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

Rupture process of the 7 May 2020 Mw 5.0 Tehran earthquake and its relation with the Damavand stratovolcano, and Mosha Fault

2021 ◽  
Author(s):  
Pınar Büyükakpınar ◽  
Mohammadreza Jamalreyhani ◽  
Mehdi Rezapour ◽  
Stefanie Donner ◽  
Nima Nooshiri ◽  
...  
Keyword(s):  
Moment Tensor ◽  
Source Parameters ◽  
Active Faults ◽  
Strong Motion ◽  
Fault Model ◽  
Focal Mechanism Solution ◽  
Strong Motion Records ◽  
Finite Fault ◽  
Finite Fault Model ◽  
Mosha Fault

<p>In May 2020 an earthquake with Mw 5.0 struck at ~40 km east of Tehran metropolis and ~15 km south of the Damavand stratovolcano. It was responsible for 2 casualties and 23 injured. The mainshock was preceded by a foreshock with Ml 2.9 and followed by a significant aftershock sequence, including ten events with Ml 3+. The occurrence of this event raised the question of its relation with volcanic activities and/or concern about the occurrence of larger future earthquakes in the capital of Iran. Tehran megacity is surrounded by several inner-city and adjacent active faults that correspond to high-risk seismic sources in the area. The Mosha fault with ~150 km long is one of the major active faults in central Alborz and east of Tehran. It has hosted several historical earthquakes (i.e. 1665 Mw 6.5 and 1830 Mw 7.1 earthquakes) in the vicinity of the 2020 Mw 5.0 Tehran earthquake’s hypocenter. In this study, we evaluate the seismic sequence of the Tehran earthquake and obtain the full moment tensor inversion of this event and its larger aftershocks, which is a key tool to discriminate between tectonic and volcanic earthquakes. Furthermore, we obtain a robust characterization of the finite fault model of this event applying probabilistic earthquake source inversion framework using near-field strong-motion records and broadband seismograms, with an estimation of the uncertainties of source parameters. Due to the relatively weak magnitude and deeper centroid depth (~12 km), no static surface displacement was observed in the coseismic interferograms, and modeling performed by seismic records. Focal mechanism solution from waveform inversion, with a significant double-couple component, is compatible with the orientation of the sinistral north-dipping Mosha fault at the centroid location. The finite fault model suggests that the mainshock rupture propagated towards the northwest. This directivity enhanced the peak acceleration in the direction of rupture propagation, observed in strong-motion records. The 2020 moderate magnitude earthquake with 2 casualties, highlights the necessity of high-resolution seismic monitoring in the capital of Iran, which is exposed to a risk of destructive earthquakes with more than 10 million population. Our results are important for the hazard and risk assessment, and the forthcoming earthquake early warning system development in Tehran metropolis.</p>

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

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.

High stress drops of short-period subevents from the 1968 Tokachi-Oki earthquake as observed on strong-motion records

1984 ◽  
Vol 74 (5) ◽  
pp. 1529-1544
Author(s):  
Jim Mori ◽  
Kunihiko Shimazaki
Keyword(s):  
Source Parameters ◽  
High Stress ◽  
Strong Motion ◽  
P Waves ◽  
Strong Motion Records ◽  
Source Dimensions ◽  
Short Period ◽  
High Dynamic ◽  
Stress Drops ◽  
Very High

Abstract Strong-motion records of the 1968 Tokachi-Oki earthquake were examined, and two very high stress drop subevents were identified. The first subevent had been previously located by Nagamune (1969), and the second subevent was located in this study using P waves recorded on short-period WWSSN records. Estimates of source parameters revealed small source dimensions (<1 per cent of the aftershock area) and very high dynamic and static stress drops in the kilobar range for both of the subevents. It is suggested that these subevents are important in driving the main rupture of this earthquake. The two subevents also produced the dominant accelerations on the strong-motion records, and it is shown that high-peak accelerations (150 to 200 cm/sec2) were recorded even at relatively large distances (100 to 200 km).

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