Orientations of Broadband Stations of the KOERI Seismic Network (Turkey) from Two Independent Methods: P- and Rayleigh-Wave Polarization

2021 ◽  
Author(s):  
Pınar Büyükakpınar ◽  
Mustafa Aktar ◽  
Gesa Maria Petersen ◽  
Ayşegül Köseoğlu
Keyword(s):  
Receiver Function ◽  
Function Analysis ◽  
Eastern Mediterranean ◽  
Moment Tensor ◽  
Eastern Mediterranean Region ◽  
P Waves ◽  
Data Set ◽  
The North ◽  
Correct Orientation ◽  
Sensor Orientation

Abstract The correct orientation of seismic sensors is critical for studies such as full moment tensor inversion, receiver function analysis, and shear-wave splitting. Therefore, the orientation of horizontal components needs to be checked and verified systematically. This study relies on two different waveform-based approaches, to assess the sensor orientations of the broadband network of the Kandilli Observatory and Earthquake Research Institute (KOERI). The network is an important backbone for seismological research in the Eastern Mediterranean Region and provides a comprehensive seismic data set for the North Anatolian fault. In recent years, this region became a worldwide field laboratory for continental transform faults. A systematic survey of the sensor orientations of the entire network, as presented here, facilitates related seismic studies. We apply two independent orientation tests, based on the polarization of P waves and Rayleigh waves to 123 broadband seismic stations, covering a period of 15 yr (2004–2018). For 114 stations, we obtain stable results with both methods. Approximately, 80% of the results agree with each other within 10°. Both methods indicate that about 40% of the stations are misoriented by more than 10°. Among these, 20 stations are misoriented by more than 20°. We observe temporal changes of sensor orientation that coincide with maintenance work or instrument replacement. We provide time-dependent sensor misorientation correction values for the KOERI network in the supplemental material.

The CIELO Seismic Experiment

2021 ◽  
Author(s):  
Heather A. Ford ◽  
Maximiliano J. Bezada ◽  
Joseph S. Byrnes ◽  
Andrew Birkey ◽  
Zhao Zhu
Keyword(s):  
Receiver Function ◽  
Function Analysis ◽  
P Wave ◽  
Crust And Upper Mantle ◽  
Waveform Data ◽  
Wyoming Craton ◽  
Sensor Orientation ◽  
Seismic Experiment ◽  
Short Period ◽  
Receiver Function Analysis

Abstract The Crust and lithosphere Investigation of the Easternmost expression of the Laramide Orogeny was a two-year deployment of 24 broadband, compact posthole seismometers in a linear array across the eastern half of the Wyoming craton. The experiment was designed to image the crust and upper mantle of the region to better understand the evolution of the cratonic lithosphere. In this article, we describe the motivation and objectives of the experiment; summarize the station design and installation; provide a detailed accounting of data completeness and quality, including issues related to sensor orientation and ambient noise; and show examples of collected waveform data from a local earthquake, a local mine blast, and a teleseismic event. We observe a range of seasonal variations in the long-period noise on the horizontal components (15–20 dB) at some stations that likely reflect the range of soil types across the experiment. In addition, coal mining in the Powder River basin creates high levels of short-period noise at some stations. Preliminary results from Ps receiver function analysis, shear-wave splitting analysis, and averaged P-wave delay times are also included in this report, as is a brief description of education and outreach activities completed during the experiment.

scholarly journals ILPYRSKOE EARTHQUAKE March 13, 2013 with Mwreg=5.8, ML=6.2, КS=13.9, I0p=8 (Kamchatsky Isthmus)

2019 ◽  
pp. 343-361 ◽  
Author(s):  
Y. Kugaenko ◽  
S. Drosnina ◽  
Vadim Saltykov ◽  
V. Pavlov ◽  
A. Lander ◽  
...  
Keyword(s):  
Focal Mechanism ◽  
Moment Tensor ◽  
Great Length ◽  
P Waves ◽  
Near Surface ◽  
Real Time Processing ◽  
North East ◽  
The North ◽  
Minimum Number ◽  
Two Stages

The strong (Mwreg=5.8, ML=6.2) near-surface seismic event (Ilpyrskoye earthquake) occurred at 03h12m on 13 March, in the Kamchatka Isthmus. It was the strongest earthquake between 1962 and 2013 for this area. The greatest macroseismic effect was observed at a distance of ~30 km, I=6–7 on the scale MSK-64. We used two independent methods for determining its regional focal mechanism: 1) regional moment tensor in-version using broadband waveforms; 2) solution based on polarities of the P waves. The results are similar: the focal mechanism of Ilpyrskoye earthquake is thrust faulting with strike-slip component; the compression axis is subhorizontal and is oriented in the north-east – south-west direction. The mechanisms for the two strongest aftershocks were also identified, as a result, a change in focal movements during the aftershock process was revealed.The analysis of the aftershock process which consists of two stages with different de-cay character was performed. The process lasted ~ 75 days. About 200 aftershocks ML=3.0–5.7 (КS=7.5–12.9) were recorded, hypocenter depth estimations vary from 0 to 10 km for about 80 % of them. The strongest aftershock was on May 6, 2013 with ML=5.7, Mwreg=4.8, at which the change in focal movements occurred. According to the results of near real time processing, aftershock cloud of Ilpyrskoye earthquake had a pronounced linearity and a great length, which was an artifact. The main cause of the artifact is the minimum number of stations involved in determining the hypocenters of most aftershocks and their quasi-linear disposition. The confidence areas within which solutions are equivalent are shown. We concluded that Ilpyrskoye earthquake is a serious argument that the area of compression between the Okhotsk and North American plates is extended further to the east and the border passes through the Kamchatka Isthmus

scholarly journals DETERMINATION OF ASEISMIC DEFORMATION ON NORTH ANATOLIAN FAULT IN ISMETPASA AND DESTEK REGIONS USING GPS DATA, TURKEY

2017 ◽  
Vol 50 (1) ◽  
pp. 182
Author(s):  
H. Yavasoglu ◽  
M.N. Alkan ◽  
K. Aladogan ◽  
I.M Ozulu ◽  
V. Ilci ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
North Anatolian Fault ◽  
Gps Data ◽  
Slip Mechanism ◽  
The North ◽  
First Results ◽  
Fault Deformation ◽  
Fault Mechanism

The North Anatolian Fault Zone (NAFZ) is one of the most destructive fault in the eastern Mediterranean region. After Izmit and Düzce earthquakes, the projects on monitoring the fault motion increase using instrumental tools like GPS, InSAR, LIDAR, creepmeter, etc. The eastern and central part of the NAFZ from Karlıova to Vezirköprü has almost strike slip mechanism. The western part of the central NAFZ from Vezirköprü to Bolu has transpressive character. The aseismic fault deformation (creep) is also important phenomena for these two sections. The InSAR and LIDAR studies showed that the Ismetpasa and Destek regions have creep motions. For this purpose, the new project has been started to proof this phenomena with GPS data and to determine quantitatively the rate of convergence and its variation along segment of the NAF between Bolu and Çorum. The main aim of this study is determination of creep rate with geodetic measurements and combination of the data obtained from seismology, geodesy and geophysics to understand fault mechanism. Therefore, in this paper we discuss tectonic phenomena on the central part of the NAFZ and present the first results of the project.

Dipping structure under Dourbes, Belgium, determined by receiver function modeling and inversion

1995 ◽  
Vol 85 (1) ◽  
pp. 254-268 ◽  
Author(s):  
Jie Zhang ◽  
Charles A. Langston
Keyword(s):  
Receiver Function ◽  
Receiver Functions ◽  
P Wave ◽  
P Waves ◽  
S Waves ◽  
The North ◽  
Shear Wave Velocities ◽  
Geophysical Surveys ◽  
Vector Rotation ◽  
Anomalous Particle

Abstract Teleseismic broadband P and S waves recorded at the NARS station NE06 (Dourbes, Belgium) are shown to exhibit strong anomalous particle motion not attributable to instrument miscalibration or malfunction. Azimuthally varying radial and tangential components have been observed on 38 recordings after vector rotation of horizontal P waves into the ray direction. The tangenital P waves attain amplitudes comparable to the radial components from the east with negative polarity and west with positive polarity, but tend to be zero in the north and south, suggesting major discontinuities in the crust dipping southward. The SH wave from the east contains a large SPmP phase, an S-to-P conversion at the free surface and then reflected back to the surface from the Moho. The polarity of this SPmP phase presents further evidence for a southward-dipping Moho. We employ ray theory for three-dimensionally dipping interfaces to compute the P-wave response. Linear inverse theory with smoothness constraints is applied to the simultaneous inversions of P-wave receiver functions for four different backazimuths. Through the progressive change of interface strike and dip and the inversion of layer shear-wave velocities, a dipping crustal model that is consistent with both the observed waveforms and results of previous local geophysical surveys has been determined. The results suggest a large velocity contrast in the shallow structure near the surface, another major interface at a depth of 12 km with dip of 10°, and a seismically transparent unit below the interface. The interface at a depth of 12 km reportedly emerges at the Midi fault 50 km north of the station NE06.

scholarly journals Drivers of the decadal variability of the North Ionian Gyre upper layer circulation during 1910–2010: a regional modelling study

2021 ◽  
Author(s):  
Feifei Liu ◽  
Uwe Mikolajewicz ◽  
Katharina D. Six
Keyword(s):  
Ocean Circulation ◽  
Adriatic Sea ◽  
Decadal Variability ◽  
Eastern Mediterranean ◽  
Circulation Model ◽  
Atmospheric Forcing ◽  
Sensitivity Experiment ◽  
Data Set ◽  
The North ◽  
Upper Layer Circulation

AbstractA long simulation over the period 1901–2010 with an eddy-permitting ocean circulation model is used to study the variability of the upper layer circulation in the North Ionian Gyre (NIG) in the Eastern Mediterranean Sea (EMed). The model is driven by the atmospheric forcing from the twentieth century reanalysis data set ERA-20C, ensuring a consistent performance of the model over the entire simulation period. The main modes of variability known in the EMed, in particular the decadal reversals of the NIG upper layer circulation observed since the late 1980s are well reproduced. We find that the simulated NIG upper layer circulation prior to the observational period is characterized by long-lasting cyclonic phases with weak variability during years 1910–1940 and 1960–1985, while in the in-between period (1940–1960) quasi-decadal NIG circulation reversals occur with similar characteristics to those observed in the recent decades. Our simulation indicates that the NIG upper layer circulation is rather prone to the cyclonic mode with occasional kicks to the anticyclonic mode. The coherent variability of the NIG upper layer circulation mode and of the Adriatic Deep Water (AdDW) outflow implies that atmospheric forcing triggering strong AdDW formation is required to kick the NIG into an anticyclonic circulation 1–2 years later. A sensitivity experiment mimicking a cold winter event over the Adriatic Sea supports this hypothesis. Our simulation shows that it is the multi-decadal variability of the salinity in the Adriatic Sea that leads to periods where low salinity prevents strong AdDW formation events. This explains the absence of quasi-decadal NIG reversals during 1910–1940 and 1960–1985.

scholarly journals Investigation of energy resources and gas discoveries in the Eastern Mediterranean region: the case of people’s expectations and social impacts in Egypt

2020 ◽  
Author(s):  
Mahmoud A. Hammad ◽  
Sonja Mlaker Kac ◽  
Sandra S. G. Haddad ◽  
Habiba S. El Rouby
Keyword(s):  
Social Services ◽  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Social Impacts ◽  
Ordinary People ◽  
High Expectations ◽  
The North ◽  
The People ◽  
Random Sampling Approach

This study discusses the expected social impacts due to the recent offshore gas findings and development in the Eastern Mediterranean region on human communities in Alexandrian in the North of Egypt. A sample of 401 respondents of ordinary people who are living in the Alexandria governorate were sampled for the study using a convenience non-random sampling approach. The study showed most people are somewhat familiar with the ongoing gas discoveries in the Mediterranean Sea. The study also revealed that the people in Egypt have relatively high expectations from these gas discoveries. The ordinary people in Egypt expected that such discoveries of gas would have many positive and negative social impacts side by side. They expected several social benefits of gas finds such as: the contribution to the diversification of the economy, infrastructural development, expanding social services, improvement of the standard of living, business and investment opportunities, employment.

The Crustal Structure of the Eastern Marmara Region Using Receiver Function Analysis

2020 ◽  
Author(s):  
Pınar Büyükakpınar ◽  
Mustafa Aktar
Keyword(s):  
Fault Zone ◽  
Receiver Function ◽  
Function Analysis ◽  
Joint Inversion ◽  
Crustal Thickness ◽  
Receiver Functions ◽  
Gradual Transition ◽  
Marmara Region ◽  
The North ◽  
Receiver Function Analysis

<p>This study focuses on the crust of the Eastern Marmara in order to understand of how much the structure is influenced by the tectonic history and also by the activity of the NAF. Recent studies have claimed that the crustal thickness varies significantly on the north and south of the NAF, which is assumed to indicate the separation line between Eurasian and Anatolian Plates. The present study aims to reevaluate the claim above, using newly available data and recently developed tools. The methods used during the study are the receiver function analysis and surface wave analysis. The first one is more intensively applied, since the second one only serves to introduce stability constraint in the inversions. Data are obtained from the permanent network of KOERI and from PIRES arrays.  The main result of the study indicates that the receiver functions for the stations close to the fault zone are essentially very different from the rest and should be treated separately. They show signs of complex 3D structures of which two were successfully analyzed by forward modeling (HRTX and ADVT). A dipping shallow layer is seen to satisfy the major part of the azimuthal variation at these two stations. For the stations off the fault on the other hand, the receiver functions show a more stable behavior and are analyzed successfully by classical methods. CCP stacking, H-k estimation, single and joint inversion with surface waves, are used for that purpose. The results obtained from these totally independent approaches are remarkably consistent with each other. It is observed that the crustal thickness does not vary significantly neither in the NS, nor in the SW direction. A deeper Moho can only be expected on two most NE stations where a gradual transition is more likely than a sharp boundary (SILT and KLYT). The structural trends, although not significant, are generally aligned in the EW direction.  In particular, a slower lower crust is observed in the southern stations, which is possibly linked to the mantle upwelling and thermal transient of the Aegean extension. Otherwise neither the velocity, nor the thickness of the crust does not imply any significant variation across the fault zone, as was previously claimed.</p>

scholarly journals Compatibility between “Arbequina” and “Souri” Olive Cultivars May Increase Souri Fruit Set

Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 910
Author(s):  
Iris Biton ◽  
Yair Many ◽  
Ali Mazen ◽  
Giora Ben-Ari
Keyword(s):  
Fruit Set ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Paternity Analysis ◽  
Olive Cultivar ◽  
Cross Pollination ◽  
The North ◽  
Olive Variety ◽  
Olive Cultivars ◽  
Arbequina Cultivar

The “Souri” olive cultivar, which is autochthonous to the eastern Mediterranean region, has been the major olive variety cultivated traditionally under rain-fed conditions in northern Israel. The aim of this study was to determine the optimal pollen donor for the olive cultivar Souri in order to maximize Souri fruit set. Artificial cross pollination of Souri flowers with several local varieties has identified the “Nabali” as the most efficient pollinizer of the Souri. However, further experiments using artificial cross pollination conducted with cultivars not common to this region have revealed the “Arbequina” as a more efficient pollinizer of the Souri cultivar than the Nabali. Based on a preliminary paternity analysis, the Nabali was identified as the dominant pollinizer of Souri trees in traditional olive orchards in the north of Israel. However, in a multi-variety orchard, molecular paternity analysis has shown Arbequina to be the most frequent pollinizer. We then tested, during two consecutive years, whether the presence of a pollen-producing Arbequina tree adjoining Souri trees in the field will increase their fruit set. We found that Souri fruit set was 8.36% when pollinized by an Arbequina tree in close proximity to them, significantly higher than the fruit set of 5.6% for Souri trees without the nearby Arbequina cultivar. On the basis of these trials, we expect that the yield of Souri orchards will improve if Arbequina trees are planted.

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