locating non volcanic tremor along the san andreas fault using a multiple array source imaging technique summary non volcanic tremor nvt has been observed at several subduction zones and at the san andreas fault saf tremor locations are commonly derived by cross correlating envelope transformed seismic traces in combination with source scanning techniques recently they have also been located by using relative relocations with master events that is low frequency earthquakes that are part of the tremor locations are derived by conventional traveltime based methods here we present a method to locate the sources of nvt using an imaging approach for multiple array data the performance of the method is checked with synthetic tests and the relocation of earthquakes we also applied the method to tremor occurring near cholame california a set of small aperture arrays i e an array consisting of arrays installed around cholame provided the data set for this study we observed several tremor episodes and located tremor sources in the vicinity of saf during individual tremor episodes we observed a systematic change of source location indicating rapid migration of the tremor source along saf

analysis of asymmetric multipathing with a generalization of the double beam method abstract an array method integrating source and receiver array beamforming is presented the method is a generalization of previous work kruger et al 1993 to independent variation of slowness and azimuth in both the source and the receiver array compared to the analysis capabilities of a single array the resolution is enhanced and asymmetric scattering configurations and multipathing can be studied the generalized double beam method dbm is applied to a data set consisting of nuclear explosions detonated in eastern kazakhstan and recorded at the yellowknife array in northern canada the multipathing found for pcp and pdp is interpreted in terms of lateral inhomogeneity in the lowermost mantle below severnaya zemlya indications for rayleigh to p wave scattering observed for the shagan river and degelen subsites of the former main test site of the ussr in eastern kazakhstan can be related to the structure in the vicinity of the two subsites

double beam analysis of anomalies in the core mantle boundary region seismic p waves from nuclear explosions at the kazakhstan test site in eastern kazakhstan kts observed at the yellowknife array yka canada are used to analyze the structure at the base of the mantle under severnaya zemlya arctic sea 18 events at the degelen subsite and 9 events at the shagan river subsite of kts are studied the simple waveforms and well controlled source parameters of nuclear explosions allow the use of the events as source arrays in addition to the usual receiver array configuration a new method double beamforming integrating both concepts is presented this method increases the resolution considerably for the degelen yka path one anomalous arrival 1 9 s before pcp slowness between p and pcp slowness is observed smaller anomalous arrivals are found 6 5 s degelen yka and 8 1 s before pcp shagan river yka these anomalous phases cannot be explained with standard earth models they are produced by reflections from an inhomogeneity in the lowermost mantle at 82 3n 107 5e under the area north of severnaya zemlya the strong variations between the wavefields for the two source receiver combinations indicate a heterogeneous structure in the lower mantle the anomaly found here is located close to an anomaly in the lowermost mantle beneath the nansen basin

the influence of foliation on the fragility of granitic rocks image analysis and quantitative microscopy fabric dependent anisotropy is important in understanding the mechanical behaviour of foliated rocks because the foliation creates mechanically weak discontinuities using optical microscopy a foliation index fix was calculated for a group of granitic rocks in southern sweden that displays a range of textures from foliated to nonfoliated image analysis from scanning electron microscope with backscattered detector sem bse images was used in order to measure the rock texture of these samples the analyses were compared with the los angeles la test which measures resistance of rock aggregate to fragmentation the results demonstrate that the measured grain size shape and spatial arrangement are important parameters controlling the fragility of the rock both the texture and foliation must be taken into account to obtain a significant relationship with the mechanical analyses we suggest that this alternative method could be a helpful tool for predicting a rock s suitability as an aggregate as it gives a better understanding of the material properties compared to mechanical testing

considerations on strength of intact sedimentary rocks abstract this study presents the results of laboratory testing of sedimentary rocks under point loading as well as in uniaxial and triaxial compression from the statistical analysis of the data different conversion factors relating uniaxial compressive and point loading strength were determined for soft to strong rocks additionally the material constant mi an input parameter for the hoek and brown failure criterion was also estimated for different limestone samples by analysing the results from a series of triaxial compression tests under different confining pressures the uniaxial compressive strength ucs of intact rocks as estimated from the point load index using conversion factors together with the hoek brown constant mi and the geological strength index gsi constitute the parameters for the calculation of the strength and deformability of rock masses

prediction of engineering properties of a selected litharenite sandstone from its petrographic characteristics using correlation and multivariate statistical techniques abstract the determination of rock strength and elastic parameters in laboratory tests requires high quality core samples which are not always available from fractured and or weathered strata the purpose of this study is to apply a correlation analysis in conjunction with multivariate statistical techniques to petrographical and laboratory geomechanical data for the investigation of correlations that exist between these properties of a selected sandstone and to suggest inexpensive predictive models in a preliminary investigation sandstone samples from a borehole drilled for a preliminary investigation of a shaft location at a hard coal region black sea turkey were tested to determine uniaxial compressive strength elastic parameters unit weight porosity point load index and quality index secondly fifteen selected samples were subjected to petrographic examination which included fifteen parameters and modal analysis based on the statistical analysis results polynomial prediction equations were developed for estimating mechanical properties from petrographic characteristics and index properties the study revealed that the influence of textural characteristics appear to be more important than mineralogy for predicting engineering properties it is also noted that type of contacts grain shape and size rock fragments with packing density and proximity are the petrographic characteristics which have significant influence upon engineering properties of the sandstones results of this study were presented in the form of correlation coefficient models and predictive models

complex evolution of transient slip derived from precise tremor locations in western shikoku japan transient slip events which occur more slowly than traditional earthquakes are increasingly being recognized as important components of strain release on faults and may substantially impact the earthquake cycle surface based geodetic instruments provide estimates of the overall slip distribution in larger transients but are unable to capture the detailed evolution of such slip either in time or in space accompanying some of these slip transients is a relatively weak extended duration seismic signal known as nonvolcanic tremor which has recently been shown to be generated by a sequence of shear failures occurring as part of the slip event by precisely locating the tremor we can track some features of slip evolution with unprecedented resolution here we analyze two weeklong episodes of tremor and slow slip in western shikoku japan we find that these slip transients do not evolve in a smooth and steady fashion but contain numerous subevents of smaller size and shorter duration in addition to along strike migration rates of 10 km d observed previously much faster migration also occurs usually in the slab dip direction at rates of 25 150 km h over distances of up to 20 km we observe such migration episodes in both the updip and downdip directions these episodes may be most common on certain portions of the plate boundary that generate strong tremor in intermittent bursts the surrounding regions of the fault may slip more continuously driving these stronger patches to repeated failures tremor activity has a strong tidal periodicity possibly reflecting the modulation of slow slip velocity by tidal stresses

the point load test for weak rock in dredging applications abstract the point load test is shown useful for weak saturated rocks which are commonly encountered in mechanical dredging operation to support the dredging use of the point load test orginally intended to obtain a field strenth index for hard rock materials a comparative testing program was initiated which included more than four hundred rock tests the resulting data base system provides test a summary of test data and comparison calculations the data base contains point load and unconfined compressive strength tests and some wet versus dry strength comparison tests applicability of the point load test was shown for the weak rock materials typical of many coastal deposits a correlation with unconfined compressive strength was demonstrated for several dredge sites and for a low strength rock simulant however correlation factors were consistently much lower than the generalized or target average values cited in testing standards which are consistent with results in hard rock tunneling and mining applications

new engineering geological weathering classifications for granitoid rocks abstract in this research several physico mechanical properties are measured on three types of alvand granitoid rocks across five weathering grades ranging from fresh to completely weathered rocks also weathering processes of the rocks are evaluated by petrographic studies it is evident that a realistic weathering classification is necessary mostly for establishing the geotechnical models in engineering geological studies for this reason development of a quantitative weathering classification is the main purpose of our study in the proposed triangular weathering classification diagrams four index tests including uniaxial compressive strength point load strength p wave velocity and quick water absorption are selected to predict weathering grades also types of weathering have been determined using two petrographic indices the new triangular engineering geological weathering classifications are supported by other researchers reported data the obtained results indicate that the classifications can be used for a wide range of granitoid rocks

possible deep fault slip preceding the 2004 parkfield earthquake inferred from detailed observations of tectonic tremor 1 earthquake predictability depends in part on the degree to which sudden slip is preceded by slow aseismic slip recently observations of deep tremor have enabled inferences of deep slow slip even when detection by other means is not possible but these data are limited to certain areas and mostly the last decade the region near parkfield california provides a unique convergence of several years of high quality tremor data bracketing a moderate earthquake the 2004 magnitude 6 0 event here i present detailed observations of tectonic tremor from mid 2001 through 2008 that indicate deep fault slip both before and after the parkfield earthquake that cannot be detected with surface geodetic instruments while there is no obvious short term precursor i find unidirectional tremor migration accompanied by elevated tremor rates in the 3 months prior to the earthquake which suggests accelerated creep on the fault 16 km beneath the eventual earthquake hypocenter

tidal modulation of nonvolcanic tremor episodes of nonvolcanic tremor and accompanying slow slip recently have been observed in the subduction zones of japan and cascadia in cascadia such episodes typically last a few weeks and differ from normal earthquakes in their source location and moment duration scaling the three most recent episodes in the puget sound southern vancouver island portion of the cascadia subduction zone were exceptionally well recorded in each episode we saw clear pulsing of tremor activity with periods of 12 4 and 24 to 25 hours the same as the principal lunar and lunisolar tides this indicates that the small stresses associated with the solid earth and ocean tides influence the genesis of tremor much more effectively than they do the genesis of normal earthquakes because the lithostatic stresses are 10 5 times larger than those associated with the tides we argue that tremor occurs on very weak faults

locating the sources of volcanic explosions and volcanic tremor at stromboli volcano italy using beam forming on diffraction hyperboloids abstract the wave field of volcano induced seismic signals at stromboli volcano italy was observed using a network of four broadband seismometers in addition to the standard spectral analysis of the recorded signals new spectral techniques such as wavelet transform and wavelet coherence analysis were also used in order to discriminate between signals related to volcanic tremor and volcanic explosions the common features of these two types of signals are characterised by the maximum of the power spectral density values located in the frequency band 2 0 hz and the main orientation of the principal axes of the particle motion ellipsoids in the frequency bands analysed the seismic signals of the volcanic explosions at stromboli cover the total frequency band whereas the spectral content of the volcanic tremor is restricted to narrow frequency bands ranging from 0 3 5 0 hz in order to localize both types of signals a modified inversion technique was used the result of this beam forming on diffraction hyperboloids of both types of signals reveal a surprisingly shallow source location ranging from 0 2 km 0 7 km above sea level suggesting that the sources of the volcanic explosions as well as of the volcanic tremor are restricted to the uppermost parts of the volcano this is in agreement with several nonseismological observations of this volcano the combination of spectral analysis of volcanic tremor and volcanic explosions with the analysis of ground displacement implies a mechanism which can be described by an ascending bubble of volcanic gas in a nearly closed volcanic system and finally the forced ejection of the material through a narrow channel at the top of the magma column

textural characterisation of rocks textural characteristics are a major factor in determining the mechanical behaviour of rocks and in the prediction of performance of rock cutting and drilling equipment the principal textural characteristics of rocks are grain size grain shape grain orientation relative proportion of grains and matrix material which were herein quantitatively measured using a modern image analysis system these features resulted in a texture coefficient represented by a single number for each rock specimen in this study a range of both textural and mechanical data for a range of rock types are given with some of the textural determination methodology correlation between textural and physical properties are also highlighted the results of drilling tests using polycrystalline diamond compact pin and hybrid and impregnated diamond core bits in the rocks are presented which demonstrate the influence of rock texture on drillability the rock texture can be used as a predictive factor for assessing the drillability and cuttability mechanical and wear performance of rocks

petrographic quantification of brecciated rocks by image analysis application to the interpretation of elastic wave velocities abstract this paper presents a new procedure to quantify the petrology of materials with complex and heterogenic rock fabric features the classical methodologies for petrographic quantification by image analysis are not appropriate for this kind of rock due to both the high chromatic complexity of these materials and the scale with which the samples are studied the proposed process is particularly interesting for materials with complex chromatic characteristics such as highly fractured rocks concrete etc two commercial varieties of highly fractured brecciated dolostones were selected for this study in order to test the designed methodology this new procedure is based on the analysis process of colour images obtained from mesoscopic sample scanning six petrographic parameters and diagrams have been designed in order to quantify the most influential aspects in compressional v p and shear v s ultrasonic wave propagation these petrographic parameters and diagrams are brecciation density brecciation density map clast size distribution fine grained matrix content shape preferred orientation and rose diagrams the results demonstrate that the proposed methodology is suitable for quantifying the petrography of these kinds of materials furthermore the variations measured in v p and v s are fully explained by the values measured for the following parameters brecciation density fine grained matrix content clast size distribution and preferred orientation of clasts

influence of orthoclase phenocrysts on point load strength of granitic rocks abstract the point load index test involves loading cylindrical block or irregular rock samples between two conical platens until sample failure the point load strength index is determined using failure load and sample dimension is widely and variously used in engineering geological studies therefore a comprehensive knowledge about the factors that could influence the index value is necessary this paper explores the effects of orthoclase phenocryst dimension on the point load strength index is of granitic materials from turkey in this context point load strength values of 117 granite core samples were determined the granites used in this study included orthoclase phenocrysts as important mineral constituents high resolution image was obtained from the freshly fractured surface of each sample the ratio of orthoclase phenocrysts rop on the failure surface was determined using image analysis when point load strength values were correlated with the ratios of orthoclase phenocrysts an inverse relationship emerged issues in order to minimize the influence of orthoclase phenocrysts on the point load strength were discussed

the effect of weathering on pore geometry and compressive strength of selected rock types from turkey weathering processes cause important changes in rock porosity besides porosity distribution of pore sizes is significant for the identification of changes due to rock weathering and its effects on fabric the formation of secondary porosity in different types of rock taken from different parts of turkey was examined and the results are presented in this paper the aim of this study was to observe changes in porosity due to weathering effective porosity mercury intrusion porosimetry and optical and scanning electron microscopy were used to evaluate the changes in pore geometry of the rocks additionally the dry density water absorption and uniaxial compressive strength of the rocks at different weathering stages were determined analysis of experimental data showed that microstructure of the rocks in relation to weathering is the main feature which controls their physical and mechanical properties the study revealed that fabric characteristics particularly the pore and fracture geometry are very important characteristics for assessment of the behaviour of weathered rock

mid mantle scatterers near the mariana slab detected with a double array method we use a cluster of deep earthquakes the fore and aftershocks of the 23 aug 1995 mw 7 1 18 8n 145 3e h 595 km event in the mariana subduction zone as source array to locate where waves scatter near the deep slab in order to obtain the high precision location needed in this context we first relocate the events with a modified master event technique using the double beam method on the relocated events and data from the warramunga array in australia we identified two non standard s to p conversions arriving about 20 5 and 24 s after the p wave the corresponding scatterers are approximately located at a depth of 790 km 720 km and a distance of 0 9 to the southeast 2 3 to the southwest of the main shock the scatterers positions correspond to the location of lithosphere subducted below the 660 km discontinuity

mineralogical geochemical constraints on intrusives in central anatolia turkey tectono magmatic evolution and characteristics of mantle source collision related rocks intrude metamorphic rocks overthrust by ophiolitic units to make up the central anatolian crystalline complex a wide variety of rock types were produced by the latest cretaceous magmatism in the complex these rocks can be divided into three distinct units 1 calc alkaline agacoren behrekdag cefalikdag celebi ekecikdag halacli karamadazi kosefakili terlemez uckapili yozgat 2 sub alkaline baranadag and 3 alkaline atdere davulalan egrialan hamit idisdagi karacayir the calc alkaline rocks are metaluminous peraluminous i to s type plutons ranging from monzodiorite to granite the sub alkaline rocks are metaluminous i type plutons ranging from monzonite to granite the alkaline rocks are metaluminous to peralkaline plutons predominantly a type ranging from foid bearing monzosyenite to granite these plutons crystallized under varying pressures 5 3 2 6 kbar and a wide range of temperatures 858 698 c from highly oxidized magmas log f o 2 17 to 12 all intrusive rocks display enrichment in lile and lree compare to hfse and have high 87 sr 86 sr and low 143 nd 144 nd ratios these characteristics indicate that these rocks are derived from a mantle source containing large subduction components and have experienced assimilation coupled with fractional crystallization afc during uprise through crust the coexistence of calc alkaline and alkaline magmatism in the complex may be ascribed to mantle source heterogeneity before collision either thermal perturbation of the metasomatized lithosphere by delamination of the thermal boundary layer or removal of a subducted plate slab breakoff are the likely mechanisms for the initiation of the collision related magmatism in the complex

correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from turkey abstract granitic rocks show a variety of engineering properties that may affect quarrying operations tunneling mining slope stability and the use of rock as a construction material the physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock the purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks a variety of granitic rock samples from different parts of turkey were subjected to petrographic studies the same samples were then tested to determine specific gravity dry and saturated unit weight water absorption effective and total porosity sonic velocity schmidt hardness point load strength index uniaxial compressive strength tensile strength and modulus of elasticity the relationships between these properties and the petrographical characteristics are described by simple regression analyses the study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy it also determined that the types of contacts grain mineral shape and size significantly influence the engineering properties of the granitic rocks

new weathering classifications for granitic rocks based on geomechanical parameters here we investigate the classification of weathering grade for granitic rocks from the malayer granitoid western iran using physico mechanical parameters the physical and mechanical properties of rock samples were measured across five weathering grades ranging from fresh rock to completely weathered statistical analyses including simple regression and multiple linear regression were applied to identify those physico mechanical parameters that are most influenced by the progression of weathering the parameters with significant correlations with weathering grade include strength retention index p wave velocity porosity brazilian tensile strength and point load index on the basis of the statistical results new classifications are developed these classifications can be used to predict the engineering properties of the malayer granitic rocks hamedan nw iran and should have more general application to the quantitative classification of granitic rocks in iran

slowness corrections one way to improve idc products the first step to identify and locate a seismic event is the association of observed onsets with common seismic sources this is especially important in the context of monitoring the comprehensive nuclear test ban treaty ctbt at the international data center idc being developed in vienna austria well defined slowness measurements are very useful for associating seismic phases to presumed seismic events shortly after installation of the first seismic arrays systematic discrepancies between measured and theoretically predicted slowness values were observed and therefore slowness measurements of seismic stations should be calibrated the observed slownesses measured with small aperture arrays some of which will be included in the international monitoring system ims now being implemented for verifying compliance with the ctbt show large scatter and deviations from theoretically expected values however in this study a method is presented by which mean slowness corrections can be derived which show relatively stable patterns specific to each array the correction of measured slowness values of these arrays clearly improved the single array location capabilities applying slowness corrections with seismic phases observed by arces fines geres and nores and associated to seismic events in the bulletins of the prototype international data center pidc in arlington va also clearly demonstrates the advantages of these corrections for arrays with large slowness deviations that are due to the influence of a dipping layer the corrections were modeled with a sine function depending on the measured azimuth in addition the measured values can be weighted with the corresponding uncertainties known from the process of deriving the mean corrections

the effect of mineralogy and textural characteristics on the strength of crystalline igneous rocks using image based textural quantification abstract the attempts made to understand and quantify the relationship between rock texture and engineering properties have been accompanied by some ambiguities and uncertainties and the majority of the approaches though focusing on particular rock types have not been so successful for even the same rock types from other regions this study therefore was aimed to investigate the relationship between the texture and strength properties of a wide range of crystalline igneous rocks along with more aspects of textural analysis for this purpose fifteen fresh samples of crystalline igneous rocks belonging to the stone quarries of the nw iran were collected and subjected to compressive and tensile strength tests ucs and bts thin sections of the samples were used to prepare the full mosaic image layers in three different optical conditions about 18 000 mineral grains were manually traced on the processed images and the obtained vector data was used for the quantification of various textural parameters including size metrics shape descriptors microfabric indices and mineral content different phase considerations full phasic monophasic multiphasic and phase ratio were applied to derive the textural characteristics of the individual and multiple minerals and their proportional ratio finally simple linear regression analysis was performed to evaluate the relationship between the texture and strength properties the results indicated that the newly developed quartz to feldspar size ratio qfsr indicator was the only textural parameter that could be significantly correlated with both compressive and tensile strength in a wide range of rock types the results also highlighted the fact that the role of quartz and feldspar encountered with different rock failure mechanisms could be different in fact the tensile strength was obviously affected by the size and content of k feldspar while the compressive strength showed a more complicated mechanism and seemed to be controlled by the interference effects of plagioclase and quartz textural properties furthermore the study indicated that the influence of grain size on the rock strength was more important than the grain shape or mineral content

effects of weathering and lithology on the quality of aggregates in the alluvial fans of northeast rivand sabzevar iran alluvial fans as depositional landforms can be considered as potential sources of aggregates as the age of alluvial fans increases their constituent sediments are exposed to longer periods of weathering and increased mineral alteration resulting in a decrease in aggregate quality in this study physical properties and point load tests were used to assess the aggregate quality on three alluvial fan surfaces relict old and young in the northeastern part of rivand village in west of sabzevar northeast iran differentiating young from old and relict fans was carried out based on geomorphic criteria such as weathering features fan surface morphology and drainage pattern the young alluvial fan is characterized by sub rounded and unvarnished clasts distributary drainage patterns and a relatively flat surface whereas old and relict fans are characterized by incised and rough surfaces tributary drainage pattern and highly weathered and varnished clasts due to their long term exposure to weathering due to a range of rock types occurring across each fan surface lithological studies were performed to eliminate the effect of lithology on aggregate quality a total of 18 rock types comprising comparable lithologies were sampled from each of the three alluvial fans results show that in almost all 18 rock types the point load test values increases from relict to young fans whereas porosity and percentage of water absorption decrease implying that aggregate quality decreases with time as a function of duration of exposure to weathering also the strength of aggregates in all three fans decreases from the fan apex to the fan toe data show that micaceous intrusive igneous rocks tuffs with high porosity and fine grained extrusive igneous rocks with some porosity are more sensitive to physical weathering and therefore have lower strength particularly on the relict and old fans overall variations in aggregate strength on these fans can be attributed to the relative ages of fans with relict and old fans containing lower quality aggregates due to the longer term exposure to weathering

pore development of the lower longmaxi shale in the southeastern sichuan basin and its adjacent areas insights from lithofacies identification and organic matter abstract x ray diffraction xrd field emission focusing ion beam scanning electron microscopy fe fib sem nitrogen gas adsorption n2ga and geochemical analyses were performed on the lower longmaxi shale in the southeastern sichuan basin and its adjacent areas to reveal the controls of shale lithofacies and organic matter om on pore development the results showed that the lower longmaxi shale primarily comprises three types of lithofacies based on shale compositions and sedimentary environment om rich siliceous shale orss om moderate mixed shale omms and om lean argillaceous shale olas orss comprises high contents of om and siliceous minerals quartz and feldspar deposited in a deep water shelf and early semi deep water shelf environment while olas consists of high clay mineral and low om contents primarily formed in a shallow water shelf environment omms witness a transition from orss to olas in sedimentary environment and shale components om hosts a higher volume of pores per unit weight compared to inorganic minerals corresponding to 0 1878 ml g and 0 00396 ml g respectively om hosted pores are dominant in orss constituting 72 whereas olas mainly consists of mineral hosted pores comprising 63 2 om hosted and mineral hosted pores in omms exist in similar proportions namely 56 4 and 43 6 respectively differentiated diagenetic paths resulting from sedimentary environment are responsible for the differences in pore development under various shale lithofacies the thermal maturity macerals and abundance of om all play a significant role in the morphology and development of om hosted pores om hosted pores are primarily founded in migrated om mainly sapropelic type instead of structured om mainly humic type in the form of secondary pores that are derived from dry gas generation stage furthermore om hosted pore development in shale gas reservoirs is slowed or even reduced because of the weakening of shale s resistance to compaction resulting from excessively high om content

assessment of rock geomechanical quality by quantitative rock fabric coefficients limitations and possible source of misinterpretations abstract rock microfabrics were quantified by image measurement system petrographic image analysis of thin sections along with common measured parameters grain area and size length of major and minor axes and their orientation some quantitative parameters aspect ratio grain boundary smoothness and fabric coefficients micropetrographic quality index k texture coefficient tc indexes of interlocking t and grain size homogeneity g were determined the reliability of these parameters for the evaluation of geomechanical properties was tested on the set of granitic rocks showing pronounced variability in rock mechanical properties none of the tested rock fabric coefficients or parameters proved a close correlation to rock mechanical properties except grain size based on experimental findings the grain size is along with porosity the controlling factor of rock mechanical properties of genetically and mineralogically similar rocks obliteration of the real effects of rock fabric parameters on the mechanical properties of rocks by application of complex fabric coefficients disables their practical use in petrography applied to geomechanics