scholarly journals Modeling of earthquake source parameters on December 12, 2018 (08:49:56,16; 36,4478° N; 140,5788° E; H = 62,0 km; Mw = 4,3, Japan)

2021 ◽  
Vol 43 (4) ◽  
pp. 105-118
Author(s):  
R.M. Pak ◽  
O.D. Hrytsai
Keyword(s):  
Focal Mechanism ◽  
Seismic Moment ◽  
Matrix Method ◽  
Moment Tensor ◽  
Source Parameters ◽  
Earthquake Source ◽  
Local Network ◽  
Seismic Moment Tensor ◽  
Earthquake Source Parameters ◽  
The Matrix

Modeling of earthquake source parameters, such as the orientation of the fault plane and the direction of the fault slip, is important for understanding the physics of earthquake source processes, determining the stress-strain state of the geological medium and seismic hazard estimation. For modeling source parameters of the earthquake on December 12, 2018 at 08:49:56,16 (UTC) in Japan (36,4478° N, 140,5788° E, Northern Ibaraki Pref region) at a depth of 62 km with a magnitude of Mw = 4.3, the waveforms inversion was used to determine seismic moment tensor and representation it through a focal mechanism. The earthquake source is considered as a point source of seismic waves which propagate in a medium represented by a set of horizontally homogeneous elastic layers. An algorithm for determining seismic tensor components based on the forward problem solved by the matrix method, and using the generalized inverse solution, selecting only direct waves is applied. The input data for determining seismic moment components are data of only direct P waves selected from the observed records at six seismic stations of the Japanese local network NIED F-net: TSK, YMZ, ASI, ONS, SBT, KSK. The seismic moment tensor components were determined through waveform inversion using the matrix method. The obtained results, presented through a focal mechanism, are compared to the results obtained by the National Research Institute of Earth Sciences and Resistance to Natural Disasters (NIED CMT solutions). As a result of focal mechanisms comparison, it is concluded that the proposed algorithm for determining seismic moment tensor components can be used if it is impossible to use another method, or requires some refinement for another method. This approach is especially relevant for regions with low seismicity and insufficient number of stations. In addition, this method reduces the effects of an inaccurate medium model, because direct waves are much less distorted than reflected and converted, and that increases the accuracy and reliability of the method.

scholarly journals Earthquake source parameters that display the first digit phenomenon

2015 ◽  
Vol 22 (5) ◽  
pp. 625-632
Author(s):  
P. A. Toledo ◽  
S. R. Riquelme ◽  
J. A. Campos
Keyword(s):  
Seismic Moment ◽  
Waiting Times ◽  
Source Parameters ◽  
Tohoku Earthquake ◽  
Earthquake Source ◽  
Coseismic Slip ◽  
Self Organized ◽  
Earthquake Source Parameters ◽  
Self Organized Criticality

Abstract. We study the main parameters of earthquakes from the perspective of the first digit phenomenon: the nonuniform probability of the lower first digit different from 0 compared to the higher ones. We found that source parameters like coseismic slip distributions at the fault and coseismic inland displacements show first digit anomaly. We also found the tsunami runups measured after the earthquake to display the phenomenon. Other parameters found to obey first digit anomaly are related to the aftershocks: we show that seismic moment liberation and seismic waiting times also display an anomaly. We explain this finding by invoking a self-organized criticality framework. We demonstrate that critically organized automata show the first digit signature and we interpret this as a possible explanation of the behavior of the studied parameters of the Tohoku earthquake.

scholarly journals Earthquake source parameters which display first digit phenomenon

2015 ◽  
Vol 2 (3) ◽  
pp. 811-832
Author(s):  
P. A. Toledo ◽  
S. R. Riquelme ◽  
J. A. Campos
Keyword(s):  
Seismic Moment ◽  
Waiting Times ◽  
Source Parameters ◽  
Tohoku Earthquake ◽  
Earthquake Source ◽  
Coseismic Slip ◽  
Self Organized ◽  
Earthquake Source Parameters ◽  
Self Organized Criticality

Abstract. We study main parameters of earthquakes from the perspective of the first digit phenomenon: the nonuniform probability of the lower first digit different from zero compared to the higher ones. We found that source parameters like coseismic slip distributions at the fault and coseismic inland displacements show first digit anomaly. We also found the tsunami runups measured after the earthquake to display the phenomenon. Other parameters found to obey first digit anomaly are related to the aftershocks: we show that seismic moment liberation and seismic waiting times also display an anomaly. We explain this finding by invoking a self-organized criticality frame. We show that critically organized automata show the first digit signature and we interpret this as a possible explanation of the behavior of the studied parameters of the Tohoku earthquake.

Earthquake source parameters at the sumatran fault zone: Identification of the activated fault plane

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Madlazim Kasmolan ◽  
Bagus Santosa ◽  
Jonathan Lees ◽  
Widya Utama
Keyword(s):  
Fault Zone ◽  
Moment Tensor ◽  
Source Parameters ◽  
Earthquake Source ◽  
Joint Analysis ◽  
Seismic Fault ◽  
Earthquake Source Parameters ◽  
Sumatran Fault ◽  
Centroid Position

AbstractFifteen earthquakes (Mw 4.1–6.4) occurring at ten major segments of the Sumatran Fault Zone (SFZ) were analyzed to identify their respective fault planes. The events were relocated in order to assess hypocenter uncertainty. Earthquake source parameters were determined from three-component local waveforms recorded by IRIS-DMC and GEOFON broadband lA networks. Epicentral distances of all stations were less than 10°. Moment tensor solutions of the events were calculated, along with simultaneous determination of centroid position. Joint analysis of hypocenter position, centroid position, and nodal planes produced clear outlines of the Sumatran fault planes. The preferable seismotectonic interpretation is that the events activated the SFZ at a depth of approximately 14–210 km, corresponding to the interplate Sumatran fault boundary. The identification of this seismic fault zone is significant to the investigation of seismic hazards in the region.

scholarly journals Strong ground motion simulation of the 27 May 2006 Yogyakarta earthquake using Empirical Green’s Function

2021 ◽  
Vol 873 (1) ◽  
pp. 012080
Author(s):  
Yeremia Hanniel ◽  
Ade Anggraini ◽  
Agus Riyanto ◽  
Drajat Ngadmanto ◽  
Wiwit Suryanto
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Moment Tensor ◽  
Source Parameters ◽  
Maximum Amplitude ◽  
Earthquake Source ◽  
Ground Acceleration ◽  
Moment Tensor Solution ◽  
Earthquake Source Parameters ◽  
Strong Ground Motion Simulation

Abstract On May 27, 2006, 05:54 am local time, a moderate crustal earthquake of magnitude Mw 6,3 struck the Yogyakarta province, especially in the Bantul regency in the south part of the province. The earthquake damaged or destroyed more than 400,000 houses and buildings and caused more than 5,700 people killed. Several earthquake stations recorded the ground vibration caused by the mainshock very well, except at the stations closest to the earthquake source, namely YOGI in Gamping, West of Yogyakarta, which experienced saturation due to significant vibration. Therefore, information about the maximum ground acceleration near the source is yet not known. We model the ground vibrations near the earthquake source using a stochastic Green’s Function approach to obtain information about the ground motions’ maximum amplitude. The earthquake source parameters we referred to is the moment tensor solution from the Harvard Moment Tensor. The calculations show that the amplitude is consistent with observations recorded at the BJI Banjarnegara (0.04g) and YOGI Yogyakarta (0.3g).

Deriving centimeter-level coseismic deformations and source parameters of small-to-moderate earthquakes from time-series Sentinel-1 SAR images

2021 ◽  
Author(s):  
Heng Luo ◽  
Teng Wang ◽  
Shengji Wei ◽  
Mingsheng Liao
Keyword(s):  
Moment Tensor ◽  
Source Parameters ◽  
Deformation Gradient ◽  
Sampling Rate ◽  
Earthquake Source ◽  
Coseismic Deformation ◽  
Sar Images ◽  
Moderate Size ◽  
Trade Offs ◽  
Earthquake Source Parameters

<p>Small-to-moderate size earthquakes occur much more frequently than large ones but are general less studied by InSAR, despite that they also provide critical information about the physics of faulting and earthquake mechanisms. The weak coseismic deformations contaminated by severe atmosphere turbulences make them difficult to be studied by single interferogram. Since the launchings on April, 2014 and April, 2016, Sentinel-1 A/B satellites began to provide large-coverage SAR images in short revisited period (6 or 12 days) with 250 km frame width. The high-temporal sampling rate of Sentinel-1 data produce sufficient images for the stacking process to greatly reduce the local atmospheric turbulence that is difficult to be handled by numerical weather models. This procedure allows the extraction of very weak coseismic deformation (i.e. sub-centimeter) for small-to-moderate size earthquakes and systematical static slip inversions of the earthquakes in a tectonically active region by InSAR.</p><p> </p><p>Here we report this stacking method and a new downsampling strategy based on quadtree mesh obtained from preliminary slip model to efficiently reduce the number of unwanted data points. Applying the proposed methods, we successfully retrieve coseismic deformations for 33 earthquakes (Mw4.1-Mw6.6) occurred in west China from Nov, 2014 to Jul 2020. Among these earthquakes, the smallest peak Line-of-Sight coseismic deformation is only ~6 mm. These InSAR-based earthquake catalogs show robust and precise absolute location (latitude, longitude and depth), therefore can be used as benchmark events to calibrate seismic based catalogues. However, strong trade-offs between earthquake source parameters (e.g. fault size vs slip) exist when the earthquake magnitude is small (in general smaller than Mw5.5). Such trade-offs are rooted due to the smaller deformation gradient in comparison with larger earthquakes. For the moderate size earthquakes (Mw6.0-6.6), the comparison between equivalent moment tensor from InSAR slip models and GCMT/W-phase solutions show that large CLVD components, as shown in the seismic-based moment tensor solutions, are mostly not necessary to explain the InSAR data. We suggest to combine geodetic and seismic datasets for more comprehensive and accurate earthquake source parameter inversions.</p>

scholarly journals Modelling of the wave fields by the modification of the matrix method in anisotropic media

2014 ◽  
Vol 6 (1) ◽  
pp. 467-485
Author(s):  
A. Pavlova
Keyword(s):  
Free Surface ◽  
Anisotropic Medium ◽  
Matrix Method ◽  
Layered Medium ◽  
Displacement Vector ◽  
Moment Tensor ◽  
Anisotropic Media ◽  
Seismic Moment Tensor ◽  
Arbitrary Boundary ◽  
The Matrix

Abstract. The modification of the matrix method of construction of wave field on the free surface of an anisotropic medium is presented. The earthquake source represented by a randomly oriented force or a seismic moment tensor is placed on an arbitrary boundary of a layered anisotropic medium. The theory of the matrix propagator in a homogeneous anisotropic medium by introducing a "wave propagator" is presented. It is shown that, for an anisotropic layered medium, the matrix propagator can be represented by a "wave propagator" in each layer. The matrix propagator P (z, z0 = 0) acts on the free surface of the layered medium and generates stress-displacement vector at depth z. The displacement field on the free surface of an anisotropic medium is obtained from the received system of equations considering the radiation condition and that the free surface is stressless. The approbation of the modification of the matrix method for isotropic and anisotropic media with TI symmetry is done. A comparative analysis of our results with the synthetic seismic records obtained by other methods and published in foreign papers is executed.

scholarly journals Determining the focal mechanisms of the events in the Carpathian region of Ukraine

2014 ◽  
Vol 3 (2) ◽  
pp. 229-239 ◽  
Author(s):  
A. Pavlova ◽  
O. Hrytsai ◽  
D. Malytskyy
Keyword(s):  
Seismic Waves ◽  
Source Parameters ◽  
Focal Mechanisms ◽  
Earthquake Source ◽  
Carpathian Region ◽  
Earthquake Source Parameters ◽  
The Matrix ◽  
Trial And Error Method ◽  
Error Method

Abstract. The modification of the matrix method for constructing the displacement field on the free surface of an anisotropic layered medium is presented. The source of seismic waves is modelled by a randomly oriented force and seismic tensor. A trial and error method is presented for solving the inverse problem of determining parameters of the earthquake source. A number of analytical and numerical approaches to determining the earthquake source parameters, based on the direct problem solutions, are proposed. The focal mechanisms for the events in the Carpathian region of Ukraine are determined by the graphical method. The theory of determination of the angles of orientation of the fault plane and the earthquake's focal mechanism are presented. The focal mechanisms obtained by two different methods are compared.

Seismic moment tensor components of an earthquake source in the eastern Himalayas, 26.61°N, 97.03°E

1985 ◽  
Vol 118 (3-4) ◽  
pp. 283-291
Author(s):  
S.K. Upadhyay ◽  
A.K. Khanna ◽  
V. Sriram ◽  
J. Prasad
Keyword(s):  
Seismic Moment ◽  
Moment Tensor ◽  
Earthquake Source ◽  
Seismic Moment Tensor ◽  
Eastern Himalayas

scholarly journals Determining the focal mechanisms of the events in the Carpathian region of Ukraine

2014 ◽  
Vol 4 (1) ◽  
pp. 109-164 ◽  
Author(s):  
A. Pavlova ◽  
O. Hrytsai ◽  
D. Malytskyy
Keyword(s):  
Seismic Waves ◽  
Source Parameters ◽  
Focal Mechanisms ◽  
Earthquake Source ◽  
Carpathian Region ◽  
Earthquake Source Parameters ◽  
The Matrix ◽  
Trial And Error Method ◽  
Error Method ◽  
Numerical Approaches

Abstract. The modification of the matrix method for constructing the displacement field on the free surface of an anisotropic layered medium is presented. The source of seismic waves is modelled by a randomly oriented force and seismic tensor. A trial and error method is presented for solving the inverse problem of determining parameters of the earthquake source. A number of analytical and numerical approaches to determining the earthquake source parameters, based on the direct problem solutions, are proposed. The focal mechanisms for the events in the Carpathian region of Ukraine are determined by the graphical method. The theory of determinating the angles of orientation of the fault plane and the earthquake's focal mechanism is presented. The focal mechanisms obtained by two different methods are compared.

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