Strong earthquake increases seismic hazard in Qinghai, China

2019 ◽

Vol 1 ◽

pp. 187

Author(s):

Vladislav Morozov ◽

Viktor Tatarinov ◽

Alexander Manevich

Keyword(s):

Stress Intensity ◽

Seismic Hazard ◽

Strong Earthquake ◽

Strain State ◽

Deterministic Approach ◽

Stress Release ◽

Epicentral Zone ◽

Crustal Earthquakes ◽

Before And After ◽

Earthquake Zone

This article describes the results of modeling the stress-strain state of the epicentral earthquake zone, which occurred on December 26, 2003 in the southeast of Iran in the province of Kerman (Bam), before and after the formation of the fault. It is shown that the main earthquake shock is located in the zone of high intensity of stresses, and the formed fault traces this zone on the surface and corresponds to its extent. Aftershocks are localized in the area of the maximum released stress intensity after the formation of the fault. Stress release stimulates the discharge of accumulated tectonic stresses in the subsequent aftershock process. The results obtained can be useful for deterministic approach to assessment and prediction of seismic hazard, as well as for geophysical observations clearly suited for the goal of predicting strong crustal earthquakes in continental regions.

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Active faults of the Kerch’s Peninsula: new results

Доклады Академии наук ◽

10.31857/s0869-56524884408-412 ◽

2019 ◽

Vol 488 (4) ◽

pp. 408-412

Author(s):

А. N. Ovsyuchenko ◽

R. N. Vakarchuk ◽

A. M. Korzhenkov ◽

A. S. Larkov ◽

А. I. Sysolin ◽

...

Keyword(s):

Seismic Hazard ◽

Strong Earthquake ◽

Late Holocene ◽

Active Fault ◽

Active Faults ◽

Fault Zones ◽

Strong Earthquakes ◽

Earthquake Sources ◽

Kerch Peninsula ◽

Seismotectonic Model

In the paper there are results of a recent study of the active faults in the Kerch Peninsula. There was compiled a Map of Active Faults - sources of the strong earthquakes occurred in Late Holocene. The map is a regional seismotectonic model of strong earthquake sources - detailed basis for a spatial prognosis of the seismic hazard. Results of the study show that the Kerch Peninsula demonstrates signs of the classical morphostructures, and a morphology of the modern peninsula contours is caused by the large active fault zones.

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The 1885 M 6.9 Earthquake in the French Guiana–Brazil Border: The Largest Midplate Event in the Nineteenth Century in South America

Seismological Research Letters ◽

10.1785/0220190325 ◽

2020 ◽

Vol 91 (5) ◽

pp. 2497-2510 ◽

Cited By ~ 1

Author(s):

Marcelo Assumpção ◽

Alberto V. Veloso

Keyword(s):

Nineteenth Century ◽

South America ◽

Seismic Hazard ◽

Strong Earthquake ◽

French Guiana ◽

Seismic Zone ◽

Attenuation Relations ◽

Stable Continental Region ◽

Felt Area ◽

Slight Damage

Abstract In 4 August 1885, 06:30 local time, a strong earthquake (reported intensities up to VI–VII modified Mercalli intensity [MMI]) was felt in the French Guiana, causing slight damage. Recently discovered newspaper records show that this event was also felt as far as Georgetown (British Guyana), Belém, and several other localities along the Amazon River toward Manaus (Brazil). The distribution of intensities and the radius of the felt area indicate a magnitude around Mw 6.9, which makes it the largest known earthquake in the stable continental region of South America, since the nineteenth century. The epicenter, determined with four different attenuation relations, lies onshore near the border between the French Guiana and Brazil, although an epicenter offshore in the continental slope cannot be ruled out with 95% confidence. The epicenter (03.4° N, 52.9°W±100 km) likely lies in the Transamazonian (2.2–2.0 Ga) geochronological province in the Guyana shield of the Amazon craton. No nearby failed rift is known onshore near the epicenter, which would place this event in the ∼30% class of nonextended stable continental crust. Other nearby smaller earthquakes (both historical and instrumental) with magnitudes up to mb 5.2, indicate a cluster of seismicity in the region of the 1885 earthquake, possibly delineating an onshore seismic zone separate from the sparse seismicity along the continental shelf. This large midplate earthquake will likely affect future reevaluations of seismic hazard in midplate South America.

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System-analytical method of strong earthquake-prone areas recognition

10.5194/egusphere-egu21-14815 ◽

2021 ◽

Author(s):

Boris Dzeboev ◽

Alexei Gvishiani ◽

Boris Dzeranov

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Analytical Method ◽

Strong Earthquake ◽

Subduction Zones ◽

Seismic Hazard Assessment ◽

Hazard Identification ◽

Strong Earthquakes ◽

Weak Earthquakes ◽

High Seismicity

Proper seismic hazard assessment is the most important scientific problem of seismology, and geophysics in general. With the development of the world economy, the importance of the problem grows and acquires global significance.Strong earthquakes (M&#160;&#8805;&#160;M0, M0 is the magnitude threshold starting from which earthquakes in the studied region are considered strong), as a rule, do not occur over the entire territory of the seismic region. Accordingly, the recognition of areas prone to future strong earthquakes is an urgent fundamental direction in research on the assessment of seismic hazard. Identification of potentially high seismicity zones in seismically active regions is important from both theoretical, and practical points of view. The currently available methods for recognition of high seismicity zones do not allow repeatedly correcting their results over time due to the invariability of the used set of recognition objects. In this work, a new system-analytical approach FCAZ (Formalized Clustering And Zoning) to the problem has been created. It uses the epicenters of rather weak earthquakes (M&#160;&#8805;&#160;MR, MR is a certain magnitude threshold of weak earthquakes) as objects of recognition. This makes it possible to develop the recognition result of zones with increased seismic hazard after the appearance of new earthquake epicenters. The latter makes FCAZ a method of systems analysis.The system-analytical method for analyzing geophysical data developed by the authors has led to the successful recognition of areas prone to the strongest, strong, and most significant earthquakes on the continents of North, and South America, Eurasia, and in the subduction zones of the Pacific Rim. At the same time, in particular, for the classical approach of strong earthquake-prone areas recognition EPA (Earthquake-Prone Areas), a new paradigm for recognition of high seismicity disjunctive nodes, and lineament intersections with training by one &#8220;reliable&#8221; class was created in the work.In the regions studied in this work, FCAZ zones occupy a relatively small area compared to the field of general seismicity &#8211; 30%&#160;&#8211;&#160;40% of the area of all seismicity, and 50%&#160;&#8211;&#160;65% of the area where earthquakes with M&#160;&#8805;&#160;MR occur. This illustrates the spatial nontriviality of the FCAZ results obtained in this work. The results of the work also show that weak seismicity can actually &#8220;manifest&#8221; the properties of geophysical fields, which in the classical EPA approach are used directly as characteristics of recognition objects (disjunctive nodes or intersections of the axes of morphostructural lineaments).The reported study was funded by RFBR, project number 20-35-70054 &#171;Systems approach to recognition algorithms for seismic hazard assessment&#187;.

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SEISMIC HAZARD OF GANJA CITY

Геология и геофизика Юга России ◽

10.23671/vnc.2014.1.55401 ◽

2014 ◽

Author(s):

З.Г. Аллахвердиева

Keyword(s):

Seismic Hazard ◽

Empirical Formula ◽

Seismic Risk ◽

Strong Earthquake ◽

Seismic Effect ◽

Point Of View ◽

Focal Points ◽

Strong Earthquakes ◽

Industrial Center

Изучение сейсмического риска города Гянджа на наш взгляд имеет большое значение, так как этот город является вторым промышленным центром республики. Для имеющихся очагов сильных землетря- сений в районе г. Гянджи на основе магнитуды вероятного максимально сильного землетрясения по эмпирической формуле М. В. Шебалина для разных глубин и расстояний был вычислен сейсмический эффект. Результаты показывают, что очаги, расположенные на районе Гек-гель и Зурнабад с сейсмической точки зрения наиболее опасные. Вероятность создания опасного сейсмического эффекта от Дашкесанских, Ге- дебекских и Келбаджарских очагов мала Investigation of seismic risk of Ganja city in our opinion is of a great importance, since this city is the second industrial center of the country. The seismic effect was calculated for existing sources of strong earthquakes in the area of Ganja city -based on the magnitude of probable maximum strong earthquake using the empirical formula of M. V. Shebalin for various depths and distances. The results show that focal points located in the areas Gek-gel and Zurnabad are most hazardous from seismic point of view. Probability of hazardous seismic effect occurrence from Dashkesan, Gedebeksk, Kelbadzhar focal points is small

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Temporal variation of seismic parameters in the western part of the India-Eurasia plate collision zone

Research in Geophysics ◽

10.4081/rg.2011.e3 ◽

2011 ◽

Vol 1 (1) ◽

pp. 3 ◽

Cited By ~ 5

Author(s):

Ioannis Baskoutas ◽

George Popandopoulos ◽

Prasanta Chingtham

Keyword(s):

Seismic Hazard ◽

Temporal Variation ◽

Strong Earthquake ◽

Earthquake Forecasting ◽

Target Area ◽

Origin Time ◽

Seismic Parameters ◽

Strong Earthquakes ◽

Mean Values ◽

North West

We examined the temporal seismicity variation in the north-west Himalayas and the adjacent regions in relation to strong earthquake occurrences in the period 1970-2010. The aim was to promote seismic hazard assessment and to show the possibilities of strong earthquake forecasting by means of the FastBEE computer tool. The temporal variation of the seismicity is expressed in terms of three basic seismic parameters: the logarithm of the number of earthquakes logN, the seismic energy released in the mode logE2/3 and the b-value of the earthquake magnitude-frequency distribution expressed by the Gutenberg-Richter relation. Significant changes to relative mean values, forming consecutive relative minima and maxima, of the obtained temporal variation series of the seismicity parameters can be considered anomalies. These anomalies were investigated before strong (magnitude Mw≥5.6.) earthquake occurrences and were successfully correlated with 12 strong earthquakes. The mean time of the duration of the anomalies before the origin time of the impending earthquake were estimated to be equal to 3.3±1.3 years. We conclude that, in the region under study, the established correlations can be useful for the intermediate-term forecasting of strong earthquakes and that the continuous monitoring of the temporal evolution of seismicity by means of the FastBEE tool can contribute to the evaluation of the seismic hazard status in a target area. The available earthquake data and the results obtained indicate that after the beginning of 2006, the temporal variation of the seismicity does not present clear prognostic anomalies. This behavior is compatible with the absence of earthquakes with a magnitude of Mw 6.0 or more in the area examined.

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Selection of the appropriate methodology for the deterministic seismic hazard assessment on the territory of the Republic of Serbia

Facta universitatis - series Architecture and Civil Engineering ◽

10.2298/fuace0601041b ◽

2006 ◽

Vol 4 (1) ◽

pp. 41-50

Author(s):

Borko Bulajic ◽

Miodrag Manic

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Strong Earthquake ◽

Hazard Analysis ◽

Seismic Hazard Assessment ◽

Earthquake Ground Motion ◽

Time Histories ◽

Deterministic Seismic Hazard ◽

The Republic ◽

Probabilistic Nature

This paper presents a discussion regarding the most common approaches to the deterministic seismic hazard analysis, as well as their relation with the probabilistic hazard analysis. Different methodologies for estimation of the strong earthquake ground motion at a site of interest on the territory of the Republic of Serbia are also discussed. When generation of the synthetic ground motion time histories on the territory of the Republic of Serbia is concerned, a method developed by Trifunac and his associates is suggested having in mind that this approach uses only those input parameters that can be easily and accurately defined while at the same time being able to model all properties of strong earthquake ground motion that are presently known as well as to consider the probabilistic nature of earthquake occurrence.

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PEMETAAN DAERAH RENTAN GEMPA BUMI SEBAGAI DASAR PERENCANAAN TATA RUANG DAN WILAYAH DI PROVINSI SULAWESI BARAT

KURVATEK ◽

10.33579/krvtk.v1i2.417 ◽

2017 ◽

Vol 1 (2) ◽

pp. 41-47

Author(s):

Marinda noor Eva

Keyword(s):

Seismic Hazard ◽

Hazard Analysis ◽

Probabilistic Seismic Hazard Analysis ◽

Seismic Hazard Analysis ◽

Probabilistic Seismic Hazard

Penelitian mengenai daerah rawan gempa bumi ini menggunakan Metode Probabilistic Seismic Hazard Analysis (PSHA) di Provinsi Sulawesi Barat, dengan tujuan untuk memetakan tingkat kerawanan bahaya gempa bumi di Kabupaten Mamasa. Penelitian ini menggunakan data kejadian gempa bumi di Pulau Sulawesi dan sekitarnya dari tahun 1900 – 2015. Hasil pengolahan PSHA menggunakan Software Ez-Frisk 7.52 yang menghasilkan nilai hazard di batuan dasar pada kondisi PGA (T = 0,0 sekon), dengan periode ulang 500 tahun dan 2500 tahun berkisar antara (149,54 – 439,45) gal dan (287,18 – 762,81) gal. Nilai hazard di batuan dasar dengan kondisi spektra T = 0,2 sekon untuk periode ulang 500 tahun dan 2500 tahun adalah (307,04 – 1010,90) gal dan (569,48 – 1849,78) gal. Nilai hazard di batuan dasar dengan kondisi spektra T = 1,0 sekon untuk periode ulang 500 tahun dan 2500 tahun diperoleh nilai (118,01 – 265,75) gal dan (223,74 – 510,92) gal. Berdasarkan analisis PSHA, nilai PGA di Provinsi Sulawesi Barat dominan dipengaruhi oleh sumber gempa sesar.

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