Introduction
Seismic surveys are divided into land and marine surveys. Although the land seismic equipments are quite different than the marine one, the source, receivers and acquisition equipments have same exploiting logic. Marine seismic is quite harder than the land seismic because of the challenging environments. In marine seismic, the need for a good ship and powerful sources, receivers and acquisition equipments are obligatory. As in the land seismic, 2-D and 3-D seismic surveys can be done for scientific purposes. This characterizes the necessary equipments for survey. The seismic survey can either be important for monitoring the shallow structures with high resolution or deep structures with low resolution. To achieve successful results in seismic survey, the true equipment selection must be necessary. Another reason for the importance of true equipment selection is the high cost of the marine seismic surveys. It is not profitable to repeat the survey.
The seismic tools can be divided as source, receivers and acquisition control. The following sections are related to the detailed information about these equipments.

Three short movies (format .MOV) from the survey are available (property of Emre Unal):
- Preparation of the Sparker source (electrod cleaning)
- Launching the streamer
- Shots recording during the experiment

Sources
Penetration depth and vertical/horizontal resolution are the most important factors in seismic surveys. These criteria are mostly depending on the source types. TNT, Water Gun, Air Gun, GI-Gun, G-Gun, Aquapulse, Air Gun arrays, Clusters, Boomer, Sparker, Flexichoc and Side Scan Sonar are the most preferable sources. These sources are used in terms of the main objectives of the seismic surveys.
TNT: This source was popular in the beginning of marine seismic surveys. The main advantage of TNT using in surveys is the presence of deep penetration capability. This advantage was actually the only positive side of this source. The disadvantages can be classified as:
1. Bubble effect caused by; heat occurrence during the explosion and emission of water vapor. The water vapor is the main cause for bubble occurrence after the explosion. This bubble effects the initial arrivals of seismic waves in terms of noise. As an example, if 20kg TNT explores, the bubbles formed due to the high heat need approximately 200msec to start contraction. The contraction results in the decreasing of bubble in volume. The large time needed for bubble contraction will affect the resultant seismic data due to the very large oscillating bubble effect.
2. TNT is not a good choice for environmental reasons since the explosion can cause some damages in the ships and economic and biological loss.
3. The seismic survey made by TNT has low vertical and horizontal resolutions.
4. TNT is not easy to use due to the unconfined explosion.
5. TNT is one of the sources, which is used for deep seismic surveys. This results in the necessity of special receivers which consist of special out-put characteristics of cable and attached depth controllers.

WATER GUN: One of the positive sides of the water guns is the presence of low amount bubble effect. The frequency interval is between 20hz to 1500hz. This also suggests that the water guns are suitable for shallow seismic. After the shooting, the trouble in rearming of the gun is the most important disadvantages. The fragility and the presence of vacuum bubble effect are the other negative sides of the techniques.

AIR GUN: Air guns are simple to use. They don’t need lots of power to rearmed. The most important negative sides can be:
1. The explosion can cause bubble formation in the water column and this eventually causes unwanted noise.
2. The seismic waves formed after the explosion may be reflected from the sea surface, which can cause unwanted signals on the data. These signals are called ghost signals.
3. Presence of low resolution data
4. Fragile out-put characteristics of receivers cable (as in the TNT).

G-GUN: G-Guns are one of the air guns which is confidence and do not need the recoiling. The air used in the steel cylinders can be used for 500000 shots repetitively. The fragile out-put characteristics of the receivers and low-resolution seismic data are the main disadvantages of this gun.

GI-GUN: The air exploring inside the steel cylinder has a very low internal pressure with respect to the outer environment. To decrease the pressure difference, an injection (I) towards the bubble must be necessary. This will result in decreasing the inner bubble pressure. This causes the preventation of the collapsing the large bubble instead of formation of many bubbles. Many bubbles are much worser than the single large bubble in terms of affecting the data. The high P/B ratio ~20 is caused by decreasing bubble effect. GI-Guns have more air volume than G-Guns, which increases the shooting repetition. As a negative sides of the GI-Guns, low resolution and fragile out-put characteristic of the receivers cable can be counted.

AQUAPULSE: The aquapulse technique in seismic sources has some similar properties of the air guns and water guns. Instead of exploring water or air, propane-oxygen mixture is explored inside the steel cylinder. This will cause diminished bubble effect in the resultant data. Each explosion needs 8 second to rearmed. This time interval is thought to be most important negative side of this source types. Low resolution and fragile out-put characteristics of the receivers are the other negative sides of this source.

AIR GUN ARRAY: Air gun arrays are different than the other types of air guns in terms of the configuration of the source and receivers. The receivers are oriented in arrays in order to decrease the bubble effect. The multidirectional source and receiver orientation are the characteristics of this source. This source has the same disadvantage as low resolution and fragility receiver cable.

CLUSTERS: To increase the shooting power, coalescence of bubble and P/B ratio, combined sources are used. GI and G Guns can be used as well as G Gun Parallel and Linear Clusters. One of the most important reason for developing the clusters is to decrease the bubble effect which influence data.

BOOMER: The electricity is one of the easiest and cheapest ways in marine seismic exploration as well as air, water and gas. One of the unique characteristics of the electricity usage in seismic exploration is the need for high-resolution shallow surveys. For high-resolution survey, high frequency (300hz to 3Khz) seismic waves are produced. This high frequency seismic waves result in monitoring the interval between the resolutions of 0.5 to 1m. This high frequency waves can not go deeper (25 to 50m). The special receivers are needed for high frequency seismic survey. The compatibility of the source and receiver is the key factor in high resolution seismic. These special receivers can also capture the huge amount of noises in the nature (microseismic waves). Thus the high amount of noise problem is one of the main disadvantages of the electric sources.

SPARKER: Sparker is the another electrical source for marine seismic. The 50Hz to 4kHz high frequency band is very good for high resolution (1m) surveys. The sparkers are easy to use and cheap. Sparkers are very good for high resolution seismic and low penetration studies. The electricity power can be very high (1000 joules or 400 kw). There is also a bubble effect which generally occurs due to the increasing temperature during the shooting. Like the boomer, the receivers must be high frequency compatible. The high noise is also a big problem in sparkers.

FLEXICHOC: The seismic surveys consisting of flexichoc is for high frequency and low penetration (50 m) researches.

SIDE SCAN SONAR: Side scan sonars are generally used for detection of the underwater objects (ships, large fish groups, archeological purposes…etc). Due to this reasons, high frequency and very high resolution needed (3.5Khz).

Recorders:
There are many different recorders for different purposes.

*DELPH (France, CNRS)
*Sercel SEAL (SN 408) SEGD (France,Ifremer)
*Syntron Syntrak 480MSRS SEGD (Germany, BGR)
*Geometrics ES2420 SEGD (Germany, AWI)
*Geometrics Strata View RX96 SEGD (DAT) (UK, NERC)
*Texas Inst. DFSV SEGD (exabyte) (SPAIN, NRA)
*Texas Inst. DFSV SEGY (NORWAY, BERGEN UNIV.)

Receivers:
The receiver selection is very important since the 2-D or 3-D configuration is generally related with the receivers. Number of channels and hydrophones are important in developing the most successful seismic survey.
OBS receivers are only the receivers located on the sea floor. In this type of receiver usage, the energy of the OBS and accessibility to the OBS are the main important sides of the survey.
*Digital Sercel : 360 channels, 4500m
*Digital Syntron: 120 channel,s 3000m
*Analogue: 96 channels, 2400m
*Analogue Teledyne: 96 channels, 2400m
*Analogue Teledyne 40508: 96 channels, 2400m
*Analogue Fjord Instrument: 120 channels, 3000m
*OBS

The above information mostly about the sources and receivers are good for comparison of different elements in seismic surveys. Between 30th Monday and 31st Tuesday, 2005; a seismic survey was made in NW Brest, France to monitor shallow geologic structures. The 2-D seismic survey was made by the ship Cote de la Manche belongs to CNRS. As a source sparker, 6 channels receiver and streamer box were used. For the acquisition of the data, DELPH was used. One printer and GPS was connected to the acquisition unit. The successive steps and the detailed information about this high frequency seismic survey is as follows:
The delph unit triggered the sparker unit and electric current formed (1000joules, 400kw). The electric transmitted between the cupper wires of two end of sparker. Every 1.555sec a new shot was produced. The sparker was located 60m away from the boat. After shooting, the reflected high resolution seismic waves were detected by the 6 channeled receiver which was also located 60m from the boat. The offset between the source and receiver was constant. By the help of the DELPH unit, having displays, PC controls and monotrace printer, the data was monitored in the OziExplorer software. This software was both for monitoring the seismic section immediately coming from the receivers but also helps to navigate the seismic survey. The GPS was connected to the software and the speed and cap via was observed from the screen. The geological structures were also monitored during the seismic survey. Different monitors in the software program contribute to understand the seaway traffic as well as the bathymetry, coastline location and possible currents. The number of shots and first initial arrival of seismic waves were monitored by the help of this program. The lat and long of the followed routes of the seismic survey was continuously observed. The lat and long and their continuous recording was vital in order to make a successful seismic survey. Each route and its seismic profiles were then interpreted geologically

Conclusions
There are many different types of sources and receivers. The objective of the seismic survey is important for selecting these seismic tools. The below figure shows relation between periods of bubble oscillation and amount of energy in different sources. Although the TNT has the highest seismic energy capability, the huge bubble oscillation effect makes TNT as a less favorable source. Whereas, the boomer and sparker has the least bubble oscillation effects with the low amount of seismic energy.
The explosive sources are powerful however their low mobility and difficult usage makes them unpopular. The air guns, gas guns, sparker and boomer are the most preferable sources in marine seismic surveys. For the low frequency and deep penetration studies, air guns and gas guns are preferred. The sparkers and boomers are preferred for high frequency and low penetration studies.