Acceleration Waveform Research Articles

Shake table test and numerical analysis of the seismic response of buried long-distance pipeline under longitudinal non-uniform excitation

To investigate the seismic response characteristics of buried pipelines under longitudinal non-uniform seismic excitation, a three-dimensional finite element overall analysis model is established on finite element analysis software based on the shaking table test of buried oil and gas pipelines under longitudinal non-uniform excitation. The calculated results are compared with the experimental analysis results to evaluate the correctness and reliability of the established model. The acceleration response, strain response, and displacement response of buried oil and gas pipelines and surrounding soil under longitudinal traveling wave excitation at different seismic intensities are compared and analyzed using finite element models to supplement the test conditions. The test and analysis results show that the longitudinal displacements at each measurement point under longitudinal non-uniform excitation follow the same pattern except for differences in displacement magnitude and the vibration pattern of the tube and soil when the peak input acceleration reaches 1.00 g. As shown by both experimental and numerical simulation results, the soil acceleration amplification coefficients along the soil height fluctuate between 0.5 and 1.5. The pipe acceleration time curves and Fourier spectrum exhibit the same simulated and experimental pipe acceleration waveforms, and they both show significant amplification in the low to medium frequency band of 5–20 Hz. The testing and numerical simulated pipeline axial strain peak curves are similar and in good agreement, indicating the high reliability of the experimental results.

Waveform harmonic suppression technology for electromagnetic standard vibration actuators based on current feedback control

To realize high-precision calibration of vibration sensors, the total harmonic distortion (THD) of the output waveform of a standard vibration actuator should be as small as possible, so a harmonic suppression technique based on current feedback control is presented. A low-cost, easy-to-implement feedback control loop of driving current is established in an electromagnetic standard vibration actuator (EVA), and the rationality of driving current in place of acceleration in the acceleration characteristic frequency band to achieve the feedback is analyzed. The influence of different values of the key parameters on the system is studied, and the acceleration characteristic frequency band of low-frequency vibration is effectively extended so that the THD of the output waveform is immensely alleviated. The effectiveness of the proposed method is verified by experiments and compared with traditional control methods, the harmonic distortion of acceleration waveform can be reduced by more than 40% without using any feedback sensors, which proves the superiority of the current feedback control method.

Evaluation of horizontal ground motion waveforms at Sedongpu Glacier during the 2017 M6.9 Mainling earthquake based on the equivalent Green's function

The terrain along the Tibet Railway is primarily steep mountains and valleys with complex geological structures. The occurrence of the Mainling earthquake indicates that the intensity of seismicity in the eastern structural junction area has strengthened, and the potential risk of earthquake-induced disasters such as landslides and debris flows is also increasing. The earthquake engineering community generally recognizes that the prediction of near-field strong ground motion can reduce the disasters caused by future large earthquakes and can guide earthquake prevention, disaster reduction and seismic design along the Sichuan–Tibet railway. The M6.9 Mainling earthquake affected the stability of Sedongpu Glacier near the epicentre. A glacier avalanche occurred under the coupling of multiple factors, including post-earthquake and precipitation events. The waveform and response spectra of a strong earthquake are key input parameters for investigating the seismic triggering mechanisms of landslides and glacier avalanches and accurately reproducing the dynamics of such disasters. In this paper, the concept of the equivalent Green's function is introduced, and various source parameter uncertainties are fully considered. The waveform and response spectra of the Mainling earthquake at Sedongpu Glacier are simulated, and the most likely seismic waveform is comprehensively assessed from multiple perspectives. This work can provide reliable acceleration waveform input for the analysis of ground motion damage and the study of earthquake-induced disaster mechanisms at important locations along the Sichuan–Tibet railway and provide a scientific reference for earthquake prevention and disaster reduction along the railway.

A dual-loop waveform distortion suppression method for electromagnetic vibrators at low frequencies

The total harmonic distortions (THDs) of output acceleration waveforms from an electromagnetic vibrator are always large due to the nonlinear stiffness, damping and magnetic intensity, which will affect the vibration calibration precision. To suppress THDs of output acceleration waveforms, a dual-loop waveform distortion suppression method based on current and velocity feedback for electromagnetic vibrators at low frequencies is presented. A counter electromotive force compensator is adopted in the current loop to remove the coupling between the current loop and velocity loop, which improves the performance of the current loop. Besides, a damping adjuster is adopted in the velocity loop to increase the damping ratio, which can improve dynamic characteristics and reduce waveform distortions when the multiple working frequencies coincide with the resonant frequency. Finally, the cooperation of the outer velocity loop and the inner current loop reduces THDs of acceleration waveforms effectively. Especially, the vibration velocity for the velocity loop is extracted by a secondary coil instead of commercial sensors, which is coaxially and separately wound around the driving coil of the electromagnetic vibrator. The proposed method is analyzed in simulation and verified by experiments, whose results show that the THDs of output acceleration waveforms are well restrained from 25% before feedback to less than 3% after feedback at low frequencies.

Data-Driven Synthesis of Broadband Earthquake Ground Motions Using Artificial Intelligence

ABSTRACTRobust estimation of ground motions generated by scenario earthquakes is critical for many engineering applications. We leverage recent advances in generative adversarial networks (GANs) to develop a new framework for synthesizing earthquake acceleration time histories. Our approach extends the Wasserstein GAN formulation to allow for the generation of ground motions conditioned on a set of continuous physical variables. Our model is trained to approximate the intrinsic probability distribution of a massive set of strong-motion recordings from Japan. We show that the trained generator model can synthesize realistic three-component accelerograms conditioned on magnitude, distance, and VS30. Our model captures most of the relevant statistical features of the acceleration spectra and waveform envelopes. The output seismograms display clear P- and S-wave arrivals with the appropriate energy content and relative onset timing. The synthesized peak ground acceleration estimates are also consistent with observations. We develop a set of metrics that allow us to assess the training process’s stability and to tune model hyperparameters. We further show that the trained generator network can interpolate to conditions in which no earthquake ground-motion recordings exist. Our approach allows for the on-demand synthesis of accelerograms for engineering purposes.

Beneficial effects of time-restricted feeding on gentamicin cytotoxicity in mouse cochlea and vestibular organs.

ObjectiveTime restricted feeding (TRF), which is an intermittent fasting protocol, has been reported to decrease the toxicity and mortality rate associated with systemic gentamicin (GM) administration. The aim of this study is to evaluate the effect of TRF on GM‐induced vestibular and auditory function in mice.MethodsJapan Central Laboratory for Experimental Animals:Institute of Cancer Research (Jcl:ICR) mice were housed in a light–dark (LD) cycle (12:12) and were divided into three groups: (1) GM treatment at a dose of 220 mg/kg with TRF (feeding time: 8 h [9:00–17:00] during the light phase [7:00–19:00]) (GM + TRF group), (2) GM treatment at a dose of 220 mg/kg without TRF (GM group), and (3) saline injection with TRF (NS + TRF group). GM or saline was injected subcutaneously for 18 days (three courses of 5 days' injection + 2 days' rest, and an additional 3 days' injection). The auditory brainstem response (ABR) and vestibular evoked potential (VsEP) were tested after the treatments. The number of sensory hair cells in the cochlear organs and the vestibular organs were quantified using microscopic images.ResultsAll animals survived until the end of the experiment. One day after the last injection, GM + TRF mice showed significantly lower ABR thresholds at 4 kHz compared to GM mice, and there was no significant difference between the GM + TRF and NS + TRF groups. There was a significant difference of VsEP between GM and GM + TRF mice only in symmetric parabolic waves with linear acceleration and ramps waveform stimulation. GM + TRF mice showed significantly less outer and inner hair cell loss compared to GM mice. GM + TRF mice showed significantly less type II hair cell loss in the utricle and the ampulla compared to GM mice.ConclusionTRF with daytime feeding reduced GM cytotoxicity in the cochlea and vestibular organs of ICR mice.Level of EvidenceNA

In situ ultrasound imaging of shear shock waves in the porcine brain

Direct measurement of brain motion at high spatio-temporal resolutions during impacts has been a persistent challenge in brain biomechanics. Using high frame-rate ultrasound and high sensitivity motion tracking, we recently showed shear waves sent to the ex vivo porcine brain developing into shear shock waves with destructive local accelerations inside the brain, which may be a key mechanism behind deep traumatic brain injuries. Here we present the ultrasound observation of shear shock waves in the acoustically challenging environment of the in situ porcine brain during a single-shot impact with sinusoidal and haversine time profiles. The brain was impacted to generate surface amplitudes of 25–33g, and to propagate a 40–50 Hz shear waves into the brain. Simultaneously, images of the moving brain were acquired at 2193 images/s, using a custom sequence with 8 interleaved ultrasound propagation events. For a long field-of-view, wide-beam emissions were designed using time-reversal ultrasound simulations and no compounding was used to avoid motion blurring. For a 40 Hz, 25g sinusoidal impact, a shock-front acceleration of 102g was measured 7.1 mm deep inside the brain. Using a haversine pulse that models a realistic impact more closely, a shock acceleration of 113g was observed 3.0 mm inside the brain, from a 50 Hz, 33g excitation. The experimental velocity, acceleration, and strain-rate waveforms in brain for the monochromatic impact are shown to be in excellent agreement with theoretical predictions from a custom higher-order finite volume method hence demonstrating the capabilities to measure rapid brain motion despite strong acoustical reverberations from the porcine skull.

A speed measuring system of hermetic centrifuge

Based on the detected vibration signal, a measurement system was designed to solve the current problem of closed centrifuge speed measurement. The system collected and adjusted the signal collected by the vibration sensor, and then send it to the control unit STM32 for spectrum analysis to get the speed frequency. The sampling data was analysed and processed in PC through serial communication. Programs were written to achieve data sampling, filtering and storage, and the important parameters such as acceleration waveforms, vibration frequency and actual speed were displayed on the screen. The experimental results show that the system can accurately calculate the real-time speed of the closed centrifuge according to the measured vibration signals, which has the advantages of high stability, detection accuracy and real-time performance.

Research on Seismic Acceleration Waveform Reproduction Based on Time-Frequency Hybrid Integration Algorithm

For the quadratic integration of seismic acceleration signal with noise and unknown initial velocity and displacement, the obtained displacement signal has serious trend error, which leads to the problem that the electrodynamic seismic simulation shaker under displacement control mode cannot accurately reproduce the seismic wave. This paper proposes the time-frequency hybrid integration algorithm based on time domain and frequency domain integration characteristics. The algorithm mainly includes two steps. The first step is to use the improved low-frequency attenuation algorithm to integrate the seismic acceleration for the first time in the frequency domain to obtain the corresponding velocity signal. The second step is to integrate the velocity signal directly in the time domain and combine it with the removal of the constant and linear terms algorithm to obtain the corresponding displacement signal. The accuracy and effectiveness of the algorithm are verified by numerical analysis and shaking table test. The results show that compared with the traditional hybrid integral algorithm, the performance improvement rates of displacement peak error and absolute error of the proposed time-frequency hybrid integral algorithm are 31.75% and 26.01%, respectively, and the accuracy of acceleration waveform reproduction is improved by 27.29%. Furthermore, when using this algorithm for the shaking table test of the seismic acceleration signal, the maximum peak error rate is only 4.92%. Therefore, this algorithm can effectively suppress the baseline drift and error accumulation caused by low-frequency noise and unknown initial state to realize the accurate reproduction of the acceleration waveform of the seismic simulation shaking table.

Assessment of the effect of passenger car wheel unbalance on driving comfort

This paper presents the results of experimental investigations of the effects of car wheel unbalance on driving safety and comfort. Basic information about types of wheel unbalance, their causes, and effects are included. The test subject was a BMW 3 Series car with rear-wheel drive. A specific unbalance was introduced on the front steered wheels. The vehicle was driven in a straight line on an asphalt road in good condition at speeds between 70 km/h and 140 km/h. During the test runs, acceleration waveforms were recorded from sensors placed on the lower control arm, driver's seat, and steering wheel. The vibration level of the unbalanced wheel increases with the driving speed and with the increase in unbalance. The highest increase in vibration amplitude occurred on the steering wheel at speeds between 100 km/h and 120 km/h. These vibrations have a direct effect on the driver. This is evidenced by negative driver perceptions such as fatigue and driving discomfort. This was also confirmed by the calculated vibration exposure levels. Driving with unbalanced wheels accelerates wear on the tyres, steering, drive, and suspension components of the vehicle.

Numerical Investigation on Dynamic Response and Failure Modes of Rock Slopes with Weak Interlayers Using Continuum-Discontinuum Element Method

In order to better understand the dynamic response and failure modes of rock slopes containing weak interlayers subjected to earthquake excitation, a series of numerical simulations were carried out using the continuum-discontinuum element method (CDEM), considering the influence of seismic amplitude and weak interlayers inclination. The seismic response characteristics of slopes were systematically analyzed according to the waveform characteristics, amplification effect, equivalent crack ratio, etc. The numerical results show that the acceleration waveform characteristics and peak ground displacement (PGD) amplification coefficient have good correspondence with the dynamic failure process of landslides. Comprehensive analysis of waveform characteristics and PGD amplification coefficient can determine the damage time, damage location, and damage degree of landslides. The landslide process can be divided into three stages according to the equivalent crack ratio: rapid generation of a large number of microcracks, expansion and aggregation of microcracks, and penetration of micro-cracks and the formation of slip surfaces. The equivalent crack ratio provides a new idea for evaluating slope stability. In addition, under the combination of different amplitudes and weak interlayers, these earthquake-induced landslides exhibit different failure modes: the failure of the gentle-dip slope is mainly local rockfall; The mid-dip and steep-dip slopes with small amplitudes experience “tensile cracking-slip-collapsing” failure; The steep-dip slopes under strong earthquake failed in the form of “tensile cracking-slip-slope extrusion-collapsing”. The research results are of great significance for a deeper understanding of the formation mechanism of rock landslides with weak interlayers and the prevention of such landslide disasters.

2D Geotechnical site-response analysis including soil heterogeneity and wave scattering

This study describes an approach for modeling wave scattering and the spatial variability of ground motion in geotechnical site-response analysis by modeling soil heterogeneity through 2D correlated random fields. Importantly, the required site-specific inputs to apply the proposed approach in a practical setting are the same as those associated with conventional 1D site-response analysis. The results, which are affected by wave scattering attenuation, are compared to those from conventional laterally homogeneous 1D site-response analyses and 1D analyses with randomized velocity profiles extracted from heterogeneous 2D velocity model realizations. A sensitivity study, involving 5400 2D model realizations, investigates the influence of random field input parameters on wave scattering and site response. The computed ground surface acceleration waveforms and transfer functions show that this method is capable of scattering seismic waves. Multiple ground-motion intensity measures are analyzed to quantify this influence and distinguish between the effects of 1D vertical heterogeneities and averaging across many nodes and realizations, from the effects of wave scattering and 2D ground-motion phenomena. The redistribution of ground-motion energy across wider frequency bands and scattering attenuation of high-frequency waves in the 2D analyses resemble features observed in empirical transfer functions computed in other studies. While analyses with 1D randomized velocity profiles are able to replicate median results from 2D analyses for some low-frequency intensity measures (e.g. transfer functions at [Formula: see text] Hz, and spectral acceleration at the fundamental period), medians and standard deviations of high-frequency intensity measures (e.g. transfer function at [Formula: see text] Hz, [Formula: see text], and Arias intensity), which are influenced by wave scattering, are not appropriately captured. Given the equivalent input information requirements as conventional 1D analysis, and the availability of large computational resources, we advocate that the proposed 2D (and eventually 3D) approach is a fruitful path forward to improve the modeling of site-response physics and realize improved predictive capabilities.

An algorithm for real time minimum toe clearance estimation from signal of in-shoe motion sensor.

An algorithm has been constructed for estimating minimum toe clearance (MTC), an important gait parameter previously proven to be a critical indicator of tripping risk. It uses data from a previously reported in-shoe motion sensor (IMS) for detecting gait events. First, candidate feature points in the IMS signal for use in detecting MTC events were identified. Then, the temporal agreement between each feature point and target MTC event was evaluated. Next, the accuracy and precision of the MTC estimated using each feature point was evaluated using a reference value obtained using a 3-D optical motion-capture system. The MTC was estimated using a geometric model and the IMS signal corresponding to the predicted MTC event. Once the best candidate feature point was identified, a real-time MTC estimation algorithm for use with an IMS was constructed. The mean values and standard deviations of measured foot motions obtained in a previous study were used for evaluating accuracy and precision. The results suggest that MTC events can be estimated by detecting the crossing point between the acceleration waveforms in the anterior-posterior and superior-inferior directions in an accuracy of 2.0% gait cycle. Using this feature point enables the MTC to be estimated in real time with an accuracy of 8.6 mm, which will enable monitoring of MTC in daily living.

Application of Transient- and Steady-State Acceleration Signals in Intelligent Tires

ABSTRACT The accelerometer-based intelligent tire has gained focus in recent years for its ability to obtain both kinematics and dynamics-related information of the tire. This paper extends the previous steady-state applications of acceleration signals, which mainly estimate tire force, sideslip, and friction coefficient from the steady-state features of acceleration waveforms, to transient acceleration applications. By using the proposed tire mixed Euler–Lagrange rolling model, it is analytically demonstrated that tire rolling acceleration can be decomposed into steady-state and transient-state components from the perspective of kinematics. It is hard to analyze the transient-state component theoretically or split it from the measured signals on real road surfaces; thus, a learning-based algorithm is developed to automatically extract discriminative features without any physical models. With this method, essential information associated with tire transient acceleration could be inferred to help improve driving safety and performance. As the application, tire wear identification with an artificial neural network is validated to be feasible based on complete acceleration signals. The prediction accuracy reaches 98.2% under different test conditions. The proposed acceleration formation mechanism is proved to be effective in explaining tire rolling acceleration as well as guiding to acquire vital information about the tire to improve vehicle safety and performance.

Immediate Effect of Restricted Knee Extension on Ground Reaction Force and Trunk Acceleration during Walking.

Gait parameters calculated from trunk acceleration reflect the features of gait; however, they cannot evaluate the gait pattern corresponding to the gait cycle. This study is aimed at investigating the differences in gait parameters calculated from trunk acceleration during gait corresponding to the gait cycle in healthy subjects with restricted knee extension. Participants included eight healthy volunteers who walked normally (NW) and with knee orthosis that restricted knee extension (ER). The ground reaction force (GRF), joint angles, and trunk acceleration during walking were measured using four force plates, a three-dimensional motion analysis system, and an inertial measurement unit. The peak GRF of the vertical components, joint ranges of motion, and moments of force were analyzed. The root mean square (RMS) and amplitude peak ratio (AR) of autocorrelation function were calculated from the trunk acceleration waveform. The first peak GRF and peak ankle dorsiflexion angles significantly increased during ER. The peak hip extension, knee flexion, knee extension angles, and the peak moment of knee extension significantly decreased during ER compared to that during NW. The acceleration AR significantly decreased during ER compared to that during NW. There was no significant difference in the RMS between the two conditions. The acceleration AR may show the temporal postural structure with restricted knee extension from the terminal stance phase for the ipsilateral limb to the initial stance phase for the contralateral limb. These results suggest that novel metrics for accelerometry gait analysis can reveal gait abnormalities, with restricted knee extension corresponding to the gait cycle.

Waveform‐based fracture identification of steel beam ends using convolutional neural networks

Beam-end fractures of steel frame building structures cause the degradation of story stiffness, which may lead to the tilt or collapse of the whole structure. However, it is difficult to recognize this kind of local damage using conventional building damage detection methods. Generally, the beam-end fracture can be recognized directly from the pulse of the waveform which is generated by the shock due to the fracture. Recently, with the development of technology of image classification and objects detection, the Convolutional Neural Networks (CNNs) have been proved as one of the effective methods for feature extraction. This study presents a beam-end fracture detection method based on acceleration waveform using CNN model. 20,000 and 200 of pseudo acceleration waveform data which generated by numerical simulation were used to train and evaluate CNN model, respectively. To figure out the best hyperparameter configuration, grid search method was used in the hyperparameter optimization. One hundred percent accuracy is recorded in evaluation which is based on single-degree-of-freedom (SDOF) database. Finally, the performance of trained and evaluated CNN model was verified by 80 real acceleration waveforms which are collected from two shake-table tests. The verification result showed almost all the data was correctly classified except one nonfracture data was misclassified as the fracture data. The proposed method is sensitive to the sudden and drastical changes in terms of acceleration waveform and can correctly identify the feature of beam-end fracture for real data with proper training. The accuracy of the proposed beam-end fracture identification from the acceleration waveform was 98.75%.

Regularized reconstruction of peak ground velocity and acceleration from very high-rate GNSS precise point positioning with applications to the 2013 Lushan Mw6.6 earthquake

Difference methods have been routinely used to compute velocity and acceleration from precise positioning with global navigation satellite systems (GNSS). A low sampling rate (say a rate not greater than 1 Hz, for example) has been always implicitly assumed for applicability of the methods, because random measurement errors are significantly amplified, either proportional to the sampling rate in the case of velocity or square-proportional to the sampling rate in the case of acceleration. Direct consequences of a low sampling rate are the distortion of the computed velocity and acceleration waveforms and the failure to obtain almost instantaneous values of velocity and acceleration. We reformulate the reconstruction of velocity and acceleration from very high-rate (50 Hz) precise GNSS as an inverse ill-posed problem and propose the criterion of minimum mean squared errors (MSE) to regularize solutions of velocity and acceleration. We successfully apply the MSE-based regularized method to reconstruct the very high-rate velocity and acceleration waveforms, the peak ground velocity (PGV) and the peak ground acceleration (PGA) from 50 Hz precise point positioning (PPP) position waveforms for the 2013 Lushan Mw6.6 earthquake. The reconstructed results of velocity and acceleration are shown to be in good agreement with the motion patterns in the PPP position waveforms and correctly recover the earthquake signal. The reconstructed GNSS-based PGA values are a few hundred times smaller than those from the strong motion seismometers.

An Adaptive Zero-Velocity Interval Detector Using Instep-Mounted Inertial Measurement Unit

The zero-velocity update (ZUPT) technique plays a key role in foot-mounted inertial navigation system, which can minimize the drift errors of low-cost inertial measurement unit (IMU) by resetting the velocity to zero when the foot is stationary. However, it is difficult to detect the zero-velocity interval (ZVI) in mixed locomotion patterns. This article presents a novel ZVI detector based on adaptive simulated energy consumption (SEC) curve. It can identify the ZVIs of various locomotion patterns, such as normal walking, fast walking, running, going upstairs, and downstairs. The SEC curve is generated based on the signal processing approach using the interlaced peak property of the IMU-measured angular rate and acceleration waveforms. Another benefit of the proposed method is that the IMU can be mounted on the instep without restrictions of orientation and position, which improves flexibility and convenience. Experiment results show that the proposed algorithm performs better than three other widely used methods in mixed gait patterns.

Colocalized Sensing and Intelligent Computing in Micro-Sensors.

This work presents an approach to delay-based reservoir computing (RC) at the sensor level without input modulation. It employs a time-multiplexed bias to maintain transience while utilizing either an electrical signal or an environmental signal (such as acceleration) as an unmodulated input signal. The proposed approach enables RC carried out by sufficiently nonlinear sensory elements, as we demonstrate using a single electrostatically actuated microelectromechanical system (MEMS) device. The MEMS sensor can perform colocalized sensing and computing with fewer electronics than traditional RC elements at the RC input (such as analog-to-digital and digital-to-analog converters). The performance of the MEMS RC is evaluated experimentally using a simple classification task, in which the MEMS device differentiates between the profiles of two signal waveforms. The signal waveforms are chosen to be either electrical waveforms or acceleration waveforms. The classification accuracy of the presented MEMS RC scheme is found to be over 99%. Furthermore, the scheme is found to enable flexible virtual node probing rates, allowing for up to 4× slower probing rates, which relaxes the requirements on the system for reservoir signal sampling. Finally, our experiments show a noise-resistance capability for our MEMS RC scheme.

When the Hydrophone Works as an Accelerometer

Abstract We show the equivalence of earthquake-induced ground acceleration and water-pressure waveforms for the case of collocated hydrophones and seafloor seismometers installed in shallow water. In particular, the comparison of the waveforms and amplitude spectra of the acceleration and water-pressure signals confirms the existence of a frequency range of “forced oscillations” in which the water-pressure variations are proportional to the vertical component of the ground acceleration. We demonstrate the equivalence of the acceleration and water-pressure signals for a set of local earthquakes (epicenter distance of a few tens of kilometers) and regional earthquakes with a wide range of magnitude (2.7<Mw<6.8), recorded by seismometers and hydrophones operating in shallow water (depth less than 80 m) in the Campi Flegrei caldera (southern Italy). We describe the “forced oscillations” theory, and we demonstrate the signals equivalence in the frequency range 0.1–10 Hz, thus extending the frequency range of application of the hydrophones as accelerometers. The high correlation between the ground acceleration, derived from the ground velocity, and hydrophone pressure signals in the mentioned frequency range enables the use of the hydrophone waveforms for standard seismological studies (i.e., earthquake source). The calibration of hydrophones by comparison with collocated accelerometers, or seismometers, is also enabled in a range of frequencies that is very difficult to reproduce in a laboratory. The results of our work also open the possibility of hydrophones being more extensively used in place of accelerometers in marine environments where accurate installation of seismic sensors is difficult or unaffordable.