Method and system for aftershock monitoring and early warning on earthquake rescue site

Abstract

The invention relates to the technical field of earthquake monitoring, in particular to a method and system for aftershock monitoring and early warning on an earthquake rescue site. The method comprises the following steps: acquiring an aftershock signal sequence of each acquisition position in a target area in a set time period in real time; and determining the P wave arrival time of the acquisition position of the first trigger condition, and sending an early warning signal to rescue workers. According to the scheme of the invention, aftershock monitoring and early warning can be carried out timely and accurately.

Description

Technical Field

[0001] The present invention relates to the field of earthquake monitoring technology, and more specifically, to a method and system for aftershock monitoring and early warning at an earthquake rescue site. Background Art

[0002] During the post-earthquake rescue process, aftershock monitoring and early warning are key measures to ensure the safety of rescue workers and residents in the disaster area. Therefore, it is necessary to continuously monitor aftershocks to avoid secondary disasters that may occur under the influence of aftershocks.

[0003] Among them, the first arrival of P wave (P wave) is the most basic and important step in microseismic identification, source location and focal mechanism interpretation. There are several common P wave picking methods, specifically: (1) Short Term Average / Long Term Average (STA / LTA) method: It uses the ratio of the short-term average to the long-term average to reflect the change in signal amplitude, and takes the P wave arrival time when the ratio is greater than a certain set threshold. The STA / LTA method has the characteristics of simple algorithm, fast calculation speed, and diverse average characteristic functions, but it is difficult to pick up low signal-to-noise ratio signals, and when the threshold is large, it may not pick up the first arrival of the P wave or increase the picking error; when the threshold is small, it may be triggered by noise too early.

[0004] Based on the above-mentioned threshold setting problems, in related technologies, such as the article "STA / LTA method for picking up the first arrival of natural seismic waves and its improved analysis" was published in Progress in Geophysics, Volume 38, Issue 4, 2023. The article mentioned that by establishing the relationship between the threshold and the background noise, two new methods for picking up the first arrival of seismic waves based on the reference threshold were proposed. This can overcome the shortcoming that the fixed threshold cannot be applied to all seismic records, and the picking accuracy and precision are improved compared with the traditional STA / LTA method.

[0005] When determining the threshold, the above scheme introduces known noise to correct the initial threshold and obtain the final threshold. However, since the P-wave signal intensity of the aftershock is weak and the environmental noise intensity in different locations is different, when the final threshold is used to pick up the P wave, there will still be problems such as missed P-wave picking and untimely warning.

[0006] (2) Artificial neural network method: The artificial neural network method uses peak amplitude, root mean square amplitude ratio within the time window, envelope slope of the peak and its preceding and following peaks, and ratio of noise to signal as neural network input factors. The artificial neural network method is a relatively comprehensive P-wave first arrival picking method with strong adaptability to microseismic waveforms, but its parameter calculation workload is large, the learning speed is slow, and the implementation is complex. It may not be able to pick up the P-wave first arrival in time.

[0007] (3) Autoregressive model: The microseismic signal is divided into two local statistical periods, and the autocorrelation minimum point is taken as the P-wave arrival time. This algorithm has high picking accuracy, but it is unstable for picking low signal-to-noise ratio and tail oscillation signals.

[0008] Therefore, it is particularly important to conduct aftershock monitoring and early warning in a timely and accurate manner. Summary of the invention

[0009] The purpose of the present invention is to propose a method and system for aftershock monitoring and early warning at an earthquake rescue site, so as to solve the problem that aftershock monitoring cannot be performed in a timely and accurate manner in the prior art; to this end, the present invention provides solutions in the following two aspects.

[0010] In a first aspect, the present invention provides a method for aftershock monitoring and early warning at an earthquake rescue site, comprising: Real-time acquisition of aftershock signal sequences within a set period of time at each acquisition location in the target area; Determine the arrival time of the P wave at the acquisition position of the first trigger condition, and send an early warning signal to the rescue personnel; the condition is that the ratio of the long-short time window average value of the aftershock signal at the current time in each set time period is greater than the corresponding long-short time threshold; the long-short time threshold is the sum of the product of the ratio of the long-short time window average value of the P wave arrival time in all matching sequences under the corresponding acquisition position and the weight; The matching sequence acquisition process is as follows: acquiring multiple historical aftershock sequences; Obtaining the cross-spectral density curves of each historical aftershock sequence and the aftershock signal sequence; classifying all cross-spectral density curves to obtain multiple clusters; taking the inverse of the frequency of the maximum peak point in the average cross-spectral density curve of each cluster obtained as the joint period of the corresponding cluster; According to the combined period, a time segment including the current time is intercepted from the aftershock signal sequence; a sliding window is performed on each historical aftershock sequence using the combined period as a window to obtain a local sequence; Calculate the mean matching degree of all local sequences between the time series segment and the corresponding historical aftershock sequences under any joint period, and take the historical aftershock sequence with the maximum value in the mean matching degree as the matching sequence; The weight is a normalized value of the maximum value.

[0011] In the above scheme, by analyzing the cross-spectral density curves of the aftershock signal sequence at different sampling positions and each historical aftershock sequence, the frequency domain relationship between the two sequences can be measured, and then the joint period can be obtained. According to the length of the joint period, the matching degree mean of the time series segment and all local time series is calculated, and the corresponding matching sequence can be obtained more finely and accurately. Then, the long-short time threshold at the current time of the corresponding sampling position is estimated by using the ratio of the long-short time threshold corresponding to each sampling position to judge the ratio of the current time of the corresponding sampling position, so that the P wave arrival time of the first trigger sampling position can be picked up more timely and accurately, thereby improving the accuracy of aftershock monitoring.

[0012] Optionally, the matching degree mean is the mean of all matching degrees in the corresponding joint period; the matching degree is: ; in, For joint cycle The matching degree between the corresponding time segment and the local sequence at the a-th sliding window in the j-th historical aftershock sequence, It is a joint cycle The standard deviation of the vibration amplitude of the corresponding time segment, It is a joint cycle The standard deviation of the vibration amplitude of the local sequence at the a-th sliding window in the corresponding j-th historical aftershock sequence, It is a joint cycle The tth vibration amplitude in the corresponding time segment, It is a joint cycle The corresponding t-th vibration amplitude in the local sequence at the a-th sliding window in the j-th historical aftershock sequence, is the length of the i-th joint period.

[0013] The above calculation of the matching degree based on the amplitude fluctuation difference and amplitude difference of the time series segment and the local sequence can obtain an accurate matching degree.

[0014] Optionally, the mean value of the matching degree is the mean value of the Pearson correlation coefficients of the time series segments under any joint period and all local sequences in the corresponding historical aftershock sequences calculated respectively.

[0015] The matching degree calculated by the above scheme can accurately measure the similarity between two sequences.

[0016] Optionally, the ratio of the long- and short-time window averages of the aftershock signal at the current moment is: ; in, For the The ratio of the average values ​​of the long and short time windows at the corresponding time of the sampling points, S and L are the number of aftershock signals in the short time window and the long time window respectively. , are the vibration amplitudes of the mth and kth aftershock signals, respectively. , are the mean vibration amplitudes of aftershock signals in the short-time window and long-time window, respectively.

[0017] Optionally, the cross-spectral density curve is obtained by performing Fourier transform on any historical aftershock sequence and aftershock signal sequence.

[0018] The cross-spectral density curve obtained in the above scheme can measure the mutual coupling degree of the corresponding two sequences at different frequencies.

[0019] Optionally, the weight is: ; is the weight of the ith joint period, In the joint cycle The corresponding maximum value is K, which is the number of joint cycles.

[0020] The above normalization method can simplify the calculation.

[0021] Optionally, the acquisition positions are locations of six seismographs evenly arranged in a triangle.

[0022] In a second aspect, a system for aftershock monitoring and early warning at an earthquake rescue site comprises: processor; A memory stores computer instructions for aftershock monitoring and early warning at an earthquake rescue site. When the computer instructions are executed by the processor, the system executes the above-mentioned method for aftershock monitoring and early warning at an earthquake rescue site.

[0023] The beneficial effects of the present invention are: The scheme of the present invention first determines the matching sequence of aftershock signal sequences at different sampling positions, and then estimates the long and short time thresholds of the corresponding sampling positions using the arrival time of the P waves in all matching sequences, so as to timely and accurately perform aftershock monitoring at each sampling position; that is, by determining the long and short time thresholds at different sampling positions, the influence of noise at different sampling positions is reduced, and the reliability of aftershock monitoring is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 A flowchart schematically shows a method for aftershock monitoring and early warning at an earthquake rescue site in this embodiment; Figure 2 The schematic diagram of the distribution of seismographs when collecting aftershock signals is shown schematically; Figure 3 The structural block diagram of a system for aftershock monitoring and early warning at an earthquake rescue site in this embodiment is schematically shown. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0026] Specifically, taking an earthquake rescue site in a certain area as an example, a method for aftershock monitoring and early warning at an earthquake rescue site in this embodiment is introduced. Figure 1 As shown, the following steps are included: Step S1, acquiring the aftershock signal to be picked up in the target area in real time.

[0027] In one embodiment, a seismograph is used to collect real-time aftershock signals. Specifically, at the earthquake rescue site, multiple seismographs are evenly arranged in a triangle at various locations, such as Figure 2 As shown in FIG. 6 , taking 6 seismographs as an example, each seismograph collects aftershock signals at different sampling times at the location where the seismograph is located. The aftershock signals represent the propagation of seismic waves.

[0028] In this embodiment, the number of aftershock signals in the aftershock signal sequence can be 400-600, and the sampling frequency of the aftershock signals is 600 Hz, wherein the sequence number corresponding to the number of samples corresponds to the sampling time.

[0029] In this embodiment, aftershock signals corresponding to all moments within a set time period at each acquisition position constitute an aftershock signal sequence, and the end moment within the set time period is the current moment.

[0030] Step S2, calculate the ratio of the long-time window average value and the short-time window average value of the aftershock signal at each acquisition position at the current moment, and determine the P wave arrival time of the acquisition position of the first trigger condition.

[0031] The above condition is that the ratio of the long- and short-time window average values ​​of the aftershock signal at the current moment of each acquisition position is greater than the long- and short-time thresholds of the corresponding acquisition position.

[0032] In this embodiment, the ratio of each acquisition position is judged according to the conditions, and when the first acquisition position meets the conditions, the time at which the ratio of the acquisition position is located is used as the P wave arrival time of the aftershock.

[0033] Taking any sampling position as the target sampling position, the ratio of the long and short time window averages of the target sampling position is calculated as: ;in, For the The ratio of the average values ​​of the long and short time windows at the corresponding time of the sampling points, S and L are the number of aftershock signals in the short time window and the long time window respectively. , are the vibration amplitudes of the mth and kth aftershock signals, respectively. , are the mean vibration amplitudes of aftershock signals in the short-time window and long-time window, respectively.

[0034] The process of obtaining the long and short time thresholds corresponding to the target sampling position includes steps S21-S24, specifically: Step S21, obtaining a plurality of historical aftershock data from different regions in the historical data.

[0035] In one embodiment, historical aftershock data of different regions where earthquakes have occurred in historical data are obtained through big data; wherein each historical aftershock data includes an aftershock waveform, a P wave arrival time, and a ratio of the long-short time window average value of the P wave arrival time. The calculation method of the ratio of the long-short time window average value is the same as the calculation method of the ratio of the long-short time window average value, which will not be repeated here.

[0036] The horizontal axis in the aftershock waveform diagram is time, and the vertical axis is vibration amplitude; the vibration amplitude corresponding to each moment in the aftershock waveform diagram constitutes the historical aftershock sequence.

[0037] It should be noted that since the aftershock signal sequence is data of a set time period obtained in real time, and the historical aftershock sequence is obtained through historical data, theoretically the length of the historical aftershock sequence is much longer than that of the aftershock signal sequence.

[0038] Step S22, obtaining a cross-spectral density curve between a historical aftershock waveform diagram and the aftershock signal in each historical aftershock data.

[0039] In one embodiment, taking the aftershock signal sequence of any sampling position as an example, Fourier transform is used to convert the time domain signals in any historical aftershock sequence and the aftershock signal sequence into frequency domain signals, and then the frequency domain signals of the two sequences are multiplied, and finally the frequency domain signals are converted into time domain signals by inverse Fourier transform to obtain the cross-spectral density, and then the cross-spectral density curve can be obtained. Since the specific process of obtaining the cross-spectral density is a prior art, it will not be described in detail here.

[0040] Among them, cross-spectral density (CSD) is a frequency domain analysis method used to describe the relationship between two signals and can measure the degree of mutual coupling between two signals at different frequencies.

[0041] In this embodiment, by obtaining the cross-spectral density of the aftershock signal sequence and the signals at different times in each historical aftershock sequence, the mutual relationship between the two signals can be obtained.

[0042] Step S23, classify all the cross-spectral density curves to obtain multiple clusters; calculate the joint period of each cluster; calculate the matching degree between the time segment under each joint period and any local sequence in the corresponding historical aftershock sequence, obtain the matching degree mean of all local sequences, and select the historical aftershock sequence corresponding to the maximum value in the matching degree mean as the matching sequence.

[0043] In one embodiment, a K-means clustering algorithm is used to classify all cross-spectral density curves; specifically, a plurality of clusters are obtained by clustering all cross-spectral density curves using the K-means clustering algorithm. Clusters.

[0044] When clustering, CH can be used to evaluate different The clustering effect of the values, select the one with the best clustering effect The value is taken as the final clustering result.

[0045] After obtaining K clusters, it is necessary to average the multiple cross-spectral density curves contained in each cluster to obtain the average cross-spectral density curve corresponding to each cluster. Specifically, the average cross-spectral density curve is obtained by averaging the cross-spectral densities at the same time in multiple cross-spectral density curves, and then obtaining the average cross-spectral density at all times. Each cluster corresponds to an average cross-spectral density curve.

[0046] In this embodiment, the average cross-spectral density curve of each cluster is obtained, and the inverse of the frequency of the maximum peak point in each average cross-spectral density curve is used as the joint period of each historical aftershock sequence and the aftershock signal sequence in the corresponding cluster.

[0047] Taking the i-th cluster as an example, the combined cycle for: ; is the frequency corresponding to the maximum peak point in the average cross-spectral density curve in the i-th cluster.

[0048] It should be noted that each cluster corresponds to a joint period, and the number of clusters is equal to the number of joint periods; the joint periods of different cross-spectral density curves in the same cluster (a cross-spectral density curve corresponds to the combination of the historical aftershock sequence and the aftershock signal sequence) are equal.

[0049] After obtaining the joint period of each cluster, it is also necessary to obtain time segments and local sequences of corresponding lengths from the aftershock signal sequence and each historical aftershock sequence according to the joint period.

[0050] Specifically, the time segment is a segment of data including the current time from the aftershock signal sequence according to the joint period. When As the starting point, intercept The aftershock signals of multiple moments before the corresponding moment (current moment) constitute a time series segment. The number of multiple moments is equal to the length of the joint period. Among them, n is the number of aftershock signals in the aftershock signal sequence, Indicates the nth vibration amplitude.

[0051] The local time series is obtained by sliding windows on each historical aftershock sequence; the length of the sliding window is the length of the joint period. For example, when any historical aftershock sequence is When As the starting point of the window, the historical aftershock sequence is sequentially slid into a window to obtain multiple local sequences; among them, It represents the n0th vibration amplitude in the historical aftershock sequence, where n0 is the number of aftershock signals in the historical aftershock sequence.

[0052] The step size of the sliding window can be set to 1, and can also be determined according to actual conditions.

[0053] In this embodiment, after obtaining the time segment under each combined cycle and all local sequences in the corresponding any historical aftershock sequence, the matching degree between the time segment under any combined cycle and each local sequence in the corresponding any historical aftershock sequence is calculated.

[0054] In one embodiment, the matching degree is: ; in, For joint cycle The matching degree between the corresponding time segment and the local sequence at the a-th sliding window in the j-th historical aftershock sequence, It is a joint cycle The standard deviation of the vibration amplitude of the corresponding time segment is used to represent the joint period The volatility of the corresponding time series, It is a joint cycle The standard deviation of the vibration amplitude of the local sequence at the a-th sliding window in the corresponding j-th historical aftershock sequence is used to represent the joint period The volatility of the corresponding local series, Represents joint cycle The volatility difference between the corresponding time segment and the local series; It is a joint cycle The tth vibration amplitude in the corresponding time segment, It is a joint cycle The corresponding t-th vibration amplitude in the local sequence at the a-th sliding window in the j-th historical aftershock sequence, Represents joint cycle The mean difference between the amplitude of the local sequence at the a-th sliding window in the corresponding time series segment and the j-th historical aftershock sequence, is the length of the i-th joint period.

[0055] In another embodiment, the matching degree may also be the Pearson correlation coefficient between the time segment and each local sequence. Specifically, the matching degree is: ; in, For joint cycle The matching degree between the corresponding time segment and the local sequence at the a-th sliding window in the j-th historical aftershock sequence, It is a joint cycle The tth vibration amplitude in the corresponding time segment, It is a joint cycle The corresponding t-th vibration amplitude in the local sequence at the a-th sliding window in the j-th historical aftershock sequence, For joint cycle The mean of the corresponding time segment, It is a joint cycle The average value of the local sequence at the a-th sliding window in the corresponding j-th historical aftershock sequence.

[0056] In this embodiment, the calculated matching mean of the time segment under any joint period and all local sequences in any corresponding historical aftershock sequence is used as an indicator to measure whether the aftershock signal sequence matches any historical aftershock sequence, and the historical aftershock sequence corresponding to the maximum value in the matching mean is selected as the matching sequence of the aftershock signal sequence. Thus, the matching sequence under each joint period can be obtained.

[0057] The reason for calculating the matching degree above is that since the P wave signal intensity of aftershocks is relatively weak and the environmental noise intensity at different locations is different, the picking deviations of different aftershock signal sequences at different periods are different. Therefore, using a fixed threshold to pick up P waves can easily lead to the phenomenon of untimely picking up of P waves. Therefore, this embodiment calculates the matching degree between sequences at each joint period based on the volatility of the aftershock signal sequence corresponding to each cluster and the historical aftershock sequence at the joint period, so as to screen out matching sequences similar to the aftershock signal sequence, and provide accurate data for the subsequent estimation of the long and short time thresholds at different adopted positions.

[0058] The purpose of obtaining the joint period is to identify the common periodic pattern of the aftershock signal sequence and the historical aftershock sequence, and to more finely search for the historical aftershock sequence with a high degree of matching with the aftershock signal sequence under the common periodic pattern, so as to obtain a more real and accurate matching sequence.

[0059] Step S24, taking the sum of the product of the ratio of the long-short time window average value of the P wave arrival time in all matching sequences of the target sampling position and the weight as the long-short time threshold.

[0060] The long and short time thresholds are: ;in, is the long-short time threshold at the current moment, is the weight of the ith joint period, is the ratio of the long and short time window averages of the P wave arrival time of the matching sequence under the i-th joint period, is the number of joint cycles.

[0061] The above weight is the maximum matching value after normalizing the maximum value of the matching mean.

[0062] The maximum value in the mean matching degree can be normalized by using the maximum and minimum value normalization method; or the following method can be used: ; is the weight of the ith joint period, It is a joint cycle The corresponding maximum value, K is the number of joint cycles, Represents the sum of the maximum matching degrees under all joint cycles.

[0063] In this embodiment, by calculating the long and short time thresholds of different sampling positions, the P wave arrival time can be monitored more accurately; at the same time, as time changes, the aftershock signal sequence of each sampling position is also changing, and the long and short time thresholds are also adaptively changed; that is, by determining the adaptively changing long and short time thresholds, the P wave arrival time can be monitored more accurately.

[0064] Step S3, sending a warning signal to rescuers based on the P wave arrival time.

[0065] In this embodiment, according to the P wave arrival time of the acquired aftershock signal, the early warning signal is transmitted to the alarm device carried by the rescue personnel to remind the rescue personnel to evacuate in time; at the same time, the early warning signal is also transmitted to the rescue command office to command the rescue personnel to evacuate.

[0066] The solution of the present invention can timely and accurately monitor aftershocks, thereby improving the reliability of aftershock monitoring.

[0067] At the same time, compared with the prior art which first denoises the seismic signal based on the traditional denoising algorithm (which may remove a portion of the real P-wave signal and may also retain a portion of the strong noise signal during denoising), and then uses a fixed long and short-time threshold to pick up the P-wave, the scheme of the present invention can pick up the P-wave arrival time more timely and accurately, thereby improving the accuracy of aftershock monitoring.

[0068] The present invention also provides a system for aftershock monitoring and early warning at earthquake rescue sites. Figure 3 As shown, the system includes a processor and a memory, wherein the memory stores computer program instructions. When the computer program instructions are executed by the processor, a method for aftershock monitoring and early warning at an earthquake rescue site according to the present invention is implemented.

[0069] The system also includes other components well known to those skilled in the art, such as a communication bus and a communication interface, whose configuration and functions are known in the art and thus will not be described in detail here.

[0070] In the present invention, the aforementioned memory may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, apparatus or device. For example, a computer-readable storage medium may be any appropriate magnetic storage medium or magneto-optical storage medium, such as a resistive random access memory RRAM (Resistive Random Access Memory), a dynamic random access memory DRAM (Dynamic Random Access Memory), a static random access memory SRAM (Static Random-Access Memory), an enhanced dynamic random access memory EDRAM (Enhanced Dynamic Random Access Memory), a high-bandwidth memory HBM (High-Bandwidth Memory), a hybrid memory cube HMC (Hybrid Memory Cube), etc., or any other medium that can be used to store the required information and can be accessed by an application, a module, or both. Any such computer storage medium may be part of a device or accessible or connectable to a device. Any application or module described in the present invention may be implemented by computer-readable / executable instructions stored or otherwise maintained by such a computer-readable medium.

[0071] In the description of this specification, “plurality” means at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0072] Although this specification has shown and described a number of embodiments of the present invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art will conceive of many modifications, changes and alternatives without departing from the ideas and spirit of the present invention. It should be understood that in the practice of the present invention, various alternatives to the embodiments of the present invention described herein may be employed.

Claims

1. A method for aftershock monitoring and early warning at an earthquake rescue site, characterized in that: include: Real-time acquisition of aftershock signal sequences within a set period of time at each acquisition location in the target area; Determine the arrival time of the P wave at the acquisition location of the first trigger condition and send an early warning signal to the rescue personnel; The condition is that the ratio of the long-short time window average value of the aftershock signal at the current time in each set time period is greater than the corresponding long-short time threshold; the long-short time threshold is the sum of the product of the ratio of the long-short time window average value of the P wave arrival time in all matching sequences at the corresponding acquisition position and the weight; The matching sequence acquisition process is as follows: acquiring multiple historical aftershock sequences; Obtaining the cross-spectral density curves of each historical aftershock sequence and the aftershock signal sequence; classifying all cross-spectral density curves to obtain multiple clusters; taking the inverse of the frequency of the maximum peak point in the average cross-spectral density curve of each cluster obtained as the joint period of the corresponding cluster; According to the combined period, a time segment including the current time is intercepted from the aftershock signal sequence; a sliding window is performed on each historical aftershock sequence using the combined period as a window to obtain a local sequence; Calculate the mean matching degree of all local sequences between the time series segment and the corresponding historical aftershock sequences under any joint period, and take the historical aftershock sequence with the maximum value in the mean matching degree as the matching sequence; The weight is a normalized value of the maximum value.

2. A method for aftershock monitoring and early warning at an earthquake rescue site according to claim 1, characterized in that: The matching degree mean is the mean of all matching degrees in the corresponding joint period; the matching degree is: ； in, For joint cycle The matching degree between the corresponding time segment and the local sequence at the a-th sliding window in the j-th historical aftershock sequence, It is a joint cycle The standard deviation of the vibration amplitude of the corresponding time segment, It is a joint cycle The standard deviation of the vibration amplitude of the local sequence at the a-th sliding window in the corresponding j-th historical aftershock sequence, It is a joint cycle The tth vibration amplitude in the corresponding time segment, It is a joint cycle The corresponding t-th vibration amplitude in the local sequence at the a-th sliding window in the j-th historical aftershock sequence, is the length of the i-th joint period.

3. The method for aftershock monitoring and early warning at an earthquake rescue site according to claim 1, characterized in that: The matching degree mean is the mean of the Pearson correlation coefficients of the time series segments under any joint period and all local sequences in the corresponding historical aftershock sequences calculated respectively.

4. A method for aftershock monitoring and early warning at an earthquake rescue site according to claim 2 or 3, characterized in that: The ratio of the long and short time window average values ​​of the aftershock signal at the current moment is: ; in, For the The ratio of the average values ​​of the long and short time windows at the corresponding time of the sampling points, S and L are the number of aftershock signals in the short time window and the long time window respectively. , are the vibration amplitudes of the mth and kth aftershock signals, respectively. , are the mean vibration amplitudes of aftershock signals in the short-time window and long-time window, respectively.

5. The method for aftershock monitoring and early warning at an earthquake rescue site according to claim 1, characterized in that: The cross-spectral density curve is obtained by performing Fourier transform on any historical aftershock sequence and aftershock signal sequence.

6. A method for aftershock monitoring and early warning at an earthquake rescue site according to claim 4, characterized in that: The weights are: ; is the weight of the ith joint period, In the joint cycle The corresponding maximum value is K, which is the number of joint cycles.

7. The method for aftershock monitoring and early warning at an earthquake rescue site according to claim 1, characterized in that: The acquisition positions are the locations of six seismographs evenly arranged in a triangle.

8. A system for aftershock monitoring and early warning at an earthquake rescue site, characterized in that: include: processor; A memory storing computer instructions for aftershock monitoring and early warning at an earthquake rescue site. When the computer instructions are executed by the processor, the system executes a method for aftershock monitoring and early warning at an earthquake rescue site according to any one of claims 1 to 7.

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