# Travel-Time Curve

## travel-time curve

[′trav·əl ‚tīm ‚kərv]
(geophysics)
A plot of P-, S-, and L-wave travel times used by seismologists to locate earthquakes.

## Travel-Time Curve

a curve describing the relation between the travel time of a seismic wave and the epicentral distance; it may be expressed in tabular or graphic form. Traveltime curves are used to determine the propagation velocity of seismic waves in the earth. A sharp change in the velocities of seismic waves indicates the existence of boundary surfaces (interfaces) within the earth. H. Jeffreys and K. E. Bullen’s traveltime curves (1940) are based on a standard model of the earth with boundary surfaces corresponding to the crust, mantle, and core. They are used in modern seismology to determine the position of earthquake foci. Regional travel-time curves account for local characteristics of regional structure and are used to interpret weak and nearby earthquakes.

References in periodicals archive ?
In the paper, based on "contactless" sensing technology and taking advantage of high-speed, high-resolution camera motion to seize image of operation driving part in the operation of HVCB, we proposed a method of image analysis and trajectory tracking technology to obtain the variable components, according to travel-time curve of circuit breaker to calculate the moving contact observation travel, (open) close time and velocity, and so forth.
Mechanical parameters of circuit breaker can be calculated by travel-time curve.
The increase of velocity with depth may usually be reliably excluded, if there is a larger number of points on the travel-time curve and these display linear dependence of time on distance.
By measuring the travel time over several distances between the source and receiver a linear travel-time curve can be obtained.
The velocity was determined from the slope of the differential travel-time curve.
In identifying the S-wave arrival times, mutual comparison of the separate travel-time curves was found to be of principal importance and, therefore, it was necessary to have the possibility of changing from displaying the data on one travel-time curve to displaying the data on another travel-time curve.
In particular, the Wichert-Herglotz method requires a smoothed travel-time curve with monotonous derivatives, which the DSS data usually do not satisfy.
By reducing their positions to correspond to a single travel-time curve, it was possible to determine the velocity by fitting a straight line to all 24 times on the reduced travel-time curve.
The smoothed travel-time curve in the form (1) was then interpreted by the Wiechert-Herglotz method.
In order to obtain a long travel-time curve, we have joined data from separate plutons.
This method is based on the averaging of group velocities for each period from all travel-time curves available.
1980, Partial derivatives of travel-time curves of reflected waves in a layered medium.

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