Analysis of fault patters based on erarthquake data on the land of Sumatera island

Geodynamics of Sumatra is interesting to study because of the unique geological setting Geodynamics of Sumatra is interesting to study because of the unique geological setting and high seismicity. This high seismicity is caused by the many faults found on land and in the surrounding waters. This paper presents the results of research that aims to determine fault patterns both on land and in the waters around Sumatra based on earthquake data from 1960-2000. The area under study is at the coordinates of 6°N - 6°S and 95°E - 109°E at an epicenter depth of <60 km with a magnitude between 4-10. The area is divided into two zones, namely the front arc and the Barisan arc. Data were obtained from ISC and Global CMT. By using the Focal Mechanism Method, the results show that the fault pattern in the Sumatran forearc Basin zone is dominated by an Reverse Fault located in the accretion zone while on the mainland of Sumatra it is dominated by Strike Slip along the Sumatran Fault System. By knowing the position and pattern of the fault, especially on the mainland of the island of Sumatra, it can be used as a reference for spatial planning. In addition, further studies will also be able to learn about the dangers or disasters caused by the fault pattern.

Assessment of social aspects of seismic hazard

This paper is intended to illustrate the applicability of the results obtained from the investigations of social aspects of seismic hazard of the Russian Federation (RF) through the example of the high-seismicity region – the Far Eastern Federal District (FED). Within the FED the comparison of the areas of various seismic zones as per regulatory maps of General Seismic Zoning dated 2016 (GSZ-2016) has been performed and population estimates for each zone have been obtained. For the first time population estimates for zones with increased seismic hazard – grades A, B and C as per GSZ-2016 – are provided. The data obtained may be used for the evaluation of additional risks for FED’s population.

Penilaian Kerentanan Bangunan Terhadap Gempa Bumi pada Gedung Perkuliahan Berlantai Tinggi di Yogyakarta

Yogyakarta termasuk daerah yang memiliki tingkat resiko gempa yang tinggi, sehingga dapat mengakibatkan bangunan-bangunan yang didirikan di Yogyakarta memiliki potensi terhadap kerusakan. Gempa bumi yang terjadi pada tanggal 27 Mei 2006 masih meninggalkan trauma bagi masyarakat Yogyakarta, dimana menurut BNPB (2012) gempa di Yogyakarta menimbulkan korban jiwa sebanyak 4.674, dan sebanyak 19.897 dinyatakan cedera berat. Sebagian besar korban diakibatkan karena tertimpa bangunan, serta material rumah. Gempa di yogyakarta menimbulkan kerusakan yang berat pada bangunan sebanyak 96.790, sebanyak 117.075 alami kerusakan yang sedang, serta sebanyak 156. 971 bangunan alami kerusakan yang ringan. Pendirian bangunan-bangunan baru di wilayah Yogyakarta khususnya diharapkan dapat menerapkan prinsip bangunan tahan gempa pada tahapan-tahapan pembangunan agar tingkat kerentanan terhadap gempa tidak besar, salah satunya adalah proyek pembangunan gedung Research and Innovation Center of Dasron Hamid yang sedang dalam tahap pembangunan. Penelitian ini bertujuan untuk mengetahui tingkat kerentanan bangunan RIC terhadap gempa menggunakan RVS (Rapid Visual Screening) berdasarkan FEMA P-154 2015. Penelitian ini menggunakan metode kuantitatif dan observasi secara langsung di lokasi pembangunan dengan mengisi formulir FEMA P-154, bangunan yang ditinjau terdiri 8 lantai yang dilengkapi 1 lantai dasar. Formulir yang digunakan adalah tipe high seismicity yang berarti tingkat seismitas di lokasi penelitian memiliki persebaran gempa yang tinggi. Dari hasil penelitian didapatkan nilai S sebesar 2,3 dengan persentase kerentanan bangunan untuk roboh adalah 0,5%, sehingga aman terhadap gempa. Hal ini dikarenakan bangunan ini didirikan setelah adanya acuan atau code meskipun memiliki ketidakberaturan seperti vertical irregularity, dan, plan irregularity.

System-Analytical Method of Earthquake-Prone Areas Recognition

Typically, strong earthquakes do not occur over the entire territory of the seismically active region. Recognition of areas where they may occur is a critical step in seismic hazard assessment studies. For half a century, the Earthquake-Prone Areas (EPA) approach, developed by the famous Soviet academicians I.M. Gelfand and V.I. Keilis-Borok, was used to recognize areas prone to strong earthquakes. For the modern development of ideas that form the basis of the EPA method, new mathematical methods of pattern recognition are proposed. They were developed by the authors to overcome the difficulties that arise today when using the EPA approach in its classic version. So, firstly, a scheme for the recognition of high seismicity disjunctive nodes and the vicinities of axis intersections of the morphostructural lineaments was created with only one high seismicity learning class. Secondly, the system-analytical method FCAZ (Formalized Clustering and Zoning) has been developed. It uses the epicenters of fairly weak earthquakes as recognition objects. This makes it possible to develop the recognition result of areas prone to strong earthquakes after the appearance of epicenters of new weak earthquakes and, thereby, to repeatedly correct the results over time. It is shown that the creation of the FCAZ method for the first time made it possible to consider the classical problem of earthquake-prone areas recognition from the point of view of advanced systems analysis. The new mathematical recognition methods proposed in the article have made it possible to successfully identify earthquake-prone areas on the continents of North and South America, Eurasia, and in the subduction zones of the Pacific Rim.

Sectional Ductility of Wide Beams

Wide beam structures are categorized as Limited Ductility Class in Turkey and elsewhere and considered not fit for construction in areas of high seismicity. One of the main reasons that wide beam structures are considered to possess limited ductility is the perceived low local ductility of the wide beams, due to the high reinforcement ratios. Wide beams have small depths, which indeed require higher reinforcement ratios to produce the necessary moment capacities, as compared to normal beams. However, the low local ductility of the wide beams can be contested. This paper presents a database of more than 150 beam sections, some of which are normal and some of which are wide beams. The moment-rotation relationships were computed for all the sections, and the sectional ductility was calculated from the yield and ultimate rotations. The relations between sectional ductility and other parameters such as section aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio were investigated. An example of the relation between ductility and section properties, in this case section aspect ratio is shown. Both positive and negative ductility were calculated and plotted. It should be noted that beams with section ratio of 0.5 are conventional beams, while the rest are wide beams. The values of ductility vary for all beams, and conventional beams have a slightly wider spread. While these parameters vary within the section database, the sectional ductility oscillates around 30, and no clear correlations could be established for any of the above-mentioned parameters. There were no significant differences between the average sectional ductility of conventional and wide beams. For this dataset, the mean positive ductility was 29.66 and 29.33 for conventional and wide beams respectively, and the mean negative ductility was 28.96 and 31.50 for conventional and wide beams, respectively.

Comparative Study of Indonesian Seismic Codes Applied on Vertically Irregular RC Building in High Seismicity Region

The Aceh earthquake suffering Indonesia in 2004, and some big ground motions afterward led the earthquake-resistant building standard provisions to be updated. The rise of ground motions increases the lateral forces, so reevaluating existing buildings is needed, especially for Irregular buildings, which are more vulnerable than the regular ones. This study investigates the increase of earthquake loads and the building response in the high seismicity region due to the updated Indonesian code from SNI 1726:2002 to SNI 1726:2012. Building A in DI Yogyakarta with vertical irregularity on a certain floor is chosen as the object to be studied. There are two types of seismic loads to be simulated, response spectrum and time history analysis. The building is simulated using the numerical program, and four ground motion histories are selected for the dynamic exiting forces. The analysis result shows an increase in the story force either in the response spectrum or the time history. By taking the building's top floor as the reference point, the increase in lateral displacement is also detected in both response spectrum and time history analysis. From the interstory drift ratio examinations, it is also found that there is a weak point located on the setback part that is not identified just by observing the total displacement. This paper compiles the comparison of two versions of the Indonesian seismic code, two types of seismic force, and two points of view in analyzing the building response. Furthermore, the result presented in this paper also beneficial for mitigating the building.

Strengthening heritage tunnels to enhance the resilience of Wellington’s transport network

Wellington city is characterised by steep hilly terrain, and as such several tunnels have been constructed since the beginning of the last century to provide critical transport access in the city. These tunnels are still used today as part of the city’s transport routes, while also being an integral part of the city’s history and heritage. Wellington is among the most seismically active areas in New Zealand. Three major active faults located within the Wellington Region and the proximity to the subduction zone are the main contributors to the high seismicity. The aging tunnels were designed and constructed prior to the advent of earthquake design standards and are subject to deterioration. Hence, they require maintenance and strengthening to ensure operational integrity and resilience to earthquake and other hazard events. Authorities have been supported by the authors in managing the risk through identifying key vulnerabilities, and prioritisation and implementation of strengthening measures. Best practice investigation and strengthening techniques have been applied through the process to ensure resilience and cost effectiveness. The paper presents case histories that highlight the value of investigations and assessment in understanding the risks, and novel strengthening measures developed to enhance resilience while preserving the heritage of the tunnels. Case histories include the seismic strengthening of the Hataitai Bus Tunnel, the Northland and Seatoun road tunnels and the investigation and assessment of the iconic Wellington Cable Car tunnels.

Tentative Intracontinental Seismic Activity in South Siberia and Russian Far East

Overwhelming majority of minor, strong and major earthquakes in south Siberia and Russian Far East coincide with relatively narrow intracontinental zones on the boundaries of blocks and lithosphere plates. The geodynamic activity of these zones connects, besides the plate interaction, with deep lithosphere structure and anomalies of the different geophysical fields as well as with blocks’ kinematics. Authors’ located areas of the seismic centers origin and the possible manifestations of the high seismicity based on the distribution of the maximal volumes of releasing seismic energy. We established these areas, with certain care, in the northeast Altai and adjacent part of the west Sayany, in the west of the east Sayany, around the Baikal Lake and in northwest Transbaikalia, in the east of Transbaikalia between the Vitim River and upper stream of the Aldan River, and in the north of the Sakhalin Island. The majority of minor and strong, rarely major, earthquakes took place in these areas. Deep and near surface structural peculiarities influence on these areas’ geodynamics and allow establishing possible levels of seismic energy releasing. We draw areas of intensive seismic energy releasing with its calculating for each from investigated regions. They gravitate towards interblock zones, which separate crust blocks and the North Eurasian Lithosphere Plate. The fulfilled investigation allows establishing specific areas of the increased seismicity in south Siberia, Russian Far East and adjacent territories.

System-analytical method of strong earthquake-prone areas recognition

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;Strong earthquakes (M&amp;#160;&amp;#8805;&amp;#160;M&lt;sub&gt;0&lt;/sub&gt;, M&lt;sub&gt;0&lt;/sub&gt; 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&amp;#160;&amp;#8805;&amp;#160;M&lt;sub&gt;R&lt;/sub&gt;, M&lt;sub&gt;R&lt;/sub&gt; 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.&lt;/p&gt;&lt;p&gt;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 &amp;#8220;reliable&amp;#8221; class was created in the work.&lt;/p&gt;&lt;p&gt;In the regions studied in this work, FCAZ zones occupy a relatively small area compared to the field of general seismicity &amp;#8211; 30%&amp;#160;&amp;#8211;&amp;#160;40% of the area of all seismicity, and 50%&amp;#160;&amp;#8211;&amp;#160;65% of the area where earthquakes with M&amp;#160;&amp;#8805;&amp;#160;M&lt;sub&gt;R&lt;/sub&gt; 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 &amp;#8220;manifest&amp;#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).&lt;/p&gt;&lt;p&gt;The reported study was funded by RFBR, project number 20-35-70054 &amp;#171;Systems approach to recognition algorithms for seismic hazard assessment&amp;#187;.&lt;/p&gt;