How was mauna loa formed

OK, the whole Hawaiian Island chain is volcanic, formed from volcanoes which rose in turn from the ocean floor, erupted, formed an island around, then became less and less active in turn as the whole island chain moves away to the NW at 2 - 4 in per year.

Mauna Loa is one of 5 volcanoes which have formed the main island Hawaii. It is still active, and is a wide flattish volcano 4169 metres above sea level (13 679 ft).

It probably started erupting under the sea about 700 000 yrs ago, and rose above the surface about 400 000 yrs ago. It is a young volcano in geological terms as the oldest rocks found on its surface are 200 000 yrs old.

There is heaps more info here, but take care as some teachers do not like you to quote Wikipedia as a reference.

http://en.wikipedia.org/wiki/Mauna_Loa