Question:medium

Which of the following sources is/are used in land seismic surveys?

Show Hint

Think about which sources need solid ground contact to work, and which one needs a body of water.
Updated On: Jul 20, 2026
  • Vibrosis
  • Dynamite
  • Airgun
  • Thumper
Show Solution

The Correct Option is A, B, D

Solution and Explanation

Step 1: Sort seismic sources into two families.
Seismic sources split broadly into two groups: ones that work by direct contact with the ground, used on land, and ones that work by making a pressure pulse in water, used at sea.

Step 2: List the land group.
The vibrator truck, often called Vibroseis (given here as "Vibrosis"), shakes the ground with a long sweep signal. Dynamite is set off in a shot hole drilled into the ground. The thumper drops a heavy weight onto a plate resting on the surface. All three need solid ground to push against, so all three are land sources.

Step 3: List the marine group.
The airgun fires a blast of compressed air underwater. The surrounding water carries the pressure pulse down to the seabed. Without water around it, an airgun cannot make a usable seismic pulse, so it is not used for work on land.

Step 4: Match to the options.
Since the question asks only for land sources, we keep the vibrator, dynamite and thumper, and drop the airgun.
\[ \boxed{\text{(A), (B) and (D)}} \]
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