scholarly journals Penentuan Karakteristik Mekanisme Gempa Tahun 2018-2019 Di Nusa Tenggara Menggunakan Metode Inversi Momen Tensor

Kappa Journal ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 31-39
Author(s):  
Sri Rizki Eka Putri ◽  
◽  
Hiden Hiden ◽  
Suhayat Minardi ◽  
◽  
...  

Nusa Tenggara is one of the areas with a high level of seismic activity in Indonesia because this area is located between the Indian Ocean plate, which moves northward and pushes the Eurasian plate. One method that is often used to determine an earthquake's epicentre is the Tensor Moment Inversion method. This study aims to determine the moment tensor magnitude of each earthquake event and determine earthquake characteristics based on the earthquake focus mechanism in Nusa Tenggara from 2018 to 2019. The earthquake with a magnitude of ≥ 5.7 SR and to find out the fault parameters, namely strike, dip, and rake using waveform data. One method that is often used to determine an earthquake's epicentre is the Tensor Moment Inversion method. The results showed that the fault planes formed were reverse faults and oblique faults. It has been calculated the moment tensor for each of the six components, namely Mxx, Myy, Mzz, Mxy, Myz and Mxz. From the results of the focal analysis of the 2018-2019 Nusa Tenggara earthquake mechanism, the values of the fault plane orientation parameters such as strike, dip and rake are obtained. For strikes in Nusa Tenggara on area 1, namely: 73° to 122°, Dip: 20° to 72° and Rake: 53° to 139°. While in field 2 for a strike, it is 232° to 280°, Dip 28° to 75°, Rake: 52° to 102°.

Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. WC65-WC75 ◽  
Author(s):  
Jing Du ◽  
Norm R. Warpinski

Although microseismic monitoring of hydraulic fractures has primarily been concerned with the dimensions, complexity, and growth of fractures or fracture systems, there is an ever-increasing desire to extract more information about the hydraulic-fracturing and/or natural fractures from microseismic data. Source mechanism analysis, which is concerned with deducing details of the failure process from the microseismic waveform data, is, therefore, attracting more attention. However, most of the studies focus more on the moment-tensor inversion than on extracting fault-plane solutions (FPSs) from inverted moment tensors. The FPSs can be extracted from the inverted moment-tensor, but there remains a question regarding how errors associated with the inversion of the moment-tensor affect the accuracy of the FPSs. We examine the uncertainties of FPS, given the uncertainties of the amplitude data, by looking into the uncertainty propagation from amplitude data into the moment-tensor and then into the resultant FPS. The uncertainty propagation method will be demonstrated using two synthetic examples.


2021 ◽  
Author(s):  
◽  
Elizabeth de Joux Robertson

<p>The aim of this project is to enable accurate earthquake magnitudes (moment magnitude, MW) to be calculated routinely and in near real-time for New Zealand earthquakes. This would be done by inversion of waveform data to obtain seismic moment tensors. Seismic moment tensors also provide information on fault-type. I use a well-established seismic moment tensor inversion method, the Time-Domain [seismic] Moment Tensor Inversion algorithm (TDMT_INVC) and apply it to GeoNet broadband waveform data to generate moment tensor solutions for New Zealand earthquakes. Some modifications to this software were made. A velocity model can now be automatically used to calculate Green's functions without having a pseudolayer boundary at the source depth. Green's functions can be calculated for multiple depths in a single step, and data are detrended and a suitable data window is selected. The seismic moment tensor solution that has either the maximum variance reduction or the maximum double-couple component is automatically selected for each depth. Seismic moment tensors were calculated for 24 New Zealand earthquakes from 2000 to 2005. The Global CMT project has calculated CMT solutions for 22 of these, and the Global CMT project solutions are compared to the solutions obtained in this project to test the accuracy of the solutions obtained using the TDMT_INVC code. The moment magnitude values are close to the Global CMT values for all earthquakes. The focal mechanisms could only be determined for a few of the earthquakes studied. The value of the moment magnitude appears to be less sensitive to the velocity model and earthquake location (epicentre and depth) than the focal mechanism. Distinguishing legitimate seismic signal from background seismic noise is likely to be the biggest problem in routine inversions.</p>


1991 ◽  
Vol 81 (1) ◽  
pp. 191-201
Author(s):  
Steven M. Day ◽  
Keith L. McLaughlin

Abstract Spall may be a significant secondary source of seismic waves from underground explosions. The proper representation of spall as a seismic source is important for forward and inverse modeling of explosions for yield estimation and discrimination studies. We present a new derivation of a widely used point force representation for spall, which is based on a horizontal tension crack model. The derivation clarifies the relationship between point force and moment tensor representations of the tension crack. For wavelengths long compared with spall depth, the two representations are equivalent, and the moment tensor time history is proportional to the doubly integrated time history of the point force. Numerical experiments verify that, for regional seismic phases, this equivalence is valid for all frequencies for which the point-source (long wavelength) approximation is valid. Further analysis shows that the moment tensor and point force representations retain their validity for nonplanar spall surfaces, provided that the average dip of the surface is small. The equivalency of the two representations implies that a singular inverse problem will result from attempts to infer simultaneously the spectra of both of these source terms from seismic waveforms. If the spall moment tensor alone is estimated by inversion of waveform data, the inferred numerical values of its components will depend inversely upon the source depth that is assumed in the inversion formalism.


2012 ◽  
Vol 12 (5) ◽  
pp. 1425-1430 ◽  
Author(s):  
K. Makropoulos ◽  
G. Kaviris ◽  
V. Kouskouna

Abstract. A homogeneous earthquake catalogue for Greece and adjacent areas covering the period 1900–2009 is presented, to be used for reliable seismic hazard studies. The catalogues of Makropoulos and Burton (1981) and Makropoulos et al. (1989), covering the time span 1900–1985, were updated for the period 1986–2009 using instrumentally determined focal coordinates, except for the magnitude from the bulletin of the ISC. For Ms, which is the magnitude scale included in the previous versions, the same procedure applied since 1964 was adopted, using the ISC body wave magnitude (mb) and a regression equation. In the present update, Mw is also calculated for the entire period 1900–2009 using a formula derived from all available moment magnitudes and directly determined by the moment tensor inversion method. Thus, a magnitude homogeneous catalogue concerning both Ms and Mw scales is presented. The extended catalogue contains 7352 events, 70% more than the 4310 events of the previous published (1989) version. The completeness test revealed that the catalogue is complete for magnitudes above 4 for the last 34 yr and that no earthquake with magnitude 6 or greater has been omitted in the whole instrumental era (1900–2009).


2020 ◽  
Author(s):  
Sattam Almadani

Abstract The main goal of this study is to quantify the rate of seismic deformation in the Gulf of Aqaba. The moment tensor summation technique based on the seismicity data, for all available historical and instrumental data (1900-2019), and reliable fault plane solutions was used to calculate the size and the shape of deformation. For the period from 1900 to 2019, the seismicity data was used to calculate the seismicity parameters (representing by the Gutenberg-Richter and moment-magnitude relations) and the spatial extent of the deformation zone. The fault parameters of forty-four earthquakes, having moment magnitudes range from 3.2 to 7.2, were used to construct the moment tensor summation and subsequently to calculate the rate of seismic deformation. The calculations showed that a predominant shear deformation acting in the Gulf of Aqaba is taken up by extension in a direction of N40.8 o E at a rate of 0.83±0.21 mm/yr. and compression in a direction of N131.6 o E at a rate of 0.32±0.05 mm/yr.; reflecting the Gulf of Aqaba is undergoing from shear deformation accommodated along a strike-slip fault. The obtained results exhibited that the present-day deformation in the Gulf of Aqaba is acting by the interaction of relative tectonic motions among African, Sinai and Arabia plates.


Author(s):  
С.Э. Казымова

В данной работе анализируется одно из крупнейших по количеству жертв (погибло около 230 тыс. человек) землетрясений в истории человечества, произошедшее 30 сентября 1139 г. в городе Гянджа (на юго-западе Азербайджана). Интенсивность данного землетрясения достигла 9 балов. В статье приведены исторические данные, представленные в различных атласах и каталогах, рукописях и летописях. С тектонической точки зрения Гянджинское землетрясение произошло на стыке Гейча-Акеринской и Лок-Карабахской зоны Артвин-Карабахской мегазоны, которая охватывает северные хребты Малого Кавказа. Цель работы. С целью исследования сейсмичности и современной геодинамики территории Гянджинского очага был построен график повторяемости за последние 1500 лет и проанализированы механизмы 4-ох очагов землетрясений координаты которых совпадают с исследуемым историческим землетрясением. Вероятность повторения сильного Гянджинского землетрясения 1139 г. в ближайшие 800 лет составила 0,30. Методы исследования. Для вычисления механизмов очага был использован алгоритм по методу инверсии волновых форм, на основе которого были получены решения тензора момента и моментные магнитуды Mw для 4-х выбранных землетрясений произошедших 30 сентября 2012 г., 2 июля 2015 г. и 6 марта 2017 г. В процессе работы изначально были определены функции Грина, которые используются при инверсии наблюдаемых трехкомпонентных широкополосных сигналов (20–100 с) с последующим разложением на скалярный сейсмический момент Мо и основные параметры ориентации пары сил – азимутальный угол, угол падения и угол скольжения. Результаты работы. Сопоставление простирания нодальных плоскостей с линиями разломов показал согласие первой нодальной плоскости с продольным Муровдагским взбросо-надвигом, и второй нодальной плоскости с поперечным Муровдаг-Зодским сдвигом. В итоге все вышесказанное указывает на то, что проанализированные современные Гянджинские землетрясения, точнее их очаговые зоны в геодинамическом отношении произошли под действием сжимающих напряжений ориентированных СВ-ЮЗ-ом направлении. This work analyzes one of the largest earthquakes in terms of the number of victims (about 230 thousand people died) in the history of mankind, which occurred on September 30, 1139 in the city of Ganja (in the south-west of Azerbaijan). The intensity of this earthquake reached 9 points. The article contains historical data presented in various atlases and catalogs, manuscripts and annals. From a tectonic point of view, the Ganja earthquake occurred at the junction of the Goycha-Akerin and Lok-Karabakh zones of the Artvin-Karabakh megazone, which covers the northern ridges of the Lesser Caucasus. The aim. In order to study the seismicity and modern geodynamics of the territory of the Ganja source, a recurrence graph was constructed for the last 1500 years.The mechanisms of four sources of earthquakes whose coordinates coincide with the studiedhistorical earthquake were analyzed. The probability of a repeat for the strong Ganja earthquake of 1139 in the next 800 years was 0.30. Research methods. To calculate the focal mechanisms, an algorithm was used according to the waveform inversion method, on the basis of which the solutions of the moment tensor and moment magnitudes Mw were obtained for 4 selected earthquakes that occurred on September 30, 2012, July 2, 2015, and March 6, 2017. In the course of work, the Green's functions were initially determined, which are used for inversion of the observed three-component broadband signals (20–100 s) with subsequent decomposition into scalar seismic moment Mo and the main parameters of the orientation of the pair of forces - azimuthal angle, angle of incidence and angle of grazing. Results. Comparison of the strike of the nodal planes with the fault lines showed the agreement of the first nodal plane with the longitudinal Murovdag upthrust fault, and the second nodal plane with the transverse Murovdag-Zod strike-slip fault. As a result, all of the above indicates that the analyzed modern Ganja earthquakes, or rather their focal zones in the geodynamic respect, occurred under the action of compressive stresses oriented NE-SW direction.


2021 ◽  
Author(s):  
◽  
Elizabeth de Joux Robertson

<p>The aim of this project is to enable accurate earthquake magnitudes (moment magnitude, MW) to be calculated routinely and in near real-time for New Zealand earthquakes. This would be done by inversion of waveform data to obtain seismic moment tensors. Seismic moment tensors also provide information on fault-type. I use a well-established seismic moment tensor inversion method, the Time-Domain [seismic] Moment Tensor Inversion algorithm (TDMT_INVC) and apply it to GeoNet broadband waveform data to generate moment tensor solutions for New Zealand earthquakes. Some modifications to this software were made. A velocity model can now be automatically used to calculate Green's functions without having a pseudolayer boundary at the source depth. Green's functions can be calculated for multiple depths in a single step, and data are detrended and a suitable data window is selected. The seismic moment tensor solution that has either the maximum variance reduction or the maximum double-couple component is automatically selected for each depth. Seismic moment tensors were calculated for 24 New Zealand earthquakes from 2000 to 2005. The Global CMT project has calculated CMT solutions for 22 of these, and the Global CMT project solutions are compared to the solutions obtained in this project to test the accuracy of the solutions obtained using the TDMT_INVC code. The moment magnitude values are close to the Global CMT values for all earthquakes. The focal mechanisms could only be determined for a few of the earthquakes studied. The value of the moment magnitude appears to be less sensitive to the velocity model and earthquake location (epicentre and depth) than the focal mechanism. Distinguishing legitimate seismic signal from background seismic noise is likely to be the biggest problem in routine inversions.</p>


2021 ◽  
Vol 3 (2) ◽  
pp. 123-132
Author(s):  
Titi Anggono ◽  
Rio Rinaldo Tarigan ◽  
Diana Alemin Barus

Sulawesi is one of the islands in Indonesia with a high level of seismicity because there are many active faults, especially in the Minahasa Peninsula area. This study discusses the moment tensor solution and the focus mechanism in the Minahasa Peninsula region from 28 September 2018 to 1 October 2018 using the ISOLA-GUI program. This program is used to process seismic data from the three components recorded by the seismogram. The data used in this study were five earthquake events consisting of earthquake foreshock, earthquake mainshock, and earthquake aftershock. With the ISOLA program, data processing is carried out which includes: crustal models, event info, selecting earthquake recording stations, preparing raw data for defining seismic sources, calculating green functions with computations, performing inversions and plotting results. In the inversion, the frequency of the band pass filter is selected to obtain the optimal reduction variance. After processing, calculating and interpreting the plot results, a fault model is obtained for each earthquake event, namely strike-slip. 


Author(s):  
J. S. Wall

The forte of the Scanning transmission Electron Microscope (STEM) is high resolution imaging with high contrast on thin specimens, as demonstrated by visualization of single heavy atoms. of equal importance for biology is the efficient utilization of all available signals, permitting low dose imaging of unstained single molecules such as DNA.Our work at Brookhaven has concentrated on: 1) design and construction of instruments optimized for a narrow range of biological applications and 2) use of such instruments in a very active user/collaborator program. Therefore our program is highly interactive with a strong emphasis on producing results which are interpretable with a high level of confidence.The major challenge we face at the moment is specimen preparation. The resolution of the STEM is better than 2.5 A, but measurements of resolution vs. dose level off at a resolution of 20 A at a dose of 10 el/A2 on a well-behaved biological specimen such as TMV (tobacco mosaic virus). To track down this problem we are examining all aspects of specimen preparation: purification of biological material, deposition on the thin film substrate, washing, fast freezing and freeze drying. As we attempt to improve our equipment/technique, we use image analysis of TMV internal controls included in all STEM samples as a monitor sensitive enough to detect even a few percent improvement. For delicate specimens, carbon films can be very harsh-leading to disruption of the sample. Therefore we are developing conducting polymer films as alternative substrates, as described elsewhere in these Proceedings. For specimen preparation studies, we have identified (from our user/collaborator program ) a variety of “canary” specimens, each uniquely sensitive to one particular aspect of sample preparation, so we can attempt to separate the variables involved.


Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 292
Author(s):  
Maria Bobrova ◽  
Sergey Stanchits ◽  
Anna Shevtsova ◽  
Egor Filev ◽  
Vladimir Stukachev ◽  
...  

The heterogeneity of the rock fabric is a significant factor influencing the initiation and propagation of a hydraulic fracture (HF). This paper presents a laboratory study of HF created in six shale-like core samples provided by RITEK LLC collected from the same well, but at different depths. For each tested sample, we determined the breakdown pressure, the HF growth rate, and the expansion of the sample at the moment when the HF reaches the sample surface. Correlations were established between the HF parameters and the geomechanical characteristics of the studied samples, and deviations from the general relationships were explained by the influence of the rock matrix. The analysis of the moment tensor inversion of radiated acoustic emission (AE) signals allows us to separate AE signals with a dominant shear component from the signals with a significant tensile component. The direction of microcrack opening was determined, which is in good agreement with the results of the post-test X-ray CT analysis of the created HF. Thus, it has been shown that a combination of several independent laboratory techniques allows one to reliably determine the parameters that can be used for verification of hydraulic fracturing models.


Sign in / Sign up

Export Citation Format

Share Document