They can also indicate the presence of geologic basins that are filled with unusually large thicknesses of sedimentary rocks. These variations are useful in locating geologic faults and ancient volcanoes, for example. Gravity measurements are made with an instrument known as a gravity meter, and maps can be produced that show differences in the pull of gravity across the state. In other words, it would be slightly more difficult for a track and field athlete to high jump or pole vault in north-central Kansas than in other parts of the state. While these variations in gravity are predictable and can be calculated for each spot on the Earth's surface, other variations in gravity, such as those caused by unknown geologic features are not predictable.įor example, in north-central Kansas, there is an anomaly known as the Midcontinent Gravity High where the Earth's gravity is about 0.006% greater than normal. Some of this variation occurs because the Earth is not a perfect sphere, and some is related to differences in elevation on the Earth's surface. The Earth's gravitational attraction varies slightly from one place to another on the Earth's surface. The physical fundamentals of various geophysical exploration techniques are discussed in the following paragraphs. While these techniques do not allow detailed examination of the rocks beneath us, they often enable geologists and geophysicists to infer the most likely properties of large volumes of rocks. Each of these techniques exploits fundamental physical aspects of Earth materials such as electrical, magnetic, acoustical, or gravitational properties. There are several means of exploring the Earth by geophysical methods. Some fundamentals of geophysical exploration Light waves are transverse waves that can travel without a medium through empty space.KGS-Petroleum: a primer for Kansas-Geophysical Exploration.

Examples of mechanical transverse waves might include some waves in a slinky spring, waves on a rope, strings in a musical instrument, and some seismic waves.The highest point of a transverse wave is the crest and the lowest point is called a trough.Mechanical waves in which the particles of matter in the medium vibrate by moving back and forth and perpendicular (at right angles) to the direction the wave travels are called transverse waves.Examples of mechanical compressional/longitudinal waves might include sound waves and some seismic waves.The place on the wave that is pushed together is called the compression and the place that is moving apart is the rarefaction.Mechanical waves in which the particles of matter in the medium vibrate by pushing together and moving apart parallel to the direction in which the wave travels are called compressional or longitudinal waves.Light waves are the only part of the electromagnetic spectrum that is visible to the human eye.Īnother way to classify waves is by how they move:.Are considered e lectromagnetic waves which are waves that can travel through matter or empty space where matter is not present.Sound waves, as with all mechanical waves, cannot be transferred or transmitted through empty space (vacuum ).For example, water waves, earthquake/seismic waves, sound waves, and the waves that travel down a rope or spring are also mechanical waves.Mechanical waves require the particles of the medium to vibrate in order for energy to be transferred.When there is no medium, certain waves (electromagnetic) can travel through empty spaceĬharacteristics of mechanical and electromagnetic waves:.When waves travel through a medium, the particles of the medium are not carried along with the wave.A medium is a material through which waves can travel.While all waves can transmit energy through a medium, certain waves can also transmit energy through empty space.Waves carry energy through empty space or through a medium without transporting matter.

A vibration is a repeated back-and-forth or up-and-down motion.

Waves are created when a source of energy (force) causes a vibration.

Soure of energy for seismac wavs