Taking up the challenge of identifying active faults for seismic hazard assessment of the city of Ulaanbaatar (Mongolia)

2020 ◽  
Author(s):  
Abeer Al Ashkar ◽  
Antoine Schlupp ◽  
Matthieu Ferry ◽  
Munkhuu Ulziibat
Keyword(s):  
Seismic Hazard ◽  
Regional Scale ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Capital City ◽  
Sensor Data ◽  
Tectonic Geomorphology ◽  
Stream Channels ◽  
Tectonic Structures ◽  
The City

<p>Ulaanbaatar, capital city of Mongolia (1.5 M inhabitants, i.e. half of the country’s population), is located in Central Mongolia where seismic activity and deformation rates are low (< 1mm/yr.). In contrast, Western Mongolia has experienced four great earthquakes (M ≥ 8) between 1905 and 1957 as well as numerous moderate ones. Some (e.g. the 1957 Bogd earthquake) have been felt at the capital located more than 500 km away. During the last decades, several active faults, located 10 km to 45 km away from Ulaanbaatar, have been discovered and studied. Tectonic Geomorphology and Paleoseismology studies indicate that these faults are able to generate earthquakes of M ≥ 6 with average recurrence times ranging from 1 kyr to 10 kyr (e.g. 1195 ± 157 yr for the Sharkhai fault). Furthermore, since 2005 very dense microseismicity swarms located 10 km NW of the City have been monitored by the Seismic Observatory of Mongolia (IAG). Further studies showed the swarms are produced by the previously undetected Emeelt fault zone along three parallel branches. Due to their proximity to a key population and economic center, all these active structures contribute significantly to increasing Seismic Hazard. During the course of these studies, we documented Quaternary activity along several supplementary faults, which demonstrates that the knowledge of active faults in the region is still incomplete and suggests seismic hazard levels should be revised. Therefore, we undertook to map, as exhaustively as possible, all active tectonic structures in a radius of 300 km around Ulaanbaatar. Here we present preliminary results based on the combined analysis of multi-source and multi-sensor data from satellite images (e.g. Pleiades, Sentinel-2, Landsat8), UAV photographs, and digital elevation models (TanDEM-X and UAV photogrammetric DEMs) in order to extract the most relevant information at various scales. We performed a detailed Tectonic Geomorphology analysis of alluvial and slope landforms to identify recent deformation affecting stream channels and associated deposits (ponds, fans and terraces). On that basis, we document segmentation, deformation patterns and kinematics, as well as relationships between faults at regional scale. Finally, we identify potential sites for future paleoseismic investigations along the main structures. Though this project is in a preliminary stage, our long-term goal is to build a comprehensive database of sources of seismic hazard to the City of Ulaanbaatar and integrate these results into seismic hazard calculations.</p>

scholarly journals Tectonic Geomorphology and Paleoseismology of the Sharkhai fault: a new source of seismic hazard for Ulaanbaatar (Mongolia)

2021 ◽  
Author(s):  
Abeer Al-Ashkar ◽  
Antoine Schlupp ◽  
Matthieu Ferry ◽  
Ulziibat Munkhuu
Keyword(s):  
Seismic Hazard ◽  
Scaling Laws ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Capital City ◽  
Tectonic Geomorphology ◽  
Time Interval ◽  
Coseismic Slip ◽  
Slip Rates ◽  
Large Earthquakes

Abstract. We present new constraints from tectonic geomorphology and paleoseismology along the newly discovered Sharkhai fault near the capital city of Mongolia. Detailed observations from high resolution Pleiades satellite images and field investigations allowed us to map the fault in detail, describe its geometry and segmentation, characterize its kinematics, and document its recent activity and seismic behavior (cumulative displacements and paleoseismicity). The Sharkhai fault displays a surface length of ~40 km with a slightly arcuate geometry, and a strike ranging from N42° E to N72° E. It affects numerous drainages that show left-lateral cumulative displacements reaching 57 m. Paleoseismic investigations document the faulting and deposition record for the last ~3000 yr and reveal that the penultimate earthquake (PE) occurred between 1515 ± 90 BC and 945 ± 110 BC and the most recent event (MRE) occurred after 860 ± 85 AD. The resulting time interval of 2080 ± 470 years is the first constraint on the Sharkhai fault for large earthquakes. On the basis of our mapping of the surface rupture and the resulting segmentation analysis, we propose two possible scenarios for large earthquakes with likely magnitudes between 6.4 ± 0.2 and 7.1 ± 0.2. Furthermore, we apply scaling laws to infer coseismic slip values and derive preliminary estimates of long-term slip rates between 0.2 ± 0.2 and 1.0 ± 0.5 mm/y. Finally, we propose that these original observations and results from a newly discovered fault should be taken into account for the seismic hazard assessment for the city of Ulaanbaatar and help build a comprehensive model of active faults in that region.

scholarly journals Probabilistic seismic hazard assessment of the Canterbury region, New Zealand

2001 ◽  
Vol 34 (4) ◽  
pp. 318-334 ◽  
Author(s):  
Mark Stirling ◽  
Jarg Pettinga ◽  
Kelvin Berryman ◽  
Mark Yetton
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Regional Scale ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Historical Seismicity ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Ground Acceleration

We present the main results of a probabilistic seismic hazard assessment of the Canterbury region recently completed for Environment Canterbury (formerly Canterbury Regional Council). We use the distribution of active faults and the historical record of earthquakes to estimate the levels of earthquake shaking (peak ground acceleration and response spectral accelerations) that can be expected across the Canterbury region with return periods of 150, 475 and 1000 years. The strongest shaking (e.g. 475 year peak ground accelerations of 0.7g or more) can be expected in the west and north to northwest of the Canterbury region, where the greatest concentrations of known active faults and historical seismicity are located. Site-specific analyses of eight towns and cities selected by Environment Canterbury show that Arthur's Pass and Kaikoura are located within these zones of high hazard. In contrast, the centres studied in the Canterbury Plains (Rangiora, Kaiapoi, Christchurch, Ashburton, Temuka and Timaru) are generally located away from the zones of highest hazard. The study represents the first application of recently-developed methods in probabilistic seismic hazard at a regional scale in New Zealand.

scholarly journals Seismogenic nodes as a viable alternative to seismogenic zones and observed seismicity for the definition of seismic hazard at regional scale

2019 ◽  
Vol 41 (4) ◽  
pp. 289-304 ◽  
Author(s):  
Paolo Rugarli ◽  
Franco Vaccari ◽  
Giuliano Panza
Keyword(s):  
Seismic Hazard ◽  
Safety Factor ◽  
Seismic Moment ◽  
Regional Scale ◽  
Seismic Hazard Assessment ◽  
Hazard Maps ◽  
Earthquake Catalogues ◽  
Definition Of ◽  
Partial Factor ◽  
Seismogenic Nodes

A fixed increment of magnitude is equivalent to multiply the seismic moment by a factor γEM related to the partial factor γq acting on the seismic moment representing the fault. A comparison is made between the hazard maps obtained with the Neo-Deterministic Seismic Hazard Assessment (NDSHA), using two different approaches: one based on the events magnitude, listed in parametric earthquake catalogues compiled for the study areas, with sources located within the seismogenic zones; the other uses the seismogenic nodes identified by means of pattern recognition techniques applied to morphostructural zonation (MSZ), and increases the reference magnitude by a constant amount tuned by the safety factor γEM.Using γEM=2.0, in most of the territory the two approaches produce totally independent, comparable hazard maps, based on the quite long Italian catalogue. This represents a validation of the seismogenic nodes method and a tuning of the safety factor γEM at about 2.

Tectonic geomorphology of High Zagros Ranges, SW Iran: an initiative towards seismic hazard assessment

2015 ◽  
Vol 74 (4) ◽  
pp. 3007-3017 ◽  
Author(s):  
Ali Faghih ◽  
Akbar Esmaeilzadeh Soudejani ◽  
Ahmad Nourbakhsh ◽  
Sara Rokni
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Tectonic Geomorphology ◽  
Sw Iran

scholarly journals Extraction of Land Information, Future Landscape Changes and Seismic Hazard Assessment: A Case Study of Tabriz, Iran

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7010
Author(s):  
Ayub Mohammadi ◽  
Sadra Karimzadeh ◽  
Khalil Valizadeh Kamran ◽  
Masashi Matsuoka
Keyword(s):  
Markov Chain ◽  
Land Cover ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
The Future ◽  
Future Potential ◽  
Potential Landscape ◽  
The City ◽  
Future Landscape

Exact land cover inventory data should be extracted for future landscape prediction and seismic hazard assessment. This paper presents a comprehensive study towards the sustainable development of Tabriz City (NW Iran) including land cover change detection, future potential landscape, seismic hazard assessment and municipal performance evaluation. Landsat data using maximum likelihood (ML) and Markov chain algorithms were used to evaluate changes in land cover in the study area. The urbanization pattern taking place in the city was also studied via synthetic aperture radar (SAR) data of Sentinel-1 ground range detected (GRD) and single look complex (SLC). The age of buildings was extracted by using built-up areas of all classified maps. The logistic regression (LR) model was used for creating a seismic hazard assessment map. From the results, it can be concluded that the land cover (especially built-up areas) has seen considerable changes from 1989 to 2020. The overall accuracy (OA) values of the produced maps for the years 1989, 2005, 2011 and 2020 are 96%, 96%, 93% and 94%, respectively. The future potential landscape of the city showed that the land cover prediction by using the Markov chain model provided a promising finding. Four images of 1989, 2005, 2011 and 2020, were employed for built-up areas’ land information trends, from which it was indicated that most of the built-up areas had been constructed before 2011. The seismic hazard assessment map indicated that municipal zones of 1 and 9 were the least susceptible areas to an earthquake; conversely, municipal zones of 4, 6, 7 and 8 were located in the most susceptible regions to an earthquake in the future. More findings showed that municipal zones 1 and 4 demonstrated the best and worst performance among all zones, respectively.

scholarly journals Neotectonic activity and paleoseismological analysis in Eastern of Antioquia, in the vicinity of Medellin city - Colombia

2015 ◽  
pp. 5-19
Author(s):  
Albeiro De Jesús Rendón-Rivera ◽  
John Jairo Gallego-Montoya ◽  
Jenny Paola Jaramillo-Rendón ◽  
Adrián González-Patiño ◽  
José Humberto Caballero-Acosta ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Age Of Onset ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Seismic Events ◽  
Small Surface ◽  
Neotectonic Activity ◽  
Neotectonic Deformation ◽  
Alluvial Terraces ◽  
Prehistoric Earthquakes

The aim of this investigation was the paleoseismological characterization of eastern Antioquia, using trenches analysis and detailed study of indicators of neotectonic activity, some of which had been reported in previous seismic hazard assessment studies of the Aburra Valley.Through techniques of neotectonic, paleoseismology and also age correlation of Quaternary deposits obtained by several authors, it was found at Alcaravanes site (Marinilla Town), evidences of three seismic events with magnitudes Mw 6.4, 6.6 and 6.5 which displaced recent deposits with maximum ages of 440,000, 37,000 and 8,000 years respectively. Likewise, two prehistoric earthquakes, both with magnitude Mw 6.5 were recognized at the Hamburgo site (Guarne Town), dated between 880,000 and 37,000 years respectively, which proves the existence and activity of La Mosca fault. Finally, the Manantiales site (Rionegro Town) revealed a couple of seismic events with magnitude Mw 6.7 and 6.6 that displaced alluvial terraces in Rio Negro basin with a maximum age of onset of neotectonic deformation of 880,000 years.Latest neotectonic findings change the perspective of seismic hazard in Medellin city and surroundings. Prehistoric earthquakes have occurred in the last million years and created small surface rupture and faulting not related with active mountain fronts. Furthermore, the evidence shows obliterated active faults and efficiency of erosion factors in modeling relief and alluvial fill in the basins of Rionegro Erosion Surface.

Cortical deformation in the Aguacaliente-Navarro fault system (Central Valley, Costa Rica) from Geodetic data (GNSS and InSAR)

2020 ◽  
Author(s):  
Juan José Portela Fernández ◽  
Alejandra Staller Vázquez ◽  
Marta Béjar Pizarro
Keyword(s):  
Costa Rica ◽  
Seismic Hazard ◽  
Seismic Hazard Assessment ◽  
Central Valley ◽  
Fault System ◽  
Moderate Seismicity ◽  
Cumulative Strain ◽  
Gnss Data ◽  
The City ◽  
Turrialba Volcano

<p>The Central Valley, Costa Rica, is subject to moderate seismicity, related to the Central Costa Rica Deformation Belt: a region with diffuse deformation, where Caribbean, Cocos and Nazca Plates, as well as the Panama Micro-plate, interact.  The Eastern part of the valley is dominated by the Aguacaliente-Navarro fault system. The city of Cartago was destroyed by an earthquake Ms 6.4 in 1910, associated with the rupture of the Aguacaliente fault. Volcanic unrest –mainly in Turrialba Volcano, with recent activity reported- is present in the area, thus resulting in a very complex interaction zone, where seismic hazard studies are crucial.</p><p>In this context, we process GNSS observations from five different campaigns -2012, 2014, 2016, 2018 and 2020- in 13 stations in the area, in order to estimate their Caribbean-fixed velocities, hence the regional cumulative strain. Additionally, we use both InSAR and GNSS data to measure volcanic deformation, aiming to refine the computed velocities by removing volcanic deformation from the tectonic signal.</p><p>The refined velocities allow us to asses a more precise cumulative strain for the Aguacaliente-Navarro fault system, which is useful to improve seismic hazard assessment in Cartago, one of the most important cities in the region.</p>

Fault Distribution, Segmentation and Earthquake Generation Potential of the Philippine Fault in Eastern Mindanao, Philippines

2015 ◽  
Vol 10 (1) ◽  
pp. 74-82 ◽  
Author(s):  
Jeffrey S. Perez ◽  
◽  
Hiroyuki Tsutsumi ◽  
Mabelline T. Cahulogan ◽  
Desiderio P. Cabanlit ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Tectonic Structures ◽  
Active Tectonic ◽  
Earthquake Generation ◽  
Geometric Segmentation ◽  
Fault Distribution

The 1,250-km-long, NNW-trending, arc-parallel Philippine fault, one of the world’s most active tectonic structures, traverses the Philippine archipelago and has been the source of surface-rupturing earthquakes during the last four centuries. In this paper, we will discuss Philippine fault distribution and segmentation in Mindanao Island by integrating detailed fault mapping together with new geological and paleoseismic data and the analysis of historical surface-rupturing earthquakes. Using geometric segmentation criteria, we have identified nine geometric segments separated by discontinuities such as en echelon steps, bends, changes in strike, gaps, steps and bifurcation in the surface trace. Fault segments ranges from 20 to 100 km in length and are capable of generating earthquakes ofMw6.6 toMw7.4. The results of our study have important implications for earthquake generation potential and seismic hazard assessment of the Philippine fault in Mindanao Island.

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