New Results for the 1968 Belice, South Italy, Seismic Sequence: Solving the Long-Lasting Ambiguity on Causative Source

Abstract We present the first estimates of moment tensor solutions and probabilistic nonlinear hypocenter locations for the 1968 Belice earthquake sequence, which is the most relevant seismic activity occurred in western Sicily in historical times. This seismic phase, including six earthquakes with magnitude between 5 and 6.4, produced severe damages and fatalities in a sector of the Nubia–Eurasia plate margin, previously considered aseismic. Poorly constrained and often controversial hypocenter locations and focal mechanism solutions available from the literature have led to a long-lasting ambiguity on the possible causative source of the sequence, also having primary effects on the regional seismotectonic modeling and seismic hazard evaluations. The two main fault models proposed in the literature alternatively assigned a primary role to the north-northwest-trending Nubia–Eurasia plate convergence, causing thrust faulting on about east-trending structures or to the differential foreland retreat driving dextral strike-slip movements on about north–south-oriented faults. By focusing on the starting and the most energetic phase of the 1968 sequence, we computed the moment tensor solutions for three of the strongest earthquakes using digitized waveforms and a time-domain waveform inversion technique. Then, we also analyzed, by means of a Bayesian hypocenter location technique, the spatial distribution of the 1968 earthquakes. All the results indicate that the 1968 Belice sequence was characterized by predominant reverse faulting occurring on about east-to-northeast-trending structures, thus solving the dualism between models previously proposed in the literature. Our findings well agree both with the geodynamic framework governed by the Nubia–Eurasia north-northwest-trending convergence and with the geological reconstructions of the regional thrust front in the western Sicily area. The results of moment tensor estimations and nonlinear hypocenter locations furnishing an improved knowledge of the most relevant seismic activity of western Sicily also concur to better constraint the seismotectonic modeling of the region.

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The major (Mw=7.0) earthquake of 30th October 2020 north Samos Island, Greece: Analysis of seismological and geodetic data

10.5194/egusphere-egu21-1581 ◽

2021 ◽

Author(s):

Alexandra Moshou ◽

Antonios Konstantaras ◽

Panagiotis Argyrakis

Keyword(s):

Service Providers ◽

Expert Knowledge ◽

Moment Tensor ◽

Focal Depth ◽

Stress Transfer ◽

Seismic Zone ◽

Western Turkey ◽

Tsunami Early Warning ◽

The North ◽

The Moment

On 30th October 2020, at 11.51 (UTC), a very strong earthquake of magnitude Mw = 7.0 struck north of the Greek island of Samos in the Aegean coast of Turkey, south of Izmir. The epicentre was determined 17km north of Samos, in the Gulf of Ephesus and was felt in many parts of Greece and western Turkey. The geographical coordinates as calculated of the manual analysis of the National Observatory of Athens (http://bbnet.gein.noa.gr/Events/2020/10/noa2020vipzs_info.html) was determined as &#160;&#966;= 37.9001&#8304;N, &#955;=26.8167&#8304;E at a focal depth at 11.8km.&#160;The earthquake triggered a tsunami that flooded the coastal district of Seferihisar (Turkey), Cesme, Izmir and the port of Samos (Greece). In the next 8 minutes after the detection of the earthquake, tsunami bulletins were issued to national focal points by the Tsunami Service Providers accredited by UNESCO&#8217;s IOC Intergovernmental Coordination Group for the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and connected seas (ICG/NEAMTWS). Greece and Turkey were put on Tsunami Watch (highest level of alert). In Seferishar the tsunami swept away many boats in the marina and the water level reached 1.5 meters causing damage to shops.Three hours later, 15:14 (UTC) a second strong event (Mw = 5.3) occurred in the same region some kilometres south of the main earthquake (&#966;=37.8223&#8304;N,&#955;=26.8652&#8304;E, http://bbnet.gein.noa.gr/Events/2020/10/noa2020viwsi_info.html). By the end of the same day that the earthquake took place, there were 65 aftershocks while a total of 576 aftershocks up to 31/12 with magnitude greater than 1.0. For the aftershocks with 3.7<ML<7.0 we applied the moment tensor inversion to determine the focal mechanism, the Seismic Moment (M0) and the Moment Magnitude (Mw). For this purpose, 3&#8211;component broadband seismological data from the Hellenic Unified Seismological Network (HUSN) at epicentral distances less than 3&#730; were selected and analysed. The preparation of the data, includes the deconvolution of instrument response, following the velocity was integrated to displacement and finally the horizontal components rotated to radial and transverse. Finally, an extensive kinematic analysis from data provided by two private sector companies networks was done.References:Athanassios Ganas, Penelope Kourkouli, Pierre Briole, Alexandra Moshou, Panagiotis Elias and Isaak Parcharidis. Coseismic Displacements from Moderate-Size Earthquakes Mapped by Sentinel-1 Differential Interferometry: The Case of February 2017 Gulpinar Earthquake Sequence (Biga Peninsula, Turkey), Remote Sensing, 2018, pp. 237 &#8211; 248Athanassios Ganas, Zafeiria Roumelioti, Vassilios Karastathis, Konstantinos Chousianitis, Alexandra Moshou, Evangelos Mouzakiotis. The Lemnos 8 January 2013 (Mw=5.7) earthquake: fault slip, aftershock properties and static stress transfer modeling in the north Aegean Sea J Seismol (2014) 18:433&#8211;455 DOI 10.1007/s10950-014-9418-3Konstantaras A. Deep Learning and Parallel Processing Spatio-Temporal Clustering Unveil New Ionian Distinct Seismic Zone. Informatics, 7(4), 39, 2020KONSTANTARAS, A. Expert knowledge-based algorithm for the dynamic discrimination of interactive natural clusters. Earth Science Informatics 9, (2016), 95-100

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Evaluation of seismic sensor orientations in the full moment tensor inversion results

10.5194/egusphere-egu21-459 ◽

2021 ◽

Author(s):

Mohammadreza Jamalreyhani ◽

Mehdi Rezapour ◽

Pınar Büyükakpınar

Keyword(s):

Moment Tensor ◽

Probabilistic Method ◽

Waveform Inversion ◽

Moment Tensor Inversion ◽

Reliable Determination ◽

Trade Offs ◽

Sensor Orientation ◽

Seismic Sensors ◽

The Moment ◽

Seismic Networks

Three-component seismograms recorded by seismic sensors are momentous data to study the source mechanism of earthquakes. Correct orientation of sensors relative to the true north is important for the waveform inversion techniques. Yet, the non-precise orientation of horizontal components of seismic sensors has been reported in many seismic networks worldwide. In this study, we evaluated the effect of sensor misorientations (deviations from the true north) on time-domain moment tensor inversion, relying on the recent sensor orientation studies on broadband seismic networks in Iran and Turkey. We selected several well-recorded countrywide local and regional moderate magnitude earthquakes, which are associated with the tectonic events, in the time period of 2012-2019. We calculated the moment tensor inversion of those events before and after applying the orientation correction using a Bayesian bootstrap-based probabilistic method. This leads to reaching the uncertainties and trade-offs of parameters and helps to stabilize the inversion. Our analysis shows that in the presence of misoriented sensors, an approximate solution is achievable. However, this includes the remarkable uncertainties in inverted parameters and makes the reliable determination of the moment tensor&#8217;s elements challenging. We also found an additional significant non-double couple component while using the misoriented radial and transverse components. Results show that the misfit and uncertainties decrease significantly when sensor orientation correction applied. We suggest that the evaluation of metadata should be part of data processing in seismic networks and data centers, to report more reliable moment tensor solutions.

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Ganja earthquake of 1139

Геология и геофизика Юга России ◽

10.46698/vnc.2021.42.74.005 ◽

2021 ◽

Author(s):

С.Э. Казымова

Keyword(s):

Moment Tensor ◽

Waveform Inversion ◽

Azimuthal Angle ◽

Point Of View ◽

Inversion Method ◽

Angle Of Incidence ◽

Nodal Plane ◽

History Of ◽

Lesser Caucasus ◽

The Moment

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.

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How to Assess the Moment Tensor Inversion Resolution for Mining Induced Seismicity: A Case Study for the Rudna Mine, Poland

Frontiers in Earth Science ◽

10.3389/feart.2021.671207 ◽

2021 ◽

Vol 9 ◽

Author(s):

Alicja Caputa ◽

Łukasz Rudziński ◽

Simone Cesca

Keyword(s):

Moment Tensor ◽

Waveform Inversion ◽

Moment Tensor Inversion ◽

Seismic Network ◽

P Wave ◽

Induced Earthquakes ◽

Mining Operations ◽

Moment Tensors ◽

The Moment ◽

Inversion Techniques

Underground exploitation of georesources can be highly correlated with induced seismic activity. In order to reduce the risk and improve the mining operations safety, the mining activity is monitored by a dedicated seismic network. Moment tensor inversion is a powerful method to investigate the rupture process of earthquakes in mines, providing information on the geometry of the earthquake source and the moment release. Different approaches have been proposed to estimate the source mechanisms, with some advantages and limitations. One of the simplest and most used methods rely on the fit of the polarity and amplitude of first P wave onsets. More advanced techniques fit the full waveforms and their spectra. Here, we test and compare moment tensor and focal mechanism estimations for both inversion techniques. In order to assess the inversion resolution, we built realistic synthetic data, accounting for real seismic noise conditions and network geometry for the Rudna copper mine, SW Poland. The Rudna mine pertains to the Legnica-Glógow Copper District, where thousands of mining induced earthquakes are detected yearly, representing a serious hazard for miners and mining infrastructures. We simulate a range of different processes and locations, considering pure double couple, deviatoric and full moment tensors with different magnitudes and located in different mining panels. Results show that the P-wave first onset inversion is very sensitive to the geometry of the seismic network, which is limited by the existing underground infrastructure. On the other hand, the quality of the moment tensor solutions for the full waveform inversion is mainly determined by the strength of mining tremor and the signal-to-noize ratio. We discuss the performance of both inversion techniques and provide recommendations toward a reliable moment tensor analysis in mines.

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OBOLESCENCE AND THE DIFFUSION OF INNOVATIONS

Izvestiâ Timirâzevskoj selʹskohozâjstvennoj akademii ◽

10.26897/0021-342x-2020-4-113-130 ◽

2020 ◽

pp. 113-130

Author(s):

A.V. GOLUBEV ◽

Keyword(s):

Diffusion Of Innovations ◽

Time Lag ◽

Practical Implementation ◽

Primary Role ◽

Innovation Development ◽

Scientific Hypothesis ◽

Scientific Papers ◽

The Moment ◽

Sociological Studies

The diffusion of innovations is described as a process in a number of scientific papers. At the same time, the causes of this process have not been sufficiently studied. The author’s goal is to consider the main regularities, under which the life cycle of innovations begins, and propose measures to enhance diffusion in modern conditions. As a scientific hypothesis, the author accepts the postulate about the primary role of the obolescence of attracted innovations in this process. The analysis revealed not only the economic proportions that initiate the start of innovation promotion, but also the influence on the diffusion rate of the obsolescence degree of innovations and the market share occupied by the new product. Methodological approaches have been developed to determine economic efficiency depending on the moment of technological change-over, as well as to determine the absolute and relative speed of innovation diffusion. Sociological studies were conducted to determine the state of innovation development and the time lag between obtaining information about an innovation and its practical implementation. The author presents his “Agroopyt” information system developed to disseminate knowledge in the agricultural sphere and ensure technology transfer in agriculture. Digital methods provide for significant accelerateion of the diffusion of innovations and expand its scope.

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Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽

10.3390/geosciences11020102 ◽

2021 ◽

Vol 11 (2) ◽

pp. 102

Author(s):

Paraskevi Nomikou ◽

Dimitris Evangelidis ◽

Dimitrios Papanikolaou ◽

Danai Lampridou ◽

Dimitris Litsas ◽

...

Keyword(s):

Fault Zone ◽

Seismic Activity ◽

Volcanic Rocks ◽

Active Tectonics ◽

Normal Fault ◽

Aegean Sea ◽

Northern Margin ◽

The North ◽

Eastern Aegean ◽

Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

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Updated Incidence of Thyroid Cancer in the North East Region of Romania after 35 Years of Chernobyl Fallout. Is There a Link between?

Diagnostics ◽

10.3390/diagnostics11050907 ◽

2021 ◽

Vol 11 (5) ◽

pp. 907

Author(s):

Laura Teodoriu ◽

Maria Christina Ungureanu ◽

Letitia Leustean ◽

Cristina Preda ◽

Delia Ciobanu ◽

...

Keyword(s):

Thyroid Cancer ◽

Age Distribution ◽

Age Groups ◽

Chernobyl Fallout ◽

Statistical Correlations ◽

North East ◽

The North ◽

East Region ◽

Radioactive Cloud ◽

The Moment

Thyroid cancer (TC) represents a worldwide problem, the consistent growth of the incidence increment issues about management of risk factors and curative treatment. Updated statistical data are not complete in the North East region of Romania and need to be improved. Therefore, through this study, we aim to renew the existing data on thyroid cancer. We conducted a retrospective study covering a period of 10 years. Data were collected from a hospital information system (InfoWorld) between 2009 and 2019. Patients’ age groups were stratified in relation with the age at the moment of the Chernobyl event. A database was obtained (Microsoft Excel) and statistical correlations were applied. In the studied period, 1159 patients were diagnosed: 968 females and 191 males, distributed by region, with the highest addressability in Iasi (529), followed by neighboring counties. Age distribution displayed that most of the thyroid cancers were in the range 4060 years old (50.94%), followed by 60–80 years old (32.41%). Most patients were diagnosed with papillary carcinoma 63.10%, then follicular 14.7%, medullary 6.74% and undifferentiated 1.02%. Romania was in the vicinity of the radioactive cloud at Chernobyl fallout, so we must deliberate whether the increased incidence of thyroid cancer in the age group 40–60 years is associated with radiogenicity (iodine 131) given the fact that over has 35 years and the half-life of other radioisotopes like Caesium-137 and Strontium -90 is completed.

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The waveform inversion of mainshock and aftershock data of the 2006 M6.3 Yogyakarta earthquake

Geoscience Letters ◽

10.1186/s40562-021-00176-w ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Hijrah Saputra ◽

Wahyudi Wahyudi ◽

Iman Suardi ◽

Ade Anggraini ◽

Wiwit Suryanto

Keyword(s):

Joint Inversion ◽

Body Wave ◽

Moment Tensor ◽

Near Field ◽

Source Parameters ◽

Waveform Inversion ◽

Moment Tensor Inversion ◽

Slip Distribution ◽

Aftershock Distribution ◽

Velocity Models

AbstractThis study comprehensively investigates the source mechanisms associated with the mainshock and aftershocks of the Mw = 6.3 Yogyakarta earthquake which occurred on May 27, 2006. The process involved using moment tensor inversion to determine the fault plane parameters and joint inversion which were further applied to understand the spatial and temporal slip distributions during the earthquake. Moreover, coseismal slip distribution was overlaid with the relocated aftershock distribution to determine the stress field variations around the tectonic area. Meanwhile, the moment tensor inversion made use of near-field data and its Green’s function was calculated using the extended reflectivity method while the joint inversion used near-field and teleseismic body wave data which were computed using the Kikuchi and Kanamori methods. These data were filtered through a trial-and-error method using a bandpass filter with frequency pairs and velocity models from several previous studies. Furthermore, the Akaike Bayesian Information Criterion (ABIC) method was applied to obtain more stable inversion results and different fault types were discovered. Strike–slip and dip-normal were recorded for the mainshock and similar types were recorded for the 8th aftershock while the 9th and 16th June were strike slips. However, the fault slip distribution from the joint inversion showed two asperities. The maximum slip was 0.78 m with the first asperity observed at 10 km south/north of the mainshock hypocenter. The source parameters discovered include total seismic moment M0 = 0.4311E + 19 (Nm) or Mw = 6.4 with a depth of 12 km and a duration of 28 s. The slip distribution overlaid with the aftershock distribution showed the tendency of the aftershock to occur around the asperities zone while a normal oblique focus mechanism was found using the joint inversion.

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Laboratory Investigation of Hydraulic Fracture Behavior of Unconventional Reservoir Rocks

Geosciences ◽

10.3390/geosciences11070292 ◽

2021 ◽

Vol 11 (7) ◽

pp. 292

Author(s):

Maria Bobrova ◽

Sergey Stanchits ◽

Anna Shevtsova ◽

Egor Filev ◽

Vladimir Stukachev ◽

...

Keyword(s):

Hydraulic Fracture ◽

Moment Tensor ◽

Sample Surface ◽

Breakdown Pressure ◽

Reservoir Rocks ◽

Shear Component ◽

Post Test ◽

Ct Analysis ◽

The Moment ◽

Ae Signals

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.

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Toward real-time estimation of regional moment tensors

Bulletin of the Seismological Society of America ◽

10.1785/bssa0860051255 ◽

1996 ◽

Vol 86 (5) ◽

pp. 1255-1269 ◽

Cited By ~ 6

Author(s):

Michael E. Pasyanos ◽

Douglas S. Dreger ◽

Barbara Romanowicz

Keyword(s):

Moment Tensor ◽

Time Estimation ◽

Computer Data ◽

Moment Tensors ◽

Central California ◽

Tensor Methods ◽

Real Time Estimation ◽

The Moment ◽

Computer Data Processing ◽

Data Processing Methods

Abstract Recent advances in broadband station coverage, continuous telemetry systems, moment-tensor procedures, and computer data-processing methods have given us the opportunity to automate the two regional moment-tensor methods employed at the UC Berkeley Seismographic Station for events in northern and central California. Preliminary solutions are available within minutes after an event has occurred and are subsequently human reviewed. We compare the solutions of the two methods to each other, as well as the automatic and revised solutions of each individual method. Efforts are being made to establish robust criteria for determining accurate solutions with human review and to fully automate the moment-tensor procedures into the already-existing automated earthquake-location system.

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