Earthquake precursors: spatial-temporal gravity changes before the great earthquakes in the Sichuan-Yunnan area

Zhu, Yongnan; Weifeng, Liang; Zhang, Song

doi:10.1007/s10950-017-9700-2

Cited by 9 publications

(5 citation statements)

References 8 publications

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“…No research conclusion can be referred to for the probability distribution form of the selected random sampling variables. However, if the expectation E(X) = µ and the variance D(X) = σ 2 > 0 of a random variable X, then for different values of the vector {X n }, when n is large enough (the sample size of 30 is generally considered to be sufficient), the mean value X n of {X n } will approximately obey a normal distribution, denoted as X n µ, σ 2 /n , as shown in Equation (3).…”

Section: Methods For Building the Sample Spacementioning

confidence: 99%

“…The former is a data-driven method, and the reliability of the calculation results depends mainly on the accumulation of historical seismic hazard data. In contrast, there is still a need for more historical seismic hazard data [3,4], and their practical application is limited to a certain extent [5]. At the same time, the assessment results of this type of method are biased toward the macro, the assessment accuracy of individual needs to be improved, and it is difficult to reflect the differences between individual buildings of the same type.…”

Section: Introductionmentioning

confidence: 99%

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A Story-Based Random Structure Modeling Method for Regional Buildings Earthquake Loss Estimation

Yang,

Lu,

Xiong

2024

Applied Sciences

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To estimate earthquake losses for regional buildings, it is important to consider the varying seismic performances of different types of buildings. To achieve this, a dynamic elastic–plastic analysis based on detailed structural modeling is more accurate than the capacity spectrum method based on a single degree of freedom to obtain the response and damage of various structures under seismic activity and provide a more precise estimate of earthquake losses for buildings. Detailed information about the building facilities is necessary to create a fine structural model. However, obtaining precise actual structural details can be challenging with existing methods, especially when there are a large number of buildings to consider. This paper proposes a new method called story-based random structure (SBRS) modeling to address this issue, which is based on the common and reasonable layout of the structure. The process involves choosing design parameters that can represent the structural arrangement of a building as variables. These parameters include the materials’ type and strength, proportions, the components’ size, and other relevant factors. The values for these variables are determined based on engineering experience and design specifications. The range of values for these variables is also determined to ensure that all design requirements are met. Finally, the Latin Hypercubic Sampling (LHS) method is used to randomly sample and combine the variables, establishing a detailed structural model of the building with structural uncertainty. According to the results of the analysis, this method can simulate the structure and component information of a building by using a probabilistic approach, even without knowing the specific structural design. This method can be based on a small amount of readily available building information and solves the problem of the rapid and refined modeling of a large number of buildings at the regional scale. It also makes it possible to estimate the earthquake loss of regional buildings based on their seismic capacity.

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Section: Methods For Building the Sample Spacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Story-Based Random Structure Modeling Method for Regional Buildings Earthquake Loss Estimation

Yang,

Lu,

Xiong

2024

Applied Sciences

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“…In this study, the deep locking characteristics obtained by GPS data inversion from 1991 to 2018 in the middle and southern segments of the Tanlu fault zone showed that the Changyi-Tancheng and Wangji-Lujiang segments of the Tanlu fault zone are in a high degree of locking and a state of compression-slip deficit. According to historical records, the 7.0M Anqiu earthquake occurred in 70 BC in the Juxian section of Anqiu, but no seismic surface rupture zone related to the earthquake has been identified to date (Zhu et al, 1991;Wang et al, 2015). In addition, Cao et al (2018) used field geological surveys, shallow seismic exploration, combined borehole profiles, and palaeoseismic detection methods, and suggested that the deep structural detection of the Anqiu-Juxian member showed that the stress was released in the middle-and low-velocity layers of the crust.…”

Section: Sectional Seismic Risk Analysis Of the Mid-southern Segment ...mentioning

confidence: 99%

Interseismic slip distribution and locking characteristics of the mid-southern segment of the Tanlu fault zone

Liu²,

LIU

et al. 2023

Preprint

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The central and southern sections of the Tanlu fault zone experience frequent seismic activity and have a dense population distribution. Infrastructure, such as high-speed rail and the South–North Water Diversion project, as well as world heritage sites, such as the Grand Canal, ancient city ruins, and cultural landscapes, is located along the fault. A strong earthquake occurring in the future may cause significant social impacts and property losses. It is necessary to clearly understand the current activity characteristics and potential seismic risk of the fault zone to scientifically and reasonably reduce the losses of earthquake disasters. However, there are little data on its current activity through geodetic data. Based on GPS observation data from 1991 to 2018, the fine slip distribution characteristics between present earthquakes in the mid–southern segment of the Tanlu fault zone were retrieved based on the fastest descent method. On this basis, the lock degree and slip rate deficit characteristics of this section were obtained. The differences in the deformation characteristics between the two phases of the mid–southern segment of the Tanlu fault zone were analysed by comparing the surface strain results from 1991 to 2007 and 2013 to 2018. The results show that the interseismic sliding rate of the mid–southern segment of the Tanlu fault zone was 0–1 mm·a-1. The northern Tancheng–Sihong section showed right-handed thrust, and the sliding rate was 0.2–1 mm·a-1. The southern Sihong–Tongcheng section was stretched left–right, and the sliding rate was 0–0.5 mm.a-1 The degree of blockage in the mid–southern segment of the Tanlu fault zone was segmented along the fault strike. In the northern section, the locking depth of the Changyi–Tancheng section was relatively high, with the deepest reaching 32 km, and the maximum compression-slide loss rate reached -1 mm·a-1; the Tancheng–Wangji closure coefficient decreased significantly, with a concentrated distribution between 0.2 and 0.7. The Wangji–Jiashan section has a high degree of closure, small and medium earthquakes are not active, and it is the unruptured section, being more prone to stress accumulation.

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“…In recent years, the rapid development of high-precision absolute gravimeters has made available time-varying gravity data obtained by the terrestrial hybrid repeated gravity observation (THRGO) system, which have been applied to investigate crustal deformation, deep crustal fluid migration, and crustal apparent density variations in tectonically active regions [6,7]. Recently, relatively accurate medium-term predictions of several large earthquakes have been made by interpreting the data of anomalous gravity changes with reference to historical local earthquake records [8][9][10]. Many scholars therefore believe that it is possible to extract the gravity signals that are probably associated with deep mass transfer processes from THRGO records [11], which is the basis for applying time-varying gravity observations to in-depth explorations of earthquake mechanisms and seismic risk prediction [12].…”

Section: Introductionmentioning

confidence: 99%

Crustal Apparent Density Variations in the Middle Segment of the North Tianshan Mountains and Their Tectonic Significance

Kong,

Liu,

Yushan

et al. 2024

Applied Sciences

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In this study, we collected mobile gravity observations in the middle segment of the North Tianshan Mountains from August 2016 to July 2022 and carried out classical adjustment calculations under the constraint of the absolute gravity datum to obtain the spatiotemporal variation pattern of the local gravity field. We used equivalent source inversion to obtain the spatiotemporal variation characteristics of crustal apparent density. We also extracted the coseismic deformation field from SAR data, using the 2016 Hutubi earthquake as an example, and constructed a model of the seismogenic fault. The gravity monitoring network in the study area performed well in resolving the earthquake source parameters. Both the time-varying gravity field and equivalent apparent density variation pattern show prominent zoning characteristics with a smoothly evolving spatial distribution over time. The variation trends of the gravity field and equivalent apparent density are in line with the orientation of tectonic structures, and their anomalous signals can be detected before and after an earthquake. The constructed seismogenic structure of the 2016 Hutubi earthquake indicates a typical thrust earthquake, probably occurring on a north-dipping blind fault beneath a region with intense crustal deformation. The subsurface tectonic system reflected by this earthquake can be informatively extended to the entire middle segment of the North Tianshan Mountains by subsurface configuration. Our findings can serve as a reference for analyzing the source characteristics of the time-varying gravity field and interpreting anomalous pre-seismic signals, and aid in understanding earthquake preparation zones and the mode of crustal tectonic movements.

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Earthquake precursors: spatial-temporal gravity changes before the great earthquakes in the Sichuan-Yunnan area

Cited by 9 publications

References 8 publications

A Story-Based Random Structure Modeling Method for Regional Buildings Earthquake Loss Estimation

A Story-Based Random Structure Modeling Method for Regional Buildings Earthquake Loss Estimation

Interseismic slip distribution and locking characteristics of the mid-southern segment of the Tanlu fault zone

Crustal Apparent Density Variations in the Middle Segment of the North Tianshan Mountains and Their Tectonic Significance

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