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

Yong, Zhang; Chen, Shi; Xing, Lelin; Liu, Mian; He, Zhanxiang

doi:10.1007/s00024-019-02356-4

Cited by 12 publications

(11 citation statements)

References 33 publications

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“…The gravity value is highly sensitive to vertical deformation [ 15 ]. Because GPS and leveling surveys can provide high-precision observations of tectonic vertical deformation, they are widely used to estimate gravity changes caused by vertical crustal movement.…”

Section: Discussionmentioning

confidence: 99%

“…A study using GRACE satellite data revealed large-scale gravity and mass changes throughout three tectonic plates and connected slabs prior to the occurrence of the 2011 Tohoku Oki Mw9.0 earthquake [ 12 ]. In previous studies on the Tibetan Plateau, high-accuracy absolute and relative gravity measurements were used to detect anomalies [ 13 , 14 , 15 , 16 , 17 ]. Before the occurrence of the 2015 Nepal Mw7.8 earthquake, a gravitational increase of up to 22.40 ± 1.11 μGal/yr was observed at four absolute gravity stations surveyed during 2010/2011–2013, and the modeled source region of the gravity field was found be consistent with the opinion that some of the southern Tibetan Plateau crust was involved in storing the strain energy that drove the Nepal earthquake [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…Before the 2008 Wenchuan Mw7.9 earthquake, an increase of approximately 30 μGal was detected in repeated measurements of absolute gravity at the Pixian station, located 35 km away from the epicenter. This increase might be caused by strain and mass (fluid) transfer within a broad seismogenic source region [ 15 ]. However, comprehensive understanding of the relationship between great earthquake preparation and gravitational change remains difficult to obtain due to the complex field source factors and certain limitations in the gravity measuring systems.…”

Section: Introductionmentioning

confidence: 99%

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Gravity Observations and Apparent Density Changes before the 2017 Jiuzhaigou Ms7.0 Earthquake and Their Precursory Significance

Yang

Chen

Zhang

et al. 2021

Entropy

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An Ms7.0 earthquake struck Jiuzhaigou (China) on 8 August 2017. The epicenter was in the eastern margin of the Tibetan Plateau, an area covered by a dense time-varying gravity observation network. Data from seven repeated high-precision hybrid gravity surveys (2014–2017) allowed the microGal-level time-varying gravity signal to be obtained at a resolution better than 75 km using the modified Bayesian gravity adjustment method. The “equivalent source” model inversion method in spherical coordinates was adopted to obtain the near-crust apparent density variations before the earthquake. A major gravity change occurred from the southwest to the northeast of the eastern Tibetan Plateau approximately 2 years before the earthquake, and a substantial gravity gradient zone was consistent with the tectonic trend that gradually appeared within the focal area of the Jiuzhaigou earthquake during 2015–2016. Factors that might cause such regional gravitational changes (e.g., vertical crustal deformation and variations in near-surface water distributions) were studied. The results suggest that gravity effects contributed by these known factors were insufficient to produce gravity changes as big as those observed, which might be related to the process of fluid material redistribution in the crust. Regional change of the gravity field has precursory significance for high-risk earthquake areas and it could be used as a candidate precursor for annual medium-term earthquake prediction.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravity Observations and Apparent Density Changes before the 2017 Jiuzhaigou Ms7.0 Earthquake and Their Precursory Significance

Yang

Chen

Zhang

et al. 2021

Entropy

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“…In absolute gravimetry, the general method for treating a vertical gradient of the earth's surface is that the vertical gravity gradient of the measurement point is first assumed to be 0, and then the absolute acceleration of the effective height of the instrument (Zumberge, 1981;Niebauer, 1989;Timmen, 2003) is obtained using the absolute gravity measurement instrument. In addition, at least two sets of relative gravimeters are used to measure the vertical gravity gradient of the measurement point either before or after conducting the absolute gravity measurement.…”

Section: Mathematical Model Of the Vibration Errormentioning

confidence: 99%

Vibration error compensation algorithm in the development of laser interference absolute gravimeters

Teng

Wang

et al. 2021

Geosci. Instrum. Method. Data Syst.

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Abstract. Measurement error arising from vibration interference is recognized as the primary obstacle limiting the accuracy and stability of laser interference absolute gravimeters. The present work addresses this issue by proposing a global search optimization algorithm that determines the optimal absolute value of gravity based on the measured time–displacement coordinates of a falling body and the signal obtained from the passive vibration isolation system of the inertial reference corner cube in a laser interference absolute gravimeter. Results of numerical calculations conducted under vibration interference conditions with added white noise resulting in a signal-to-noise ratio of 40 dB demonstrate the following. The accuracy and standard deviation of the gravimeter obtained using the proposed algorithm are −0.04 µGal (1µGal=1×10-8 m s−2) and 0.24 µGal, respectively, while those values obtained by the standard least-squares solution are 10.19 and 154.11 µGal, respectively. The test results indicate that the average response of the reference value of acceleration due to gravity superimposed by a disturbance of 1.00 µGal is 1.01 µGal using the proposed algorithm and 0.87 µGal using the standard least-squares solution.

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“…The groundwater temperature may be slightly affected or even unchanged if the temperature sensor is far from the aquifer during the propagation of seismic waves. With local hydrological data and continuous GPS data in the nearby stations, Zhang et al (2019) studied the gravity change near the epicenter of the Wenchuan M w 7.9 earthquake. Their results showed that the absolute gravity change observed at the Pixian station did not match the calculation result caused by the groundwater level change and vertical deformation and related superficial reasons, which suggests that the pre-earthquake gravity increase may be caused by strain and mass (fluid) transfer in a broad seismogenic source.…”

Section: Study Of the Wenchuan Earthquake And Its Sequencementioning

confidence: 99%

Continental Earthquakes: Physics, Simulation, and Data Science—Introduction

Zhang

Goebel

et al. 2019

Pure Appl. Geophys.

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During May 12-14, 2018, the International Conference for the Decade Memory of the Wenchuan Earthquake, in connection to the 4th International Conference on Continental Earthquakes (4th ICCE) and the 12th General Assembly of the Asian Seismological Commission (ASC), was held in Chengdu, China. There have been several outcomes of the Conference (for example, the book published jointly by Higher Education Press and Springer) as well as the present special issue. Among the 58 submissions, 34 have been accepted after peer review. Some of the papers came from the presentations during the Conference, but with additional submissions, the scope of this special issue is far beyond that of the proceedings of the meeting.

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

Cited by 12 publications

References 33 publications

Gravity Observations and Apparent Density Changes before the 2017 Jiuzhaigou Ms7.0 Earthquake and Their Precursory Significance

Gravity Observations and Apparent Density Changes before the 2017 Jiuzhaigou Ms7.0 Earthquake and Their Precursory Significance

Vibration error compensation algorithm in the development of laser interference absolute gravimeters

Continental Earthquakes: Physics, Simulation, and Data Science—Introduction

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