Interaction among neighbouring rectangular finite strike slip faults in a linear viscoelastic half space representing lithosphere-asthenosphere system

There are seismically active regions consisting of fault system with a number of neighbouring earthquake faults. A movement across any one of them may affect the nature of stress accumulation near the others. Mathematical models may be developed to study these interactions and the pattern of interseismic stresses during the aseismic period in between two consecutive seismic events. In this paper, the lithosphere-asthenosphere system is being represented by a linear viscoelastic half space. The material of the half space is expected to possess the properties of both Maxwell and Kelvin type materials. It is assumed that the system is under a steady shear stress generated by some tectonic phenomena. For obtaining the solution for displacement, strain and stresses from the resulting boundary value problem, Integral transform, Green’s function techenique and correspondence principle have been used. Appropriate estimates of the model parameters were used in carrying out the numerical computations for investigating the nature of interactions among the faults.

Ambient noise Love wave attenuation tomography for the LASSIE array across the Los Angeles basin

The Los Angeles basin is located within the North America–Pacific plate boundary and contains multiple earthquake faults that threaten greater Los Angeles. Seismic attenuation tomography has the potential to provide important constraints on wave propagation in the basin and to provide supplementary information on structure in the form of the distribution of anelastic properties. On the basis of the amplitude information from seismic interferometry from the linear LASSIE array in the Los Angeles basin, we apply station-triplet attenuation tomography to obtain a 2D depth profile for the attenuation structure of the uppermost 0.6 km. The array crosses four Quaternary faults, three of which are blind. The attenuation tomography resolves strong attenuation (shear attenuation Qs ~ 20) for the fault zones and is consistent with sharp boundaries across them.

A STUDY ON RECENT EARTHQUAKES IN AND AROUND BANGLADESH

Bangladesh is a South Asian country with a dense population situated in a very vulnerable position of earthquake faults where sudden earthquakes can cause a great loss of lives and properties. This paper deals with the magnitude and focal depth of earthquakes that have been felt from 2015 to 2019 having Richter magnitude more than 3. Maximum earthquakes with a magnitude of 3.0 to 4.9 have occurred at the northern side of Bangladesh whereas at the eastern side the values are between 4.0 to 5.9. It was seen that considerable earthquakes occurred in 2019 at the northern side of Bangladesh that indicates a major earthquake may happen in this area from the stored energy and can cause a devastating effect. It has been observed that Earthquake with more than 3 Richter magnitudes has happened in all five years in February, April, August, and September where January and December have comparatively fewer earthquake records. Focal depths have been found to be higher in 2016 related to other years. A correlation equation has been developed between magnitude and focal depth.

Analisis Riwayat Waktu Gempa Sesar pada Sistem Fondasi Tiang

In Indonesia, many active faults that can cause earthquakes, one of them is the Palu Koro fault which extends approximately 240 km from the north (Palu City) to the south (Malili) to the Gulf of Bone. The effect of this earthquake fault caused enormous damage to infrastructure. The lower structure, namely the foundation, is part of a structure that transmits the load received from axial and lateral forces which then continues into the ground below. This foundation plays a big role in making the structure stand firm; however, pile failures still often occur in Indonesia. Because of that in this journal will be analyzing of the time history of earthquake faults in the pile foundation system. This analysis requires the assistance of a geotechnical based program. The program can process the data provided so that it produces a result that can be analyzed. The results can be in the form of internal forces, and displacement. The result of this curve we can see the effect of the earthquake fault on the foundation. From these results, it is expected to provide data to help plan structures to be built in areas prone to earthquake faults.AbstrakWilayah Indonesia banyak terdapat sesar aktif yang dapat menimbulkan gempa salah satunya sesar aktif di Sulawesi adalah sesar Palu Koro yang memanjang kurang lebih 240 km dari utara (Kota Palu) ke selatan (Malili) hingga Teluk Bone. Pengaruh gempa sesar ini menimbulkan kerusakan yang sangat besar dalam infrastruktur. Struktur bawah yakni Fondasi ialah bagian dari suatu struktur yang meneruskan beban yang diterima dari gaya aksial dan lateral yang kemudian meneruskan ke dalam tanah di bawahnya. Fondasi inilah berperan besar membuat struktur tersebut dapat berdiri kukuh akan tetapi kegagalan tiang masih sering terjadi di Indonesia. Dengan demikian pada jurnal ini dilakukan analisis riwayat waktu gempa sesar pada sistem fondasi tiang. Analisis ini membutuhkan bantuan program berbasis geoteknik. Program dapat mengolah data-data yang diberikan sehingga menghasilkan suatu hasil yang dapat di analisis. Hasil tersebut dapat berupa kurva gaya dalam dan perpindahan. Hasil dari kurva ini kita dapat melihat pengaruh dari gempa sesar tersebut terhadap fondasi. Dari hasil tersebut diharapkan dapat memberikan data-data untuk membantu merencanakan bangunan struktur yang akan dibangun di wilayah yang rawan akan gempa sesar.

ANALYSIS AND DESIGN OF MULTI-STOREY STEEL STRUCTURES ACCORDING TO DIFFERENT METHODS IN 2018 EARTHQUAKE REGULATIONS

Earthquake loads are the biggest obstacle to the design of multi-storey and irregular structures in countries located in the earthquake zone and with active earthquake faults. It is a dangerous natural disaster that can result in loss of life and property depending on the intensity of the earthquake. It is important to use comprehensive and up-to-date standards and regulations for the calculation of earthquake loads. In this study, considering TBDY-2018, dynamic behavior of multi-storey steel structure with irregularity called A1 Torsional Irregularity has been investigated. For seismic load calculations, mode combination method and equivalent earthquake load method, which are linear analysis methods, were used. In a 10-storey steel structure, central inverted V braces were used and the positions of these braces were changed and a total of 4 models were produced. Structural analyzes were made using the "Etabs" program. Then, the results obtained in the two methods used were compared, and in the structural analysis of the models used, it was seen that the internal forces and displacements gave greater results when the calculations were made with the Equivalent Earthquake Load Method. In addition, it has been stated that the torsional irregularity coefficient of the structure is effective in the horizontal displacement of the structure.

Complexity of Fracturing in Terms of Non-Extensive Statistical Physics: From Earthquake Faults to Arctic Sea Ice Fracturing

Fracturing processes within solid Earth materials are inherently a complex phenomenon so that the underlying physics that control fracture initiation and evolution still remain elusive. However, universal scaling relations seem to apply to the collective properties of fracturing phenomena. In this article we present a statistical physics approach to fracturing based on the framework of non-extensive statistical physics (NESP). Fracturing phenomena typically present intermittency, multifractality, long-range correlations and extreme fluctuations, properties that motivate the NESP approach. Initially we provide a brief review of the NESP approach to fracturing and earthquakes and then we analyze stress and stress direction time series within Arctic sea ice. We show that such time series present large fluctuations and probability distributions with “fat” tails, which can exactly be described with the q-Gaussian distribution derived in the framework of NESP. Overall, NESP provide a consistent theoretical framework, based on the principle of entropy, for deriving the collective properties of fracturing phenomena and earthquakes.