Estimation of Source Spectra, Attenuation, and Site Responses from Strong-Motion Data Recorded in the 2019 Changning Earthquake Sequence

2020 ◽  
Vol 110 (2) ◽  
pp. 410-426
Author(s):  
Jiangyi Li ◽  
Bengang Zhou ◽  
Mianshui Rong ◽  
Su Chen ◽  
Yue Zhou
Keyword(s):  
Source Parameters ◽  
Amplitude Spectrum ◽  
Strong Motion ◽  
Earthquake Sequence ◽  
Propagation Path ◽  
Mountainous Areas ◽  
S Wave ◽  
Ground Acceleration ◽  
Generalized Inversion Technique ◽  
Q Values

ABSTRACT This study used 306 accelerograms recorded at 22 strong-motion stations to investigate the source parameters, quality factor (Q), and site effects of S-wave Fourier acceleration amplitude spectrum (FAS) of the 2019 MS 6.0 Changning earthquake sequence in China with surface-wave magnitudes (MS) of 4.1–6.0. The generalized inversion technique (GIT) was adopted. The inverted stress drop of the mainshock was 1.15 MPa, and those of the aftershocks varied from 0.11 to 1.04 MPa with an average value of 0.43 MPa. The MS of these earthquakes were larger than Mw with an average magnitude difference of 0.22. The inverted Q values increase rapidly with frequencies at 0.5–4.0 Hz from 62 to 2920 and become less dependent at 4.0–25.0 Hz. Such a phenomenon indicates that the propagation path attenuation mechanism transited to intrinsic at high frequencies. A bilinear Q(f) model for which Q(f)=237.6f1.27 (Q<1280) and Q=1280 at higher frequencies was obtained. The high-frequency attenuation model of the study area was κ=0.0420+0.0001262R. The inverted site responses of the 22 stations were compared with those calculated using the horizontal-to-vertical spectral ratio (HVSR) method. In general, the amplification curves of most stations obtained with the GIT were similar to those of HVSR, and the amplification levels were relatively higher. Contrarily, obvious discrepancies were observed between the results estimated from the two methods at several stations. Such effects were attributed to the limitation that the majority of the stations were distributed along the boundary of the basin and mountainous areas, and the inverted Q values were representative of the specific area rather than the pure basin and mountainous areas. Finally, a nonlinear soil site effect was observed at 51GXT in earthquakes with peak ground acceleration greater than 300  cm/s2. The nonlinearity obviously aggravated the site amplification at 1.0–5.0 Hz.

Nonlinear Site Effects from the 30 November 2018 Anchorage, Alaska, Earthquake

2021 ◽  
Author(s):  
John D. Thornley ◽  
Utpal Dutta ◽  
John Douglas ◽  
Zhaohui (Joey) Yang
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
North American Plate ◽  
Peak Ground Velocity ◽  
Reference Station ◽  
Earthquake Hazards ◽  
Ground Acceleration ◽  
Nonlinear Site Response ◽  
Generalized Inversion Technique ◽  
Versus Peak

ABSTRACT Anchorage, Alaska, is a natural laboratory for recording strong ground motions from a variety of earthquake sources. The city is situated in a tectonic region that includes the interface and intraslab earthquakes related to the subducting Pacific plate and crustal earthquakes from the upper North American plate. The generalized inversion technique was used with a local rock reference station to develop site response at >20 strong-motion stations in Anchorage. A database of 94 events recorded at these sites from 2005 to 2019 was also compiled and processed to compare their site response with those in the 2018 Mw 7.1 event (main event). The database is divided into three datasets, including 75 events prior to the main event, the main event, and 19 aftershocks. The stations were subdivided into the site classes defined in the National Earthquake Hazards Reduction Program based on estimated average shear-wave velocity in of the upper 30 m (VS30), and site-response results from the datasets were compared. Nonlinear site response was observed at class D and DE sites (VS30 of 215–300 and 150–215  m/s, respectively) but not at class CD and C sites (VS30 of 300–440 and 440–640  m/s, respectively). The relationship of peak ground acceleration versus peak ground velocity divided by VS30 (shear-strain proxy) was shown to further support the observation that sites with lower VS30 experienced nonlinear site response.

Non-parametric spectral modelling of source parameters, path attenuation and site effects from broad-band waveforms of the Alborz earthquakes (2005–2017)

2019 ◽  
Vol 219 (3) ◽  
pp. 1514-1531
Author(s):  
Somayeh Ahmadzadeh ◽  
G Javan Doloei ◽  
Stefano Parolai ◽  
Adrien Oth
Keyword(s):  
Source Parameters ◽  
Broad Band ◽  
Site Amplification ◽  
Earthquake Source ◽  
Frequency Range ◽  
S Wave ◽  
Magnitude Range ◽  
Earthquake Source Parameters ◽  
Generalized Inversion Technique ◽  
Non Parametric

SUMMARY S-wave spectral amplitudes from 312 crustal earthquakes recorded at the Iranian National Broadband Seismic Network in the Alborz region between 2005 and 2017 are analysed in order to evaluate earthquake source parameters, path attenuation and site amplification functions using the non-parametric generalized inversion technique (GIT). We exploit a total number of 1117 seismograms with ML 3–5.6 in the frequency range 0.3–20 Hz. The evaluated non-parametric attenuation functions decay uniformly with distance for the entire frequency range and the estimated S-wave quality factor shows low Q values with relatively strong frequency dependence. We assume the omega-square source model to retrieve earthquake source parameters from the inverted source spectra. The obtained stress drops range from 0.02 to 16 MPa with a mean value of 1.1 MPa. Stress drop and radiated energy show fairly self-similar scaling with seismic moment over the available magnitude range; however, the magnitude range of this study is too narrow to draw a definite conclusion on source scaling characteristics. The obtained moment magnitude Mw and the local magnitude ML are linearly correlated and approximately equivalent in the range of Mw 3–4. For larger events, Mw generally underestimates ML by about 0.1–0.5 magnitude units. The estimated site amplification functions for horizontal component (GIT H) are nearly flat with no obvious pre-dominant frequency peaks for most stations, as expected for the sites of permanent broad-band seismic stations located on rock, though a few stations show amplification peaks from 1 to 8 Hz, with a maximum amplification of about a factor of 7 with respect to the reference site. The evaluated site responses for the vertical components present remarkable amplification or deamplification, leading to differences of the H/V amplitude levels in comparison with the GIT H amplification curves. The results of this study provide a valuable basis for predicting appropriate ground motions in a context of seismic hazard assessment.

scholarly journals PROBABILISTIC HAZARD ASSESSMENT, USING ARIAS INTENSITY EQUATION, IN THE EASTERN PART OF THE GULF OF CORINTH (GREECE)

2017 ◽  
Vol 43 (1) ◽  
pp. 527
Author(s):  
V. Zygouri
Keyword(s):  
Hazard Analysis ◽  
Source Parameters ◽  
Probabilistic Approach ◽  
Strong Motion ◽  
Earthquake Hazard ◽  
Propagation Path ◽  
Arias Intensity ◽  
Site Class ◽  
Attenuation Relationships ◽  
Gulf Of Corinth

Shallow earthquakes cause serious damage near the trace of faults. The growth of major cities in hazard prone areas and the public anxiety associated with risks in critical facilities has focused attention to those areas. The Gulf of Corinth constitutes an area prone to high seismicity. During the last 2000 years several strong seismic events have caused extensive collapses, death casualties and widespread landslide phenomena. Strong motion attenuation relationships are considered a significant parameter for any earthquake hazard analysis. Attenuation relationships used in probabilistic hazard assessments predict ground motions components (in this case arias intensity) as a function of source parameters (magnitude and mechanism), propagation path (fault distance) and site effects (site class). In the eastern part of the Gulf of Corinth arias intensity equations were applied for a number of large E-W trending faults dominating the seismic potential of the area. Those faults have already been associated with landslide phenomena according to historic records and by using new methodologies a probabilistic approach of their behaviour has been accomplished for different recurrence intervals.

scholarly journals Source parameters of the 2007 Noto Hanto earthquake sequence derived from strong motion records at temporary and permanent stations

2008 ◽  
Vol 60 (10) ◽  
pp. 1011-1016 ◽  
Author(s):  
Takahiro Maeda ◽  
Masayoshi Ichiyanagi ◽  
Hiroaki Takahashi ◽  
Ryo Honda ◽  
Teruhiro Yamaguchi ◽  
...  
Keyword(s):  
Source Parameters ◽  
Strong Motion ◽  
Earthquake Sequence ◽  
Strong Motion Records ◽  
Noto Hanto Earthquake ◽  
2007 Noto Hanto Earthquake

SEISMOLOGICAL AND ENGINEERING PARAMETERS OF 24 and 26 SEPTEMBER, 2019 MARMARA SEA EARTHQUAKES

2020 ◽  
Author(s):  
Eser Çakti ◽  
Fatma Sevil Malcioğlu ◽  
Hakan Süleyman
Keyword(s):  
Earthquake Engineering ◽  
Prediction Models ◽  
Source Parameters ◽  
Strong Motion ◽  
P Wave ◽  
Corner Frequency ◽  
Marmara Sea ◽  
S Wave ◽  
Data Set ◽  
The North

<p>On 24<sup>th</sup> and 26<sup>th</sup>  September 2019, two earthquakes of M<sub>w</sub>=4.5 and M<sub>w</sub>=5.6 respectively took place in the Marmara Sea. They were associated with the Central Marmara segment of the North Anatolian Fault Zone, which is pinpointed by several investigators as the most likely segment to rupture in the near future giving way to an earthquake larger than M7.0. Both events were felt widely in the region. The M<sub>w</sub>=5.6 event, in particular, led to a number of building damages in Istanbul, which were larger than expected in number and severity. There are several strong motion networks in operation in and around Istanbul. We have compiled a data set of recordings obtained at the stations of the Istanbul Earthquake Rapid Response and Early Warning operated by the Department of Earthquake Engineering of Bogazici University and of the National Strong Motion Network operated by AFAD. It consists of 148 three component recordings, in total.  444 records in the data set, after correction, were analyzed to estimate the source parameters of these events, such as corner frequency, source duration, radius and rupture area, average source dislocation and stress drop. Duration characteristics of two earthquakes were analyzed first by considering P-wave and S-wave onsets and then, focusing on S-wave and significant durations. PGAs, PGVs and SAs were calculated and compared with three commonly used ground motion prediction models (i.e  Boore et al., 2014; Akkar et al., 2014 and Kale et al., 2015). Finally frequency-dependent Q models were estimated using the data set and their validity was dicussed by comparing with previously developed models.</p>

scholarly journals A SOURCE PARAMETERS STUDY OF THE AFTERSHOCK SEQUENCE OF THE KOZANI- GREVENA 1995 EARTHQUAKE BASED ON ACCELERATION RECORDS

2004 ◽  
Vol 36 (3) ◽  
pp. 1457 ◽  
Author(s):  
A. A. Panou ◽  
C. B. Papazachos ◽  
Ch. Papaioannou ◽  
P. M. Hatzidimitriou
Keyword(s):  
Source Parameters ◽  
Strong Motion ◽  
Aftershock Sequence ◽  
Propagation Path ◽  
Data Set ◽  
Near Surface ◽  
Anelastic Attenuation ◽  
Geological Formation ◽  
Good Agreement

Strong motion recordings of the May 13, 1995 Mw=6.6, earthquake sequence that occurred in the Kozani-Grevena region (Western Macedonia, Greece) have been analyzed for the determination of their source parameters. The data set for this study comes from a temporarily deployed accelerograph network and the source parameters using the shear-wave displacement spectra have been estimated. For this estimation the spectral records have been corrected for the site effects and for the propagation path (geometrical spreading and anelastic attenuation). The magnitude of each event was also re-calculated by estimating appropriate station corrections. The derived relationships arelogMo =(1.43 ±0.09) M, + (16.92 ± 0.29), 2.0 < ML< 5.0 (1)logfc = (-0.56± 0.08) · ML + (2.52 + 0.29), 2.0 < ML< 5.0 (2)logM0 = (-2.20 + 0.08) · log fc + (23.16 ± 0.84), 0.6 < fc < 10.0 (3)The near-surface attenuation parameter κ0 has also been determined for the strong motion stations sites. These values of κ0 are in good agreement with those of Margaris and Boore (1998) for the geological formation on which each station was positioned. The obtained source parameters are in good agreement with those from previous studies for the Aegean region.

Source, Propagation Path, and Site Characteristics Separated from Strong Motion Records during the 2016 Kumamoto, Japan, Earthquake Sequence

2019 ◽  
Vol 19 (6) ◽  
pp. 6_42-6_54
Author(s):  
Kazuhiro SOMEI ◽  
Kimiyuki ASANO ◽  
Tomotaka IWATA ◽  
Ken MIYAKOSHI ◽  
Kunikazu YOSHIDA ◽  
...  
Keyword(s):  
Strong Motion ◽  
Earthquake Sequence ◽  
Propagation Path ◽  
Strong Motion Records ◽  
Site Characteristics

Estimating Rupture Dimensions of Three Major Earthquakes in Sichuan, China, for Early Warning and Rapid Loss Estimates

2020 ◽  
Vol 110 (2) ◽  
pp. 920-936 ◽  
Author(s):  
Jiawei Li ◽  
Maren Böse ◽  
Max Wyss ◽  
David J. Wald ◽  
Alexandra Hutchison ◽  
...  
Keyword(s):  
Real Time ◽  
Early Warning ◽  
Line Source ◽  
Source Parameters ◽  
Strong Motion ◽  
Preventive Action ◽  
Fault Rupture ◽  
S Wave ◽  
Finite Fault ◽  
Source Models

ABSTRACT Large earthquakes, such as Wenchuan in 2008, Mw 7.9, Sichuan, China, provide an opportunity for earthquake early warning (EEW), as many heavily shaken areas are far (∼50  km) from the epicenter and warning times could be sufficient (≥5  s) to take preventive action. On the other hand, earthquakes with magnitudes larger than ∼M 6.5 are challenging for EEW because source dimensions need to be defined to adequately estimate shaking. Finite-fault rupture detector (FinDer) is an approach to identify fault rupture extents from real-time seismic records. In this study, we playback local and regional onscale strong-motion waveforms of the 2008 Mw 7.9 Wenchuan, 2013 Mw 6.6 Lushan, and 2017 Mw 6.5 Jiuzhaigou earthquakes to study the performance of FinDer for the current layout of the China Strong Motion Network. Overall, the FinDer line-source models agree well with the observed spatial distribution of aftershocks and models determined from waveform inversion. However, because FinDer models are constructed to characterize seismic ground motions (as needed for EEW) instead of source parameters, the rupture length can be overestimated for events radiating high levels of high-frequency motions. If the strong-motion data used had been available in real time, 50%–80% of sites experiencing intensity modified Mercalli intensity IV–VII (light to very strong) and 30% experiencing VIII–IX (severe to violent) could have been issued a warning with 10 and 5 s, respectively, before the arrival of the S wave. We also show that loss estimates based on the FinDer line source are more accurate compared to point-source models. For the Wenchuan earthquake, for example, they predict a four to six times larger number of fatalities and injured, which is consistent with official reports. These losses could be provided 1/2∼3  hr faster than if they were based on more complex inversion rupture models.

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