seismo-, seism-, -seism, -seisms, -seisma, -seismically, -seismical, -seismal, -seismic

An earthquake hazard which refers to anything associated with an earthquake that may affect the normal activities of people.

This includes surface faulting, ground shaking, landslides, liquefaction, tectonic deformation, tsunamis, and seiches (the sloshing of a closed body of water from earthquake shaking; including, swimming pools, ponds, lakes, etc.).

Seismic imaging directs an intense sound source into the ground to evaluate subsurface conditions and to detect high concentrations of contamination.

Receivers called geophones, analogous to microphones, pick up “echoes” that come back up through the ground and record the intensity and time of the “echo” on computers.

Data processing turns these signals into images of the geologic structure. This technology is similar in principle to active electromagnetic survey technology.

Here are more etails about seismic imaging.

A measure of the size of an earthquake based on the area of fault rupture, the average amount of slip, and the force that was required to overcome the friction sticking the rocks together that were offset by faulting. Seismic moment can also be calculated from the amplitude spectra of seismic waves.

A "slip" is the relative displacement of formerly adjacent points on opposite sides of a fault, measured on the fault surface.

The "spectrum" is a curve showing amplitude and phase as a function of frequency or period, or how much of each type of shaking there is from an earthquake.

A reference to symmetrical fluctuations where the water-level rise is exactly equal to the water-level decline which is typical of standing waves set up on rivers, reservoirs, ponds, and lakes at a time that corresponds with the passage of seismic waves in other parts of the world.

An elastic wave generated by an impulse such as an earthquake or an explosion. Seismic waves may travel either along or near the earth's surface ("Rayleigh" and "Love" waves) or through the earth's interior ("P" and "S" waves).

Waves of Destruction

Earthquakes are said to radiate destruction much like bomb blasts in that seismic waves burst from the underground hypocenter (the point within the earth where an earthquake rupture starts; also known as the focus).

Surface waves consist of heaving waves produced by P and S waves. The P wave is the fastest wave which is generated by the fault rupture and it compresses and stretches the rock area. The S wave is slower but often the more destructive wave as it shakes rock from side to side.

• P waves, which compress and stretch rock, deliver the quake's initial thrust.
• Slower and often more destructive S waves follow, slithering side to side.
• S waves tear buildings off foundations and can churn wet soils into a mixture that acts like quicksand, causing buildings to tilt.
• At ground level, P and S waves produce surface waves that can flatten bridges, crack windows, or simply pass unnoticed.
• Eventually the waves weaken as they roll away from the hypocenter; but the seismic echoes of powerful quakes can resonate across and around the globe

A "Rayleigh wave" is a seismic surface wave causing the ground to shake in an elliptical motion, with no transverse, or perpendicular, motion.

A "Love wave" is a surface wave having a horizontal motion that is transverse (or perpendicular) to the direction the wave is traveling.

A reference to earthquakes or surface waves produced with acoustic or sonic energy for geophysical explorations of minerals, oil, etc.: "New seismic methods have become lucrative for oil companies."

"The seismic method was observed by a group of physicists who noticed that whenever an earthquake took place in Alaska then oil production in the Western Canadian Sedimentary Basin significantly increased because of the great waves of energy that moved at hundreds of meters a second were breaking apart rock formations that contained oil."

1. The intensity, frequency, and distribution of earthquakes in a specific area.
2. The geographic and historical distribution of earthquakes.
3. The likelihood of an area being subject to natural earthquakes.

The natural activity or group of phenomena associated with earthquakes.

A recording of cardiac vibrations as they affect the entire body by various techniques.

The analysis of movements of the chest as an indication of the functioning of the heart.

A chronograph (an instrument that records time with great accuracy) for determining the time at which an earthquake shock happens: Earthquakes do take place in Southern California where scientists use seismochronographs to track the precise time of earthquakes and the shocks.

An instrument for administering vibrations as a method of medical treatment.

1. A reference to a region that is prone to seismic activity.
2. The base of the seismogenic zone is the top of the more ductile asthenosphere (the ductile part of the earth just below the lithosphere, including the lower mantle which is about 180 km thick).
3. Capable of generating earthquakes.

Many of the world’s most disastrous earthquakes and volcanic eruptions take place at subduction zones, or areas under the ocean where one tectonic plate collides with another, sending sections of Earth’s crust down into the mantle.

The deep layers of seismic activity in these areas are called Wadati-Benioff zones and can be found as deep as 700 km.

Some areas are known to host parallel planes of seismicity referred to as double Benoiff zones, or DBZs, but these have been thought to be rare.

Analysis of global seismicity catalogs and characterization of the layer separation at 16 subduction zones revealed two parallel seismic strips, rather than a single broad zone, in most cases.

1. The record of an earthquake's vibrations and intensity made by a seismograph.
2. A record written by a seismograph in response to ground motions produced by an earthquake, explosion, or other ground-motion sources.

1. An instrument for recording vibrations of the Earth, particularly of earthquakes or artificially induced energy for the exploration of underlying rock formations and the interior of the Earth.
2. Any of various devices for measuring and recording the vibrations and intensities of earthquakes.
3. An instrument for recording automatically the phenomena of earthquakes.

A seismograph, or seismometer, is an instrument used to detect and record earthquakes. Generally, it consists of a mass attached to a fixed base. During an earthquake, the base moves and the mass does not. The motion of the base with respect to the mass is commonly transformed into an electrical voltage. The electrical voltage is recorded on paper, magnetic tape, or another recording medium.

This record is proportional to the motion of the seismometer mass relative to the earth, but it can be mathematically converted to a record of the absolute motion of the ground.

The term seismograph generally refers to the seismometer and its recording device as a single unit.