Seismic phase signal pickup method based on time window length transformation
By varying the time window length and combining theoretical time travel with time-domain long and short window techniques, the seismic phase signal is automatically acquired, solving the problems of inaccurate acquisition and high manpower consumption in existing technologies, and achieving efficient and accurate seismic phase signal extraction.
Patent Information
- Application Number
- CN202511037490.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-11-11
AI Technical Summary
Current technologies for picking up seismic phase signals are not accurate or stable enough, are labor-intensive and lack standardized methods, and have large errors, especially in complex seismic wave propagation environments.
A method based on changing the time window length is adopted, which combines theoretical travel time and time-domain long and short window techniques. By changing the time window length of the preliminary and final actual arrival times, the phase signal is automatically picked up, including the calculation of the theoretical travel time of the phase and the determination of the preliminary and final actual arrival times.
It improves the accuracy and reliability of seismic phase signal acquisition, reduces manual intervention, is highly adaptable, can stably extract signals under complex seismic wave conditions, reduces noise impact, and improves work efficiency.
Smart Images
Figure CN120928438A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of natural earthquake signal processing technology, and in particular to a method for picking up specific seismic phase signals based on a variable time window length. Background Technology
[0002] Seismic waves generated by natural earthquakes encounter impedance differences such as discontinuities or scatterers within the Earth's interior. After reflection, refraction, or conversion, the resulting phase signals recorded by surface seismic sensors are called phase signals. Efficient and accurate acquisition of phase signals is a crucial step in seismic signal processing for subsequent seismic wave analysis and research. Traditional phase signal acquisition methods typically rely on manual selection or extraction based on fixed time windows. These methods are often affected by low signal-to-noise ratios, phase overlap, and unclear temporal characteristics, leading to inaccurate or unstable acquisition results. Especially in complex seismic wave propagation environments, existing automatic acquisition methods often suffer from significant errors. Furthermore, manual acquisition methods are labor-intensive and lack standardized methods, especially when encountering high background noise or weak phase signals.
[0003] Therefore, there is an urgent need for a new method that can overcome the shortcomings of existing technologies, improve the speed of seismic phase signal acquisition, and enhance the accuracy and reliability of seismic phase signal acquisition, so as to improve the efficiency, accuracy and robustness of natural earthquake data analysis. Summary of the Invention
[0004] In view of the above-mentioned problems in the prior art, the present invention provides a method for picking up seismic phase signals based on changing time window length, so as to solve the technical problems in the prior art such as inaccurate or unstable picking results, high manpower consumption, inconsistent standards, and easy introduction of human error.
[0005] This invention provides a method for picking up seismic phase signals based on a variable time window length, comprising the following steps:
[0006] Step S1: Calculate the theoretical arrival time of the seismic phase using the ray tracing method.
[0007] Step S2: Select the time window length, set the time window at the theoretical arrival time, and determine the preliminary actual arrival time through the time domain long and short window method;
[0008] Step S3: Change the time window length, reduce the time window scale, set the time window at the initial actual arrival time, and determine the final actual arrival time through the time domain long and short window method.
[0009] In one embodiment, step S1 includes,
[0010] Step S11: Set the spatial location, specifying the location of the earthquake source and the location of the seismic sensor.
[0011] Step S12: Set up the velocity model and provide a one-dimensional velocity model;
[0012] Step S13: Select the target seismic phase and choose the target seismic phase with the expected theoretical travel time.
[0013] Step S14: Calculate the theoretical travel time. Based on information including spatial location, velocity model, and target phase, calculate the theoretical arrival time Ta of the target phase.
[0014] In one embodiment, step S2 includes,
[0015] Step S21: Initially select long and short time windows, and determine the length of the long time window as WA1 and the length of the short time window as WA2;
[0016] Step S22, sliding time window: Starting from the theoretical arrival time, slide the time window continuously to the right on the time domain waveform signal according to the step size of step1. The end point of the long time window is the start point of the short time window, and the long time window and the short time window slide synchronously.
[0017] Step S23: Calculate the amplitude ratio of the long and short windows. Calculate the ratio of the maximum absolute amplitude amp1 in the short window to the maximum absolute amplitude amp2 in the long window, denoted as α.
[0018] Step S24: Obtain the preliminary actual arrival time. Set the threshold to β. Assuming that when sliding to time Tb, the amplitude ratio of the long and short windows α is greater than the threshold β, then Tb is recorded as the preliminary actual arrival time.
[0019] In one embodiment, before step S21, step S2 further includes,
[0020] Step S20: Time-domain waveform preprocessing. Preprocessing operations are performed on the time-domain waveform signal to reduce noise interference and improve the signal-to-noise ratio.
[0021] In one embodiment, step S3 includes,
[0022] Step S31: Change the long and short time windows, select the time window length again, narrow the range of long and short time windows, and determine the long time window length as WB1 and the short time window length as WB2, where WB1 is less than WA1 and WB2 is less than WA2.
[0023] Step S32: Slide the time window. Starting from the initial actual arrival time Tb, slide the time window to the right on the time domain waveform signal according to the step size of step2. Here, step2 is less than step1. The end point of the long time window is the start point of the short time window, and the long time window and the short time window slide synchronously.
[0024] Step S33: Calculate the amplitude ratio of the long and short windows. Calculate the ratio of the maximum absolute amplitude amp1 in the short window to the maximum absolute amplitude amp2 in the long window, denoted as α.
[0025] Step S34: Obtain the final actual arrival time. Set the threshold to γ. Assuming that when sliding to time Tc, the long-short window amplitude ratio α is greater than the threshold γ, then Tc is recorded as the final actual arrival time.
[0026] In one embodiment, WA1 = 20s, WA2 = 2s, step1 = 0.2s, and β = 2.5.
[0027] In one embodiment, WB1 = 4s, WB2 = 0.2s, step2 = 0.1s, and γ = 2.5.
[0028] In one embodiment, the one-dimensional velocity model is a PREM model or an AK135 model.
[0029] In one embodiment, the theoretical time travel in step S14 is calculated using Taup software.
[0030] In one embodiment, the time-domain waveform preprocessing in step S20 includes mean removal, trend removal, pinch-out removal, and zero-phase-shift bandpass filtering.
[0031] Compared with the prior art, the beneficial effects of the phase signal picking method based on the changing time window length provided by the embodiments of the present invention are as follows:
[0032] 1. The embodiments of the present invention have a high degree of automation, which can realize the automatic extraction of seismic phase signals, reduce manual intervention, save a lot of time and labor costs, and greatly improve work efficiency;
[0033] 2. The embodiments of the present invention improve the picking accuracy. By combining theoretical travel time with long and short window methods, the phase signals can be extracted more accurately. Especially in complex or low signal-to-noise ratio seismic data, the situation of false identification or missed identification can be reduced.
[0034] 3. The embodiments of the present invention are highly adaptable. The long and short window method can adapt to the time domain characteristics of different seismic phases and can still extract seismic phase signals stably and effectively under complex seismic wave propagation conditions.
[0035] 4. The embodiments of the present invention optimize the signal-to-noise ratio by changing the length of the time window, which can effectively reduce the impact of noise on the picking results and improve the reliability of signal recognition. Attached Figure Description
[0036] Figure 1 A flowchart illustrating a phase signal acquisition method based on a variable time window length provided in an embodiment of the present invention;
[0037] Figure 2 This is a schematic diagram of the ray path corresponding to the seismic phase signal involved in a seismic phase signal picking method based on a variable time window length provided in an embodiment of the present invention;
[0038] Figure 3 This is a schematic diagram of automatic phase acquisition involved in a phase signal acquisition method based on a variable time window length provided in an embodiment of the present invention. Detailed Implementation
[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0040] Various embodiments and features of this application are described herein with reference to the accompanying drawings.
[0041] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.
[0042] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application, which have the features described in the claims and are therefore all within the scope of protection defined herein.
[0043] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.
[0044] Specific embodiments of this application are described below with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to ascertain the true intent based on the user's historical operations, and to avoid unnecessary or redundant details that would obscure this application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in various ways with substantially any suitable detailed structure.
[0045] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.
[0046] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are for illustrative purposes only and are not intended to limit the scope of the invention. The following description, in conjunction with... Figure 1-3 The preferred embodiments of the present invention will be described in further detail below:
[0047] This invention is based on a collaborative approach of theoretical travel time and time-domain long and short window methods with varying window lengths. It aims to improve the efficiency, accuracy, and robustness of earthquake data analysis by calculating the theoretical propagation time of natural earthquake phase signals (i.e., "theoretical travel time of seismic phases") and combining it with time-domain long and short window techniques. Through a two-stage transformation of the time window length, it picks up the phase signals and their actual arrival times from the earthquake data. Its core lies in the effective combination and application of theoretical travel time calculation and time-domain long and short window methods. First, a wider long and short time window is used to prevent the phase signal from being mistakenly selected as noise; then, a narrower long and short time window is used to improve the accuracy of arrival time picking.
[0048] like Figure 1 As shown, this embodiment of the invention provides a method for picking up seismic phase signals based on a changing time window length, including:
[0049] Step S1, as follows Figure 2 As shown, the theoretical travel time of the seismic phase is calculated using the ray tracing method. This step involves calculating the theoretical arrival time of the seismic phase, taking into account the velocity structure of the subsurface medium. Utilizing the location of the seismic source and the spatial position of the sensor, the theoretical travel time of the target seismic phase is output. The calculation result provides a preliminary estimate of the arrival time of the seismic phase. This theoretical travel time will serve as the basis for subsequent time window setting. The theoretical travel time of the seismic phase can be calculated using Taup software. Taup is a classic command-line program in seismology that can calculate the theoretical travel time of the seismic phase based on a one-dimensional layered Earth velocity model and the ray tracing method. The specific steps of step S1 include…
[0050] Step S11: Set the spatial location, and give the location of the earthquake source (longitude, latitude, depth) and the location of the earthquake sensor (longitude, latitude, elevation);
[0051] Step S12: Set up the velocity model and provide a one-dimensional velocity model. Usually, the PREM model or AK135 model is selected.
[0052] Step S13: Select the target seismic phase. Select the target seismic phase for the expected theoretical travel time calculation, such as P phase, PmP phase, PcP phase, or PPiKP phase, etc.
[0053] Step S14: Calculate the theoretical travel time. Based on information such as spatial location, velocity model, and target phase, use Taup software to calculate the theoretical arrival time Ta of the target phase.
[0054] Step S2, as follows Figure 3As shown, the time window length is selected, and the time window is set at the theoretical arrival time. The preliminary actual arrival time is determined by the long and short window method in the time domain. The long and short window method is a technique that adapts to different types of signals by adjusting the size of the analysis window. The short time window is usually used to capture rapid changes in the signal, and is particularly suitable for accurately locating the arrival time of the seismic phase. The long time window is used to enhance the signal-to-noise ratio and suppress the influence of noise, and is suitable for use when the signal is weak or the seismic phases overlap. The short window can improve the accuracy of the signal arrival time, while the long window helps to identify weaker seismic phases and signal characteristics in complex backgrounds. The combination of the long and short window methods can effectively improve the accuracy and robustness of picking up seismic phase signals in complex environments. Specifically, step S2 includes...
[0055] Step S20: Time-domain waveform preprocessing. Preprocess the time-domain waveform signal to minimize noise interference and improve the signal-to-noise ratio, such as removing the mean, removing the trend, removing the peaks, and zero-phase-shift bandpass filtering.
[0056] Step S21: Initially select long and short time windows, and determine the length of the long time window (LTA) as WA1 = 20s and the length of the short time window (STA) as WA2 = 2s (Note: The lengths of the long and short time windows can be adjusted appropriately according to the actual waveform quality).
[0057] Step S22: Sliding time window. Starting from the theoretical arrival time Ta, continuously slide the time window (including long and short time windows) to the right on the time-domain waveform signal with a step size of step1 = 0.2s. The end point of the long time window is the starting point of the short time window, and the long and short time windows slide synchronously. Set time windows near the theoretical travel time, and perform signal analysis based on long and short windows of different lengths. By selecting an appropriate window length, it is possible to adapt to the time-domain characteristics of different seismic phases, making signal identification more accurate. The short window is used to capture the precise arrival time of the seismic phase, while the long window is used to improve the signal-to-noise ratio and reduce the influence of background noise. Combining the long and short windows, the seismic phase signal is searched based on the signal-to-noise ratio. For each time window near the theoretical travel time, the quality of the seismic phase signal is evaluated using the signal-to-noise ratio, thereby further determining the actual arrival time of the seismic phase.
[0058] Step S23: Calculate the amplitude ratio of the long and short windows. Calculate the ratio of the maximum absolute amplitude amp1 in the short window to the maximum absolute amplitude amp2 in the long window, denoted as α.
[0059] Step S24: Obtain the preliminary actual arrival time. Set the threshold to β = 2.5. Assuming that when sliding to time Tb, the long and short window amplitude ratio α is greater than the threshold β, then Tb is recorded as the preliminary actual arrival time.
[0060] Step S3 involves changing the time window length and reducing the time window scale. A time window is set at the initial actual arrival time, and the final actual arrival time is determined using a time-domain long / short window method. Changing the time window length and reducing the time window scale allows for further searching of a smaller range and higher precision of the actual arrival time. Through the above steps, the actual arrival time of the phase signal can be accurately picked up within a time window near the theoretical travel time. Step S3 specifically includes…
[0061] Step S31: Change the long and short time windows, select the time window length again, narrow the range of long and short time windows, and determine the long time window length as WB1 = 4s and the short time window length as WB2 = 0.2s (Note: The lengths of the long and short time windows can be adjusted according to the actual waveform quality).
[0062] Step S32: Slide the time window. Starting from the initial actual arrival time Tb, slide the time window (including long time window and short time window) to the right on the time domain waveform signal with a step size of step2 = 0.1s. The end point of the long time window is the start point of the short time window, and the long time window and the short time window slide synchronously.
[0063] Step S33: Calculate the amplitude ratio of the long and short windows. Calculate the ratio of the maximum absolute amplitude amp1 in the short window to the maximum absolute amplitude amp2 in the long window, denoted as α.
[0064] Step S34: Obtain the final actual arrival time. Set the threshold to γ = 2.5. Assuming that when sliding to time Tc, the long-short window amplitude ratio α is greater than the threshold γ, then Tc is recorded as the final actual arrival time.
[0065] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.
Claims
1. A method for picking up seismic phase signals based on a variable time window length, characterized in that, Includes the following steps: Step S1: Calculate the theoretical arrival time of the seismic phase using the ray tracing method. Step S2: Select the time window length, set the time window at the theoretical arrival time, and determine the preliminary actual arrival time through the time domain long and short window method; Step S3: Change the time window length, reduce the time window scale, set the time window at the initial actual arrival time, and determine the final actual arrival time through the time domain long and short window method.
2. The method for picking up seismic phase signals based on the changing time window length according to claim 1, characterized in that: Step S1 includes, Step S11: Set the spatial location, specifying the location of the earthquake source and the location of the seismic sensor. Step S12: Set up the velocity model and provide a one-dimensional velocity model; Step S13: Select the target seismic phase and choose the target seismic phase with the expected theoretical travel time. Step S14: Calculate the theoretical travel time. Based on information including spatial location, velocity model, and target phase, calculate the theoretical arrival time Ta of the target phase.
3. The method for picking up seismic phase signals based on the changing time window length according to claim 1, characterized in that: Step S2 includes, Step S21: Initially select long and short time windows, and determine the length of the long time window as WA1 and the length of the short time window as WA2; Step S22, sliding time window: Starting from the theoretical arrival time, slide the time window continuously to the right on the time domain waveform signal according to the step size of step1. The end point of the long time window is the start point of the short time window, and the long time window and the short time window slide synchronously. Step S23: Calculate the amplitude ratio of the long and short windows. Calculate the ratio of the maximum absolute amplitude amp1 in the short window to the maximum absolute amplitude amp2 in the long window, denoted as α. Step S24: Obtain the preliminary actual arrival time. Set the threshold to β. Assuming that when sliding to time Tb, the amplitude ratio of the long and short windows α is greater than the threshold β, then Tb is recorded as the preliminary actual arrival time.
4. The method for picking up seismic phase signals based on the changing time window length according to claim 3, characterized in that: Before step S21, step S2 also includes, Step S20: Time-domain waveform preprocessing. Preprocessing operations are performed on the time-domain waveform signal to reduce noise interference and improve the signal-to-noise ratio.
5. The method for picking up seismic phase signals based on the changing time window length according to claim 3, characterized in that: Step S3 includes, Step S31: Change the long and short time windows, select the time window length again, narrow the range of long and short time windows, and determine the long time window length as WB1 and the short time window length as WB2, where WB1 is less than WA1 and WB2 is less than WA2. Step S32: Slide the time window. Starting from the initial actual arrival time Tb, slide the time window to the right on the time domain waveform signal according to the step size of step2. Here, step2 is less than step1. The end point of the long time window is the start point of the short time window, and the long time window and the short time window slide synchronously. Step S33: Calculate the amplitude ratio of the long and short windows. Calculate the ratio of the maximum absolute amplitude amp1 in the short window to the maximum absolute amplitude amp2 in the long window, denoted as α. Step S34: Obtain the final actual arrival time. Set the threshold to γ. Assuming that when sliding to time Tc, the long-short window amplitude ratio α is greater than the threshold γ, then Tc is recorded as the final actual arrival time.
6. The method for picking up seismic phase signals based on the changing time window length according to claim 3, characterized in that: The values are: WA1 = 20s, WA2 = 2s, step1 = 0.2s, and β = 2.
5.
7. The method for picking up seismic phase signals based on a changing time window length according to claim 5, characterized in that: The parameters are: WB1 = 4s, WB2 = 0.2s, step2 = 0.1s, and γ = 2.
5.
8. The method for picking up seismic phase signals based on the changing time window length according to claim 2, characterized in that: The one-dimensional velocity model is either the PREM model or the AK135 model.
9. The method for picking up seismic phase signals based on a changing time window length according to claim 2, characterized in that: The theoretical time travel in step S14 is calculated using Taup software.
10. The method for picking up seismic phase signals based on a changing time window length according to claim 4, characterized in that: Step S20 time-domain waveform preprocessing includes mean removal, trend removal, pinch-out removal, and zero-phase-shift bandpass filtering.