Q: What is an earthquake and what causes them to happen?
Ans: An earthquake is caused by a sudden slip on a geological fault line. The tectonic plates are always slowly moving, but they get stuck at their edges du to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the Earth’s crust and cause the shaking that we feel.
Q: What’s the difference between foreshocks and aftershocks?
Ans: “Foreshock” and “aftershock” are relative terms. Foreshocks are earthquakes that precede larger earthquakes in the same location. Aftershocks are smaller earthquakes that occur in the same general area following a larger event or “main shock”.
As a general rule, aftershocks represent minor readjustments along the portion of a fault that slipped at the time of the main shock. The frequency of these aftershocks decreases with time, but they can go for weeks or some times months.
Q: Can the position of the Moon or the Planets affect seismicity?
Ans: The Moon, Sun and other planets have an influence on the Earth in the form of perturbation (small changes) to the gravitational field. Many studies in the past have shown no significant correlations between the rates of earthquakes occurrence and the seme-di-urnal tides when using large earthquake catalogues.
Dos and Don’ts:
1. If indoors, drop to the ground. Take cover by getting under a sturdy table or other piece of furniture. If there is no desk or table, cover the face and head with arms and crouch in an inside corner of the building.
2. If outdoors, move away from buildings, trees, street lights and utility wires.
3. If in a moving vehicles, stop as quickly and stay in the vehicle.
4. If trapped under debris, do not light a match; do not move about or kick up dust; tap on a pipe or wall so rescuers can locate you.
5. Use a whistle if one is available. Shout only as a last resort. Shouting can cause you to inhale dangerous amounts of dusts.
Nepal Earthquake Images