Borehole construction and its effect on the environment

I have always wondered why everyone wants to own a borehole. Recently, I learned that Nigeria is seriously prone to earthquakes because of the number of boreholes being bored on a daily basis.

1. Can some one please explain if there is any adverse effect of borehole construction on environment (mostly on ground water)? Is there any study done particularly for the The Nigerian terrain ?
2. Is this true that there is danger of earthquake in areas hugely drilled by bore holes?
3. Does every country have different regulations for bore hole drilling?