Tanks are large diameter (Say, 30 - 50 m) cylindrical-shaped Reinforced Concrete structures. It can also be made of steel plate with vertical beam supports @ say, 3.0 m as well as horizontal beams. However, whatever may be a structure made of, all the forces that tend to destroy it are taken into account when design engineers do stress analysis.
Generally speaking, the structure is designed and built to carry a load 1.5 times (Safety Factor (SF)=1.5) larger than the imposed loads. Piles may be used in soft land in BD whereby it is a single RC slab on top of many piles. But, in the case of countries like SA, it may be bench type circular grade beams below the tank wall, but without piles and the interior space inside the circle filled with sand or sandy soil compacted.
Many tanks are built in a single area and the tank yard is fully surrounded by retaining walls to stop oil flowing out in an accident. There are also separate walls with holes behind which fire brigade staff can safely pump foam/water in case of emergency.
Please note that for a 8 m high tank the vertical load is 8 t/m2 (only for oil/water and not other loads) on the soil. BD soil may not bear more than 4 t/m2. Horizontal wind load is not that much but the horizontal component of earthquake load is too high, may by 25% of the total dead and live loads depending upon the intensity of earthquake.
A design engineer considers all these destabilizing factors. I have noted you have quite a knack in civil engineering. May be you could have done also good had you studied engineering and worked in a developed country to gain experience.