scholarly journals Spatial Temporal Condition of Recent Seismicity In The Northern Part of Sumatra

Elkawnie ◽  
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Inna Nurana ◽  
Andrean Vesalius Hasiholan Simanjuntak ◽  
Muksin Umar ◽  
Djati Cipto Kuncoro ◽  
Syamsidik Syamsidik ◽  
...  
Keyword(s):  
High Stress ◽  
Statistical Parameter ◽  
Temporal Analysis ◽  
Seismic Gap ◽  
Time To Failure ◽  
Interface Zone ◽  
Prone Area ◽  
Subduction System ◽  
Parameter Values ◽  
Stress Accumulation

The condition of stress and recent seismicity in the seismic-prone area can be statistically analyzed with the Gutenberg-Richter relation. We apply this relation to the hypocenter distribution for the period 1970-2020 with M ≥ 4 and depth ≤ 200 km  in the northern part of Sumatra. Spatially, The results obtained, a-values and b-values, figure a lateral heterogeneity and stress accumulation with dense structures at the interface zone in the subduction system and the northern segmentation of the Seulimeum fault. In time, both zones illustrate a slow time-to-failure cycle and seismic gap with high stress accumulation in the specific clusters with high seismic parameter values. The results of the spatial temporal analysis illustrate that each major earthquake event is usually preceded by a low statistical parameter value.

Model Verification of Mixed Dynamic Systems

1978 ◽  
Vol 100 (2) ◽  
pp. 266-273 ◽  
Author(s):  
J. D. Chrostowski ◽  
D. A. Evensen ◽  
T. K. Hasselman
Keyword(s):  
Experimental Data ◽  
Parameter Estimation ◽  
Dynamic Systems ◽  
Statistical Parameter ◽  
Model Verification ◽  
Passive Networks ◽  
Parameter Values ◽  
Basic Configuration ◽  
General Method

A general method is presented for using experimental data to verify math models of “mixed” dynamic systems. The term “mixed” is used to suggest applicability to combined systems which may include interactive mechanical, hydraulic, electrical, and conceivably other types of components. Automatic matrix generating procedures are employed to facilitate the modeling of passive networks (e.g., hydraulic, electrical). These procedures are augmented by direct matrix input which can be used to complement the network model. The problem of model verification is treated in two parts; verification of the basic configuration of the model and determination of the parameter values associated with that configuration are addressed sequentially. Statistical parameter estimation is employed to identify selected parameter values, recognizing varying degrees of uncertainty with regard to both experimental data and analytical results. An example problem, involving a coupled hydraulic-mechanical system, is included to demonstrate application of the method.

scholarly journals INSPECTION POLICIES IN AIRCRAFT SERVICE

Aviation ◽  
2004 ◽  
Vol 8 (4) ◽  
pp. 3-9 ◽  
Author(s):  
Konstantin N. Nechval ◽  
Nicholas A. Nechval
Keyword(s):  
Crack Propagation ◽  
High Stress ◽  
Simple Approach ◽  
Structural Components ◽  
Aircraft Structure ◽  
Numerical Examples ◽  
Usual Approach ◽  
Long Period ◽  
Parameter Values ◽  
Initial Cracks

As aircraft structures begin to age (that is, as flight hours accumulate), existing subcritical cracks or new cracks can grow in some high‐stress points of the structural components. The usual approach is to inspect the structures periodically. Thus, a catastrophic accident during flight can be avoided. The problem then arises of choosing a sequence of inspection times which avoids both too many inspections, which may be costly, and too few inspections, that may also be costly due to a crack in an aircraft structure component not being detected for a long period. In this paper, a simple approach is proposed, where after each inspection (if a crack is not detected), we choose the next inspection point so that a crack may occur within an interval between successive inspection times with a given probability. It allows one to find the inspection policies for detection of initial cracks in critical structural components of aircraft under the assumption that the parameter values of the underlying distributions are unknown; this constraint is often met in practice. Furthermore, obtaining inspection schedules under crack propagation is considered. To illustrate the proposed technique based on ancillary statistics, numerical examples are given.

scholarly journals Multiaxial Fatigue Spectrum Editing by Using Combined Wavelet Analysis and Stress Invariant Approach

2018 ◽  
Vol 165 ◽  
pp. 16009
Author(s):  
Anahita Imanian ◽  
Kelvin Leung ◽  
Nagaraja Iyyer
Keyword(s):  
Fatigue Damage ◽  
Fatigue Testing ◽  
Fatigue Crack Initiation ◽  
Statistical Parameter ◽  
Multiaxial Fatigue ◽  
Loading Path ◽  
Plane Stress Condition ◽  
Structural Fatigue ◽  
Wavelet Transform Analysis ◽  
Parameter Values

The practicalities of structural fatigue testing limit the fidelity of the cyclic load history that can be applied to a test structure. Testing is, therefore, a compromise between fatigue damage fidelity and test economy. A new methodology is proposed for multiaxial loading spectrum editing to extract cycles that contribute negligible damage during fatigue crack initiation. The method is based on projection by projection (PbP) technique and wavelet transform analysis (WTA) procedure. In this approach, the cycles with negligible contribution to damage in every decoupled projected loading path (i.e. obtained from PbP approach) are extracted using the WTA procedure. Each extracted segment is then replaced with an equivalent cycle that produces the same amount of damage. The effectiveness of the edited spectrums is evaluated by the degree of fatigue damage retention as the original damage and preservation of statistical parameter values. As a case study, the proposed approach has been applied to the numerically produced random bending-torsion fatigue spectrum in plane-stress condition. The result shows an average of 75% reduction of the original spectrums with retention of 90% of the original spectrums’ damage values.

scholarly journals TEKSTUR SEDIMEN PERMUKAAN DASAR LAUT DI PERAIRAN TANJUNG DATU, SAMBAS-KALIMANTAN BARAT

2016 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Udaya Kamiludin ◽  
Hananto Kurnio ◽  
Noor C.D. Aryanto
Keyword(s):  
Marine Environment ◽  
Fine Particles ◽  
Statistical Parameter ◽  
Fine Sand ◽  
Silty Sand ◽  
Medium Sand ◽  
Statistical Parameters ◽  
S Parameter ◽  
Area Classification ◽  
Parameter Values

Dasar laut perairan Tanjung Datu ditempati oleh tekstur sedimen dengan jenis lanau pasiran (sZ), pasir lanauan (zS), pasir (S) dan pasir sedikit kerikilan [(g)S]. Parameter statistik berupa modus jatuh antara lanau kasar (4,5 Ø)-pasir menengah (1,5 Ø), kepencongan negatif-positif dengan kurtosis berbentuk monomodal-bimodal. Distribusi partikel tegak lurus pantai menunjukan frekuensi modus pasir halus dan menengah yang bertambah ke arah lepas pantai; dan untuk yang sejajar pantai, pasir halusnya cenderung bertambah ke bagian tengah daerah penelitian. Klasifikasi pasir terhadap kelas pemilahan berdasarkan nilai deviasi standar, dan plot skater memperlihatkan bahwa satuan pasir dan pasir sedikit kerikilan mempunyai kesesuaian dengan lingkungan marin disertai adanya kelebihan partikel kasar dan halus. Kata Kunci : Sedimen permukaan, parameter statistik, lingkungan marin, Perairan Tanjung Datu. Tanjung Datu waters occupied by sandy silt (sZ), silty sand (zS), sand (S), and slightly gravellly sand sediment texture. The above unit has the statistical parameter values, comprising: mode falls between coarse silt (4.5 Ø)-medium sand (1.5 Ø), negative-positive skewness with kurtosis monomodal-bimodal shape. The distribution of particles perpendicular to the coast showing modes frequencies of fine to medium sand increases towards offshore. The parallel distribution contains modes of fine sand tends to increase to the central part of the study area. Classification of sand to a class of sorting based on the value of standard deviation, and the scatter plot shows that the sand and slightly gravellly sand units have compatibility with the marine environment with excess coarse and fine particles. Key words: Surface sediment, statistical parameters, marine environment, Tanjung Datu Waters.

scholarly journals The seismicity of central and north-east Himalayan region

2019 ◽  
Vol 49 (3) ◽  
pp. 265-281
Author(s):  
Susheel Kumar ◽  
Nitin Sharma
Keyword(s):  
Temporal Analysis ◽  
River Valley ◽  
Himalayan Region ◽  
Seismic Gap ◽  
Indus River ◽  
Seismic Belt ◽  
Study Region ◽  
Latitude Belt ◽  
North East ◽  
Spatial And Temporal Analysis

Abstract The Himalayan range extends upto 2400 km arc from Indus river valley in the west to Brahmaputra river valley in the east of India. Due to distinct geological structures of Himalayan seismic belt, seismicity in Himalaya is inhomogeneous. The inhomogeneity in seismicity is responsible for a number of seismic gaps in the Himalayan seismic belt. Thus Iin the present study, we proposed the study of spatial and temporal evolution of seismicity in entire central and north-east Himalayan region by using Gutenberg-Richter relationship. A detailed study on the behavior of natural seismicity in and around the seismic gap regions is carried out. The study region is segmented in four meridional regions (A) 80°E to 83.5°E, (B) 83.5°E to 87.5°E, (C) 87.5°E to 90°E and (D) 90°E to 98°E along with a fixed latitude belt. The homogeneous catalogue with 3 ≤ Mb ≤ 6.5 is used for the spatial and temporal analysis of seismicity in terms of b-value. It is find out that pockets of lower b-values are coinciding over and around stress accumulated regions. The observed low b-value before occurrence of the Nepal earthquake of 25th April, 2015 supports the argument of impending occurrence of moderate to large magnitude earthquake in Sikkim and north-east Himalayan region in future.

Persistent earthquake-rupture segmentation due to variable interseismic slip accumulation within the southern Hellenic subduction plate-interface zone in Greece

2020 ◽  
Author(s):  
Vasso Saltogianni ◽  
Vasiliki Mouslopoulou ◽  
Onno Oncken ◽  
Andrew Nicol ◽  
Michael Gianniou ◽  
...  
Keyword(s):  
Earthquake Rupture ◽  
Thrust Faults ◽  
Large Magnitude ◽  
Plate Interface ◽  
Slip Rates ◽  
Interface Zone ◽  
Fault Slip Rates ◽  
Fault Interactions ◽  
Gps Velocities ◽  
Subduction System

<p>Increasing evidence suggests that large thrust-faults that splay from the plate-interface to extend within the upper-plate have a significant impact on subduction seismogenesis. The manner in which these two elements, the plate-interface itself and its splay-thrust faults, interact with one another during the earthquake cycle remains, however, poorly explored. Here, we use GPS velocities, constrained by millennial fault slip-rates, to quantify the accumulation (and partitioning) of strain on individual faults of the plate-interface zone and capture their possible interactions. We zoom into the southern Hellenic Subduction System (HSS), where the greatest (M8.3) earthquake and tsunami ever recorded in the Mediterranean was produced by slip on a splay-thrust fault. Our analysis shows that the HSS is kinematically segmented and strain is accumulated at spatially variable rates along individual structures of the plate-interface zone. We find that insterseismic locking reaches up to ~85% and ~45% on the western and eastern segments, respectively, and on structures different to those that ruptured historically. Although the western HSS has been more active recently (e.g. 365 BC), the eastern HSS carries currently higher potential for large-magnitude (M>6) earthquakes andits interface-zone appears to be closer to failure. Elastic fault-interactions are responsible for both significant inter-segment variability in strain-accumulation and millennial uniformity in earthquake rupture-segmentation between eastern and western HSS.</p>

scholarly journals Collective cell migration without proliferation: density determines cell velocity and wave velocity

2017 ◽  
Author(s):  
Sham Tlili ◽  
Estelle Gauquelin ◽  
Brigitte Li ◽  
Olivier Cardoso ◽  
Benoît Ladoux ◽  
...  
Keyword(s):  
Cell Migration ◽  
Wave Velocity ◽  
Signal To Noise Ratio ◽  
Cell Monolayer ◽  
Temporal Analysis ◽  
Collective Cell Migration ◽  
Cell Radius ◽  
Cell Velocity ◽  
Spatio Temporal ◽  
Parameter Values

AbstractCollective cell migration contributes to morphogenesis, wound healing or tumor metastasis. Culturing epithelial monolayers on a substrate enables to quantify such tissue migration. By using narrow strips, we stabilise the front shape; by inhibiting cell division, we limit density increase and favor steady migration; by using long strips, we observe a confined cell monolayer migrating over days. A coherent collective movement propagates over millimeters; cells spread and density decreases from the monolayer bulk toward the front. Cell velocity (∼micrometer per minute) increases linearly with cell radius, and does not depend explicitly on the distance to the front. Over ten periods of backwards propagating velocity waves, with wavelength ∼millimeter, are detected with a signal-to-noise ratio enabling for quantitative spatio-temporal analysis. Their velocity (∼ten micrometers per minute) is ten times the cell velocity; it increases linearly with the cell radius. Their period (∼two hours) is spatially homogeneous, and increases with the front density. When we inhibit the formation of lamellipodia, cell velocity drops while waves either disappear, or have a smaller amplitude and slower period. Our phenomenological model assumes that both cell and wave velocities are related with the activity of lamellipodia, and that the local stretching in the monolayer bulk modulates traction stresses. We find that parameter values close to the instability limit where waves appear yield qualitative and quantitative predictions compatible with experiments, including the facts that: waves propagate backwards; wave velocity increases with cell radius; lamellipodia inhibition attenuates, slows down or even suppresses the waves. Together, our experiments and modelling evidence the importance of lamellipodia in collective cell migration and waves.

scholarly journals Interseismic Coupling beneath the Sikkim–Bhutan Himalaya Constrained by GPS Measurements and Its Implication for Strain Segmentation and Seismic Activity

2020 ◽  
Vol 12 (14) ◽  
pp. 2202
Author(s):  
Shuiping Li ◽  
Tingye Tao ◽  
Fei Gao ◽  
Xiaochuan Qu ◽  
Yongchao Zhu ◽  
...  
Keyword(s):  
Spatial Correlation ◽  
Seismic Activity ◽  
Convergence Rates ◽  
Three Dimensional ◽  
Seismic Gap ◽  
Gps Measurements ◽  
Southern Tibet ◽  
Megathrust Earthquakes ◽  
Loading Effects ◽  
Stress Accumulation

The Sikkim–Bhutan seismic gap has witnessed a long earthquake quiescence since the 1714 M7.5~8.5 earthquake. The state of stress accumulation beneath the Sikkim–Bhutan Himalaya and its spatial correlation with seismicity remains unclear due to the lack of geodetic measurements and the low levels of seismic activity. We compile Global Positioning System (GPS) measurements in southern Tibet with the available velocities in the Sikkim–Bhutan Himalaya to reveal the characteristics of strain buildup on the Main Himalayan Thrust (MHT). We correct non-tectonic hydrological loading effects in a GPS time series to accurately determine the Three-Dimensional (3D) velocities of each continuous station. Extensive GPS measurements yield convergence rates of 16.2~18.5 mm/y across the Sikkim–Bhutan Himalaya, which is quite consistent with that observed elsewhere in the Himalaya. Based on a double-ramp structure of the MHT, a refined 3D coupling image is inverted using a dense network of GPS velocities. The result indicates significant along-strike variations of fault coupling beneath the Sikkim–Bhutan Himalaya. The locking width (coupling > 0.5) of western Bhutan reaches ~100 km, which is 30~40% wider than Sikkim and eastern Bhutan. An obvious embayment of decoupling zone near the border between Sikkim and western Bhutan is recognized, and coincides spatially with the rupture terminates of the 1934 Mw8.2 and the 1714 M7.5~8.5 earthquakes, indicating that the large megathrust earthquakes along the Sikkim–Bhutan Himalaya are largely segmented by the spatial variation of frictional properties on the MHT. Using a new compilation of seismic records in the Sikkim–Bhutan Himalaya, we analyze the spatial correlation between fault coupling and seismic activity. The result suggests that the seismicity in the Bhutan Himalaya is broadly distributed, instead of restricted in the lower edge of the interseismic locking zone. This implies that the seismic activity in the Bhutan Himalaya is not uniquely controlled by the stress accumulation at the downdip end of the locked portion of the MHT.

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