scholarly journals The S-wave Velocity Structure of Shallow Subsurface Obtained by Continuous Wavelet Transform of Short Period Rayleigh Waves

2007 ◽  
Vol 28 (7) ◽  
pp. 903-913 ◽  
Author(s):  
Hee-Ok Jung ◽  
Bo-Ra Lee
Keyword(s):  
Wavelet Transform ◽  
Wave Velocity ◽  
Continuous Wavelet Transform ◽  
Rayleigh Waves ◽  
Velocity Structure ◽  
Continuous Wavelet ◽  
S Wave ◽  
Shallow Subsurface ◽  
Short Period

scholarly journals The Study of Automatic Picking of P and S Wave Arrival and Identification of Earthquake Sequence Pattern using Scalogram in Obspy (Python)

2021 ◽  
Vol 873 (1) ◽  
pp. 012014
Author(s):  
Sri Kiswanti ◽  
Indriati Retno Palupi ◽  
Wiji Raharjo ◽  
Faricha Yuna Arwa ◽  
Nela Elisa Dwiyanti
Keyword(s):  
Wavelet Transform ◽  
Continuous Wavelet Transform ◽  
Arrival Time ◽  
Continuous Wavelet ◽  
S Wave ◽  
S Waves ◽  
Automatic Picking ◽  
Earthquake Record ◽  
Initial Identification ◽  
Wave Arrival

Abstract Initial identification on an earthquake record (seismogram) is something that needs to be done precisely and accurately. Moreover, the discovery of a series of unexpected successive earthquake events has caused unpreparedness for the community and related agencies in tackling these events. Determining the arrival time of the P and S waves becomes an important parameter to finding the location of the earthquake source (hypocenter) as well as further information related to the earthquake event. However, manual steps that are currently often used are considered to be less effective, because it requires a lot of time in the process. Continuous Wavelet Transform (CWT) analysis can be a solution for this problem. With further CWT analysis in the form of a scalogram, can help to determine the arrival time of P and S waves automatically (automatic picking) becomes simpler. In addition, further CWT analysis can also be utilized to help identify the sequence of earthquake events (foreshock, mainshock, aftershock) through the resulting scalogram pattern.

Determination of the Slip-Up Time for Slip Form System Using Surface Wave Velocity

2013 ◽  
Author(s):  
H. S. Kim ◽  
Y. J. Kim ◽  
W. J. Chin ◽  
H. Yoon
Keyword(s):  
Compressive Strength ◽  
Wavelet Transform ◽  
Surface Wave ◽  
Wave Velocity ◽  
Continuous Wavelet Transform ◽  
Setting Time ◽  
Continuous Wavelet ◽  
Surface Wave Velocity ◽  
Form System

When applying the slip form system, the early setting time of concrete corresponds to the hardening time of early-age concrete indicating that cast-in-place concrete has developed sufficient strength to be safely stripped off the form. This hardening time is thus an important indicator for the determination of the slip-up velocity of the slip form system. Therefore, need is for a technique enabling to evaluate the early hardening time of concrete in order to secure the safety of the slip form system and the quality of the constructed concrete. Among the methods using ultrasonic waves, this paper applies the surface wave velocity to evaluate the degree of hardening of concrete so as to estimate the early setting time and decide the slip-up time of the slip form system. To that goal, penetration resistance test, compressive strength test and surface wave velocity measurement test are performed concurrently with respect to the mix materials and curing temperature of concrete. The test results are used to derive the relationship between the compressive strength and surface wave velocity according to the early hardening time of concrete. Continuous wavelet transform is applied for the measurement of the surface wave velocity. The validity of the application of the continuous wavelet transform is verified through numerical analysis. Finally, the surface wave velocity required for the slip-up of the slip form system is proposed and the applicability of the proposed surface wave velocity for the determination of the climbing time of the slip form system is verified by means of tests on a reduced-scale slip form system prototype.

scholarly journals Crustal velocity structure of the Deccan Volcanic Province, Indian Peninsula, from observed surface wave dispersion

2014 ◽  
Vol 57 (4) ◽  
Author(s):  
Gaddale Suresh ◽  
Satbir S. Teotia ◽  
Sankar N. Bhattacharya
Keyword(s):  
Wave Velocity ◽  
Rayleigh Waves ◽  
Velocity Structure ◽  
Crustal Thickness ◽  
P Wave ◽  
Upper Crust ◽  
S Wave ◽  
Deccan Volcanic Province ◽  
Epicentral Zone ◽  
Volcanic Province

<p>Through inversion of fundamental mode group velocities of Love and Rayleigh waves, we study the crustal and subcrustal structure across the central Deccan Volcanic Province (DVP), which is one of the world’s largest terrestrial flood basalts. Our analysis is based on broadband seismograms recorded at seismological station Bhopal (BHPL) in the central India from earthquakes located near west coast of India, with an average epicentral distance about 768 km. The recording station and epicentral zone are situated respectively on the northern and southern edges of DVP with wave paths across central DVP. The period of group velocity data ranges from 5 to 60 s for Rayleigh waves and 5 to 45 s for Love waves. Using the genetic algorithm, the observed data have been inverted to obtain the crust and subcrustal velocity structure along the wavepaths. Using this procedure, a similar velocity structure was also obtained earlier for the northwestern DVP, which is in the west of the present study region. Comparison of results show that the crustal thickness decreases westward from central DVP (39.6 km) to northwestern DVP (37.8 km) along with the decrease of thickness of upper crust; while the thickness of lower crust remains nearly same. From east to west S-wave velocity in the upper crust decreases by 2 to 3 per cent, while P-wave velocity in the whole crust and subcrust decreases by 3 to 6 per cent. The P- and S-wave velocities are positively correlated with crustal thickness and negatively correlated with earth’s heat flow. It appears that the elevated crustal and subcrustal temperature in the western side is the main factor for low velocities on this side.</p>

scholarly journals Continuous Wavelet Transform of Schwartz Distributions in DL2′(Rn), n ≥ 1

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1106
Author(s):  
Jagdish N. Pandey
Keyword(s):  
Wavelet Transform ◽  
Function Space ◽  
Continuous Wavelet Transform ◽  
Inversion Formula ◽  
Continuous Wavelet ◽  
The Real ◽  
Schwartz Distributions ◽  
Distributional Sense ◽  
Wavelet Inversion

We define a testing function space DL2(Rn) consisting of a class of C∞ functions defined on Rn, n≥1 whose every derivtive is L2(Rn) integrable and equip it with a topology generated by a separating collection of seminorms {γk}|k|=0∞ on DL2(Rn), where |k|=0,1,2,… and γk(ϕ)=∥ϕ(k)∥2,ϕ∈DL2(Rn). We then extend the continuous wavelet transform to distributions in DL2′(Rn), n≥1 and derive the corresponding wavelet inversion formula interpreting convergence in the weak distributional sense. The kernel of our wavelet transform is defined by an element ψ(x) of DL2(Rn)∩DL1(Rn), n≥1 which, when integrated along each of the real axes X1,X2,…Xn vanishes, but none of its moments ∫Rnxmψ(x)dx is zero; here xm=x1m1x2m2⋯xnmn, dx=dx1dx2⋯dxn and m=(m1,m2,…mn) and each of m1,m2,…mn is ≥1. The set of such wavelets will be denoted by DM(Rn).

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