Correlation between earthquake b value and VP/VS ratio in Japan

2021 ◽  
Author(s):  
Pei-Ying Wu ◽  
Sean Kuanhsiang Chen ◽  
Yih-Min Wu
Keyword(s):  
Pore Pressure ◽  
Earth Science ◽  
B Value ◽  
The Other ◽  
Japan Meteorological Agency ◽  
Likelihood Method ◽  
Earthquake Catalog ◽  
Injection Wells ◽  
B Values ◽  
Value Determination

<p>Earthquake b value is primarily controlled by differential stress in the crust. Pore pressure has also been reported influencing b value locally. In nature, the influence can only be observed in the subsurface crust by injection wells. It remains unclear whether the influence of pore pressure on b value can be observed in the scale of the entire crust. To this end, we assume that pore pressure increases proportionally with V<sub>P</sub>/V<sub>S</sub> ratio, which is derived from seismic tomography studies, to examine correlation between V<sub>P</sub>/V<sub>S</sub> ratio and b value. We investigated this correlation in Japan because it is one of the most earthquake-prone countries with dense seismic networks and high-quality earthquake catalogs. We used an earthquake catalog from the Japan Meteorological Agency from 1998 to 2011 Feb to calculate the b values in the inland region of Japan above the 30 km depth. The selected period is based on a stable completeness of magnitude (M<sub>c</sub>) since 1998 and the strong clustering effects by the both 2011 Tohoku and 2016 Kumamoto earthquakes. We then calculated M<sub>c</sub> and b value by maximum curvature method and maximum likelihood method, respectively, in the grids of 0.1  0.1  10 km with a radius of 30 km from the center of the grids. The b value determination requires the number of earthquakes with magnitudes greater than the M<sub>c </sub>over 150 within the radius. For the V<sub>P</sub>/V<sub>S</sub> ratios, we used the latest data derived from the National Research Institute for Earth Science and Disaster Resilience, Japan, to resample them to the same grids as b values. We simply resampled the V<sub>P</sub>/V<sub>S</sub> ratios by either averaging them into the grids of b values, or weighting them through a triangular function to the grids center of b values in depths. We analyzed b value as a function of V<sub>P</sub>/V<sub>S</sub> ratio and binned the b values within every 0.01 V<sub>P</sub>/V<sub>S</sub> interval to calculate the means and medians for liner regressions. Our preliminarily results show that there is little correlation between entire b values and V<sub>P</sub>/V<sub>S </sub>ratios among different depth ranges (0-10 km, 10-20 km, 20-30 km). We observed a linear negative relation in the binned data at the 10-20 km depth, however, this relation is not likely observed in the other depths. It may imply that the influence of pore pressure on b value could vary with depths. We’ll calculate the b values using entire magnitude range method and compare the results to the other localized geophysical observations.</p>

Temporal b-value variation before and after ML ≥ 6.0 Taiwan earthquakes from 2012 to 2019

2021 ◽  
Author(s):  
Po-Yuan Chen ◽  
Sean Kuanhsiang Chen ◽  
Yih-Min Wu
Keyword(s):  
Physical Process ◽  
Large Earthquake ◽  
B Value ◽  
Likelihood Method ◽  
Earthquake Catalog ◽  
B Values ◽  
Stress Changes ◽  
Before And After ◽  
Window Approach ◽  
Central Weather Bureau

<p>Recent studies show that earthquake b values gradually decrease before large earthquakes at the epicenters and then immediately increase after the earthquakes. Temporal b-value variations may result from crustal stress changes associated with a large earthquake. However, the physical process is rarely observed and remains unclear. Taiwan island is a young orogeny leading to frequent earthquakes with magnitudes greater than M<sub>L</sub> 6.0, which provides an excellent laboratory to examine the physical process. We calculated b-value variation before and after M<sub>L</sub> ≥ 6.0 Taiwan earthquakes at the epicenters from 2012 to 2019. The time period is based on an enhancement of earthquake detection capability from the Central Weather Bureau Seismic Network in Taiwan, which allows the magnitude of completeness (M<sub>c</sub>) down to 1.5 in the inland region. We used a relocated earthquake catalog to precisely estimate b value and M<sub>c </sub>by the maximum likelihood method and maximum curvature method, respectively. We designed three steps in our research. First, we calculated the b value and M<sub>c</sub> at the epicenters of the M<sub>L</sub> ≥ 6.0 earthquakes in overall 8 years to know the background seismic activity. Based on this, second, we calculated b values and M<sub>c</sub> per half year to test the sensitivity between the radius from epicenters (r) and the number of earthquakes with magnitudes greater than M<sub>c</sub> (n). Finally, we will apply moving window approach with specific criteria to continuously calculate temporal b-value variations. Our results showed that spatial b values in Taiwan in overall 8 years have an average of 1.0. The b values are systematically lower in the epicenters of M<sub>L</sub> ≥ 6.0 earthquakes from 2012 to 2019. We have determined suitable r and n values for each earthquake at the epicenters and some epicenters share similar r and n values. We preliminarily observed temporal b-value decreases before the 2018 M<sub>w</sub> 6.4 Hualien earthquake. Considering temporal b-value variation by moving windows, we aim to realize whether temporal b-value variation by a large earthquake can be frequently observed in Taiwan.</p>

scholarly journals Spatial Variations in Seismicity Characteristics in and Around the Source Region of the 2019 Yamagata-Oki Earthquake, Japan

2020 ◽  
Author(s):  
Taku Ueda ◽  
Aitaro Kato ◽  
Yoshihiko Ogata ◽  
Lina Yamaya
Keyword(s):  
Source Region ◽  
B Value ◽  
Spatial Variations ◽  
Japan Meteorological Agency ◽  
Earthquake Catalog ◽  
Shear Strain Rate ◽  
Study Region ◽  
Etas Model ◽  
Seismicity Rate ◽  
Background Seismicity

Abstract The 2019 {\text{M}}_{\text{j}} 6.7 Yamagata-Oki Earthquake occurred adjacent to the northeastern edge of the source region of the 1964 {\text{M}}_{\text{j}} 7.5 Niigata Earthquake, offshore of Yamagata Prefecture, Japan. Few aftershocks occurred in the source region of the Yamagata-Oki earthquake immediately following the Niigata earthquake, and the recent seismicity rate in this region is extremely low compared with that of the surrounding region. This spatial variation in seismicity may allow us to elucidate plausible physical processes that shape the spatiotemporal evolution of these shallow-crustal environments. Here, we investigate the spatial variations in seismicity characteristics by applying the HIerarchical Space–Time Epidemic Type Aftershock Sequence (HIST-ETAS) model to an earthquake catalog compiled by the Japan Meteorological Agency for events in and around the Yamagata-Oki earthquake rupture region. We compare spatial variations in the background seismicity rate and aftershock productivity estimated from the HIST-ETAS model with the geophysical features in the study region. The background seismicity rate is high along the eastern margin of the Sea of Japan and correlates well with a previously identified zone that possesses a high geodetic shear strain rate. The two major earthquakes occurred in and around an active shear zone, suggesting that the background seismicity rate may serve as a key parameter for evaluating seismic hazard across the Japanese Archipelago. Furthermore, the source region of the Yamagata-Oki earthquake has a higher aftershock productivity, lower b-value, and lower seismic-wave velocity than that of the Niigata earthquake. We interpret this low-velocity zone to be a well-developed damaged rock that resulted in both a reduction in the b-value and an increase in aftershock productivity based on previous laboratory experiments and numerical results; this damage makes the rock more ductile at the macroscopic scale. The higher ductility in the source region of the Yamagata-Oki earthquake may have worked as a soft barrier against the propagation of dynamic rupture that occurred during the Niigata earthquake.

scholarly journals Box Counting Fractal Dimension and Frequency Size Distributon of Earthquakes in the Central Himalaya Region

2021 ◽  
Vol 26 (2) ◽  
pp. 127-136
Author(s):  
Ram Krishna Tiwari ◽  
Harihar Paudyal
Keyword(s):  
Fractal Dimension ◽  
High Stress ◽  
High Strength ◽  
B Value ◽  
Earthquake Catalog ◽  
Central Himalaya ◽  
Study Region ◽  
B Values ◽  
Box Counting ◽  
Earthquake Distribution

To establish the relations between b-value and fractal dimension (D0) for the earthquake distribution, we study the regional variations of those parameters in the central Himalaya region. The earthquake catalog of 989 events (Mc = 4.0) from 1994.01.31 to 2020.10.28 was analyzed in the study. The study region is divided into two sub-regions (I) Region A: 27.3°N -30.3°N and 80°E -84.8°E (western Nepal and vicinity) and (II) Region B: 26.4°N -28.6°N and 84.8°E -88.4°E (eastern Nepal and vicinity). The b-value observed is within the range between 0.92 to 1.02 for region A and 0.64 to 0.74 for region B showing the homogeneous nature of the variation. The seismic a-value for those regions ranges respectively between 5.385 to 6.007 and 4.565 to 5.218. The low b-values and low seismicity noted for region B may be related with less heterogeneity and high strength in the crust. The high seismicity with average b-values obtained for region A may be related with high heterogeneity and low strength in the crust. The fractal dimension ≥1.74 for region A and ≥ 1.82 for region B indicate that the earthquakes were distributed over two-dimensional embedding space. The observed correlation between D0 and b is negative for western Nepal and positive for eastern Nepal while the correlation between D0 and a/b value is just opposite for the respective regions. The findings identify both regions as high-stress regions. The results coming from the study agree with the results of the preceding works and reveal information about the local disparity of stress and change in tectonic complexity in the central Himalaya region.

scholarly journals Analisis Percepatan Tanah Maksimum, Intensitas Maksimum Dan Periode Ulang Gempa Untuk Menentukan Tingkat Kerentanan Seismik Di Jawa Barat (Periode Data Gempa Tahun 1974-2016)

Wahana Fisika ◽  
2017 ◽  
Vol 2 (2) ◽  
pp. 12
Author(s):  
Elza Anisa Suwandi ◽  
Indriana Lucky Sari ◽  
Waslaluddin Waslaluddin
Keyword(s):  
Return Period ◽  
Seismic Vulnerability ◽  
B Value ◽  
Maximum Intensity ◽  
Likelihood Method ◽  
Earthquake Catalog ◽  
Earthquake Intensity ◽  
West Java ◽  
Ground Acceleration ◽  
Maximum Earthquake

Penelitian ini bertujuan untuk menentukan tingkat kerentanan seismik di Jawa Barat berdasarkan data gempa bumi periode tahun 1974 – 2016 dengan  Ms≥4.0 SR yang diperoleh dari katalog gempa NEIC-USGS pada batasan wilayah 5°36’18’’ LS - 8°58’30’’ LS dan 106°9’ BT – 109°59’2.4’’ BT menggunakan Metode Donovan dan Metode Matuschka. Penelitian ini dilakukan terhadap 1543 titik pengamatan. Sedangkan untuk menentukan periode ulang gempa, sebelumnya dilakukan pembagian wilayah menjadi 5 wilayah dan menentukan b value juga indeks seismisitas terlebih dahulu menggunakan Metode Likelihood. Dari hasil analisis menunjukkan bahwa percepatan tanah maksimum Metode Donovan berkisar antara 27.76 Gal – 110.01 Gal dan intensitas gempa maksimumnya  VII MMI – VIII MMI. Sedangkan, percepatan tanah maksimum Metode Matuschka berkisar antara 69.16 Gal – 229.55 Gal dan intensitas gempa maksimumnya VI MMI – VIII MMI. Berdasarkan hasil kedua metode tersebut dapat dikorelasikan dengan frekuensi gempa dan event gempa yang merusak di Jawa Barat dari rentang 42 tahun, didapat metode yang sesuai dengan wilayah keadaan Jawa Barat yaitu Metode Matuschka. Selain itu diperoleh periode ulang gempa berdasarkan b value yang  berkisar antara 0.40 – 0.79 dan indeks seismisitas yang berkisar antara 0.21 – 0.85 yaitu 33 – 125 tahun. Tingkat kerentanan seismik tertinggi di Jawa Barat berada di daerah Cianjur, kecamatan Cidaun tepatnya pada koordinat 7°28’39.047’’ LS dan 107°16’44.213’’ BT. Tingginya kerentanan seismik diakibatkan oleh tingginya nilai percepatan tanah maksimum  This research aims to determine the level of seismic vulnerability in West Java based on earthquake data period 1974 - 2016 with Ms≥4.0 SR Obtained from the NEIC-USGS earthquake catalog on the territorial boundaries 5°36’18’’ LS - 8°58’30’’ LS dan 106°9’ BT – 109°59’2.4’’ BT using the Donovan Method and the Matuschka Method. The study was conducted on 1543 observation points. Meanwhile, to determine the return period of the earthquake, previously done division into 5 areas and determine the b value also seismicity index first using Likelihood Method. From the analysis results show that the maximum land acceleration Donovan Method ranged between 27.76 Gal – 110.01 Gal and maximum earthquake intensity VII MMI – VIII MMI. Meanwhile, the maximum ground acceleration Matuschka method ranges between 69.16 Gal - 229.55 Gal and maximum earthquake intensity VI MMI - VIII MMI. Based on the results of both methods can be correlated with the frequency of earthquakes and destructive earthquake events in West Java from the span of 42 years, the method obtained in accordance with the region of West Java circumstances is Matuschka method. In addition, the earthquake return period based on b values ranging from 0.40 to 0.79 and seismicity index ranging from 0.21 to 0.85 is 33 – 125 years. The highest level of seismic vulnerability in West Java is located in Cianjur area, Cidaun sub-district precisely in coordinates 7°28’39.047’’ LS dan 107°16’44.213’’ BT. The high seismic vulnerability is due to the high maximum land acceleration rate, maximum intensity of the earthquake and short period of earthquake repetition in the area. : Seismic Vulnerability Level, Peak Ground Acceleration, Maximum Intensity of Earthquake, Earthquake Re-Period

scholarly journals ANALISIS TINGKAT SEISMISITAS DAN TINGKAT KERAPUHAN BATUAN DI MALUKU UTARA

2015 ◽  
Vol 17 (1) ◽  
pp. 94
Author(s):  
Vienda Gaby Lumintang ◽  
Guntur Pasau ◽  
Seni J Tongkukut
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Method ◽  
B Value ◽  
Likelihood Method ◽  
Earthquake Catalog ◽  
Maximum Likelihood Analysis ◽  
Repetition Period ◽  
Earthquake Recurrence ◽  
A Value ◽  
Likelihood Analysis

ANALISIS TINGKAT SEISMISITAS DAN TINGKAT KERAPUHAN BATUAN DI MALUKU UTARA ABSTRAK Telah dilakukan penelitian untuk menentukan tingkat seismisitas dan tingkat kerapuhan batuan melalui perhitungan nilai a dan b secara spasial di Maluku Utara menggunakan katalog gempa ANSS tahun 1963-2015 dengan metode maksimum likelihood, menghitung kemungkinan waktu terjadinya kembali gempa bumi merusak secara spasial, serta untuk menenentukan daerah-daerah yang sangat rawan berpotensi gempa merusak di wilayah Maluku Utara. Perhitungan nilai a dan b dari data ANSS untuk wilayah Maluku Utara menunjukkan besar nilai b adalah berkisar pada 0,75-1,5 dan nilai a adalah berkisar pada 6,5-10. Periode ulang gempa bumi untuk wilayah Maluku Utara dengan magnitude Mw = 6,5 adalah 3-19 tahun, gempa dengan magnitude Mw = 7 adalah 5-52 tahun, dan gempa dengan magnitude Mw = 7,5 adalah 15-140 tahun. Daerah-daerah yang berpotensi mengalami gempa bumi merusak adalah wilayah Laut Maluku, Ternate, Tidore, sebagian wilayah Kabupaten Halmahera Utara dan Barat, Pulau Kasiruta dan Pulau Obi. Kata kunci: nilai-b, seismisitas, maximum likelihood   ANALYSIS OF SEISMICITY LEVEL AND ROCKS FRAGILITY LEVEL IN NORTH MALUKU ABSTRACT A research has ben conducted to determine the seismicity level and rocks fragility level through spatially calculation of a  value and b value in North Maluku using ANSS earthquake catalog of years 1963-2015 with maximum likelihood method, spatially calculate possible time of  destructive earthquake recurrence, and to determine areas that highly prone to potentially destructive earthquake in North Maluku. A value and b value calculation of ANSS data of North Maluku region shows that b value is in the range of 0.75-1.5 and a value is in the range of 6.5-10. Earthquake repetition period of North Maluku region based on ANSS data with magnitude Mw = 6.5 is 3-19 years, for earthquake with magnitude Mw = 7 is 5-52 years and for earthquake with magnitude Mw = 7.5 is 15-140 years. Areas that potentially have destructive earthquake is Molucca Sea region, Ternate, Tidore, parts of North and West Halmahera District, Kasiruta Island and Obi Island. Keywords: b value, seismicity, maximum likelihood

scholarly journals Homogenized earthquake catalog and b-value mapping for Ethiopia and its adjoining regions

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Geremew Lamessa ◽  
Tilahun Mammo ◽  
Tarun K.Raghuvanshi
Keyword(s):  
Red Sea ◽  
B Value ◽  
Moment Magnitude ◽  
Ethiopian Rift ◽  
Rift System ◽  
Earthquake Catalog ◽  
Gulf Of Aden ◽  
East African Rift System ◽  
Main Ethiopian Rift ◽  
B Values

AbstractThe Ethiopian rift which is part of East African Rift system passes through the middle of the country making it one of the most seismically active regions in the world. Thus, significant and damaging earthquakes have been reported and recorded in the past in this region. A homogeneous earthquake catalog is of basic importance for studying the earthquake occurrence pattern in space and time and for many engineering applications including assessment of seismic hazard, estimation of peak ground accelerations and determination of long-term seismic strain rates.The first earthquake catalogue for Ethiopia was prepared by Pierre Gouin and later, different authors attempted to compile a catalogue using different time period intervals and different earthquake magnitude scales. The b-value mapping and its implication never done for Ethiopia and its environs. The main purpose of the study is therefore first compile and homogenize earthquake catalog of Ethiopia including Read Sea and Gulf of Aden regions into Moment magnitude Mw scale through completeness analysis in time and magnitudes. Secondly, mapping b-values for different Seismgenic regions and understand its implications for magma induced Seismicity in the regions.During the present study, a new homogenized earthquake catalog in moment magnitude scale (Mw), covering about 3814 events is prepared for Ethiopia including Red sea and Gulf of Aden regions. The present study area is bounded within Latitude (40N − 200)N and Longitude (340N − 480)N E and have a magnitude range of Mw (3.0–7.1) with a total coverage period of 56 years (1960 to 2016). The catalog has been analyzed for magnitude completeness (Mc) using Gutenberg’s Frequency Magnitude Distribution law and it is found to be complete respectively for Mc ≥ 4.6 ± 0.03, Mc ≥ 4.6 ± 0.03, Mc ≥ 3.2, Mc ≥ 3.1 and Mc ≥ 5.1 for Afar including red sea and Gulf of Aden, Afar rift and Dabbahu Volcano, Northern, Central, and Southern Main Ethiopian Rifts. Further, the corresponding average b-value of the regions Afar including Red Sea and Gulf of Aden, Afar and Dabbahu Volcano separately, Northern Main Ethiopian Rift, Central Main Ethiopian Rift and Southern Main Ethiopian Rift respectively are estimated to be 1.17 ± 0.05, 1.15 ± 0.05, 0.843, 0.826 and 1.03 with respective period of completeness from 2003 to 2014, 2005 to 2014, 2001 to 2003, 2001 to 2003 and 1960 to 2016 for the regions. Later, mapping of the b-values in the Gutenberg-Richter relation from the newly developed catalog was performed by binning the regions into minimum of 0.050x0.050 for Afar and Dabbahu region, 0.10x0.10 for Main Ethiopian rifts and 0.20x0.20 for the other regions. Thus, the b-value characteristics of various seismogenic zones within the area have been discussed. Hence, in this study, we clearly observed that magma chamber movement including mapping of volcanic centers and magmatic segments are mapped using b-values.

scholarly journals Characteristic of the 2010-2020 Earthquakes in North Arm of Sulawesi based on Focal Mechanism and b-value

2021 ◽  
Vol 873 (1) ◽  
pp. 012031
Author(s):  
A P Astuti ◽  
E M Elsera ◽  
M F I Massinai ◽  
M A Akbar
Keyword(s):  
Focal Mechanism ◽  
Subduction Zones ◽  
Maximum Likelihood Method ◽  
B Value ◽  
Strike Slip ◽  
Likelihood Method ◽  
B Values ◽  
The North ◽  
North Sulawesi ◽  
High Level

Abstract The north arm of Sulawesi has a fairly high level of seismicity. The North Sulawesi arm is bounded in the south by the Palu-Koro Fault, the northern part is bounded by the North Sulawesi Trench and the Molluca Sea Thrust in the east. Therefore, this study aims to analyze the characteristic of the 2010-2020 earthquakes in the north arm of Sulawesi by analyzing the earthquake’s focal mechanism and mapping the b-value using the maximum likelihood method. From this study, we obtained the focal mechanism consist of thrust and strike-slip, this is due to the activity of faults and subduction zones in the North arm of Sulawesi such as the Palu-koro fault, the Gorontalo Fault, North Sulawesi Trench, Molucca Sea Collision, and several other faults that affect the seismicity of this region. The variation of the b-value ranging from 0.5-1.1 These studies indicate that thrust fault regions have lower b-values, while strike-slip fault regions have intermediate b-values. Meanwhile, areas with active volcanoes tend to have high b-values. The results of this research can be used as a basis for decision making related to earthquake mitigation in this area in the future.

scholarly journals The Reliance of the Earthquake B-Value on Depth and Focal Mechanism

2021 ◽  
Vol 54 (1D) ◽  
pp. 1-10
Author(s):  
Emad Al-Heety
Keyword(s):  
Moment Tensor ◽  
Focal Depth ◽  
Seismic Hazard Assessment ◽  
B Value ◽  
Strike Slip ◽  
Focal Mechanisms ◽  
Likelihood Method ◽  
Centroid Moment Tensor ◽  
B Values ◽  
Completeness Magnitude

The earthquake size distribution (b-value) is a significant factor to recognize the seismic activity, seismotectonic, and seismic hazard assessment. In the current work, the connection of the b-constant value with the focal depth and mechanism was studied. The effect of the study scale (global, regional and local) on the dependence of b-value on the focal mechanisms was investigated. The database is quoted from the Global Centroid Moment Tensor catalog. The selected earthquakes are the shallow normal, reverse and strike-slip events. The completeness magnitude (Mc) is 5.3. The maximum likelihood method is utilized to compute the b-value. The obtained results show that the b-value is decreasing with depth to range 10-20 km, then increases to the depth of 40km. The turning point of b-value (increasing of b-value) locates at the depth of the transition brittle-ductile zone. Globally and regionally, low, moderate, and high b-values are associated with reverse, strike-slip, and normal focal mechanisms, respectively, while locally, the relation between b-values and focal mechanisms shows different association trends, such as low, moderate, and high b-values are associated with normal, strike-slip, and reverse focal mechanisms and so on.

scholarly journals Statistical analysis of aftershock sequences related with two major Nepal earthquakes: April 25, 2015, MW 7.8, and May 12, 2015, MW 7.2

2016 ◽  
Vol 59 (5) ◽  
Author(s):  
Prasanta Chingtham ◽  
Babita Sharma ◽  
Sumer Chopra ◽  
Pareshnath SinghaRoy
Keyword(s):  
Scaling Laws ◽  
Main Shock ◽  
B Value ◽  
Temporal Variations ◽  
Aftershock Sequence ◽  
Earthquake Catalog ◽  
Study Region ◽  
Nepal Himalaya ◽  
B Values ◽  
Aftershock Sequences

Present study describes the statistical properties of aftershock sequences related with two major Nepal earthquakes (April 25, 2015, MW 7.8, and May 12, 2015, MW 7.2) and their correlations with the tectonics of Nepal Himalaya. The established empirical scaling laws such as the Gutenberg–Richter (GR) relation, the modified Omori law, and the fractal dimension for both the aftershock sequences of Nepal earthquakes have been investigated to assess the spatio-temporal characteristics of these sequences. For this purpose, the homogenized earthquake catalog in moment magnitude, MW is compiled from International Seismological Center (ISC) and Global Centroid Moment Tensor (GCMT) databases during the period from April 25 to October 31, 2015. The magnitude of completeness, MC, a and b-values of Gutenberg–Richter relationship for the first aftershock sequence are found to be 3.0, 4.74, 0.75 (±0.03) respectively whereas the MC, a and b-values of the same relationship for the second aftershock sequence are calculated to be 3.3, 5.46, 0.90 (±0.04) respectively. The observed low b-values for both the sequences, as compared to the global mean of 1.0 indicate the presence of high differential stress accumulations within the fractured rock mass of Nepal Himalaya. The calculated p-values of 1.01 ± 0.05 and 0.95 ± 0.04 respectively for both the aftershock sequences also imply that the aftershock sequence of first main-shock exhibits relatively faster temporal decay pattern than the aftershock sequence of second main-shock. The fractal dimensions, DC values of 1.84 ± 0.05 and 1.91 ± 0.05 respectively for both the aftershock sequences of Nepal earthquakes also reveal the clustering pattern of earthquakes and signifies that the aftershocks are scattered all around the two dimensional space of fractured fault systems of the Nepal region. The low b-value and low DC observed in the temporal variations of b-value and DC before the investigated earthquake (MW 7.2) suggest the presence of high-stress concentrations in the thrusting regimes of the Nepal region before the failure of faults. Moreover, the decrease of b-value with the corresponding decrease of DC observed in their temporal variations can primarily act as an indicator for possible prediction of major earthquakes in the study region.

scholarly journals Theory and Applications of the Unit Gamma/Gompertz Distribution

Mathematics ◽  
2021 ◽  
Vol 9 (16) ◽  
pp. 1850
Author(s):  
Rashad A. R. Bantan ◽  
Farrukh Jamal ◽  
Christophe Chesneau ◽  
Mohammed Elgarhy
Keyword(s):  
Stochastic Ordering ◽  
Real Data ◽  
Rate Function ◽  
The Other ◽  
Likelihood Method ◽  
Model Parameters ◽  
Data Sets ◽  
Gompertz Distribution ◽  
Probability And Statistics ◽  
Analytical Behavior

Unit distributions are commonly used in probability and statistics to describe useful quantities with values between 0 and 1, such as proportions, probabilities, and percentages. Some unit distributions are defined in a natural analytical manner, and the others are derived through the transformation of an existing distribution defined in a greater domain. In this article, we introduce the unit gamma/Gompertz distribution, founded on the inverse-exponential scheme and the gamma/Gompertz distribution. The gamma/Gompertz distribution is known to be a very flexible three-parameter lifetime distribution, and we aim to transpose this flexibility to the unit interval. First, we check this aspect with the analytical behavior of the primary functions. It is shown that the probability density function can be increasing, decreasing, “increasing-decreasing” and “decreasing-increasing”, with pliant asymmetric properties. On the other hand, the hazard rate function has monotonically increasing, decreasing, or constant shapes. We complete the theoretical part with some propositions on stochastic ordering, moments, quantiles, and the reliability coefficient. Practically, to estimate the model parameters from unit data, the maximum likelihood method is used. We present some simulation results to evaluate this method. Two applications using real data sets, one on trade shares and the other on flood levels, demonstrate the importance of the new model when compared to other unit models.

Sign in / Sign up

Export Citation Format

Share Document