scholarly journals Evidence for Large Holocene Earthquakes along the Denali Fault in Southwest Yukon, Canada

2020 ◽  
Vol 26 (2) ◽  
pp. 149-166
Author(s):  
AndréE Blais-Stevens ◽  
John J. Clague ◽  
Janice Brahney ◽  
Panya Lipovsky ◽  
Peter J. Haeussler ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Sediment Cores ◽  
Fault Scarp ◽  
Strike Slip ◽  
Flower Structure ◽  
Denali Fault ◽  
Eastern Front ◽  
Dextral Strike Slip Fault ◽  
Alaska Highway Corridor ◽  
Dextral Strike Slip

ABSTRACT The Yukon–Alaska Highway corridor in southern Yukon is subject to geohazards ranging from landslides to floods and earthquakes on faults in the St. Elias Mountains and Shakwak Valley. Here we discuss the late Holocene seismic history of the Denali fault, located at the eastern front of the St. Elias Mountains and one of only a few known seismically active terrestrial faults in Canada. Holocene faulting is indicated by scarps and mounds on late Pleistocene drift and by tectonically deformed Pleistocene and Holocene sediments. Previous work on trenches excavated against the fault scarp near the Duke River reveals paleoseismic sediment disturbance dated to ∼300–1,200, 1,200–1,900, and 3,000 years ago. Re-excavation of the trenches indicates a fourth event dated to 6,000 years ago. The trenches are interpreted to show a negative flower structure produced by extension of sediments by dextral strike-slip fault movement. Nearby Crescent Lake is ponded against the fault scarp. Sediment cores reveal four abrupt sediment and diatom changes reflecting seismic shaking at ∼1,200–1,900, 1,900–5,900, 5,900–6,200, and 6,500–6,800 years ago. At the Duke River, the fault offsets sediments, including two White River tephra layers (∼1,900 and 1,200 years old). Late Pleistocene outwash gravel and overlying Holocene aeolian sediments show in cross section a positive flower structure indicative of post-glacial contraction of the sediments by dextral strike-slip movement. Based on the number of events reflecting ∼M6, we estimate the average recurrence of large earthquakes on the Yukon part of the Denali fault to be about 1,300 years in the past 6,500–6,800 years.

scholarly journals Coseismic fault-slip distribution of the 2019 Ridgecrest Mw6.4 and Mw7.1 earthquakes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yang Gao ◽  
HuRong Duan ◽  
YongZhi Zhang ◽  
JiaYing Chen ◽  
HeTing Jian ◽  
...  
Keyword(s):  
Strike Slip ◽  
Fault Slip ◽  
Slip Distribution ◽  
Synthetic Aperture ◽  
Seismic Events ◽  
Interferometric Synthetic Aperture Radar ◽  
The Past ◽  
Dextral Strike Slip Fault ◽  
Fault Slip Distribution ◽  
Dextral Strike Slip

AbstractThe 2019 Ridgecrest, California seismic sequence, including an Mw6.4 foreshock and Mw7.1 mainshock, represent the largest regional seismic events within the past 20 years. To obtain accurate coseismic fault-slip distribution, we used precise positioning data of small earthquakes from January 2019 to October 2020 to determine the dip parameters of the eight fault geometry, and used the Interferometric Synthetic Aperture Radar (InSAR) data processed by Xu et al. (Seismol Res Lett 91(4):1979–1985, 2020) at UCSD to constrain inversion of the fault-slip distribution of both earthquakes. The results showed that all faults were sinistral strike-slips with minor dip-slip components, exception for dextral strike-slip fault F2. Fault-slip mainly occurred at depths of 0–12 km, with a maximum slip of 3.0 m. The F1 fault contained two slip peaks located at 2 km of fault S4 and 6 km of fault S5 depth, the latter being located directly above the Mw7.1hypocenter. Two slip peaks with maximum slip of 1.5 m located 8 and 20 km from the SW endpoint of the F2 fault were also identified, and the latter corresponds to the Mw6.4 earthquake. We also analyzed the influence of different inversion parameters on the fault slip distribution, and found that the slip momentum smoothing condition was more suitable for the inversion of the earthquakes slip distribution than the stress-drop smoothing condition.

scholarly journals Structural analysis of S-wave seismics around an urban sinkhole; evidence of enhanced subrosion in a strike-slip fault zone

2017 ◽  
Author(s):  
Sonja H. Wadas ◽  
David C. Tanner ◽  
Ulrich Polom ◽  
Charlotte M. Krawczyk
Keyword(s):  
Strike Slip ◽  
Strike Slip Fault ◽  
Key Factors ◽  
S Wave ◽  
Seismic Profiles ◽  
Reflection Seismic ◽  
Dextral Strike Slip Fault ◽  
Seismic Sections ◽  
The Town ◽  
Dextral Strike Slip

Abstract. In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the subrosion, we carried out several shear wave reflection seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement, in the form of a NW–SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks (

scholarly journals First evidence of active transpressive surface faulting at the front of the eastern Southern Alps, northeastern Italy. Insight on the 1511 earthquake seismotectonics

2018 ◽  
Author(s):  
Emanuela Falcucci ◽  
Maria Eliana Poli ◽  
Fabrizio Galadini ◽  
Giancarlo Scardia ◽  
Giovanni Paiero ◽  
...  
Keyword(s):  
Strike Slip ◽  
Southern Alps ◽  
Strike Slip Fault ◽  
Fault System ◽  
The Past ◽  
Fold And Thrust Belt ◽  
Northeastern Italy ◽  
Dextral Strike Slip Fault ◽  
Seismic Lines ◽  
Dextral Strike Slip

Abstract. We investigated the eastern corner of northeastern Italy, where the NW-SE trending dextral strike-slip fault systems of western Slovenia intersects the south-verging fold and thrust belt of the eastern Southern Alps . The area suffered the largest earthquakes of the region, among which are the 1511 (Mw 6.3) event and the two major shocks of the 1976 seismic sequence, with Mw = 6.4 and 6.1 respectively. The Colle Villano thrust and the Borgo Faris-Cividale strike-slip fault have been first analyzed by interpreting industrial seismic lines and then by performing morpho-tectonic and paleoseismological analyses. These different datasets indicate that the two structures define an active, coherent transpressive fault system that activated twice in the past two millennia, with the last event occurring around the 15th–17th century. The chronological information, and the location of the investigated fault system suggest its activation during the 1511 earthquake.

scholarly journals Structural Overview and Morphotectonic Evolution of a Strike-Slip Fault in the Zone of North Almora Thrust, Central Kumaun Himalaya, India

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Lalit M. Joshi ◽  
Pitamber D. Pant ◽  
Bahadur S. Kotlia ◽  
Girish C. Kothyari ◽  
Khayingshing Luirei ◽  
...  
Keyword(s):  
Shear Zone ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Asymmetry Factor ◽  
Base Line ◽  
Gradient Index ◽  
River Channels ◽  
Fluvial Terraces ◽  
Dextral Strike Slip Fault ◽  
Dextral Strike Slip

The aim of the present research is to provide the base line details of the NNW-SSE trending Raintoli fault (RF) which is running parallel to the North Almora Thrust (NAT) along the Saryu valley from Seraghat-Naichun to Seri in the central sector of the Uttarakhand Himalaya, India. The RF is characterized as dextral strike slip fault and behaves as a ductile shear zone within the zone of NAT. The dextral sense of shear movement of RF is delineated by the fabric of the shear zone rocks including microscopically observed indicators such as sigma and delta porphyroclasts, quartz c-axis, and the field structural data. Additionally, in the quaternary period the dextral strike slip fault is reactivated with oblique slip component as characterized by various geomorphic indicators, for example, triangular facets, abandoned river channels, unpaired fluvial terraces, and V-shaped valleys with recurrent seismicity. Further, the morphometric parameters including Valley Floor Width to Valley Height (Vf), asymmetry factor (AF), and gradient index (GI) further prove active nature of RF as suggested by low values of hypsometric integration, V-shaped valley, higher gradient index, and tilting of Saryu basin.

scholarly journals VÝZKUM POZDNĚ KVARTÉRNÍ AKTIVITY ZLOMU KOSÍŘE V HORNOMORAVSKÉM ÚVALU ANEB PROČ JE DOBRÉ STUDOVAT SVAHOVINY A SEISMOGRAMY

2016 ◽  
Vol 22 (1-2) ◽  
Author(s):  
Petr Špaček ◽  
Vít Ambrož
Keyword(s):  
Late Pleistocene ◽  
Late Quaternary ◽  
Slip Rate ◽  
Fault Scarp ◽  
Strike Slip ◽  
Tectonic Activity ◽  
Temporary Increase ◽  
Normal Faulting ◽  
Major Fault ◽  
Complex Sequences

Preliminary results of a research into the late Quaternary slip of a major fault in the seismically active Upper Morava Basin are given. Three trenches, up to 6 m deep, were excavated at the foot of the Kosíř Fault scarp near Stařechovice and Čelechovice. The exposed complex sequences of colluvium and loess, now only partly dated by OSL and 14C, is heavily faulted. The faulting is explained by a tectonic slip at the Kosíř Fault and, in the Stařechovice trench, also by simultaneous slope deformations. None of the faults do off set the Holocene topsoil but the youngest of them were clearly active aft er the deposition of the youngest loess and indicate the slip of up to 1.4 m in Late Pleistocene. In Čelechovice trenches the minimum vertical throw of 4 m is indicated for the lower part of the sequence with assumed Late Pleistocene age. The geometry of the deformed zone suggests an oblique normal faulting with significant strike-slip component. The sense of shearing in the horizontal plane was not resolved. Minimum tectonic slip rate of 0.1‒0.3 mm/year in Late Pleistocene is suggested but this must be confi rmed by new dating. Our observations reveal surprisingly young and large deformation which may suggest a temporary increase of tectonic activity during Late Pleistocene.

scholarly journals Pull-apart basin tectonic model is structurally impossible for Kashmir basin, NW Himalaya

2016 ◽  
Author(s):  
A. A. Shah
Keyword(s):  
Strike Slip ◽  
Strike Slip Fault ◽  
Fault System ◽  
Nw Himalaya ◽  
Tectonic Model ◽  
Pull Apart Basin ◽  
Piggyback Basin ◽  
Kashmir Basin ◽  
Dextral Strike Slip Fault ◽  
Dextral Strike Slip

Abstract. Kashmir Basin in NW Himalaya is considered a Neogene-Quatermary piggyback basin that was formed as result of the continent-continent collision of Indian and Eurasian plates. This model however is recently challenged by a pull-apart basin model, which argues that a major dextral strike-slip fault through Kashmir basin is responsible for its formation. And here it is demonstrated that the new tectonic model is structurally problematic, and conflicts with the geomorphology, geology, and tectonic setting of Kashmir basin. It also conflicts, and contradicts with the various structural features associated with a typical dextral strike-slip fault system where it shows that such a major structure cannot pass through the middle of the basin. It is demonstrated that such a structure is structurally, and kinematically impossible, and could not exist.

scholarly journals Interpretasi Struktur Geologi Berdasarkan Fault Fracture Density (FFD) dan Implikasinya Terhadap Potensi Likuefaksi di Daerah Kalibening, Kabupaten Banjarnegara, Jawa Tengah

EKSPLORIUM ◽  
2021 ◽  
Vol 42 (1) ◽  
pp. 47
Author(s):  
Huzaely Latief Sunan ◽  
Akhmad Khahlil Gibran ◽  
Maulana Rizki Aditama ◽  
Sachrul Iswahyudi ◽  
Fajar Rizki Widiatmoko ◽  
...  
Keyword(s):  
Bouguer Anomaly ◽  
Shallow Groundwater ◽  
Geological Structure ◽  
Mapping Method ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Fracture Density ◽  
Geological Structures ◽  
Dextral Strike Slip Fault ◽  
Dextral Strike Slip

ABSTRAK Keberadaan struktur geologi sering dikaitkan dengan bencana tanah longsor dan gempa bumi. Daerah Kalibening merupakan lokasi yang cukup menarik untuk dilakukan penelitian terkait hal tersebut. Daerah ini tersusun atas satuan batuan berumur Pleistosen dan Resen. Berdasarkan stratigrafinya, batuan tersebut terpotong oleh struktur sesar. Hal ini berarti menjadikan sesar di daerah tersebut termasuk dalam kategori sesar aktif. Morfologi yang tinggi dengan suatu cekungan di tengahnya mengindikasikan bahwa daerah tersebut pembentukannya dipengaruhi oleh sesar. Penelitian ini bertujuan untuk menentukan pola struktur geologi yang mengontrol daerah penelitian. Untuk menentukan pola struktur geologi, digunakan metode pemetaan struktur Fault Fracture Density (FFD) yang dikombinasikan dengan peta residual anomali Bouguer dan peta kelurusan hillshade. Secara umum, hal yang paling penting dalam mempelajari struktur geologi adalah geometri elemen struktur. Model konseptual struktur geologi selanjutnya digunakan untuk menganalisis potensi likuefaksi yang ada pada daerah penelitian. Interpretasi struktur menunjukkan adanya sesar mendatar dekstral yang diikuti sesar-sesar penyerta dan cekungan pull-apart yang diduga merupakan hasil pensesaran normal yang timbul dari mekanisme strike-slip. Sesar mendatar dekstral ini menghasilkan cekungan yang terisi oleh sedimen lepas yang rentan mengalami likuefaksi jika terjadi gempa bumi dan gerakan tanah. Kajian ini menyimpulkan bahwa daerah Kalibening rentan terjadi likuefaksi karena adanya pergerakan sesar mendatar dekstral, sedimen lepas yang mendominasi daerah penelitian, dan muka air tanah yang dangkal. ABSTRACT The existence of geological structures is often associated with landslides and earthquakes. The Kalibening area is an interesting location for research on that purpose. This area is composed of Pleistocene and Recent rocks units. Based on its stratigraphy, the rocks in the area are truncated by fault structure. It means that the fault in the area is categorized as an active fault. The high morphology and a basin existence on its center indicate that the area formation was controlled by faults. The research is carried out to determine the trend of the geological structures that control the study area. To determine the trend of the geological structure, a structural mapping method of Fault Fracture Density (FFD) map combined with the Bouguer anomaly residual map and hillshade lineaments map is used. In general, the most important thing in the study of structural geology is the geometry of the structural elements. The conceptual model of geological structures is subsequently used to analyze the liquefaction potential of the study area. The interpretation of the structures shows the existence of dextral strike-slip fault followed by companion faults and pull-apart basin that is inferred as the result of normal faulting in the strike-slip mechanism. The dextral strike-slip fault produces a basin filled with loose sediment that is prone to liquefaction in the event of an earthquake and ground motion. This study concludes that the Kalibening area is prone to liquefaction due to the existence of the movement of dextral strike-slip fault, loose sediments that dominate the study area, and shallow groundwater table.

Tertiary extension in the central British Columbia Intermontane Belt: magnetic and paleomagnetic evidence from the Endako region

2001 ◽  
Vol 38 (4) ◽  
pp. 657-678 ◽  
Author(s):  
Carmel Lowe ◽  
Randolph J Enkin ◽  
Lambertus C Struik
Keyword(s):  
British Columbia ◽  
Strike Slip ◽  
Paleomagnetic Data ◽  
Magnetic Data ◽  
Euler Deconvolution ◽  
The West ◽  
Near Surface ◽  
Dextral Strike Slip Fault ◽  
Slip Displacement ◽  
Dextral Strike Slip

New magnetic and paleomagnetic data for central British Columbia support and quantify the hypothesis that the area underwent significant Tertiary-age transtensional deformation. Paleomagnetically determined tilts in Eocene rocks indicate that four fault-bounded pits, which constitute the Endako molybdenum mine, were displaced on a series of normal (probably listric) faults that have separations of less than a kilometre. The interpretation also suggests there can be little vertical offset on the Denak West Fault, which separates the Denak East and Denak West pits. Regional paleomagnetic data indicate a predominance of easterly directed tilts to the east of the Casey Fault, but to the west a large variation in the orientation and magnitude of tilts is observed. Results at one site proximal to the Casey Fault indicate a component of dip-slip displacement on this dominantly dextral strike-slip fault. Mapped northeast- and northwest-trending faults commonly correspond to linear zones of steep magnetic gradient and near-surface magnetic sources. Several additional northwest- and northeast-trending lineaments are imaged in the magnetic data where no faults are mapped (particularly over massive and lithologically homogeneous phases of the Endako batholith). Euler deconvolution solutions confirm most such lineaments are also associated with shallow magnetic sources. In profile, they have either a fault or dyke character and are interpreted to be unmapped faults, some locally intruded by mafic dykes, which cut the region into a series of fault-bounded blocks.

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