Changes

==Source==

==Source==

Numerous energy sources exist, including various explosives (dynamite and primacord) (Figure 1), gas or air guns, weight drop mechanisms, vibrator systems (Figure 2), and even firearms, such as .50 caliber machine guns (fired single shot) and shotguns. Applications, advantages, and disadvantages of some of these sources are listed in Table 1.

Numerous energy sources exist, including various explosives (dynamite and primacord) ([[:file:seismic-data-acquisition-on-land_fig1.png|Figure 1]]), gas or air guns, weight drop mechanisms, vibrator systems ([[:file:seismic-data-acquisition-on-land_fig2.png|Figure 2]]), and even firearms, such as .50 caliber machine guns (fired single shot) and shotguns. Applications, advantages, and disadvantages of some of these sources are listed in Table 1.

 

 

{| class = "wikitable"

{| class = "wikitable"

Explosive sources are typically buried. Some examples include dynamite in “shot holes” ranging in depth from 10 to [[length::300 ft]] (3 to 100 m) and primacord in trenches covered by a few inches of soil. However, in some cases, both of these sources can be exposed on the surface. The other sources are generally truck mounted, but specialty vehicles are often used as transport when required by surface or environmental conditions (e.g., wet ground or arctic tundra). Many areas are inaccessible, and require helicopter support. In such cases, all aspects of the operation must be portable enough to be loaded onto helicopters and then move by hand into position.

Explosive sources are typically buried. Some examples include dynamite in “shot holes” ranging in depth from 10 to [[length::300 ft]] (3 to 100 m) and primacord in trenches covered by a few inches of soil. However, in some cases, both of these sources can be exposed on the surface. The other sources are generally truck mounted, but specialty vehicles are often used as transport when required by surface or environmental conditions (e.g., wet ground or arctic tundra). Many areas are inaccessible, and require helicopter support. In such cases, all aspects of the operation must be portable enough to be loaded onto helicopters and then move by hand into position.

Source locations, or shotpoints, are sometimes single points, but are often positioned in arrays. A shotpoint array is specifically designed to impart maximum seismic energy into the ground and/or minimize seismic noise such as ground roll. Arrays may be as simple as lining up several vibrator trucks (Figure 3) or as complex as drilling and shooting six-point star patterns (Figure 4). Shotpoint intervals range from over [[depth::1000 ft]] (300 m) to less than [[length::100 ft]] (30 m) and are often in intervals evenly divisible into 5280. However, modern seismic is typically shot with fairly short shotpoint intervals ranging from 55 to [[length::440 ft]] (17 to 134 m). Shooting patterns can be off end or split spread (Figure 5). Split spread is probably the most common and has an equal number of geophone groups in front of and behind the shot.

Source locations, or shotpoints, are sometimes single points, but are often positioned in arrays. A shotpoint array is specifically designed to impart maximum seismic energy into the ground and/or minimize seismic noise such as ground roll. Arrays may be as simple as lining up several vibrator trucks ([[:file:seismic-data-acquisition-on-land_fig3.png|Figure 3]]) or as complex as drilling and shooting six-point star patterns ([[:file:seismic-data-acquisition-on-land_fig4.png|Figure 4]]). Shotpoint intervals range from over [[depth::1000 ft]] (300 m) to less than [[length::100 ft]] (30 m) and are often in intervals evenly divisible into 5280. However, modern seismic is typically shot with fairly short shotpoint intervals ranging from 55 to [[length::440 ft]] (17 to 134 m). Shooting patterns can be off end or split spread ([[:file:seismic-data-acquisition-on-land_fig5.png|Figure 5]]). Split spread is probably the most common and has an equal number of geophone groups in front of and behind the shot.

 

 

 

==Receiver==

==Receiver==