Active fault segmentation and seismic hazard in Hoa-Binh reservoir, Vietnam

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Phan Trinh ◽  
Hoang Vinh ◽  
Nguyen Huong ◽  
Ngo Liem
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Slip Rate ◽  
Normal Fault ◽  
Seismic Attenuation ◽  
Fault System ◽  
Ground Acceleration ◽  
Hydropower Dam ◽  
Large Dam ◽  
Hoa Binh

AbstractBased on remote sensing, geological data, geomorphologic analysis, and field observations, we determine the fault system which is a potential source of earthquakes in Hoa-Binh reservoir. It is the sub-meridian fault system composed of fault segments located in the central part of the eastern and western flanks of the Quaternary Hoa-Binh Graben: the Hoa-Binh 1 fault is east-dipping (75–80°), N-S trending, 4 km long, situated in the west of the Hoa-Binh Graben, and the Hoa-Binh 2 is a west-dipping (75–80°), N-S trending; 8.4 km long fault, situated in the east of the Hoa-Binh Graben. The slip rate of normal fault in Hoa-Binh hydropower dam was estimated at 0.3–1.1 mm/yr. The Maximum Credible Earthquake (MCE) and Peak Ground Acceleration (PGA) in the Hoa-Binh hydropower dam have been assessed. The estimated MCE of HB.1 and HB.2 is 5.6 and 6.1 respectively, and the maximum PGA at Hoa-Binh dam is 0.30 g and 0.40 g, respectively. The assessment of seismic hazard in Hoa-Binh reservoir is a typical example of seismic hazards of a large dam constructed in an area of low seismicity and lack of law of seismic attenuation.

scholarly journals Active fault databases: building a bridge between earthquake geologists and seismic hazard practitioners, the case of the QAFI v.3 database

2017 ◽  
Vol 17 (8) ◽  
pp. 1447-1459 ◽  
Author(s):  
Julián García-Mayordomo ◽  
Raquel Martín-Banda ◽  
Juan M. Insua-Arévalo ◽  
José A. Álvarez-Gómez ◽  
José J. Martínez-Díaz ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Slip Rate ◽  
Seismic Hazard Assessment ◽  
Recurrence Interval ◽  
Maximum Magnitude ◽  
Geological Evidence ◽  
Seismic Parameters ◽  
Standard Quality

Abstract. Active fault databases are a very powerful and useful tool in seismic hazard assessment, particularly when singular faults are considered seismogenic sources. Active fault databases are also a very relevant source of information for earth scientists, earthquake engineers and even teachers or journalists. Hence, active fault databases should be updated and thoroughly reviewed on a regular basis in order to keep a standard quality and uniformed criteria. Desirably, active fault databases should somehow indicate the quality of the geological data and, particularly, the reliability attributed to crucial fault-seismic parameters, such as maximum magnitude and recurrence interval. In this paper we explain how we tackled these issues during the process of updating and reviewing the Quaternary Active Fault Database of Iberia (QAFI) to its current version 3. We devote particular attention to describing the scheme devised for classifying the quality and representativeness of the geological evidence of Quaternary activity and the accuracy of the slip rate estimation in the database. Subsequently, we use this information as input for a straightforward rating of the level of reliability of maximum magnitude and recurrence interval fault seismic parameters. We conclude that QAFI v.3 is a much better database than version 2 either for proper use in seismic hazard applications or as an informative source for non-specialized users. However, we already envision new improvements for a future update.

Geomorphic evidence for active, co-seismic slip along a low-angle normal fault: Panamint Valley, California

2020 ◽  
Author(s):  
Eric Kirby ◽  
Israporn (Grace) Sethanant ◽  
John Gosse ◽  
Eric McDonald ◽  
J Doug Walker
Keyword(s):  
Seismic Hazard ◽  
Normal Fault ◽  
Basin And Range ◽  
Detachment Fault ◽  
Airborne Lidar ◽  
Fault System ◽  
Seismic Slip ◽  
The Past ◽  
Detachment Faults ◽  
Fault Scarps

<p>The mechanical feasibility of co-seismic displacement along low-angle normal fault systems remains an outstanding problem in tectonics.  In the southwestern Basin and Range of North America, large magnitude extension during Miocene – Pliocene time was accommodated along a regionally extensive system of low-angle detachment faults.  Whether these faults remain active today and, if so, whether they rupture during large earthquakes are questions central to understanding the geodynamics of distributed lithospheric deformation and associated seismic hazard.  Here we evaluate the geometric and kinematic relationships of fault scarps developed in Pleistocene – Holocene alluvial and lacustrine deposits with low-angle detachment faults observed along the western flank of the Panamint Range, in eastern California.  We combine analysis of high-resolution topography generated from airborne LiDAR and photogrammetry with a detailed chronology of alluvial fan surfaces and a calibrated soil chronosequence to characterize the recent activity of the fault system.  The range-front fault system is coincident with a low-angle (15-20°), curviplanar detachment fault that is linked to strike-slip faults at its southern and northern ends.  Fanglomerate deposits in the hanging wall of the detachment are juxtaposed with brecciated bedrock in the footwall across a narrow fault surface marked by clay-rich gouge.  Isochron burial dating of the fanglomerate using the <sup>26</sup>Al and <sup>10</sup>Be requires displacement in the past ~800 ka.  The degree of soil development in younger alluvial deposits in direct fault contact with the footwall block suggest displacement along the main detachment in the past as ~80-100 ka.  The geometry of recent fault scarps in Holocene alluvium mimic range-scale variations in strike of the curviplanar detachment fault, suggesting that scarps merge with the detachment at depth.  Moreover, fault kinematics inferred from displaced debris-flow levees and from fault striae on the bedrock range front are consistent with slip on a low-angle detachment system beneath the valley.  Finally, paleoseismic results from a trench at the southern end of the fault system suggest 3-4 surface ruptures during past ~4-5 ka, the most recent of which (MRE) occurred ~330-485 cal yr BP.  Scarps related to the MRE can be traced for at least ~50 km northward along the range front and imply surface displacements of 2-4 meters during this event.  Thus, we conclude that ongoing dextral shear along the margin of the Basin and Range is, in part, accommodated by co-seismic slip along low-angle detachment faults in Panamint Valley.  Our results have important implications for the interaction of fault networks and seismic hazard in the region.</p>

scholarly journals A systems-based approach to parameterise seismic hazard in regions with little historical or instrumental seismicity: The South Malawi Active Fault Database

2020 ◽  
Author(s):  
Jack N. Williams ◽  
Hassan Mdala ◽  
Åke Fagereng ◽  
Luke N. J. Wedmore ◽  
Juliet Biggs ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Slip Rate ◽  
Fault Slip ◽  
Slip Rates ◽  
Scaling Relationships ◽  
Regional Strain ◽  
Earthquake Scaling ◽  
Recurrence Intervals ◽  
Fault Slip Rate

Abstract. Seismic hazard is frequently characterised using instrumental seismic records. However, in regions where the instrumental record is short relative to earthquake repeat times, extrapolating it to estimate seismic hazard can misrepresent the probable location, magnitude, and frequency of future large earthquakes. Although paleoseismology can address this challenge, this approach requires certain geomorphic settings and carries large inherent uncertainties. Here, we outline how fault slip rates and recurrence intervals can be estimated through an approach that combines fault geometry, earthquake-scaling relationships, geodetically derived regional strain rates, and geological constraints of regional strain distribution. We then apply this approach to the southern Malawi Rift where, although no on-fault slip rate measurements exist, there are theoretical and observational constraints on how strain is distributed between border and intrabasinal faults. This has led to the development of the South Malawi Active Fault Database (SMAFD), the first database of its kind in the East African Rift System (EARS) and designed so that the outputs can be easily incorporated into Probabilistic Seismic Hazard Analysis. We estimate earthquake magnitudes of MW 5.4–7.2 for individual fault sections in the SMAFD, and MW 6.0–7.8 for whole fault ruptures. These potentially high magnitudes for continental normal faults reflect southern Malawi's 11–140 km long faults and thick (30–35 km) seismogenic crust. However, low slip rates (intermediate estimates 0.05–0.8 mm/yr) imply long recurrence intervals between events: 102–105 years for border faults and 103–106 years for intrabasinal faults. Sensitivity analysis indicates that the large range of these estimates can be reduced most significantly from an improved understanding of the rate and partitioning of rift-extension in southern Malawi, earthquake scaling relationships, and earthquake rupture scenarios. Hence these are critical areas for future research. The SMAFD provides a framework for using geological and geodetic information to characterize seismic hazard in low strain rate settings with few on-fault slip rate measurements, and could be adapted for use elsewhere in the EARS or globally.

Probabilistic seismic hazard assessments for Northern Southeast Asia (Indochina): Smooth seismicity approach

2020 ◽  
Vol 36 (1_suppl) ◽  
pp. 69-90 ◽  
Author(s):  
Teraphan Ornthammarath ◽  
Pennung Warnitchai ◽  
Chung-Han Chan ◽  
Yu Wang ◽  
Xuhua Shi ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Southeast Asia ◽  
Epistemic Uncertainty ◽  
Slip Rate ◽  
Earthquake Catalog ◽  
Maximum Magnitude ◽  
Ground Acceleration ◽  
Motion Models ◽  
Smoothed Seismicity ◽  
Ground Motion Models

We present an evaluation of the 2018 Northern Southeast Asia Seismic Hazard Model (NSAHM18) based on a combination of smoothed seismicity, subduction zone, and fault models. The smoothed seismicity is used to model observed distributed seismicity from largely unknown sources in the current study area. In addition, due to a short instrumental earthquake catalog, slip rate and characteristic earthquake magnitudes are incorporated through the fault model. To achieve this objective, the compiled earthquake catalogs and updated active fault databases in this region were reexamined with consistent use of these input parameters. To take into account epistemic uncertainty, logic tree analysis has been implemented incorporating basic quantities such as ground-motion models (GMMs) for three different tectonic regions (shallow active, subduction interface, and subduction intraslab), maximum magnitude, and earthquake magnitude frequency relationships. The seismic hazard results are presented in peak ground acceleration maps at 475- and 2475-year return periods.

A stochastic model for site ground motions from temporally dependent earthquakes

1987 ◽  
Vol 77 (4) ◽  
pp. 1110-1126
Author(s):  
Anne S. Kiremidjian ◽  
Shigeru Suzuki
Keyword(s):  
Seismic Hazard ◽  
Stochastic Model ◽  
Ground Motion ◽  
Ground Motions ◽  
Large Earthquake ◽  
Fault System ◽  
Seismic Gap ◽  
Attenuation Relationship ◽  
Ground Acceleration ◽  
A Site

Abstract A stochastic model is presented for estimating probabilities of exceeding site ground motions due to temporally dependent earthquake events. The model reflects the hypothesized dependence of the size of large earthquake events on the time of occurrence of the last major earthquake. An empirical attenuation relationship is used to describe the ground motion at a site originating from a well-defined fault system. The application of the model to the Middle America Trench is discussed. The seismic hazard potential in Mexico City is computed in terms of probabilities of exceeding peak ground acceleration levels. The results indicate that consideration of the seismic gap is important for estimating the seismic hazard at a site. It is also observed that site hazard estimates are greatly dependent on the specific attenuation relationship used. The need for other approaches of ground motion estimation is recognized.

scholarly journals Geometry and slip rate of the Aigion fault, a young normal fault system in the western Gulf of Corinth

Geology ◽  
2007 ◽  
Vol 35 (4) ◽  
pp. 355 ◽  
Author(s):  
L.C. McNeill ◽  
C.J. Cotterill ◽  
J.M. Bull ◽  
T.J. Henstock ◽  
R. Bell ◽  
...  
Keyword(s):  
Slip Rate ◽  
Normal Fault ◽  
Fault System ◽  
Gulf Of Corinth

scholarly journals Fast Holocene slip and localized strain along the Liquiñe-Ofqui strike-slip fault system, Chile

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luis Astudillo-Sotomayor ◽  
Julius Jara-Muñoz ◽  
Daniel Melnick ◽  
Joaquín Cortés-Aranda ◽  
Andrés Tassara ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Strain Localization ◽  
Slip Rate ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Fault System ◽  
Plate Convergence ◽  
Active Tectonic ◽  
Millennial Time Scale ◽  
Hazard Assessments

AbstractIn active tectonic settings dominated by strike-slip kinematics, slip partitioning across subparallel faults is a common feature; therefore, assessing the degree of partitioning and strain localization is paramount for seismic hazard assessments. Here, we estimate a slip rate of 18.8 ± 2.0 mm/year over the past 9.0 ± 0.1 ka for a single strand of the Liquiñe-Ofqui Fault System, which straddles the Main Cordillera in Southern Chile. This Holocene rate accounts for ~ 82% of the trench-parallel component of oblique plate convergence and is similar to million-year estimates integrated over the entire fault system. Our results imply that strain localizes on a single fault at millennial time scale but over longer time scales strain localization is not sustained. The fast millennial slip rate in the absence of historical Mw > 6.5 earthquakes along the Liquiñe-Ofqui Fault System implies either a component of aseismic slip or Mw ~ 7 earthquakes involving multi-trace ruptures and > 150-year repeat times. Our results have implications for the understanding of strike-slip fault system dynamics within volcanic arcs and seismic hazard assessments.

scholarly journals Geologic and geodetic constraints on the seismic hazard of Malawi’s active faults: The Malawi Seismogenic Source Database (MSSD)

2021 ◽  
Author(s):  
Jack N. Williams ◽  
Luke N. J. Wedmore ◽  
Åke Fagereng ◽  
Maximilian J. Werner ◽  
Hassan Mdala ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Active Faults ◽  
Slip Rate ◽  
Slip Rates ◽  
Source Database ◽  
Seismogenic Sources ◽  
Seismogenic Source ◽  
Recurrence Intervals ◽  
Seismic Reflector

Abstract. Active fault data are commonly used in seismic hazard assessments, but there are challenges in deriving the slip rate, geometry, and frequency of earthquakes along active faults. Herein, we present the open-access geospatial Malawi Seismogenic Source Database (MSSD), which describes the seismogenic properties of faults that have formed during East African rifting in Malawi. We first use empirical observations to geometrically classify active faults into section, fault, and multi-fault seismogenic sources. For sources in the North Basin of Lake Malawi, slip rates can be derived from the vertical offset of a seismic reflector that is estimated to be 75 ka based on dated core. Elsewhere, slip rates are constrained from advancing a ‘systems-based’ approach that partitions geodetically-derived rift extension rates in Malawi between seismogenic sources using a priori constraints on regional strain distribution in magma-poor continental rifts. Slip rates are then combined with source geometry and empirical scaling relationships to estimate earthquake magnitudes and recurrence intervals, and their uncertainty is described from the variability of outcomes from a logic tree used in these calculations. We find that for sources in the Lake Malawi’s North Basin, where slip rates can be derived from both the geodetic data and the offset seismic reflector, the slip rate estimates are within error of each other, although those from the offset reflector are higher. Sources in the MSSD are 5–200 km long, which implies that large magnitude (MW 7–8) earthquakes may occur in Malawi. Low slip rates (0.05–2 mm/yr), however, mean that the frequency of such events will be low (recurrence intervals ~103–104 years). The MSSD represents an important resource for investigating Malawi’s increasing seismic risks and provides a framework for incorporating active fault data into seismic hazard assessment in other tectonically active regions.

scholarly journals Review of Seismic Characteristics in Erbil City, the Capital of the Kurdistan Region of Iraq

2019 ◽  
Vol 9 (2) ◽  
pp. 161-170
Author(s):  
Zina A. AbdulJaleel ◽  
Bahman O. Taha
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
Seismic Hazard Assessment ◽  
Normal Fault ◽  
World Health ◽  
Arabian Plate ◽  
Ground Acceleration ◽  
Site Class ◽  
Class D ◽  
Seismic Characteristics

Erbil city essentially suffers from the risk of earthquakes generated by Zagros-Taurus Belt. The central objective of this study is to identify the seismic characteristics and required seismic parameters for structural analysis. The methodology concentrated on reviewing the seismology and geology of Erbil city. It was concluded that the tectonically classified by an outer platform of the low folded zone in the position of Western Zagros Fold-Thrust Belt of the Arabian plate, geologically covered by Quaternary sediments and lithologically described by fluvial sediments, and the dynamic soil properties classified by site Class D. Seismicity review indicated that the seismic source is characterized by strike-slip (normal) fault and majority events exhibit at the shallow crustal with expected moment magnitude between 6 and 7.5. It was observed that the peak ground acceleration (PGA) has been updated, especially after the last cyclic earthquake in the region. The summary of the previous seismic hazard indicates that the PGA according to the World Health Organization, Global Seismic Hazard Assessment Program, and Uniform building code is identified by the value higher than 0.3 g for 475 years return period, while according to national probabilistic seismic hazard analysis studies in Iraq and Arabian Peninsula is identified by 0.4 g for 2% probability of exceedance in 50 years (2475 years return period), and estimated PGA to be 0.25 g for 10% likelihood of exceedance in 50 years (475 years return period), in a term of 5% damped at bedrock condition. Proposed spectral acceleration (Sa) in Erbil city at 0.2 and 1.0 s evaluated to be 1.0 g and 0.53 g, for the site Class D and compared with Sa in the literature.

scholarly journals Late Quaternary faulting in southern Matese (central Italy): implications for earthquake potential in the southern Apennines

2021 ◽  
Author(s):  
Paolo Boncio ◽  
Eugenio Auciello ◽  
Vincenzo Amato ◽  
Pietro Aucelli ◽  
Paola Petrosino ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Central Italy ◽  
Slip Rate ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Fault System ◽  
Southern Apennines ◽  
Mountain Front ◽  
Point Data ◽  
Earthquake Potential

Abstract. We studied in detail the Gioia Sannitica active normal fault (GF) along the Southern Matese Fault system in the southern Apennines of Italy. The current activity of the fault system and its potential to produce strong earthquakes have been underestimated so far, and are now defined. Precise mapping of the GF fault trace on a 1 : 20,000 geological map and several point data on geometry, kinematics and throw rate are made available in electronic format. The GF, and in general the entire fault system along the southern Matese mountain front, is made of slowly-slipping faults, with a long active history revealed by the large geologic offsets, mature geomorphology, and complex fault pattern and kinematics. Present activity has resulted in Late Quaternary fault scarps resurrecting the foot of the mountain front, and Holocene surface faulting. The slip rate varies along-strike, with maximum Late Pleistocene – Holocene throw rate of ~0.5 mm/yr. Activation of the 11.5 km-long GF can produce up to M 6.1 earthquakes. If activated together with the 18 km-long Ailano-Piedimonte Matese fault (APMF), the seismogenic potential would be M 6.8. The slip history of the two faults is compatible with a contemporaneous rupture. The observed Holocene displacements on the GF and APMF are compatible with activations during some poorly known historical earthquakes, such as the 1293 (M 5.8), 1349 (M 6.8; southern prolongation of the rupture on the Aquae Iuliae fault?) and CE 346 earthquakes. A fault rupture during the 847 poorly-constrained historical earthquake is also compatible with the dated displacements.

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