Gravity Changes Before and After the 2008 Mw 7.9 Wenchuan Earthquake at Pixian Absolute Gravity Station in More Than a Decade

2019 ◽  
Vol 177 (1) ◽  
pp. 121-133 ◽  
Author(s):  
Yong Zhang ◽  
Shi Chen ◽  
Lelin Xing ◽  
Mian Liu ◽  
Zhitang He
Keyword(s):  
Wenchuan Earthquake ◽  
Absolute Gravity ◽  
Gravity Station ◽  
Gravity Changes ◽  
Before And After

Gravity changes before and after the 2015 Mw7.8 Nepal earthquake

2020 ◽  
Author(s):  
Weimin Xu ◽  
Shi Chen ◽  
Hongyan Lu
Keyword(s):  
Source Region ◽  
Absolute Gravity ◽  
Nepal Earthquake ◽  
Source Regions ◽  
Gravity Changes ◽  
Seismogenic Source ◽  
Before And After ◽  
Gravity Measurements ◽  
The Absolute ◽  
Regional Gravity

<p>Based on the absolute gravity measurements of 4 gravimetric stations (Shigatse, Zhongba, Lhasa and Naqu) in southern Tibet surveyed from 2010 to 2013, we modeled the source region as a disk of 580 km in diameter by Hypocentroid model, shown that the gravity increase at these stations may be related to mass changes in the source region of the 2015 Mw7.8 Nepal earthquake. We analyzed the characteristics of gravity variations from the repeated regional gravity network, which including the 4 absolute gravimetric stations and 13 relative gravimetric stations from 2010 to 2019, to study the characteristics of gravity changes before and after the earthquake.</p><p>We firstly estimated the reliability of the absolute gravity measurements by the errors of each station, and considered the effect of vertical displacement, denudation of surface mass, GIA correction and the secular and background gravity changes. Secondly we employed the Bayesian adjustment method for the relative gravimetric network data analysis, which was more robust and adaptive for solving problems caused by irregular nonlinear drift of different gravimeters, and then carried out error analysis for the repeated relative gravity measurements. Furthermore, we took the Shigatse station as example, which covered absolute and relative measurements and was most close to the Hypocenter of the inversion Hypocentroid model, the hydrologic effects of the Shigatse station was modeled exactly, and the results shown that the secular and background gravity changes were much smaller than the observed gravity changes. Lastly we studied the characteristics of gravity changes before and after the earthquake through the Hypocentroid model, we found the coincident gravity increase both in absolute and repeated regional gravity results before the earthquake, and gravity decreased after the earthquake, which suggested that the pre-earthquake gravity increase may be caused by strain and mass (fluid) transfer in broad seismogenic source regions of the earthquake. Moreover, the study indicated that high-precision ground gravity measurements (absolute and relative) may provide a useful method for monitoring mass changes in the source regions of potential large earthquakes.</p><p> </p><p><strong>Acknowledgment: </strong>This research is supported by National Key R&D Program of China (Grant No.2018YFC1503806 and No.2017YFC1500503) and National Natural Science Foundation of China (Grant No.U1939205 and No.41774090).</p>

scholarly journals Thirty years of precise gravity measurements at Mt. Vesuvius: an approach to detect underground mass movements

2013 ◽  
Vol 56 (4) ◽  
Author(s):  
Giovanna Berrino ◽  
Vincenzo d’Errico ◽  
Giuseppe Ricciardi
Keyword(s):  
Ground Deformation ◽  
Reference Station ◽  
Absolute Gravity ◽  
Volcanic Area ◽  
Gravity Station ◽  
Gravity Changes ◽  
Gravity Measurements ◽  
Elevation Changes ◽  
Gravity Network

<p>Since 1982, high precision gravity measurements have been routinely carried out on Mt. Vesuvius. The gravity network consists of selected sites most of them coinciding with, or very close to, leveling benchmarks to remove the effect of the elevation changes from gravity variations. The reference station is located in Napoli, outside the volcanic area. Since 1986, absolute gravity measurements have been periodically made on a station on Mt. Vesuvius, close to a permanent gravity station established in 1987, and at the reference in Napoli. The results of the gravity measurements since 1982 are presented and discussed. Moderate gravity changes on short-time were generally observed. On long-term significant gravity changes occurred and the overall fields displayed well defined patterns. Several periods of evolution may be recognized. Gravity changes revealed by the relative surveys have been confirmed by repeated absolute measurements, which also confirmed the long-term stability of the reference site. The gravity changes over the recognized periods appear correlated with the seismic crises and with changes of the tidal parameters obtained by continuous measurements. The absence of significant ground deformation implies masses redistribution, essentially density changes without significant volume changes, such as fluids migration at the depth of the seismic foci, i.e. at a few kilometers. The fluid migration may occur through pre-existing geological structures, as also suggested by hydrological studies, and/or through new fractures generated by seismic activity. This interpretation is supported by the analyses of the spatial gravity changes overlapping the most significant and recent seismic crises.</p>

MULTIFRACTAL FLUCTUATIONS OF JIUZHAIGOU TOURISTS BEFORE AND AFTER WENCHUAN EARTHQUAKE

Fractals ◽  
2013 ◽  
Vol 21 (01) ◽  
pp. 1350001 ◽  
Author(s):  
KAI SHI ◽  
WEN-YONG LI ◽  
CHUN-QIONG LIU ◽  
ZHENG-WEN HUANG
Keyword(s):  
Wenchuan Earthquake ◽  
Moving Average ◽  
Long Term Memory ◽  
Short Term ◽  
Dynamical Mechanism ◽  
Before And After ◽  
Previous State ◽  
Multifractal Behavior ◽  
Multifractal Nature

In this work, multifractal methods have been successfully used to characterize the temporal fluctuations of daily Jiuzhai Valley domestic and foreign tourists before and after Wenchuan earthquake in China. We used multifractal detrending moving average method (MF-DMA). It showed that Jiuzhai Valley tourism markets are characterized by long-term memory and multifractal nature in. Moreover, the major sources of multifractality are studied. Based on the concept of sliding window, the time evolutions of the multifractal behavior of domestic and foreign tourists were analyzed and the influence of Wenchuan earthquake on Jiuzhai Valley tourism system dynamics were evaluated quantitatively. The study indicates that the inherent dynamical mechanism of Jiuzhai Valley tourism system has not been fundamentally changed from long views, although Jiuzhai Valley tourism system was seriously affected by the Wenchuan earthquake. Jiuzhai Valley tourism system has the ability to restore to its previous state in the short term.

scholarly journals Monsoonal control on a delayed response of sedimentation to the 2008 Wenchuan earthquake

2019 ◽  
Vol 5 (6) ◽  
pp. eaav7110 ◽  
Author(s):  
Fei Zhang ◽  
Zhangdong Jin ◽  
A. Joshua West ◽  
Zhisheng An ◽  
Robert G. Hilton ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Transport Processes ◽  
Delayed Response ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Depositional Processes ◽  
Before And After ◽  
Sediment Transfer ◽  
Large Earthquakes ◽  
Earthquake Cycles

Infrequent extreme events such as large earthquakes pose hazards and have lasting impacts on landscapes and biogeochemical cycles. Sediments provide valuable records of past events, but unambiguously identifying event deposits is challenging because of nonlinear sediment transport processes and poor age control. Here, we have been able to directly track the propagation of a tectonic signal into stratigraphy using reservoir sediments from before and after the 2008 Wenchuan earthquake. Cycles in magnetic susceptibility allow us to define a precise annual chronology and identify the timing and nature of the earthquake’s sedimentary record. The grain size and Rb/Sr ratio of the sediments responded immediately to the earthquake. However, the changes were muted until 2 years after the event, when intense monsoonal runoff drove accumulation of coarser grains and lower Rb/Sr sediments. The delayed response provides insight into how climatic and tectonic agents interact to control sediment transfer and depositional processes.

Hydrothermal fluid migration due to interaction with shallow magma: Insights from gravity changes before and after the 2015 eruption of Cotopaxi volcano, Ecuador

2019 ◽  
Vol 387 ◽  
pp. 106667 ◽  
Author(s):  
Antonina Calahorrano-Di Patre ◽  
Glyn Williams-Jones ◽  
Maurizio Battaglia ◽  
Patricia Mothes ◽  
Elizabeth Gaunt ◽  
...  
Keyword(s):  
Hydrothermal Fluid ◽  
Fluid Migration ◽  
Gravity Changes ◽  
Cotopaxi Volcano ◽  
Before And After

Gravity Changes Associated with theMs8.0 Wenchuan Earthquake Detected by GRACE

2010 ◽  
Vol 53 (4) ◽  
pp. 542-554 ◽  
Author(s):  
Wu-Xing WANG ◽  
Yao-Lin SHI ◽  
Guo-Hua GU ◽  
Jing ZHANG ◽  
Shi CHEN
Keyword(s):  
Wenchuan Earthquake ◽  
Gravity Changes

Analysis of the River Flow and Sediment Concentration Change before and after Wenchuan Earthquake

2013 ◽  
Vol 316-317 ◽  
pp. 236-240
Author(s):  
Feng Qian ◽  
Bo Hu ◽  
Jing Jun Liu ◽  
Ming Biao Xiong ◽  
Heng Hu
Keyword(s):  
River Water ◽  
Wenchuan Earthquake ◽  
River Flow ◽  
Sediment Concentration ◽  
Concentration Data ◽  
Soil And Water Loss ◽  
Monthly Average ◽  
Obvious Change ◽  
Before And After ◽  
Regional Influence

Wenchuan earthquake triggered floods, landslide, collapse and secondary geological disaster,trigger a new soil and water loss, having the significant influence to the local river water quality.According to shaba and jiangyou station 2006 January to 2011 December flow and sediment concentration data for statistical analysis, this paper discusses the disaster area river water and sediment changes on the influence of river water quality before and after the earthquake. Results show that,the monthly average flow change trend does not take place obvious change before and after the earthquake,during the earthquake the monthly average sediment concentration is higher than any other in the same period of monthly average sediment concentration,jiangyou station and shaba station the average daily flow rate on May has no obvious change before and after earthquake, the earthquake for different regional influence is different , different regions of different section of the average sediment coefficient has certain space diversity,in jiangyou station the average sediment coefficient before the earthquake is more than the average sediment coefficient after the earthquake but the change of average sediment coefficient in shaba station was not significant before and after the earthquake.

scholarly journals Research on absolute gravity variations in geodynamic laboratory in Książ in the period of 2007- 2011

2012 ◽  
Vol 47 (4) ◽  
pp. 169-176 ◽  
Author(s):  
Marek Kaczorowski ◽  
Tomasz Olszak ◽  
Janusz Walo ◽  
Marcin Barlik
Keyword(s):  
Extreme Values ◽  
Absolute Gravity ◽  
Absolute Gravimeter ◽  
Gravimetric Measurements ◽  
Gravity Changes ◽  
University Of Technology ◽  
Gravity Measurements ◽  
Water Level Variations ◽  
Gravimetric System ◽  
Absolute Measurements

ABSTRACT In 2006 a gravimetric pavilion was installed inside the Geodynamic Laboratory (LG) in Książ. The pavilion was equipped with two pillars intended to serve relative and absolute gravimetric measurements. Installation of measurement platform for absolute gravity measurements inside gravimetric pavilion of LG made it possible to perform four sessions of absolute gravity measurements: two of them in 2007 (June 10-12 and Nov. 21-22), one in 2008 (Apr. 21-22) and one in 2011 (June 19-21). In 2007 the absolute measurements were performed using two FG5 ballistic gravimeters. In April 2007 the measurements were performed by Dr Makinen from Geodetic Institute of Finnish Academy of Science with application of FG5 No. 221 absolute gravimeter. In June 2007 and in the years 2008 and 2011 such gravimetric measurements were performed by the team from Department of Geodesy and Astronomical Geodesy of Warsaw University of Technology using FG5 No. 230 absolute gravimeter. Elaboration of observation sessions from both gravimeters was performed in the Department of Higher Geodesy following the procedures used in constituting of uniform gravimetric system of geodynamic polygons reference. This constituting of gravimetric system comprised inter alia application of identical models of lithospheric tides (global model by Wenzel, 1997) and ocean tides (Schwiderski, 1980) (reduction of absolute measurements with tidal signals). Observations performed during summer of 2007, autumn of 2007, and spring of 2008 and 2011 indicated existence of small changes of absolute gravity of the order of 1 Gal. Maxima of accelerations appear in the spring period, and minima in the autumn period. This effect is connected with the influence of global hydrological factors the annual amplitude of which is ca 1,5 Gal and achieve extreme values in the spring-autumn interval. Very small value of observed amplitude of gravity changes in the period of extreme variability suggests that the observed gravity changes in LG are caused only by global phenomenon. This proves high degree of „independence” of gravimetric measurement base in LG from the local environmental factors such as ground water level variations, ground humidity, impact of snow cover, etc. At this moment the instrumental environment of absolute measurements obtains particular value, especially in the case of the tiltmeters and relative the gravimeter Lacoste& Romberg (LR-648). The relative gravity measurements as performed simultaneously with absolute gravity measurements enable us to determine the local tidal ephemeredes which makes it possible to replace the global tidal modal with ocean tidal model with the more realistic, locally determined tidal parameters (the local tidal ephemeredes).

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