Evaluation of Seismically Induced Soft Sediment Deformation Structures Vis-à-Vis their Probable Earthquake Sources in Kashmir Basin, NW Himalaya

2020 ◽  
pp. 2150003 ◽  
Author(s):  
Maqbool Yousuf ◽  
Kaiser Bukhari

This study discusses the composition and distribution of paleo-liquefaction structures, their triggering mechanisms, probable source and the dynamics of source faults expressed in the Kashmir basin (KB), NW Himalaya. Stratigraphic evidences of deformational structures along concomitant fault zones are highly preserved throughout the basin. The KB was frequently confronted with recurrent seismic activities along intra basinal active faults and adjacent active faults during differential uplift of Himalaya, which resulted in various deformation structures during and after the evolution of the KB. Past earthquake events released a significant part of the slip deficit along intra basinal active faults and vertically offset quaternary deposits by 1–3[Formula: see text]m and originated different and extensively deformation structures. In this context, stratigraphic sections and paleo-surface ruptures have been meticulously mapped to determine the seismic nature and the source of resultant causative earthquakes. The results of this study suggest that besides southern thrust systems, intrabasinal active faults are the main probable seismogenic sources responsible for development of these structures and play an important role in releasing the accumulated stresses in this region.

2020 ◽  
Vol 50 (1) ◽  
Author(s):  
Luciano Alessandretti ◽  
Lucas Veríssimo Warren ◽  
Maurício Guerreiro Martinho dos Santos ◽  
Matheus Carvalho Virga

Terra Nova ◽  
1997 ◽  
Vol 9 (5) ◽  
pp. 208-212 ◽  
Author(s):  
P.G. Silva ◽  
J.C. Canaveras ◽  
S. Sanchez-Moral ◽  
J. Lario ◽  
E. Sanz

2000 ◽  
Vol 49 (4) ◽  
pp. 197-214 ◽  
Author(s):  
Dan Bowman ◽  
Dorit Banet-Davidovich ◽  
Hendrik J. Bruins ◽  
Johannes Van der Plicht

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 721
Author(s):  
Ukhwan Byun ◽  
A.J. (Tom) van Loon ◽  
Kyoungtae Ko

The Gyeokpori Formation in the Buan volcanic area primarily contains siliciclastic rocks interbedded with volcanoclastics. These sediments are characterized by a variety of soft-sediment deformation structures (SSDS). The SSDS in the Gyeokpori Formation are embedded in poorly sorted conglomerates; slump folds are also present in the formation. The deformation mechanisms and triggers causing the deformation are not yet clear. In the present study, the trigger of the SSDS in the Gyeokpori Formation was investigated using facies analysis. This included evaluation of the reworking process of both cohesive and non-cohesive sediments. The analysis indicates that the SSDS are directly or indirectly associated with the alternation of conglomerates and mud layers with clasts. These layers underwent non-cohesive and cohesive deformation, respectively, which promoted SSDS formation. The slump folds were controlled by the extent of cohesive and non-cohesive deformation experienced by the sediment layers in the slope environment. The SSDS deformation style and morphology differ, particularly in the case of reworking by slump activity. This study contributes to the understanding of lacustrine slope-related soft-sediment deformation structures.


Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 408 ◽  
Author(s):  
King ◽  
Quigley ◽  
Clark

We digitize surface rupture maps and compile observational data from 67 publications on ten of eleven historical, surface-rupturing earthquakes in Australia in order to analyze the prevailing characteristics of surface ruptures and other environmental effects in this crystalline basement-dominated intraplate environment. The studied earthquakes occurred between 1968 and 2018, and range in moment magnitude (Mw) from 4.7 to 6.6. All earthquakes involved co-seismic reverse faulting (with varying amounts of strike-slip) on single or multiple (1–6) discrete faults of ≥ 1 km length that are distinguished by orientation and kinematic criteria. Nine of ten earthquakes have surface-rupturing fault orientations that align with prevailing linear anomalies in geophysical (gravity and magnetic) data and bedrock structure (foliations and/or quartz veins and/or intrusive boundaries and/or pre-existing faults), indicating strong control of inherited crustal structure on contemporary faulting. Rupture kinematics are consistent with horizontal shortening driven by regional trajectories of horizontal compressive stress. The lack of precision in seismological data prohibits the assessment of whether surface ruptures project to hypocentral locations via contiguous, planar principal slip zones or whether rupture segmentation occurs between seismogenic depths and the surface. Rupture centroids of 1–4 km in depth indicate predominantly shallow seismic moment release. No studied earthquakes have unambiguous geological evidence for preceding surface-rupturing earthquakes on the same faults and five earthquakes contain evidence of absence of preceding ruptures since the late Pleistocene, collectively highlighting the challenge of using mapped active faults to predict future seismic hazards. Estimated maximum fault slip rates are 0.2–9.1 m Myr-1 with at least one order of uncertainty. New estimates for rupture length, fault dip, and coseismic net slip can be used to improve future iterations of earthquake magnitude—source size—displacement scaling equations. Observed environmental effects include primary surface rupture, secondary fracture/cracks, fissures, rock falls, ground-water anomalies, vegetation damage, sand-blows / liquefaction, displaced rock fragments, and holes from collapsible soil failure, at maximum estimated epicentral distances ranging from 0 to ~250 km. ESI-07 intensity-scale estimates range by ± 3 classes in each earthquake, depending on the effect considered. Comparing Mw-ESI relationships across geologically diverse environments is a fruitful avenue for future research.


Sign in / Sign up

Export Citation Format

Share Document