scholarly journals Analysis of Spatiotemporal variations in mid-upper tropospheric methane during the Wenchuan Ms8.0 earthquake by three indices

2019 ◽  
Author(s):  
Jing Cui ◽  
Xuhui Shen
Keyword(s):  
Methane Concentration ◽  
Vertical Direction ◽  
Background Field ◽  
Gradient Index ◽  
Average Increase ◽  
Longmenshan Fault Zone ◽  
Deep Crust ◽  
Distribution Features ◽  
Before And After ◽  
Longmenshan Fault

Abstract. This research studied the spatiotemporal variation in methane in the mid-upper troposphere during the Wenchuan earthquake (12 May, 2008) using AIRS retrieval data and discussed the methane anomaly mechanism. Three indices were proposed and used for analysis. Our results show that the methane concentration increased significantly in 2008, with an average increase of 5.12 * 10−8, compared to the average increase of 1.18 * 10−8 in the previous five years. The Alice and Diff indices can be used to identify methane concentration anomalies. The two indices showed that the methane concentration distribution before and after the earthquake broke the distribution features of the background field. As the earthquake approached, areas of high methane concentration gradually converged towards the west side of the epicenter from both ends of the Longmenshan fault zone. Moreover, a large anomalous area was centered at the epicenter eight days before the earthquake occurred, and a trend of strengthening, weakening and strengthening appeared over time. The Gradient index showed that the vertical direction obviously increased before the main earthquake, and the value was positive. The gradient value is negative during coseismic or postseismic events. The gradient index reflects the gas emission characteristics to some extent. We also determined that the methane release was connected with the deep crust-mantle stress state, as well as microfracture generation and expansion. However, due to the lack of any technical means to accurately identify the source and content of methane in the atmosphere before the earthquake, an in-depth discussion has not been conducted, and further studies on this issue may be needed.

scholarly journals Analysis of spatiotemporal variations in middle-tropospheric to upper-tropospheric methane during the Wenchuan <i>M</i><sub>s</sub> = 8.0 earthquake by three indices

2019 ◽  
Vol 19 (12) ◽  
pp. 2841-2854 ◽  
Author(s):  
Jing Cui ◽  
Xuhui Shen ◽  
Jingfa Zhang ◽  
Weiyu Ma ◽  
Wei Chu
Keyword(s):  
Methane Concentration ◽  
Vertical Direction ◽  
Background Field ◽  
Gradient Index ◽  
Average Increase ◽  
Local Index ◽  
Deep Crust ◽  
Distribution Features ◽  
Before And After ◽  
Longmenshan Fault

Abstract. This research studied the spatiotemporal variation in methane in the middle to upper troposphere during the Wenchuan earthquake (12 May 2008) using AIRS retrieval data and discussed the methane anomaly mechanism. Three indices were proposed and used for analysis. Our results show that the methane concentration increased significantly in 2008, with an average increase of 5.12×10-8, compared to the average increase of 1.18×10-8 in the previous 5 years. The absolute local index of change of the environment (ALICE) and differential value (diff) indices can be used to identify methane concentration anomalies. The two indices showed that the methane concentration distribution before and after the earthquake broke the distribution features of the background field. As the earthquake approached, areas of high methane concentration gradually converged towards the west side of the epicenter from both ends of the Longmenshan fault zone. Moreover, a large anomalous area was centered at the epicenter 8 d before the earthquake occurred, and a trend of strengthening, weakening and strengthening appeared over time. The gradient index showed that the vertical direction obviously increased before the main earthquake and that the value was positive. The gradient value is negative during coseismic or post-seismic events. The gradient index reflects the gas emission characteristics to some extent. We also determined that the methane release was connected with the deep crust–mantle stress state, as well as micro-fracture generation and expansion. However, due to the lack of any technical means to accurately identify the source and content of methane in the atmosphere before the earthquake, an in-depth discussion has not been conducted, and further studies on this issue may be needed.

scholarly journals Mapping the <i>b</i>-values along the Longmenshan fault zone before and after the 12 May 2008, Wenchuan, China, <i>M<sub>S</sub></i> 8.0 earthquake

2008 ◽  
Vol 8 (6) ◽  
pp. 1375-1385 ◽  
Author(s):  
Y. Z. Zhao ◽  
Z. L. Wu
Keyword(s):  
Fault Zone ◽  
High Stress ◽  
B Value ◽  
Slip Distribution ◽  
Longmenshan Fault Zone ◽  
Magnitude Distribution ◽  
The North ◽  
Significant Difference ◽  
Before And After ◽  
Longmenshan Fault

Abstract. The b-value in the Gutenberg-Richter frequency-magnitude distribution, which is assumed to be related to stress heterogeneity or asperities, was mapped along the Longmenshan fault zone which accommodated the 12 May 2008, Wenchuan, MS 8.0 earthquake. Spatial distributions of b-value before and after the Wenchuan earthquake, respectively, were compared with the slip distribution of the mainshock. It is shown that the mainshock rupture nucleated near to, but not within, the high-stress (low b-value) asperity in the south part of the Longmenshan fault, propagating north-eastward to the relatively low stress (high b-value) region. Due to the significant difference between the rupture process results from different sources, the comparison between slip distribution and pre-seismic b-value distribution leads to only conclusion of the rule-of-thumb. The temporal change of b-value before the mainshock shows a weak trend of decreasing, being hard to be used as an indicator of the approaching of the mainshock. Distribution of b-values for the aftershocks relates the termination of the mainshock rupture to the harder patch along the Longmenshan fault to the north.

scholarly journals Seismic Structure of Local Crustal Earthquakes beneath the Zipingpu Reservoir of Longmenshan Fault Zone

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Haiou Li ◽  
Xiwei Xu ◽  
Wentao Ma ◽  
Ronghua Xie ◽  
Jingli Yuan ◽  
...  
Keyword(s):  
Fault Zone ◽  
Three Dimensional ◽  
P Wave ◽  
The Tibetan Plateau ◽  
Seismic Structure ◽  
Infiltration Depth ◽  
Low Velocity ◽  
Longmenshan Fault Zone ◽  
Velocity Models ◽  
Longmenshan Fault

Three-dimensional P wave velocity models under the Zipingpu reservoir in Longmenshan fault zone are obtained with a resolution of 2 km in the horizontal direction and 1 km in depth. We used a total of 8589 P wave arrival times from 1014 local earthquakes recorded by both the Zipingpu reservoir network and temporary stations deployed in the area. The 3-D velocity images at shallow depth show the low-velocity regions have strong correlation with the surface trace of the Zipingpu reservoir. According to the extension of those low-velocity regions, the infiltration depth directly from the Zipingpu reservoir itself is limited to 3.5 km depth, while the infiltration depth downwards along the Beichuan-Yingxiu fault in the study area is about 5.5 km depth. Results show the low-velocity region in the east part of the study area is related to the Proterozoic sedimentary rocks. The Guanxian-Anxian fault is well delineated by obvious velocity contrast and may mark the border between the Tibetan Plateau in the west and the Sichuan basin in the east.

Perbedaan Pengetahuan Remaja Putri Sebelum Dan Sesudah Diberikan Penyuluhan Tentang Fluor Albus Di SMP Negeri 3 Penebel

2019 ◽  
Vol 2 (1) ◽  
pp. 18-23
Author(s):  
Kadek Sri Ariyanti ◽  
Rini Winangsih ◽  
Desak Made Firsia Sastra Putri
Keyword(s):  
Reproductive Health ◽  
Adolescent Girls ◽  
Young Women ◽  
Random Sampling ◽  
Statistical Test ◽  
Wilcoxon Test ◽  
Average Score ◽  
Average Increase ◽  
Before And After ◽  
Test Result

Background and purpose: Adolescence is a period of transition from childhood to adulthood. The problems facing adolescents are often related to reproductive health, one of which is fluorine albus. Many teenagers do not care about the fluoride of albus despite the enormous impact on women's reproductive health. One reason is the lack of knowledge about fluorine albus. Based on KISARA data there are 90.91% of girls in Denpasar City do not know the cause of fluorine albus. The purpose of this study was to determine differences in knowledge of young women before and after being given counseling about fluor albus. Method: The research design used was pre-experimental with one group pretest posttest design using 70 respondents taken by stratified random sampling. The results showed that the average score of adolescent girls' knowledge about fluor albus before being given counseling was 11.56 and after counseling was 14.23. There was an average increase in knowledge of 2.67. Results: Statistical test result using wilcoxon test get value p = 0.000 so that hypothesis accepted. Conculusion: It can be concluded that there is difference of adolescent knowledge about fluorine albus before and after given counseling.

scholarly journals Evaluation of crustal inhomogeneity parameters in the southern Longmenshan fault zone and adjacent regions

2020 ◽  
Vol 24 (6) ◽  
pp. 1175-1188
Author(s):  
Xiao-Ping Fan ◽  
Yi-Cheng He ◽  
Cong-Jie Yang ◽  
Jun-Fei Wang
Keyword(s):  
Fault Zone ◽  
Lower Crust ◽  
Tectonic Deformation ◽  
Upper Crust ◽  
Crust And Upper Mantle ◽  
Study Region ◽  
Waveform Data ◽  
Longmenshan Fault Zone ◽  
Deformation Features ◽  
Longmenshan Fault

AbstractBroadband teleseismic waveform data from 13 earthquakes recorded by 70 digital seismic stations were selected to evaluate the inhomogeneity parameters of the crustal medium in the southern Longmenshan fault zone and its adjacent regions using the teleseismic fluctuation wavefield method. Results show that a strong inhomogeneity exists beneath the study region, which can be divided into three blocks according to its structure and tectonic deformation features. These are known as the Sichuan-Qinghai Block, the Sichuan-Yunnan Block, and the Mid-Sichuan Block. The velocity fluctuation ratios of the three blocks are approximately 5.1%, 3.6%, and 5.1% in the upper crust and 5.1%, 3.8%, and 4.9% in the lower crust. The inhomogeneity correlation lengths of the three blocks are about 10.1 km, 14.0 km, and 10.7 km in the upper crust and 11.8 km, 17.0 km, and 11.8 km in the lower crust. The differences in the crustal medium inhomogeneity beneath the Sichuan-Yunnan Block, the Sichuan-Qinghai Block, and the Mid-Sichuan Block may be related to intensive tectonic movement and material flow in the crust and upper mantle.

Distinct tectonic activities in Guangxi, China due to large earthquakes on the Longmenshan fault zone

2020 ◽  
Vol 307 ◽  
pp. 106557
Author(s):  
Huaizhong Yu ◽  
Jing Zhao ◽  
Xiaoxia Liu ◽  
Chen Yu ◽  
Chong Yue ◽  
...  
Keyword(s):  
Fault Zone ◽  
Longmenshan Fault Zone ◽  
Longmenshan Fault ◽  
Large Earthquakes ◽  
Tectonic Activities

Seismic Potential Around the Northeastern Edge of the Longmenshan Fault Zone as Inferred from Seismological Observations

2019 ◽  
Vol 177 (1) ◽  
pp. 37-53 ◽  
Author(s):  
Reiken Matsushita ◽  
Kazutoshi Imanishi ◽  
Makiko Ohtani ◽  
Yasuto Kuwahara ◽  
Jiuhui Chen ◽  
...  
Keyword(s):  
Fault Zone ◽  
Longmenshan Fault Zone ◽  
Seismic Potential ◽  
Longmenshan Fault

scholarly journals Anatomy of a buckling galactic bar

2019 ◽  
Vol 629 ◽  
pp. A52 ◽  
Author(s):  
Ewa L. Łokas
Keyword(s):  
Outer Part ◽  
Vertical Direction ◽  
Dark Matter Halo ◽  
Stellar Disk ◽  
Stellar Orbits ◽  
Buckling Instability ◽  
Bending Waves ◽  
Before And After ◽  
The Galaxy ◽  
Circular Frequency

Using N-body simulations we study the buckling instability in a galactic bar forming in a Milky Way-like galaxy. The galaxy is initially composed of an axisymmetric, exponential stellar disk embedded in a spherical dark matter halo. The parameters of the model are chosen so that the galaxy is mildly unstable to bar formation and the evolution is followed for 10 Gyr. A strong bar forms slowly over the first few gigayears and buckles after 4.5 Gyr from the start of the simulation becoming much weaker and developing a pronounced boxy/peanut shape. We measure the properties of the bar at the time of buckling in terms of the mean acceleration, velocity, and distortion in the vertical direction. The maps of these quantities in face-on projections reveal characteristic quadrupole patterns which wind up over a short timescale. We also detect a secondary buckling event lasting much longer and occurring only in the outer part of the bar. We then study the orbital structure of the bar in periods before and after the first buckling. We find that most of the buckling orbits originate from x1 orbits supporting the bar. During buckling the ratio of the vertical to horizontal frequency of the stellar orbits decreases dramatically and after buckling the orbits obey a very tight relation between the vertical and circular frequency: 3ν = 4Ω. We propose that buckling is initiated by the vertical resonance of the x1 orbits creating the initial distortion of the bar that later evolves as kinematic bending waves.

scholarly journals Influence of water and lubricant fluids on peak strength of Queenston shale from southern Ontario

2018 ◽  
Vol 55 (4) ◽  
pp. 455-476
Author(s):  
Hayder Mohammed Salim Al-Maamori ◽  
Mohamed Hesham El Naggar ◽  
Silvana Micic ◽  
K.Y. Lo
Keyword(s):  
Mechanical Properties ◽  
Polymer Solution ◽  
Laboratory Tests ◽  
Triaxial Compression ◽  
Vertical Direction ◽  
Southern Ontario ◽  
Construction Period ◽  
Before And After ◽  
Influence Of Water ◽  
Similar Decrease

The strength of Milton Queenston shale (MQS) before and after soaking in water and lubricant fluids (LFs) was examined. The investigated LFs (i.e., bentonite and polymer solutions) are utilized in the microtunnelling technique (MTT) to facilitate the installation of tunnel or pipe sections. To investigate the relevant mechanical properties of MQS under different wetting conditions, a series of laboratory tests including Brazilian split, uniaxial compression, and triaxial compression were carried out. These tests were performed on vertically and horizontally cored specimens with respect to the rock bedding. Fresh specimens (i.e., intact) and specimens soaked for 100 days in LFs and in water were examined. The 100 day period was selected, as it may reasonably represent the construction period where some swelling of the Queenston shale can occur. It was revealed that the strength of MQS substantially decreased after soaking. With greater impact in the vertical direction, both water and bentonite solution caused similar decrease in MQS strength of 23%–70%, while polymer solution caused a smaller decrease of 10%–57%. Accordingly, strength envelopes of MQS were established for vertical and horizontal directions before and after soaking.

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