**7.3 Dam foundations**

A site investigation shall be carried out prior to construction to verify the nature of the foundation. By knowing the actual foundation condition at the site, the earth dam can then be designed accordingly. An embankment foundation is said to be suitable if it is able to provide stable support for the bridge under all conditions of

saturation and loading and that it provides adequate leakage resistance to avoid excessive water loss [42, 43].

The foundation of the dam may be broadly classified into three types which are rock foundations, coarse-grained material foundations and fine-grained material foundation [43].

These foundations may need to be treated to stabilize any weakness and also to reduce leakage. On the other hand, rock foundation must be inspected for erosive leakage and excessive uplift pressure. If such conditions exist, the foundation must be considered grouting [9, 43].

## **7.4 Dam seismicity**

Induced earthquakes refer to the earthquakes and slight tremors that result from human activity that alter the stresses and stresses on the Earth's crust. Most of the induced earthquakes are of low magnitude [44].

Seismic hazard from induced seismic activity can be assessed using techniques similar to natural earthquakes, although one account for unstable earthquakes. Earthquakes vibrating from induced earthquakes appear to be similar to those observed in natural tectonic earthquakes, although differences in rupture depth need to be taken into account. This means that ground motion models derived from natural seismic recordings can be used, which are often more numerous in robust motion databases compared to induced earthquake data. Then, a risk assessment can be performed, taking into account earthquake risk and the vulnerability of vulnerable items (such as local residents and building stock). Finally, risk can, in theory at least, be mitigated, either through modifications of the risk or reduced exposure or vulnerability [44].
