The major portion of the city is at the sea level while the maximum height of the city is at 450 metres. It covers a total area of 437.71 square kilometers which is an aggregation of seven islands joined together by means of century long reclamation.
The soil type is predominantly sandy due to its proximity to the sea. In the suburbs, the soil cover is largely alluvial and loamy. The underlying rock of the region is composed of black Deccan basalt flows, and their acid and basic variants dating back to the late Cretaceous and early Eocene eras. Mumbai falls in the seismic zone that may experience an earthquake up to a magnitude of 6.5 on the Richter scale.
