scholarly journals Evaluation of the depth of the Pantanal sedimentar basin based on seismic events

2021 ◽  
Vol 10 (9) ◽  
pp. e57710918243
Author(s):  
Amanda Letícia Abegg da Silveira ◽  
Gustavo Marques e Amorim ◽  
Dhonatan Diego Pessi ◽  
Normandes Matos da Silva ◽  
Camila Leonardo Mioto ◽  
...  
Keyword(s):  
Seismic Waves ◽  
Sedimentary Basin ◽  
Seismic Station ◽  
Seismic Events ◽  
Mato Grosso ◽  
Loss Of Information ◽  
Northern Portion

The main objective of this study is qualify the seismic activities captured at the Santo Antônio do Leverger seismic station (SALV), state of Mato Grosso, Brazil. The choice of this station was due to its location in the northern portion of the Pantanal Sedimentary Basin, considered historically as one of the seismogenic regions of Brazil. The methodology involved downloading the files through the poet.py script, where the events were identified, selected and stored within 440 km from the SALV station. Once confirmed, filtrations were applied using the Butterworth method. This method minimizes the loss of information recorded by events that have occurred. Thus, most events indicate disagreement with the applied filters, demonstrating that there is a structure that influences the propagation of the wave, changing its original speed and frequency. The triggering method was applied to the behavior of seismic waves that crossed the sedimentary interval of the Pantanal Basin. The results were plotted on maps, overlaid in the form of sub-regions of the Pantanal using the QGIS geoprocessing software, in which the geological contacts were determined. Thus, it was possible to observe that each sub-region presents a different profile for each event, with sub-regions that tend to increase the signal's acceleration, maintain it or slow it down.

scholarly journals Lithospheric structure models applied for locating the Romanian seismic events

1994 ◽  
Vol 37 (3) ◽  
Author(s):  
M. Rizescu ◽  
E. Popescu ◽  
V. Oancea ◽  
D. Enescu
Keyword(s):  
Constant Velocity ◽  
Seismic Waves ◽  
Seismic Events ◽  
Lithospheric Structure ◽  
Structural Units ◽  
Data Set ◽  
Velocity Models ◽  
Seismic Sequences ◽  
Geological Information ◽  
Propagation Velocities

The paper presents our attempts made for improving the locations obtained for local seismic events, using refined lithospheric structure models. The location program (based on Geiger method) supposes a known model. The program is run for some seismic sequences which occurred in different regions, on the Romanian territory, using for each of the sequences three velocity models: 1) 7 layers of constant velocity of seismic waves, as an average structure of the lithosphere for the whole territory; 2) site dependent structure (below each station), based on geophysical and geological information on the crust; 3) curves deseribing the dependence of propagation velocities with depth in the lithosphere, characterizing the 7 structural units delineated on the Romanian territory. The results obtained using the different velocity models are compared. Station corrections are computed for each data set. Finally, the locations determined for some quarry blasts are compared with the real ones.

An Optimum 2D Seismic-Wavefield Reconstruction in Densely and Nonuniformly Distributed Stations: The Metropolitan Seismic Observation Network in Japan

2021 ◽  
Author(s):  
Takahiro Shiina ◽  
Takuto Maeda ◽  
Masayuki Kano ◽  
Aitaro Kato ◽  
Naoshi Hirata
Keyword(s):  
Metropolitan Area ◽  
Seismic Waves ◽  
Seismic Station ◽  
Weighting Functions ◽  
Seismic Observation ◽  
Tokyo Metropolitan ◽  
Tokyo Metropolitan Area ◽  
Spatial Weights ◽  
Observation Network ◽  
Seismic Wavefield

Abstract We propose an optimization method for applying the seismic-wave gradiometry (SWG) method to a dense seismic station network consisting of nonuniformly distributed seismographs. As a nonuniformly distributed station array, we consider the station layout of the Metropolitan Seismic Observation Network (MeSO-net) operated in and around the Tokyo metropolitan area, Japan. In this study, thereby, we numerically investigate optimum shapes of weighting functions, which control the spatial weights of individual stations when estimating waveforms at any grid points in the SWG method, to reconstruct seismic wavefields propagating in the MeSO-net. The functions with isotropic spatial weights are found to be appropriate for wavefield reconstructions with seismic waves incoming from practically all directions, even for nonuniformly distributed stations. The reproducibility of the wavefields is greatly improved by changing the shapes of the spatial weights reflecting density of the stations. Further plausible wavefield reconstructions are made by considering the propagation directions of the seismic waves. In these cases, if the weight of a contribution for a wavefield reconstruction is larger at far stations with a direction perpendicular to the wave propagation direction, then the reproducibility of the waveforms is significantly increased. In addition, the spatial gradients of the amplitudes are well reproduced by the optimized SWG method even though the optimization only focused on the amplitudes. Therefore, our proposed optimization scheme can be used to accurately estimate seismic wavefields in a nonuniformly distributed station array. Actually, the weighting functions optimized in this study succeeded to reconstruct the seismic wavefield of a shallow crustal earthquake that occurred around the Tokyo metropolitan area, based on the observed seismograms obtained by the MeSO-net.

Seismic Rays

2017 ◽  
Author(s):  
John A. Adam
Keyword(s):  
Inverse Problem ◽  
Seismic Tomography ◽  
Seismic Waves ◽  
Seismic Station ◽  
Three Dimensional ◽  
Arrival Times ◽  
The Earth ◽  
Straight Lines ◽  
Ray Path ◽  
Uniform Composition

This chapter focuses on the underlying mathematics of seismic rays. Seismic waves caused by earthquakes and explosions are used in seismic tomography to create computer-generated, three-dimensional images of Earth's interior. If the Earth had a uniform composition and density, seismic rays would travel in straight lines. However, it is broadly layered, causing seismic rays to be refracted and reflected across boundaries. In order to calculate the speed along the wave's ray path, the time it takes for a seismic wave to arrive at a seismic station from an earthquake needs to be determined. Arrival times of different seismic waves allow scientists to define slower or faster regions deep in the Earth. The chapter first presents the relevant equations for seismic rays before discussing how rays are propagated in a spherical Earth. The Wiechert-Herglotz inverse problem is considered, along with the properties of X in a horizontally stratified Earth.

scholarly journals Repetitive fracturing during spine extrusion at Unzen volcano, Japan

Solid Earth ◽  
2015 ◽  
Vol 6 (4) ◽  
pp. 1277-1293 ◽  
Author(s):  
O. D. Lamb ◽  
S. De Angelis ◽  
K. Umakoshi ◽  
A. J. Hornby ◽  
J. E. Kendrick ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Station ◽  
Physical Models ◽  
Ductile Deformation ◽  
Seismic Events ◽  
Seismic Velocities ◽  
Strain Localisation ◽  
Cyclic Activity ◽  
Geophysical Field ◽  
Unzen Volcano

Abstract. Rhythmic seismicity associated with spine extrusion is a well-documented phenomenon at a number of dome-forming volcanic systems. At Unzen volcano, Japan, a 4-year dome-forming eruption concluded with the emplacement of a spine from October 1994 to February 1995, offering a valuable opportunity to further investigate seismogenic processes at dome-forming volcanoes. Using continuous data recorded at a seismic station located close to the dome, this study explores trends in the seismic activity during the extrusion of the spine. We identify a total of 12 208 volcano-seismic events in the period between October 1994 and February 1995. Hourly event counts indicate cyclic activity with periods of ∼ 40 to ∼ 100 h, attributed to pulsatory ascent defined by strain localisation and faulting at the conduit margins. Waveform correlation revealed two strong clusters (a.k.a. multiplets, families) which are attributed to fracturing along the margins of the shallow, ascending spine. Further analysis indicates variable seismic velocities during the spine extrusion as well as migration of the cluster sources along the spine margins. Our interpretation of the results from seismic data analyses is supported by previously published field and experimental observations, suggesting that the spine was extruded along an inclined conduit with brittle and ductile deformation occurring along the margins. We infer that changes in stress conditions acting on the upper and lower spine margins led to deepening and shallowing of the faulting sources, respectively. We demonstrate that the combination of geophysical, field and experimental evidence can help improve physical models of shallow conduit processes.

scholarly journals Towards a standard typology of endogenous landslide seismic sources

2018 ◽  
Author(s):  
Floriane Provost ◽  
Jean-Philippe Malet ◽  
Clément Hibert ◽  
Agnès Helmstetter ◽  
Mathilde Radiguet ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Seismic Waves ◽  
Surface Processes ◽  
Seismic Sources ◽  
Seismic Events ◽  
Earth Surface ◽  
Seismic Signals ◽  
Fluid Circulation ◽  
Source Mechanisms ◽  
Standard Classification

Abstract. In the last decade, numerous studies focused on the analysis of seismic waves generated by Earth surface processes such as landslides. The installation of seismometers on unstable slopes revealed a variety of seismic signals suspected to be generated by slope deformation, weathering of the slope material or fluid circulation. A standard classification for seismic sources generated by unstable slopes needs to be proposed in order to compare the seismic activity of several unstable slopes and identify possible correlation of the seismic activity rate with triggering factors. The objective of this work is to discuss the typology and source mechanisms of seismic events detected at close distances (

scholarly journals MUDANÇAS RECENTES DE LEITO NO BAIXO CURSO DO RIO TAQUARI, NO PANTANAL MATO-GROSSENSE

2001 ◽  
Vol 49 ◽  
Author(s):  
Carlos R. Padovani
Keyword(s):  
Sedimentary Basin ◽  
Landsat Tm ◽  
Quaternary Sediments ◽  
Drainage Pattern ◽  
Mato Grosso ◽  
Meandering Channel ◽  
Course Changes ◽  
Paraná Basin ◽  
The Subject ◽  
Parana Basin

Uma das características marcantes do rio Taquari, no curso inferior, é a sua capacidade de deposição de sedimentos, com a formação de um grande leque aluvial que provoca a instabilidade do leito principal, comprometendo a navegação e as atividades econômicas desenvolvidas no local. As mudanças observa-das no baixo curso do rio Taquari, entre 1966 e 1997, através da interpretação de imagens de satélite Landsat TM-5 e levantamentos de coordenadas com GPS levaram à constatação da existência de um novo canal principal, que se formou em decorrência do desvio de curso pelo rompimento da margem direita, no local conhecido como "Arrombado Zé da Costa". Este novo canal é responsável por 70 % da vazão atual em detrimento da grande redução da descarga no leito antigo. As informações coletadas, além de permitirem a atualização das cartas de drenagem, tornando possível a análise e comparação com mapas anteriores a 1966 podem ser utilizadas, também, na definição de situações de risco para as atividades humanas e na determinação de formas adequadas de manejo e utilização da área. RECENT CHANGES IN THE LOWER COURSE OF TAQUARI RIVER IN THE PANTANAL, BRAZIL Abstract The Taquari river flows from the Parana Basin Plateaus of Mato Grosso State to the lowland region of Pantanal. The Pantanal Cenozoic Sedimentary Basin is made up of unconsolidated Quaternary sediments deposited over the pre-cambrian basement and showing geological boundary on the east side with rocks of Paleozoic and Mesozoic age from the Parana Basin (figure 1). One can notice that the Taquari river in its upper course has a meandering channel. The sinuosity is decreased very sharply in the middle and lower courses due to intense sediment deposition The consequence of this alluvial sedimentation process can be easily seen in the middle of the river course by several lobes causing an unstable drainage pattern with many points of avulsion. like one named "Arrombado Zé da Costa" (figure 2) which is responsible for 70% of the actual discharge and shifting the main channel course. The subject of this work was to map the lower course changes of the Taquari river that took place from 1966 to 1997 by the Landsat TM-05 satellite images interpretation and GPS data (figure 2). The natural changes in the lower Taquari river, were expressive for 31 years and these changes have been accelerated by the effects of human activities in the area.

scholarly journals A catastrophic landslide triggered debris flow in China’s Yigong: factors, dynamic processes, and tendency

2020 ◽  
Vol 24 (1) ◽  
pp. 71-82
Author(s):  
Jun Li ◽  
Ningsheng Chen ◽  
Yuandi Zhao ◽  
Mei Liu ◽  
Weiyu Wang
Keyword(s):  
Debris Flow ◽  
Seismic Waves ◽  
Seismic Station ◽  
Ground Vibration ◽  
Development Trend ◽  
Dynamic Processes ◽  
Discharge Process ◽  
Thaw Cycle ◽  
Geological Conditions ◽  
The Future

A Catastrophic Landslide Triggered Debris Flow (CLDF) hazard with a scale of 0.3 billion m3 occurred in the Zhamunong gully on April 9th, 2000. It is of great scientific and engineering significance to study the main controlling factors and dynamic processes of this CLDF, and the future development trend of similar hazards. First, we collect the data of the prehazard precipitation, temperature and earthquake, as well as the seismic waves generated by the disaster. Second, we use multiple methods on the data, including the EPA and SPI computing methods, Fast Fourier transform (FFT), the engineering geological survey, the calculation method of landslide stability, the FLAC numerical simulation method and rock mechanics experiment, etc. Third, the processed data is analyzed, and the results are shown as follows: (1) The motivating factors of the 2000 CLDF were a long-term freeze-thaw cycle, a dry-wet cycle and an earthquake. It is reasonable that the Ms 4.8 earthquake was a direct inducing factor before the occurrence of the 2000 CLDF. (2) Based on the ground vibration spectrum recorded by the Linzhi seismic station, the dynamic processes of the 2000 LTDF have four processes, which are the joint and crack development process in the landslide, the crack fracture and sliding process, the landslide translating into the debris flow and the movement and deposition of the debris flow. (3) The density of the 2000 CLDF is 2.0 t·m-3, the average velocity of the 2000 CLDF is 30.12 m·s-1, and the discharge process of the 2000 CLDF first increases and then decreases. (4) Based on the adequately internal and external geological conditions, a CLDF of the Zhamunong gully may occur in the future. The research results are useful in establishing a foundation for further study on the dynamic mechanism of CLDFs and hazard reduction countermeasures.

2000-2020: Two Decades of Evolution of Hydraulic Fracturing-Induced Seismicity in the Western Canada Sedimentary Basin

2021 ◽  
Author(s):  
Germán Rodríguez-Pradilla ◽  
David Eaton ◽  
Melanie Popp
Keyword(s):  
Hydraulic Fracturing ◽  
Induced Seismicity ◽  
Sedimentary Basin ◽  
Unit Area ◽  
Critical Parameters ◽  
Seismic Events ◽  
Western Canada ◽  
Maximum Magnitude ◽  
Western Canada Sedimentary Basin ◽  
Canada Sedimentary Basin

Abstract The goal of this work is to calibrate a regional predictive model for maximum magnitude of seismic activity associated with hydraulic-fracturing in low-permeability formations in the Western Canada Sedimentary Basin (WCSB). Hydraulic fracturing data (i.e. total injected volume, injection rate, and pressure) were compiled from more than 40,000 hydraulic-fractured wells in the WCSB. These wells were drilled into more than 100 different formations over a 20-year period (January 1st, 2000 and January 1st, 2020). The total injected volume per unit area was calculated utilizing an area of 0.2° in longitude by 0.1° in latitude (or approximately 13x11km, somewhat larger than a standard township of 6x6 miles). This volume was then used to correlate with reported seismicity in the same unit areas. Collectively, within the 143 km2 area considered in this study, a correlation between the total injected volume and the maximum magnitude of seismic events was observed. Results are similar to the maximum-magnitude forecasting model proposed by A. McGarr (JGR, 2014) for seismic events induced by wastewater injection wells in central US. The McGarr method is also based on the total injected fluid per well (or per multiple nearby wells located in the same unit area). However, in some areas in the WCSB, lower injected fluid volumes than the McGarr model predicts were needed to induce seismic events of magnitude 3.0 or higher, although with a similar linear relation. The result of this work is the calculation of a calibration parameter for the McGarr model to better predict the magnitudes of seismic events associated with the injected volumes of hydraulic fracturing. This model can be used to predict induced seismicity in future unconventional hydraulic fracturing treatments and prevent large-magnitude seismic events from occurring. The rich dataset available from the WCSB allowed us to carry out a robust analysis of the influence of critical parameters (such as the total injected fluid) in the maximum magnitude of seismic events associated with the hydraulic-fracturing stimulation of unconventional wells. This analysis could be replicated for any other sedimentary basin with unconventional wells by compiling similar stimulation and earthquake data as in this study.

Contribution to the Vernonieae (Asteraceae) of the Cerrado: a transfer to Lessingianthus, in a new rank and with a new name

Phytotaxa ◽  
2015 ◽  
Vol 238 (1) ◽  
pp. 82
Author(s):  
Guilherme Medeiros Antar ◽  
BENOÎT LOEUILLE
Keyword(s):  
Leaf Surface ◽  
Mato Grosso ◽  
New Name ◽  
The North ◽  
Abaxial Leaf Surface ◽  
Leaf Surfaces ◽  
North Eastern ◽  
Northern Portion ◽  
Distrito Federal ◽  
First Time

Vernonia monocephala subsp. irwinii is a member of the genus Lessingianthus and is hereby transferred to that genus with a new status and a new name, L. semirii. It differs from L. monocephalus by its subsessile to petiolate (vs. sessile) leaves, largely attenuate (vs. rounded to attenuate) leaf bases, adaxial leaf surfaces drying black (vs. greenish), tomentose to velutinous (vs. villous) abaxial leaf surface and stem indument, and number of florets per head (up to 120 vs. up to 210). Both species are native to provinces of the Cerrado Domain, but they do not occur sympatrically: L. semirii is restricted to the North-eastern floristic province (Bahia, Maranhão, Tocantins and Pará states) and northern portion of the Central-western floristic province (Mato Grosso state), whereas L. monocephalus occurs in Distrito Federal and Goiás states in the Central-western, Central and South-eastern floristic provinces. Lessingianthus semirii is hereby described and illustrated for the first time; a distribution map is provided and affinities of this species are discussed.

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