Synchronous magnitude estimation method and device for extracting P wave arrival time in earthquake early warning system

Abstract

The present invention relates to a synchronous magnitude estimation method and device for extracting the arrival time of a P wave in an earthquake early warning system, and the method comprises: obtaining the instantaneous STP / LTP ratio of an observation signal at a preset position at each moment in real time; determining the arrival time of the P wave based on the instantaneous STP / LTP ratio of the observation signal at each moment and a preset threshold; determining the first STP / LTP ratio of the observation signal within a preset time period after the arrival time of the P wave based on the arrival time of the P wave; estimating the magnitude of the preset position based on the first STP / LTP ratio and a pre-acquired source distance R. By obtaining the instantaneous STP / LTP ratio of the observation signal at each moment in real time, determining the arrival time of the P wave based on the instantaneous STP / LTP ratio of the observation signal at each moment and a pre-set threshold, and being able to quickly perform magnitude estimation within a preset time period after the arrival of the P wave, the efficiency of earthquake early warning is improved compared with the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field, and in particular to a synchronous magnitude estimation method and device for extracting P wave arrival time in an earthquake early warning system. Background Art

[0002] The current earthquake magnitude is a measure of the strength of an earthquake. Magnitude estimation is a very important part of the earthquake early warning system. In the earthquake early warning system, not only the accuracy of the magnitude estimation should be considered, but also the timeliness of the algorithm should be considered to provide more time for earthquake prevention and disaster reduction. There are many methods for real-time magnitude estimation, mainly including: periodic methods, displacement amplitude methods, energy methods and machine learning methods.

[0003] There are many studies on the periodic method and displacement amplitude method. In the periodic method, the earthquake magnitude is estimated by calculating the dominant period of earthquake motion based on real-time seismic velocity records. This method has certain limitations, its stability is poor, and its accuracy and stability are easily affected by the sampling rate and data preprocessing. c Method) Based on the superior period method, an improved calculation method of characteristic period is proposed, which is more stable and reliable than the period method. However, this method will have a "saturation phenomenon" when estimating strong earthquakes, and its accuracy is also affected by the length of the time window.

[0004] Regarding the energy-based method, in the Istanbul Earthquake Early Warning System in Turkey, the cumulative absolute velocity value (CAV) parameter is used as one of the important criteria for magnitude estimation. The limitation of this method is that the parameter calculation takes a certain amount of time.

[0005] In recent years, with the rapid development of computer technology, machine learning and other technologies have also been applied to magnitude estimation. The machine learning model error of this method is significantly smaller than that of traditional methods, but it also needs to extract parameters from the seismic data 3s after the arrival of the P wave, and there are still certain limitations in real-time methods.

[0006] Although the above-mentioned method has good effect in terms of magnitude estimation accuracy, it still has certain limitations in terms of the real-time performance of the algorithm. It usually takes 3s-5s after the arrival of the P wave to estimate the magnitude, and it is impossible to obtain the magnitude estimation result synchronously and quickly when the P wave arrives. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method and device for magnitude estimation based on P-wave phase detection in an earthquake early warning system, which solves the technical problem that the magnitude estimation method in the prior art has certain limitations in the real-time performance of magnitude estimation, and usually requires magnitude estimation to be performed 3s-5s after the arrival of the P wave, and cannot obtain the magnitude estimation result synchronously and quickly when the P wave arrives.

[0009] (II) Technical solution

[0010] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0011] The embodiment of the present invention provides a synchronous magnitude estimation method for extracting P wave arrival time in an earthquake early warning system, comprising:

[0012] S1. Obtain the instantaneous STP / LTP ratio of the observation signal of the preset position at each moment in real time;

[0013] S2, determining the P wave arrival time based on the instantaneous STP / LTP ratio of the observed signal at each moment and a preset threshold;

[0014] S3. Based on the P wave arrival time, determine a first STP / LTP ratio of the observation signal within a preset time period after the P wave arrival time;

[0015] S4. Estimate the magnitude of the preset location based on the first STP / LTP ratio and the pre-acquired source distance R.

[0016] Preferably,

[0017] The observation signal is a signal collected by a MEMS network strong motion instrument preset at a preset position.

[0018] Preferably, the S1 specifically includes:

[0019] Formula (1) is used to obtain the instantaneous STP / LTP ratio of the observed signal at each moment in real time;

[0020] The formula (1) is:

[0021]

[0022] Where i is the sequence number of the time sliding window of the observation signal;

[0023] j is the sequence number in the short time window of the observed signal;

[0024] k is the sequence number in the long time window of the observed signal;

[0025] x j is the observed signal within the short time window;

[0026] is the mean value of the observed signal in the short time window;

[0027] x k is the observed signal in the long time window;

[0028] is the mean of the observed signal in the long time window;

[0029] L is the long time window width of the time sliding window;

[0030] S is the short window width of the time sliding window;

[0031] is the relative power of the observed signal in the i-th short-time window;

[0032] is the relative power of the observed signal in the i-th long-time window.

[0033] Preferably, the S2 specifically includes:

[0034] Determine whether the STP / LTP ratio is greater than the preset threshold; if so, use the time corresponding to the STP / LTP ratio as the P wave arrival time.

[0035] Preferably,

[0036] The first STP / LTP ratio is the maximum STP / LTP ratio of the observation signal within a preset time period after the P wave arrives.

[0037] Preferably,

[0038] The preset time period is 2 seconds.

[0039] Preferably, the S4 specifically includes:

[0040] Based on the first STP / LTP ratio and the pre-acquired focal distance R, the magnitude is estimated using formula (2);

[0041] Wherein, the formula (2) is:

[0042] M=Alog(P SNR )+Blog(R)+C;

[0043] Among them, P SNR is the first STP / LTP ratio;

[0044] M is the magnitude;

[0045] A is a preset first parameter;

[0046] B is a preset second parameter;

[0047] C is a preset third parameter.

[0048] Preferably,

[0049] The preset first parameter A, the preset second parameter B, and the preset third parameter C are respectively determined in advance by performing regression analysis on the magnitude, the first STP / LTP ratio, and the focal distance in the historical records.

[0050] On the other hand, this embodiment also provides a synchronous magnitude estimation device for extracting the arrival time of P waves in an earthquake early warning system, characterized in that the device executes any of the above-mentioned synchronous magnitude estimation methods for extracting the arrival time of P waves in an earthquake early warning system.

[0051] (III) Beneficial effects

[0052] The beneficial effects of the present invention are: a method and device for estimating magnitude by extracting P-wave arrival time in an earthquake early warning system of the present invention, by acquiring the instantaneous STP / LTP ratio of the observation signal at each moment, analyzing it from the energy perspective, determining the arrival time of the P-wave based on the instantaneous STP / LTP ratio of the observation signal at each moment and a preset threshold, and being able to perform magnitude estimation synchronously with the extraction of the P-wave arrival time within a preset time period after the arrival of the P-wave, which greatly improves the efficiency of earthquake early warning compared with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A flow chart of a synchronous magnitude estimation method for extracting P wave arrival time in an earthquake early warning system of the present invention;

[0054] FIG2 is a time efficiency comparison diagram of a synchronous magnitude estimation method for extracting P wave arrival time in an earthquake early warning system of the present invention and an existing method in an embodiment of the present invention;

[0055] Figure 2(a) is a sequence diagram of the UD direction acceleration signal of the continuous observation signal within a certain period of time;

[0056] FIG2( b ) is a sequence diagram of STP / LTP corresponding to FIG2( a );

[0057] Figure 3 is the first STP / LTP ratio P in the embodiment of the present invention SNR A graph showing the relationship between focal distance and earthquake magnitude. DETAILED DESCRIPTION

[0058] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0059] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0060] See also Figure 1 This embodiment provides a synchronous magnitude estimation method for extracting P wave arrival time in an earthquake early warning system, including:

[0061] S1. Obtain the instantaneous STP / LTP ratio of the observation signal of the preset position at each moment in real time.

[0062] S2. Determine the arrival time of the P wave based on the instantaneous STP / LTP ratio of the observed signal at each moment and a pre-set threshold.

[0063] S3. Based on the P wave arrival time, determine a first STP / LTP ratio of the observation signal within a preset time period after the P wave arrival time.

[0064] S4. Estimate the magnitude of the preset location based on the first STP / LTP ratio and the pre-acquired source distance R.

[0065] In the practical application of this embodiment, the observation signal is a signal collected by a MEMS network strong motion detector preset at a preset position.

[0066] In the practical application of this embodiment, S1 specifically includes:

[0067] Formula (1) is used to obtain the instantaneous STP / LTP ratio of the observed signal at each moment in real time.

[0068] The formula (1) is:

[0069]

[0070] Where i is the sequence number of the time sliding window of the observation signal.

[0071] j is the sequence number in the short time window of the observed signal.

[0072] k is the sequence number in the long time window of the observed signal.

[0073] x j is the observed signal within a short time window.

[0074] is the mean value of the observed signal in the short time window.

[0075] x k is the observed signal in the long time window.

[0076] is the mean of the observed signal in the long time window.

[0077] L is the long window width of the time sliding window.

[0078] S is the short window width of the time sliding window.

[0079] is the relative power of the observed signal in the i-th short-time window.

[0080] is the relative power of the observed signal in the i-th long-time window.

[0081] In a specific application, the long time window is set to 3 seconds and the short time window is set to 0.1 seconds.

[0082] In the actual application of this embodiment, S2 specifically includes: determining whether the STP / LTP ratio is greater than the preset threshold value, and if so, taking the time corresponding to the STP / LTP ratio as the P wave arrival time.

[0083] In practical applications of this embodiment, the first STP / LTP ratio is the maximum STP / LTP ratio of the observation signal within a preset time period after the P wave arrives.

[0084] The first STP / LTP ratio corresponding to the P wave arrival time determined in S2 has a clear physical meaning. The appearance of the first STP / LTP ratio indicates that the seismic P wave signal energy has reached the maximum value in the time sliding window, which effectively represents the seismic energy information of the P wave. The first STP / LTP ratio parameter is highly robust and can be applied to weak noise, general noise and strong noise environments. It is less affected by the background noise of different instruments, and the performance of this parameter is relatively stable in different environments. The first STP / LTP ratio has a dimensionless characteristic. For instruments of different specifications, it can be directly calculated in the measurement unit of the instrument used to obtain a new parameter. The new parameter has a wide range of application, saves costs in the processing of seismic records, and improves data processing efficiency.

[0085] In the actual application of this embodiment, the preset time period is 2 seconds.

[0086] In a specific application, after obtaining the arrival time of the P wave, the first STP / LTP ratio corresponding to the P wave after the arrival of the P wave is searched within a preset time period starting from the arrival time of the P wave, and the first STP / LTP ratio will appear within 2 seconds from the arrival time of the P wave, and sometimes even almost synchronized with the arrival time of the P wave. That is to say, the first STP / LTP ratio in the present invention can appear within 2 seconds from the arrival time of the P wave, or it may be synchronized with the arrival time of the P wave, or it may appear 1 second from the arrival time of the P wave. The existing magnitude estimation method is to determine through statistics that the time window after the arrival time of the P wave is set to the 3rd-5th second. Compared with the existing magnitude estimation method, this embodiment provides a synchronous magnitude estimation method for extracting the P wave at the arrival time in an earthquake early warning system, and obtains the magnitude estimation parameters synchronously at the arrival time of the P wave without the need for other calculations, which greatly reduces the time used for magnitude estimation and improves the efficiency of earthquake early warning.

[0087] In the practical application of this embodiment, S4 specifically includes:

[0088] Based on the first STP / LTP ratio and the pre-acquired focal distance R, the magnitude is determined using formula (2).

[0089] Wherein, the formula (2) is:

[0090] M=Alog(P SNR )+Blog(R)+C;

[0091] Among them, P SNR is the first STP / LTP ratio.

[0092] like Figure 3 As shown, the first STP / LTP ratio (P SNR ) has an obvious attenuation relationship with the focal distance R, and the first STP / LTP ratio is also closely related to the magnitude. The larger the magnitude, the larger the first STP / LTP ratio.

[0093] M is the magnitude.

[0094] A is a preset first parameter.

[0095] B is a preset second parameter.

[0096] C is a preset third parameter.

[0097] The application field (magnitude estimation field) of the rapid magnitude estimation method based on signal-to-noise ratio feature analysis proposed in this application is completely different from the existing STP / LTP method (P-wave arrival time extraction field). The STP / LTP method is applied in the field of P-wave arrival time extraction, and its purpose (function) is to determine when the seismic P wave arrives. The new parameter (the instantaneous STP / LTP ratio of the observation signal) proposed in this embodiment is applied in the field of magnitude estimation, and its purpose (function) is to estimate the magnitude of the earthquake.

[0098] The rapid magnitude estimation method based on signal-to-noise ratio feature analysis proposed in this embodiment is a new method in the field of magnitude estimation. Compared with the existing magnitude estimation methods, the new method greatly reduces the time used for magnitude estimation and improves the efficiency of earthquake early warning.

[0099] Compared with the prior art, the rapid magnitude estimation method based on signal-to-noise ratio feature analysis proposed in this embodiment is more robust and can be applied to weak noise, general noise and strong noise environments. It is not easily affected by instrument background noise, and the parameter performance is relatively stable under different environments.

[0100] The method for rapid magnitude estimation based on signal-to-noise ratio feature analysis proposed in this embodiment has the characteristic of being dimensionless. The proposed new parameter (the instantaneous STP / LTP ratio of the observed signal) is a dimensionless quantity, see formula (1). The new parameter (the instantaneous STP / LTP ratio of the observed signal) has no unit. For instruments of different specifications, the new parameter (the instantaneous STP / LTP ratio of the observed signal) can be directly calculated using the measurement unit of the instrument used. The new parameter (the instantaneous STP / LTP ratio of the observed signal) has a wide range of applicability, saves costs in the processing of earthquake records, and improves data processing efficiency.

[0101] In the actual application of this embodiment, the preset first parameter A, the preset second parameter B, and the preset third parameter C are respectively determined in advance by performing regression analysis on the magnitude, the first STP / LTP ratio, and the focal distance in the historical records.

[0102] On the other hand, this embodiment also provides a synchronous magnitude estimation device for extracting the arrival time of P waves in an earthquake early warning system, characterized in that the device executes any of the above-mentioned synchronous magnitude estimation methods for extracting the arrival time of P waves in an earthquake early warning system.

[0103] The following uses some M3.0-M8.0 earthquakes in Sichuan Province as examples to describe in detail the implementation effect of the synchronous magnitude estimation method for extracting P wave arrival time in an earthquake early warning system of this embodiment:

[0104] As shown in Table 1, the results of applying the existing magnitude estimation method and the magnitude estimation method of the present invention to the data of M3.0-M7.0 earthquake events show that the magnitude estimation method of the present invention and the existing magnitude estimation method have a good degree of fit. Among them, the determination coefficient indicates the degree of fit of the regression model, and the error variance indicates the degree of error dispersion of the regression model.

[0105] Table 1

[0106]

[0107] As shown in Figure 2(a) and Figure 2(b), the magnitude estimation method of the present invention has good timeliness. Figure 2(a) is a sequence diagram of the UD direction acceleration signal of the continuous observation signal in a certain period of time, and Figure 2(b) is a corresponding STP / LTP sequence diagram. It can be seen from Figure 2(a) and Figure 2(b) that after the earthquake motion P wave arrives, the new parameter P is determined. SNR The time required is significantly less than that of the existing P d The time corresponding to the new parameters is very close to the arrival time of the P wave. Usually the first STP / LTP ratio (P SNR ) The corresponding time is within 2 seconds of the P-wave arrival time, and sometimes even synchronized, which greatly improves the magnitude estimation effect.

[0108] In the present embodiment, a synchronous magnitude estimation method and device for P-wave arrival time extraction in an earthquake early warning system is provided, which obtains the instantaneous STP / LTP ratio of the observation signal at each moment, analyzes it from the energy perspective, determines the arrival time of the P wave based on the instantaneous STP / LTP ratio of the observation signal at each moment and a pre-set threshold, and can perform magnitude estimation synchronously with the P-wave arrival time extraction within a preset time period after the arrival of the P wave, which greatly improves the efficiency of earthquake early warning compared with the existing technology.

[0109] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0110] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0111] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0112] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0113] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A synchronous magnitude estimation method for extracting P wave arrival time in an earthquake early warning system, characterized in that: include: S1. Obtain the instantaneous STP / LTP ratio of the observation signal of the preset position at each moment in real time; S2, determining the P wave arrival time based on the instantaneous STP / LTP ratio of the observed signal at each moment and a preset threshold; S3. Based on the P wave arrival time, determine a first STP / LTP ratio of the observation signal within a preset time period after the P wave arrival time; The first STP / LTP ratio is the maximum STP / LTP ratio of the observation signal within a preset time period after the P wave arrives; S4. estimating the magnitude of the earthquake at the preset location based on the first STP / LTP ratio and the pre-acquired source distance R; The S4 specifically includes: Based on the first STP / LTP ratio and the pre-acquired focal distance R, the magnitude is estimated using formula (2); Wherein, the formula (2) is: ； in, P SNR is the first STP / LTP ratio; M is the magnitude; A is a preset first parameter; B is a preset second parameter; C is a preset third parameter.

2. The method according to claim 1, characterized in that The observation signal is a signal collected by a MEMS network strong motion instrument preset at a preset position.

3. The method according to claim 2, characterized in that The S1 specifically includes: Formula (1) is used to obtain the instantaneous STP / LTP ratio of the observed signal at each moment in real time; The formula (1) is: ； in, i is the sequence number of the time sliding window of the observation signal; j is the sequence number in the short time window of the observed signal; k is the sequence number in the long time window of the observed signal; x j is the observed signal within the short time window; is the mean value of the observed signal in the short time window; x k is the observed signal in the long time window; is the mean of the observed signal in the long time window; L is the long time window width of the time sliding window; S is the short window width of the time sliding window; For the i The relative power of the observed signal within a short time window; For the i The relative power of the observed signal within a long time window.

4. The method according to claim 3, characterized in that The S2 specifically includes: Determine whether the STP / LTP ratio is greater than the preset threshold; if so, use the time corresponding to the STP / LTP ratio as the P wave arrival time.

5. The method according to claim 4, characterized in that The preset time period is 2 seconds.

6. The method according to claim 5, characterized in that The preset first parameter A, the preset second parameter B, and the preset third parameter C are respectively determined in advance by performing regression analysis on the magnitude, the first STP / LTP ratio, and the focal distance in the historical records.

7. A synchronous magnitude estimation device for extracting P wave arrival time in an earthquake early warning system, characterized in that: The device executes the synchronous magnitude estimation method of P wave arrival time extraction in the earthquake early warning system as described in any one of claims 1-6 above.

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