scholarly journals Seismicity Parameters Analysis In Space-Time Distribution For Northeast India.

2021 ◽  
Author(s):  
Auchitya Kumar Pandey
Keyword(s):  
Spatial Variation ◽  
Northeast India ◽  
Likelihood Method ◽  
Magnitude Distribution ◽  
Seismicity Parameters ◽  
A Value ◽  
Annual Probability ◽  
Seismogenic Source ◽  
Hazard Level ◽  
Frequency Magnitude Distribution

Abstract A complete homogeneous earthquake catalogue is prepared to estimate seismicity parameters and their spatial-temporal variation in nine seismogenic source zones for Northeast India. The value of seismicity parameters like a-value, b-value, and MC value i.e., 7.37, 0.93(± 0.013), and 4.6, respectively have been estimated from the frequency-magnitude distribution. Moreover, the maximum-likelihood method has been utilized to map the spatial variation of the above parameters. The spatial variation of low b-values is dominant in the Indo-Burman Range, the Main Boundary Thrust, and the vicinity of the Sagaing fault. High seismic activity rate has been obtained in the Indo-Burman range as observed from spatial variation of a-value parameter. Furthermore, the return periods and the annual probability of an earthquake have been calculated for each zone. The results of this seismicity parameter provide useful information about the hazard level of a particular zone and further helps in preparing the hazard map of Northeast India.

scholarly journals Analisis Distribusi Frekuensi-Magnitudo Gempabumi Di Wilayah Sulawesi Utara

Jurnal MIPA ◽  
2013 ◽  
Vol 2 (2) ◽  
pp. 156
Author(s):  
Sarah Selviana Homer ◽  
Guntur Pasau ◽  
Ferdy .
Keyword(s):  
Maximum Likelihood ◽  
Earthquake Damage ◽  
Likelihood Method ◽  
Earthquake Parameters ◽  
Magnitude Distribution ◽  
North Sulawesi ◽  
Western Area ◽  
Damage Data ◽  
Frequency Magnitude Distribution ◽  
Frequency Magnitude

Analisis Distribusi Frekuensi-Magnitudo Gempa Bumi di Wilayah Sulawesi Utara telah dilakukan. Analisis Distribusi Frekuensi-Magnitudo Gempa Bumi menggunakan metode maximum likelihood merupakan upaya mitigasi dalam menentukan nilai parameter gempa (nilai ɑ-b), perulangan gempa merusak, serta daerah berpotensi gempa merusak. Hasil data ANSS menunjukan bahwa pada timur (dalam arah utara-selatan) mempunyai nilai ɑ-b yang lebih rendah dibandingkan barat wilayah SULUT, dengan nilai masing-masing sekitar 7-7,8 dan 0,8-1,5. Hasil perhitungan perulangan gempa merusak (Magnitudo Mw = 7) sekitar 15-20 tahun. Daerah berpotensi gempa merusak adalah : Kabupaten Kepulauan Sangihe, Kabupaten Kepulauan Sitaro, kota Bitung (terutama kecamatan Lembah Utara dan Selatan).Analysis of Frequency-Magnitude Distribution of earthquakes in North Sulawesi region has been performed. Analysis of Frequency-Magnitude Distribution of earthquakes using the maximum likelihood method in determining the value of mitigating earthquake parameters (values ​​ɑ-b), recurrence earthquake damage, as well as the potential area of ​​earthquake damage. Data of ANSS is showed that in east (in the direction north-south) has lower than of a-b that that in the western area of ​​North Sulawesi, with each value of around 7 to 7.8 and from 0.8 to 1.5. Calculation of recurrence earthquake damage (Magnitude Mw = 7) resulted in a period of 15-20 years old. Areas with potential earhquake damage are: District Sangihe Islands, Islands District Sitaro, Bitung city (especially north and south valley districts).

Amelogenesis Imperfecta Prevalence in a Colombian Population: A Retrospective Study

2021 ◽  
Vol 40 ◽  
Author(s):  
Lizeth Paola Naranjo Jiménez ◽  
Myriam Adriana Muñoz Briceño ◽  
Ángela Suárez Castillo ◽  
Claudia Patricia Lamby Tovar ◽  
Sandra Janeth Gutierrez Prieto
Keyword(s):  
Urban Areas ◽  
Tooth Enamel ◽  
Amelogenesis Imperfecta ◽  
Cross Sectional ◽  
Prevalence Studies ◽  
Magnitude Distribution ◽  
Preventive Actions ◽  
History Of ◽  
And Behavior ◽  
Frequency Magnitude Distribution

Background: Amelogenesis imperfecta (AI) is a hereditary condition that affects the structure of tooth enamel and causes sensitivity, predisposition to cavities, and psychological problems. In Colombia, its frequency, magnitude, distribution, and behavior are unknown, so it is necessary to carry out prevalence studies to implement preventive actions. Purpose: To determine the prevalence of AI in patients who have attended the Pontificia Universidad Javeriana clinics in Bogotá. Methods: A retrospective cross-sectional observational study was carried out, whose sample included 1,394 medical records of patients who attended between January 2015 and December 2017. Results: The prevalence of AI was 0.6 %, corresponding to 8 people affected, 4 men and 4 women between the ages of 9 and 10 years. The most frequent phenotype was hypoplastic in 7 patients (87.5 %) and one person had a hypocalcified phenotype (12.5 %). Taurodontism was the most frequent anomaly in the 8 patients (100 %). Seven of the eight patients (87.5 %) had a family history of AI. All the individuals had a lower-middle socioeconomic level and came from urban areas. Conclusions: This study is the first approximation to determine the prevalence of AI in a group of the Colombian population. Although the prevalence was low, it is comparable with the findings of other studies.

A Retrospective Analysis of b-Value Changes Preceding Strong Earthquakes

2021 ◽  
Author(s):  
Nicolas D. DeSalvio ◽  
Maxwell L. Rudolph
Keyword(s):  
B Value ◽  
Earthquake Precursors ◽  
Earthquake Catalog ◽  
Traffic Light ◽  
Magnitude Distribution ◽  
Parameter Combination ◽  
Definition Of ◽  
Value Changes ◽  
Frequency Magnitude Distribution ◽  
Optimal Set

Abstract Earthquake precursors have long been sought as a means to predict earthquakes with very limited success. Recently, it has been suggested that a decrease in the Gutenberg–Richter b-value after a magnitude 6 earthquake is predictive of an imminent mainshock of larger magnitude, and a three-level traffic-light system has been proposed. However, this method is dependent on parameters that must be chosen by an expert. We systematically explore the parameter space to find an optimal set of parameters based on the Matthews correlation coefficient. For each parameter combination, we analyze the temporal changes in the frequency–magnitude distribution for every M ≥ 6 earthquake sequence in the U.S. Geological Survey Comprehensive Earthquake Catalog for western North America. We then consider smaller events, those with a foreshock magnitude as small as 5, and repeat the analysis to assess its performance for events that modify stresses over smaller spatial regions. We analyze 25 M ≥ 6 events and 88 M 5–6 events. We find that no perfect parameter combination exists. Although the method generates correct retrodictions for some M 5 events, the predictions are dependent on the retrospectively selected parameters. About 80%–95% of magnitude 5–6 events have too little data to generate a result. Predictions are time dependent and have large uncertainties. Without a precise definition of precursory b-value changes, this and similar prediction schemes are incompatible with the IASPEI criteria for evaluating earthquake precursors. If limitations on measuring precursory changes in seismicity and relating them to the state of stress in the crust can be overcome, real-time forecasting of mainshocks could reduce the loss of lives.

Mapping b-Value Anomalies Along the Indonesian Island Chain: Implications for Upcoming Earthquakes

2014 ◽  
Vol 08 (04) ◽  
pp. 1450010 ◽  
Author(s):  
Santi Pailoplee
Keyword(s):  
Spatial Relationship ◽  
B Value ◽  
Fixed Number ◽  
Earthquake Catalogue ◽  
Suitable Assumption ◽  
B Values ◽  
Magnitude Distribution ◽  
Risk Areas ◽  
Frequency Magnitude Distribution ◽  
Frequency Magnitude

In this study, the geospatial frequency–magnitude distribution (FMD) b-value images of the prospect sources of upcoming earthquakes were investigated along the Indonesian Sunda Margin (ISM) that strikes parallel to and near the Indonesian Island chain. After enhancing the completeness and stability of the earthquake catalogue, the seismicity data were separated according to their seismotectonic setting into shallow crustal and Intraslab earthquakes. In order to verify the spatial relationship between the b-values and the occurrence of subsequent major earthquakes, the complete shallow crustal seismicity dataset (1980–2005) was truncated into the 1980–2000 sub-dataset. Utilizing the suitable assumption of fixed-number of earthquakes, retrospective tests of both the complete and truncated datasets supported that areas of comparatively low b-values could reasonably be expected to predict likely hypocenters of future earthquakes. As a result, the present-day distributions of b-values derived from the complete (1980–2005) shallow crustal and Intraslab seismicity datasets revealed eight and six earthquake-prone areas, respectively, along the ISM. Since most of these high risk areas proposed here are quite close to the major cities of Indonesia, attention should be paid and mitigation plans should be developed for both seismic and tsunami hazards.

A Probabilistic Seismic Hazard Analysis of Northeast India

2006 ◽  
Vol 22 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Sandip Das ◽  
Ishwer D. Gupta ◽  
Vinay K. Gupta
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Response Spectra ◽  
Northeast India ◽  
Entire Area ◽  
The Past ◽  
Hazard Response ◽  
Hazard Level ◽  
Spectral Velocity ◽  
Pseudo Spectral

Seismic hazard maps have been prepared for Northeast India based on the uniform hazard response spectra for absolute acceleration at stiff sites. An approach that is free from regionalizing the seismotectonic sources has been proposed for performing the hazard analysis. Also, a new attenuation model for pseudo-spectral velocity scaling has been developed by using 261 recorded accelerograms in Northeast India. In the present study, the entire area of Northeast India has been divided into 0.1° grid size, and the hazard level has been assessed for each node of this grid by considering the seismicity within a 300-km radius around the node. Using the past earthquake data, the seismicity for the area around each node has been evaluated by defining a and b values of the Gutenberg-Richter recurrence relationship, while accounting for the incompleteness of the earthquake catalogue. To consider the spatial distribution of seismicity around each node, a spatially smoothed probability distribution function of the observed epicentral distances has been used. Uniform hazard contours for pseudo-spectral acceleration as the hazard parameter have been obtained for an exposure time of 100 years and for 50% confidence level at different natural periods for both horizontal and vertical components of ground motion. The trends reflected by these contours are broadly consistent with the major seismotectonic features in the region.

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