Rapid Estimation of Earthquake Magnitude by a New Wavelet‐Based Proxy

Atefi, Sanam; Heidari, Reza; Mirzaei, Noorbakhsh; Siahkoohi, Hamid Reza

doi:10.1785/0220170146

Cited by 6 publications

(4 citation statements)

References 32 publications

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“…Similar to Ziv [29], we used the power spectrum of a signal within the first few seconds of P-wave arrival to determine the frequency features of the signal. However, Ziv [29] used Fourier transform to determine the power spectrum, similar to Atefi et al [3], we adopted wavelet transform coefficients C(k; sÞ for such calculation [3]: The wavelet transform of a time-frequency f t ð Þ (here, the initial few seconds after P-wave arrival) is defined as the inner product of f t ð Þ and w (wavelet family), resulting in wavelet coefficient C. This time-frequency transform of f t ð Þ was formulated as Eq. (8) [7][8][9][10][11].…”

Section: Methods Based On S Fcwtmentioning

confidence: 99%

“…Then, the best line is fitted to the measurements using the least-squares method. Atefi et al [3] introduced a wavelet-based proxy, log-averaged scale klog, using weighted average power spectrum of different scales to obtain empirical magnitude-scaling relationship. In this study, we use frequency values which have maximum power spectrum.…”

Section: Methods Based On S Fcwtmentioning

confidence: 99%

“…In this study, we use frequency values which have maximum power spectrum. To better cooperation, we use the same database used in Atefi et al [3]. Figure 2 presents the results obtained on the basis of s max P , s c , and s f cwt in the 4-s time window.…”

Section: Methods Based On S Fcwtmentioning

confidence: 99%

“…Given the occurrence of destructive earthquakes in seismically intensive regions, the resultant human and financial losses, and the scientific inability to predict earthquakes, investigations into earthquake early warning systems (EEWSs), and their development are critical requirements. Accordingly, researchers have recently proposed many approaches to improving EEWS performance [1,3,4,12,14,15,17,26,27,29]. Earthquake records generally contain valuable information on seismic sources [20]; records of the first waves of an earthquake contain information on magnitude, and those of second waves carry information on energy [2,12].…”

Section: Introductionmentioning

confidence: 99%

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A frequency-based parameter for rapid estimation of magnitude

et al. 2017

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This study introduce a new frequency parameter called s fcwt , which can be used to estimate earthquake magnitude on the basis of the first few seconds of P-waves, using the waveforms of earthquakes occurring in Japan. This new parameter is introduced using continuous wavelet transform as a tool for extracting the frequency contents carried by the first few seconds of P-wave. The empirical relationship between the logarithm of s fcwt within the initial 4 s of a waveform and magnitude was obtained. To evaluate the precision of s fcwt , we also calculated parameters s max p and s c . The average absolute values of observed and estimated magnitude differences (jM est À M obs j) were 0.43, 0.49, and 0.66 units of magnitude, as determined using s max p , s c , and s fcwt , respectively. For earthquakes with magnitudes greater than 6, these values were 0.34, 0.56, and 0.44 units of magnitude, as derived using s max p , s c , and s fcwt , respectively. The s fcwt parameter exhibited more precision in determining the magnitude of moderate-and small-scale earthquakes than did the s c -based approach. For a general range of magnitudes, however, the s max p -based method showed more acceptable precision than did the other two parameters.

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