scholarly journals Slow strain waves in blocky geological media from GPS and seismological observations on the Amurian plate

2016 ◽  
Author(s):  
Victor G. Bykov ◽  
Sergei V. Trofimenko
Keyword(s):  
Active Faults ◽  
Periodic Variation ◽  
Observation Data ◽  
Strain Waves ◽  
Crustal Block ◽  
Amurian Plate ◽  
Block Movement ◽  
Observation Series ◽  
New Evidence ◽  
Gps Station

Abstract. Based on the statistical analysis of spatiotemporal distribution of earthquake epicenters and perennial geodetic observation series, new evidence is obtained for the existence of slow strain waves in the Earth. The results of our investigation allow us to identify the dynamics of seismicity along the northern boundary of the Amurian plate as a wave process. Migration of epicenters of weak earthquakes (2 ≤ М ≤ 4) is initiated by the east-west propagation of a strain wave front at an average velocity of 2.7 km/day. We have found a synchronous quasi-periodic variation of seismicity in equally spaced clusters with spatial periods of 3.5° and 7.26° comparable with the length of slow strain waves. The geodetic observations at GPS sites in proximity to local active faults show that in a number of cases, the GPS site coordinate seasonal variations exhibit a significant phase shift, whereas the time series of these GPS sites differ significantly from a sinusoid. Based on experimental observation data and the developed model of crustal block movement we have shown that there is one possible interpretation for this fact that the trajectory of GPS station position disturbance is induced by migrating of crustal deformation in the form of slow waves.

scholarly journals Slow strain waves in blocky geological media from GPS and seismological observations on the Amurian plate

2016 ◽  
Vol 23 (6) ◽  
pp. 467-475 ◽  
Author(s):  
Victor G. Bykov ◽  
Sergey V. Trofimenko
Keyword(s):  
Active Faults ◽  
Periodic Variation ◽  
Observation Data ◽  
Strain Waves ◽  
Crustal Block ◽  
Amurian Plate ◽  
Block Movement ◽  
Observation Series ◽  
New Evidence ◽  
Gps Station

Abstract. Based on the statistical analysis of spatiotemporal distribution of earthquake epicenters and perennial geodetic observation series, new evidence is obtained for the existence of slow strain waves in the Earth. The results of our investigation allow us to identify the dynamics of seismicity along the northern boundary of the Amurian plate as a wave process. Migration of epicenters of weak earthquakes (2 ≤  M ≤ 4) is initiated by the east–west propagation of a strain wave front at an average velocity of 1000 km yr−1. We have found a synchronous quasi-periodic variation of seismicity in equally spaced clusters with spatial periods of 3.5 and 7.26° comparable with the length of slow strain waves. The geodetic observations at GPS sites in proximity to local active faults show that in a number of cases, the GPS site coordinate seasonal variations exhibit a significant phase shift, whereas the time series of these GPS sites differ significantly from a sinusoid. Based on experimental observation data and the developed model of crustal block movement, we have shown that there is one possible interpretation for this fact that the trajectory of GPS station position disturbance is induced by migration of crustal deformation in the form of slow waves.

scholarly journals Empirical Relationship for Assessing the Near-Field Horizontal Coseismic Displacement Using GPS Seismology Data

2021 ◽  
Vol 60 (1) ◽  
pp. 31-50
Author(s):  
Ryad Darawcheh ◽  
Riad Al Ghazzi ◽  
Mohamad Khir Abdul-wahed
Keyword(s):  
Near Field ◽  
Empirical Relationship ◽  
Active Faults ◽  
Historical Earthquakes ◽  
Dead Sea ◽  
Fault System ◽  
Coseismic Displacement ◽  
Data Set ◽  
Earthquake Parameters ◽  
Gps Station

In this research, a data set of horizontal GPS coseismic displacement in the near-field has been assembled around the world in order to investigate a potential relationship between the displacement and the earthquake parameters. Regression analyses have been applied to the data of 120 interplate earthquakes having the magnitude (Mw 4.8-9.2). An empirical relationship for prediction near-field horizontal GPS coseismic displacement as a function of moment magnitude and the distance between hypocenter and near field GPS station has been established using the multi regression analysis. The obtained relationship allows assessing the coseismic displacements associated with some large historical earthquakes occurred along the Dead Sea fault system. Such a fair relationship could be useful for assessing the coseismic displacement at any point around the active faults.

scholarly journals Comment on: “Interseismic Strain Accumulation near Lisbon (Portugal) from Space Geodesy” by Fonseca et al. (2021)

2021 ◽  
Author(s):  
Luis Matias
Keyword(s):  
Relative Velocity ◽  
Strain Accumulation ◽  
Geophysical Research ◽  
First Order ◽  
Crustal Block ◽  
Tectonic Lineament ◽  
The Moment ◽  
Gnss Data ◽  
Strain Rate Field ◽  
New Evidence

The paper by Fonseca et al. (2021), hereafter referred as FON21, published in Geophysical Research Letters2 make several conclusions that are not convincingly supported by the evidence of the data that is made available. In this comment we will address the following statements: 1) FON21 “provides new evidence of sinistral simple shear driven by a NNE-SSW first-order tectonic lineament; 2) “PSInSAR vertical velocities corroborate qualitatively the GNSS strain-rate field, showing uplift/subsidence where the GNSS data indicate contraction/extension”; 3) FON21 proposes “the presence of a small block to the W of Lisbon moving independently toward the SW with a relative velocity of 0.96 ± 0.20 mm/yr”; 4) FON21 shows “that the contribution of intraplate faults to the seismic hazard in the LMA is more important than currently assumed”. We conclude that more evidence needs to be collected to confirm or infirm FON21 statements and conclusions. For the moment the proposal of an autonomous crustal block moving with significant velocity in relation to the neighboring domain should be considered speculative and unproved.

A test development of a data driven model to simulate chlorophyll data at Tongyeong bay in Korea

2020 ◽  
Author(s):  
Sung Dae Kim ◽  
Sang Hwa Choi
Keyword(s):  
Solar Radiation ◽  
Periodic Variation ◽  
Training Data ◽  
Training Dataset ◽  
Sequence Length ◽  
Observation Data ◽  
The Public ◽  
Ocean Science ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Hidden Layer

<p>A pilot machine learning(ML) program was developed to test ML technique for simulation of biochemical parameters at the coastal area in Korea. Temperature, chlorophyll, solar radiation, daylight time, humidity, nutrient data were collected as training dataset from the public domain and in-house projects of KIOST(Korea Institute of Ocean Science & Technology). Daily satellite chlorophyll data of MODIS(Moderate Resolution Imaging Spectroradiometer) and GOCI(Geostationary Ocean Color Imager) were retrieved from the public services. Daily SST(Sea Surface Temperature) data and ECMWF solar radiation data were retrieved from GHRSST service and Copernicus service. Meteorological observation data and marine observation data were collected from KMA (Korea Meteorological Agency) and KIOST. The output of marine biochemical numerical model of KIOST were also prepared to validate ML model. ML program was configured using LSTM network and TensorFlow. During the data processing process, some chlorophyll data were interpolated because there were many missing data exist in satellite dataset. ML training were conducted repeatedly under varying combinations of sequence length, learning rate, number of hidden layer and iterations. The 75% of training dataset were used for training and 25% were used for prediction. The maximum correlation between training data and predicted data was 0.995 in case that model output data were used as training dataset. When satellite data and observation data were used, correlations were around 0.55. Though the latter corelation is relatively low, the model simulated periodic variation well and some differences were found at peak values. It is thought that ML model can be applied for simulation of chlorophyll data if preparation of sufficient reliable observation data were possible.</p>

scholarly journals Recent Changes in Temperature and Precipitation of the Summer and Autumn Seasons over Fujian Province, China

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1900
Author(s):  
Zhiguo Ma ◽  
Qinyu Guo ◽  
Feiyue Yang ◽  
Huiling Chen ◽  
Wenqing Li ◽  
...  
Keyword(s):  
Periodic Variation ◽  
Annual Precipitation ◽  
Trend Test ◽  
Observation Data ◽  
Fujian Province ◽  
Average Temperature ◽  
Temperature And Precipitation ◽  
Seasonal Oscillation ◽  
Variation Characteristics ◽  
Major Cycle

Based on the observation data of daily temperature and precipitation in summer and autumn of 68 representative meteorological stations in Fujian Province from 1971 to 2018, using the climate Tendency Rate, Mann-Kendall trend test, Morlet wavelet analysis and other methods, this paper analyzes the variation trends of air temperature and annual precipitation and the wavelet periodic variation characteristics of annual precipitation time series in summer and autumn of Fujian Province over a period of approximately 48 years. The results show that over the approximately 48 years, the temperature and precipitation in summer and autumn in Fujian showed an obvious upward trend, which had a mutation around 2000, but the mutation time was different, and the precipitation was slightly earlier. The annual temperature and precipitation in summer and autumn experienced three oscillations on the 28a scale. In the 28a time scale of summer autumn seasonal oscillation, there are three negative centers and two positive centers. According to the characteristics of annual average temperature and annual precipitation in the first major cycle, the annual precipitation in summer and autumn will continue to increase in the future.

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