JP2012237559A - Method for evaluating optimization of seismometer arrangement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating optimization of seismometer arrangement considering both of the margin time of an earthquake and the magnitude of vibration.SOLUTION: In the method for evaluating optimization of seismometer arrangement, an arbitrary area in which seismometer arrangement is to be evaluated is set, probability Pe that the margin time becomes a predetermined value and more on a position where the magnitude of vibration becomes a predetermined value and more is found out by using data of earthquakes generated in the past in the set area and earthquakes of which the generation in the future is expected, and seismometer arrangement is quantitatively evaluated based on the found probability Pe.

Description

  The present invention relates to a method for optimizing seismometer placement for earthquakes that have occurred in the past or are expected to occur in the future.

Early earthquake information that can be used for disaster prevention and mitigation measures, such as the Japan Meteorological Agency's emergency earthquake bulletin and the Shinkansen early earthquake warning system, can be used for disaster prevention and mitigation measures by estimating the location and scale of the epicenter immediately after an earthquake. When providing this early earthquake information, it is important to properly arrange seismometers (earthquake detection points) for earthquakes that are expected to occur.
Therefore, calculation of margin time using parameters such as P-wave velocity and S-wave velocity, that is, the time from the output of early earthquake information by P-wave to the arrival of the main oscillation as S-wave, the epicenter distance and magnitude By calculating the probability that the margin time will be greater than a certain value in the region where the magnitude of the shaking is greater than a certain value. The arrangement of seismometers (earthquake detection points) is quantitatively evaluated for routes, etc., and optimization is examined.

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However, the margin time and the magnitude of the earthquake shake vary depending on the location and scale of the earthquake (seismic source location) and scale, the location of the seismometer (earthquake detection point), and the location where the evaluation is performed. Not.
In view of the above situation, an object of the present invention is to provide an optimization evaluation method for the arrangement of seismometers (earthquake detection points) in consideration of both the allowance time and the magnitude of shaking when an earthquake occurs.

In order to achieve the above object, the present invention provides
[1] In the seismometer layout optimization evaluation method, by setting an arbitrary area to evaluate the seismometer layout, and using data of earthquakes that occurred in the past or expected to occur in this area, A probability Pe that a margin time becomes a predetermined value or more at a point where the magnitude of the shake becomes a predetermined value or more is obtained, and the seismometer arrangement is quantitatively evaluated based on the obtained probability Pe. To do.

[2] In the method for optimizing seismometer placement described in [1] above, the magnitude of the shaking uses a seismic motion index such as a maximum acceleration, a maximum speed, and an SI value in addition to the measured seismic intensity. .
[3] In the optimization evaluation method of the seismometer arrangement according to [1] or [2], the calculation formula of the probability Pe is:
Pe = N (A ≧ a, Tm ≧ t; x, y) / N (A ≧ a; x, y)
Here, N (A ≧ a; x, y) is the number of input earthquakes where the ground motion index at a given point (x, y) is a predetermined value a or more, N (A ≧ a, Tm ≧ t; x , y) represents the number of input earthquakes whose seismic motion index at the arbitrary point (x, y) is a predetermined value a or more and a margin time is t (seconds) or more.

  [4] In the method for optimizing seismometer placement according to any one of [1] to [3] above, the quantitative evaluation in which the kilometer distance and the latitude / longitude of the target railway line in the arbitrary region are linked. It is characterized by constructing a database.

  The arrangement of seismometers for outputting early-time earthquake information has been studied focusing on the margin time so far, but the margin time is an index independent of the magnitude of the shaking caused by the earthquake. Therefore, according to the present invention, by optimizing the arrangement of the seismometers (earthquake detection points) in consideration of both the earthquake surplus time and the magnitude of the shake, safety at the time of the occurrence of the earthquake can be improved. .

It is a schematic diagram which shows the route set virtually with the seismometer (earthquake detection point) arrangement model of the metropolitan area which concerns on this invention. It is the distribution map of the earthquake which occurred in the past selected on the condition which concerns on this invention. It is a figure which shows the evaluation value (Pe) map of the seismometer arrangement | positioning in five alarm detection points which show 1st Example of this invention. It is a figure which shows the evaluation value (Pe) map of the seismometer arrangement | positioning in three alarm detection points which show 2nd Example of this invention. It is a figure which shows the relationship between the evaluation value (Pe) of the seismometer arrangement | positioning which concerns on this invention, and the kilometer about the virtual route. It is a figure which shows the relationship between the evaluation value (Pe) of the seismometer arrangement | positioning which concerns on this invention, and the kilometer of the virtual route.

  The seismometer placement optimization evaluation method of the present invention sets an arbitrary region for evaluating the seismometer placement, and by using data of earthquakes that occurred in the past and predicted to occur in the future in this region, A probability Pe that the margin time becomes a predetermined value or more at a point where the magnitude of the shake becomes a predetermined value or more is obtained, and the seismometer arrangement is quantitatively evaluated based on the obtained probability Pe.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a schematic diagram showing a metropolitan seismometer (earthquake detection point) arrangement model according to the present invention and a virtually set route, and FIG. 2 is a distribution map of earthquakes that occurred in the past selected under certain conditions.
As shown in FIG. 1, five virtual alarm detection points 1 to 5 and virtual routes 1 and 2 are arranged. The virtual alarm detection point (virtual seismometer placement point) and virtual route can be set arbitrarily, but here the virtual alarm detection point (virtual seismometer placement point) is the applicant's metropolitan area earthquake observation. The detection points and virtual routes by the network are routes that pass over the location of the applicant's national laboratory. In these figures, the horizontal axis indicates longitude, and the vertical axis indicates latitude.

Here, we are evaluating earthquakes that have actually occurred in the past. The selection conditions for the earthquake are earthquakes with a magnitude of 5.5 or more and an epicenter depth of 100 km or less that actually occurred from 1923 to 2009. The distribution map is shown in FIG. In FIG. 2, the size of the circle corresponds to the size of the magnitude.
The earthquake used for evaluation can be applied not only to earthquakes that have actually occurred in the past, but also to earthquakes that are expected to occur in the future. In addition to the measured seismic intensity, seismic motion indices such as maximum acceleration, maximum speed, SI value, and the like can be used as the magnitude of shaking.

Next, a first embodiment of the present invention will be described.
FIG. 3 is a diagram showing an evaluation value (Pe) map of the seismometer arrangement showing the first embodiment of the present invention.
In this embodiment, there are five alarm detection points (seismometer placement points) 1 to 5, and the evaluation formula is as follows.
Pe = N (A ≧ a, Tm ≧ t; x, y) / N (A ≧ a; x, y)
Here, Pe is an evaluation value, N (A ≧ a; x, y) is the number of input earthquakes whose seismic motion index at a given point (x, y) is equal to or greater than a predetermined value a, N (A ≧ a, Tm ≧ t; x, y) represents the number of input earthquakes in which the earthquake motion index at the arbitrary point (x, y) is a predetermined value a or more and a margin time is t (seconds) or more.

The input earthquake is an earthquake having a magnitude of 5.5 or more and an epicenter depth of 100 km or less that occurred from 1923 to 2009, as used in the distribution map of FIG.
In the above evaluation formula, the evaluation value (Pe) is calculated by setting a as the seismic intensity of 4.5 and t as the margin time of 5 seconds. Based on the value of Pe, the evaluation value is high as the arrangement of the seismometers. 3 is plotted in FIG. 3 from 1.0 (white) indicating 0.0 to black (black) indicating that the evaluation value is low.

FIG. 3 shows the distribution of evaluation values (Pe) of seismometer placement in an arbitrary area. In such an arbitrary area, evaluation can be performed using the average value of all evaluation values (Pe) in that area. it can.
Next, a second embodiment of the present invention will be described.
FIG. 4 is a diagram showing an evaluation value (Pe) map of the seismometer arrangement showing the second embodiment of the present invention.

In this embodiment, there are three alarm detection points (seismometer arrangement points) 1 to 3.
Using the same evaluation formula as shown in the first embodiment, the evaluation value (Pe) is calculated by setting a to a seismic intensity of 4.5 and t to a surplus time of 5 seconds. From white) to 0.0 (black) was similarly plotted in FIG.
FIG. 4 also shows the distribution of evaluation values (Pe) of seismometer placement in an arbitrary area. In such an arbitrary area, evaluation is made with the average value of all evaluation values (Pe) in that area. Can do.

  FIG. 5 is a diagram showing the relationship between the evaluation value (Pe) of the seismometer arrangement and the kilometer of the virtual route 1 according to the present invention. In the virtual route 1, there are five alarm detection points and three alarm detection points. It is plotted on top of each other. FIG. 6 is a diagram showing the relationship between the evaluation value (Pe) of the seismometer arrangement and the kilometer of the virtual route 2, and the case where there are five alarm detection points and three points on the virtual route 2 are overlapped. Plot.

In these figures, the kilometer (km) on the horizontal axis indicates the distance from the starting point of each virtual route, with virtual route 1 starting from the southwest end and virtual route 2 starting from the west end. The vertical axis plots the evaluation value (Pe) for the kilometer of the virtual route.
5 and 6, St3 indicates an evaluation value (Pe) with respect to a kilometer when there are three alarm detection points (seismometer arrangement points), and St5 indicates five points. St3 indicates that when three alarm detection points (seismometer placement points) are present, St5 indicates the average value of the evaluation values (Pe) over all the virtual routes in the case of five locations.

  In these figures, Ave. St5 and Ave. When comparing St3, Ave. In St5, Pe is larger, and it can be seen that the alarm detection point (the seismometer arrangement point) is more effective at five locations than at three locations. Also, Ave. St5 and Ave. The difference from St3 is larger in FIG. 6 than in FIG. 5, and it can be seen that the effect of increasing the alarm detection point is larger in the virtual route 2 than in the virtual route 1. Furthermore, Ave. By changing the number and arrangement of alarm detection points (seismic meter arrangement points) so that the value of St is increased, optimization of the arrangement of alarm detection points (seismometer arrangement points) can be considered.

  In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The optimization evaluation method for seismometer arrangement of the present invention can be used as an optimization evaluation method for seismometer (earthquake detection point) arrangement in consideration of both the seismic margin time and the magnitude of shaking.

Claims (4)

  By setting an arbitrary area to evaluate the seismometer placement, and using data of earthquakes that occurred in the past or expected to occur in the arbitrary area, the magnitude of the shaking will exceed the predetermined value A seismometer placement optimization evaluation method characterized in that a probability Pe at which a margin time becomes a predetermined value or more at a point is obtained, and a seismometer placement is quantitatively evaluated based on the obtained probability Pe.   2. The method for optimizing seismometer arrangement according to claim 1, wherein the magnitude of the shaking uses a seismic motion index such as maximum acceleration, maximum speed, SI value, etc. in addition to the measured seismic intensity. In the optimization evaluation method of the seismometer arrangement according to claim 1 or 2, the calculation formula of the probability Pe is:
Pe = N (A ≧ a, Tm ≧ t; x, y) / N (A ≧ a; x, y)
Here, N (A ≧ a; x, y) is the number of input earthquakes where the ground motion index at a given point (x, y) is a predetermined value a or more, N (A ≧ a, Tm ≧ t; x , y) represents the number of input earthquakes whose seismic motion index at the arbitrary point (x, y) is a predetermined value a or more and a margin time is t (seconds) or more. Evaluation method.   The seismometer layout optimization evaluation method according to any one of claims 1 to 3, wherein a database for quantitative evaluation is made by linking the latitude and longitude of the target railway track in the arbitrary region. Seismometer layout optimization evaluation method characterized by

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