Page:Niger Delta Ecosystems- the ERA Handbook, 1998.djvu/179

Environmental Impact of the Oil Industry 15.5 SPECIFIC IMPACTS

15.5.1 SEISMIC PROSPECTING ACTIVITY

Interfaces of seismic activities and the environment (from an SPDC fact book of 1993):

SPDC Eastern Division Seismic Activity from (from an SPDC fact book of 1993):

There are five main specific impacts of seismic surveying.

As shown in the table above, the lines cleared for seismic surveying cover great distances, often giving access to otherwise relatively inaccessible areas.

Onshore, these can set up shock waves strong enough to damage buildings and certainly have a compacting effect upon soil structure. Also, if the boreholes are not back-filled with the same material that came out of them and compacted to a natural state, localised drainage and or water-logging problems can arise.

Although seismic prospecting is only a temporary exercise and much of the damaged vegetation recovers, some economic tree crops may be irrecoverably damaged or lost, while mangrove forests seem to be especially damaged with survey lines remaining 177