Lithosphere is the crust and upper mantle of the earth.
Answer:
Explanation:
Push factors: Push factors are those factors that force an individual to leave a place. If not left the individual will have to risk something. some examples of push factors are Famine, drought, conflict or extreme religious activity.
Pull factors: pull factors are those factors that attract an individual or group to leave their home. It is the desirability of a place that attracts, also, called place utility. Better job opportunity, Better Economic activity and better living standards are are some factors in pull factor.
Because they have the most to lose, imagine it like you have 10 towers and all collapsed from a tsunami. And the village next to you also collapses. The ten towers lost way more money and people in it then the villages
In short answer, The developed country just simply has a lot more to lose then the lesser developed one.
They do not occur only during spring they occur when the sun, moon, and earth are all alined.
Continental drift is the name of this theory.