wind + surge + rain; a calm eye is not the all-clear. |
| IMD stages | Pre-cyclone watch 72 h, alert 48 h, warning 24 h before expected adverse weather; post-landfall outlook 12 h before expected landfall. |
Measures: always include the reason
Earthquake: safe construction and retrofitting reduce collapse. Flood: drainage and storage reduce water accumulation; zoning reduces exposure. Cyclone: warnings plus accessible shelters and evacuation reduce life risk; resilient construction reduces damage.