high as desired). Additionally, the seismic wavelet cannot be precisely removed to yield spikes or impulses (the ideal aim is the dirac delta function) corresponding to reflections on seismograms. A factor that contributes to the varying nature of the seismic wavelets corresponding to explosive sources is the fact that with each explosion at the prescribed locations, the subsurface's physical properties near the source get altered; this consequently results in changes in the seismic wavelet as it passes by these regions. Vibratory sources (also known as Vibroseis) are the most commonly used seismic sources in the oil and gas industry. An aspect that sets this type of source apart from explosives or other sources is that it offers direct control over the seismic signal transmitted into the subsurface i.e. energy can be transmitted into the subsurface over a known range of frequencies over a specified period of time. Vibratory sources typically host trucks that are mounted with heavy plates which repeatedly hit the ground to transmit seismic energy to the subsurface. The figure on the right shows one such Vibroseis, known as the Nomad 90. Vibratory sources are often employed where vast areas need to be explored and where the acquisition region does not feature densely populated or densely vegetated areas; highly varying topography also inhibits the employment of vibratory sources. Additionally, wet regions are also suboptimal for vibratory source use since these trucks are extremely heavy and hence tend to damage property in wet terrains. Weight Drop sources, such as the hammer source, are simpler seismic sources that are typically employed for near-surface seismic refraction surveys. This type of source often only involves a weight source (e.g. hammer) and a plate (alongside a trigger to initiate recording on receivers) and hence is logistically feasible at most locations. Its usage mainly being in the near-surface surveys is associated with the smaller amplitudes generated and hence smaller penetration depths compared to vibratory and explosive sources. As in the case of explosive sources, weight drop sources also utilize an unknown source wavelet which offers difficulty in optimal vertical stacking and deconvolution. Source types for marine acquisition Air-gun is the most commonly used seismic source in marine seismic acquisition since the 1970s. The air-gun is a chamber that is filled with highly pressurized, compressed air which is rapidly released into the water to generate an acoustic pulse (signal). The factors contributing to its common