Portable optically stimulated luminescence age map of a paleoseismic exposure

The quality and quantity of geochronologic data used to constrain the history of major earthquakes in a region exerts a first-order control on the accuracy of seismic hazard assessments that affect millions of people. However, evaluations of geochronological data are limited by uncertainties related to inherently complex depositional processes that may vary spatially and temporally. To improve confidence in models of earthquake timing, we use a high-density suite of radiocarbon and optically stimulated luminescence (OSL) ages with a grid of 342 portable OSL samples to explore spatiotemporal trends in geochronological data across an exemplary normal fault colluvial wedge exposure. The data reveal a two-dimensional age map of the paleoseismic exposure and demonstrate how vertical and horizontal trends in age relate to dominant sedimentary facies and soil characteristics at the site. Portable OSL data provide critical context for the interpretation of 14C and OSL ages, show that geochronologic age boundaries between pre- and post-earthquake deposits do not match stratigraphic contacts, and provide the basis for selecting alternate Bayesian models of earthquake timing. Our results demonstrate the potential to use emergent, portable OSL methods to dramatically improve paleoseismic constraints on earthquake timing.

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Disorder-Induced Low-Frequency Raman Band Observed in Deposited MoS2 Films

Applied Spectroscopy ◽

10.1366/000370294774369063 ◽

1994 ◽

Vol 48 (6) ◽

pp. 733-736 ◽

Cited By ~ 41

Author(s):

N. T. McDevitt ◽

J. S. Zabinski ◽

M. S. Donley ◽

J. E. Bultman

Keyword(s):

Crystal Structure ◽

Thin Films ◽

Raman Band ◽

Low Frequency ◽

Pulsed Laser ◽

Laser Deposition ◽

First Order ◽

Order Spectrum ◽

History Of ◽

Frequency Feature

Crystalline disorder in thin films plays an important role in determining their properties. Disorder in the crystal structure of MoS2 films prepared by magnetron sputtering and pulsed laser deposition was evaluated with the use of Raman spectroscopy. The peak positions and bandwidths of the first-order Raman bands, in the region 100 to 500 cm−1, were used as a measure of crystalline order. In addition, a low-frequency feature was observed at 223 cm−1 that is not part of the normal first-order spectrum of a fully crystalline specimen. Data presented here demonstrate that this band is characteristic of crystalline disorder, and its intensity depends on the annealing history of the film. This behavior seems to be analogous to the disorder found in graphite thin films.

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Contrasting geomorphic and stratigraphic responses to normal fault development during single and multi-phase rifting

10.31223/x5j03h ◽

2021 ◽

Author(s):

Sofia Pechlivanidou ◽

Anneleen Geurts ◽

Guillaume Duclaux ◽

Robert Gawthorpe ◽

Christos Pennos ◽

...

Keyword(s):

Normal Fault ◽

Sedimentary Facies ◽

Surface Processes ◽

Extension Direction ◽

Multi Phase ◽

Fault Growth ◽

Stratigraphic Evolution ◽

The Impact ◽

Topographic Evolution ◽

Previous Phase

Understanding the impact of tectonics on surface processes and the resultant stratigraphic evolution in multi-phase rifts is challenging, as patterns of erosion and deposition related to older phases of extension are overprinted by the subsequent extensional phases. In this study, we use a one-way coupled numerical modelling approach between a tectonic and a surface processes model to investigate topographic evolution, erosion and basin stratigraphy during single and multi-phase rifting. We compare the results from the single and the multi-phase rift experiments for a 5 Myr period during which they experience equal amounts of extension, but with the multi-phase experiment experiencing fault topography inherited from a previous phase of extension. Our results demonstrate a very dynamic evolution of the drainage network that occurs in response to fault growth and linkage and, to depocentre overfilling and overspilling. However, we observe profound differences between topographic and depocenter development during single and multi-phase rifting with implications for sedimentary facies development. Our quantitative approach, enables us to better understand the impact of changing extension direction on the distribution of sediment source areas and the syn-rift stratigraphic development through time and space.

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Earthquake Disaster Mitigation Mapping By Modeling of Land Layer and Site Effect Zone in The Kota Baru of South Lampung

Jurnal Ilmiah Pendidikan Fisika Al-Biruni ◽

10.24042/jipfalbiruni.v8i1.3705 ◽

2019 ◽

Vol 8 (1) ◽

pp. 53-67 ◽

Cited By ~ 2

Author(s):

Nandi Haerudin ◽

Rustadi Rustadi ◽

Helmy Fitriawan ◽

Deassy Siska ◽

Muchammad Farid

Keyword(s):

Site Effect ◽

Dominant Frequency ◽

Soil Characteristics ◽

Disaster Mitigation ◽

Tectonic Activity ◽

Earthquake Risk ◽

Sediment Thickness ◽

Layer Model ◽

History Of ◽

The City

Kota Baru is the satellite city of Bandar Lampung. The city is prepared for the expansion of the city of Bandar Lampung. Zonation map of earthquake risk is required for Kota Baru due to its location within the reach of earthquake energy of Semangko subduction fault. In this study, we model the earthquake-prone zone map based on the soil characteristics (site effect) combined with the underground layer model to get a detailed description of the horizontal and vertical soil character. The microtremor method is performed to obtain the zonation effect mapping. Whereas, the ground layer modeling is obtained using the geoelectrical method. The modeling results show that the study area is far from tectonic activity based on the history of past earthquake events. However, this area has a large sediment thickness and has a low dominant frequency value, so it is an area that is vulnerable to earthquakes

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New insight on tide-dominated estuary and delta in the Eocene-Miocene Mrayt Group, North-Western Rif, Morocco

10.31223/x59p7r ◽

2021 ◽

Author(s):

Hamoumi Naima ◽

choukri chacrone ◽

Silvia Spezzaferri

Keyword(s):

Sedimentary Facies ◽

Carbonate Sediments ◽

Sedimentary Deposits ◽

Depositional Processes ◽

Sea Level Fluctuation ◽

The Subject ◽

Depositional Systems ◽

New Interpretation ◽

Petrographic Study ◽

North Western

The sedimentary deposits of Eocene-Miocene Mrayt Group, North-Western Rif, Morocco has been the subject of controversy by previous authors regarding their depositional environment. Detailed sedimentological study based on petrographic and sedimentary facies analysis, ichnofacies interpretation and paleocurrent measurements, leads to several results and new insights. Petrographic study provided the first evidence of mixed siliciclastic and carbonate sediments and their nomenclature: silty micrites, micritic siltstones, micritic sandstones, sandy micrite, and allochemic sandstones, as well as the nature of the sources and its geological context. Twenty two sedimentary facies that have never been described before are identified, and based on their succession and association a new interpretation of depositional processes and depositional systems are proposed. The paleoenvironments of the Mrayt Group are interpreted as littoral and shallow marine settings: tides- dominated estuary, tides-dominated delta systems and open coast tidal flat, under complex hydrodynamics strongly influenced by river discharge, tidal currents, waves and storms action.Sedimentation occurred in “the Maghrebian basin” under the interplay of: i) tectonics related to the Cenozoic collision of the African and Eurasian continental plates, ii) Cenozoic alternation of warm climate and cooling due to the increasing influence of Antarctica glaciation, iii) sediments supplies induced by rejuvenation of sedimentary sources and iv) sea level fluctuation related to the advance and retreat of ice-sheet on Antarctica.

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New constraints on the exhumation history of the western Tauern Window (European Alps) from thermochronology, thermokinematic modeling, and topographic analysis

International Journal of Earth Sciences ◽

10.1007/s00531-021-02094-w ◽

2021 ◽

Author(s):

Reinhard Wolff ◽

Ralf Hetzel ◽

István Dunkl ◽

Aneta A. Anczkiewicz

Keyword(s):

Hanging Wall ◽

Thermal Relaxation ◽

Slip Rate ◽

Normal Fault ◽

European Alps ◽

Valley Bottom ◽

Topographic Analysis ◽

Tauern Window ◽

History Of ◽

Exhumation History

AbstractThe Brenner normal fault bounds the Tauern Window to the west and accommodated a significant portion of the orogen-parallel extension in the Eastern Alps. Here, we use zircon (U–Th)/He, apatite fission track, and apatite (U–Th)/He dating, thermokinematic modeling, and a topographic analysis to constrain the exhumation history of the western Tauern Window in the footwall of the Brenner fault. ZHe ages from an E–W profile (parallel to the slip direction of the fault) decrease westwards from ~ 11 to ~ 8 Ma and suggest a fault-slip rate of 3.9 ± 0.9 km/Myr, whereas AFT and AHe ages show no spatial trends. ZHe and AFT ages from an elevation profile indicate apparent exhumation rates of 1.1 ± 0.7 and 1.0 ± 1.3 km/Myr, respectively, whereas the AHe ages are again spatially invariant. Most of the thermochronological ages are well predicted by a thermokinematic model with a normal fault that slips at a rate of 4.2 km/Myr between ~ 19 and ~ 9 Ma and produces 35 ± 10 km of extension. The modeling reveals that the spatially invariant AHe ages are caused by heat advection due to faulting and posttectonic thermal relaxation. The enigmatic increase of K–Ar phengite and biotite ages towards the Brenner fault is caused by heat conduction from the hot footwall to the cooler hanging wall. Topographic profiles across an N–S valley in the fault footwall indicate 1000 ± 300 m of erosion after faulting ceased, which agrees with the results of our thermokinematic model. Valley incision explains why the Brenner fault is located on the western valley shoulder and not at the valley bottom. We conclude that the ability of thermokinematic models to quantify heat transfer by rock advection and conduction is crucial for interpreting cooling ages from extensional fault systems.

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Southward expanding plate coupling due to variation in sediment subduction as a cause of Andean growth

Nature Communications ◽

10.1038/s41467-021-27518-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jiashun Hu ◽

Lijun Liu ◽

Michael Gurnis

Keyword(s):

Sediment Transport ◽

Three Dimensional ◽

Mountain Building ◽

Crustal Shortening ◽

First Order ◽

The Andes ◽

Tectonic Processes ◽

History Of ◽

Plate Coupling ◽

Trench Sediments

AbstractGrowth of the Andes has been attributed to Cenozoic subduction. Although climatic and tectonic processes have been proposed to be first-order mechanisms, their interaction and respective contributions remain largely unclear. Here, we apply three-dimensional, fully-dynamic subduction models to investigate the effect of trench-axial sediment transport and subduction on Andean growth, a mechanism that involves both climatic and tectonic processes. We find that the thickness of trench-fill sediments, a proxy of plate coupling (with less sediments causing stronger coupling), exerts an important influence on the pattern of crustal shortening along the Andes. The southward migrating Juan Fernandez Ridge acts as a barrier to the northward flowing trench sediments, thus expanding the zone of plate coupling southward through time. Consequently, the predicted history of Andean shortening is consistent with observations. Southward expanding crustal shortening matches the kinematic history of inferred compression. These results demonstrate the importance of climate-tectonic interaction on mountain building.

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