The decorrelation and Gaussian smoothing method is implemented in GRACE monthly gravity field products to obtain annual and seasonal gravity changes in Japan and its vicinity,as well as time series gravity changes of several pointsResults show regional gravity fields in Japan and its vicinity varied from positively to negatively and from area to area in five years before the Japan MW 90 earthquake,obviously positive to negative gravity changes were formed in 1~2 yearsTime series gravity changes of several points indicate the Japan earthquake displayed the similar time variation gravity phenomenon with the 1976 Tangshan earthquake in ChinaThese results reflect mass migration,mass movement and energy accumulation in Japan and its vicinity before the earthquake occurred

Gravity Changes Observed by GRACE before the Japan M_W9.0 Earthquake

A pilot survey for mapping the fault structure around the Geuredong volcano by using high-resolution global gravity

Separated attenuation values have not been used in post-seismic variation research, although the scattering attenuation (Qs−1) parameter that can be used to estimate crustal inhomogeneity due to cracks. In this study, three earthquakes that occurred in Kumamoto (M7.3), Tottori (M6.6), and Gyeongju (M5.8) in 2016 were investigated by applying a multiple lapse time window analysis to seismograms recorded before and after the events. At a low frequency, significantly greater variation of the Qs−1 value was observed than the intrinsic attenuation (Qi−1) for the Kumamoto earthquake, whereas similarly large variation was observed for the Gyeongju earthquake. For the surrounding Kumamoto earthquake area of increased attenuation, even higher decreases in Qs–1 and Qi–1 were also observed. The increases occurred within a two year-period after mainshock. The large increases in attenuation, corresponding to regions with high peak ground acceleration, were limited to the basin area with an elevation below 500 m. Furthermore, post-seismic increases in attenuation values were found to correlate with the magnitude and length of the quiet periods of the earthquakes. From this study, Qs–1 and Qi–1 were shown as new parameters that can quantitatively measure the post-seismic deformation due to crustal earthquake.

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Temporal variation in scattering and intrinsic attenuation due to earthquakes in East Asia.

This study compares the Gravity Recovery And Climate Experiment (GRACE)/GRACE Follow-On (GFO) errors with the coseismic gravity variations generated by earthquakes above Mw8.0s that occurred during April 2002~June 2017 and evaluates the influence of monthly model errors on the coseismic signal detection. The results show that the precision of GFO monthly models is approximately 38% higher than that of the GRACE monthly model and all the detected earthquakes have signal-to-noise ratio (SNR) larger than 1.8. The study concludes that the precision of the time-variable gravity fields should be improved by at least one order in order to detect all the coseismic gravity signals of earthquakes with M ≥ 8.0. By comparing the spectral intensity distribution of the GFO stack errors and the 2019 Mw8.0 Peru earthquake, it is found that the precision of the current GFO monthly model meets the requirement to detect the coseismic signal of the earthquake. However, due to the limited time length of the observations and the interference of the hydrological signal, the coseismic signals are, in practice, difficult to extract currently.

Evaluation of GRACE/GRACE Follow-On Time-Variable Gravity Field Models for Earthquake Detection above Mw8.0s in Spectral Domain

The co-seismic and post-seismic deformation caused by Sumatra-Adaman earthquake are computed by using RL04 GSM monthly gravity model of GRACE published by CSR.The analysis and comparison of numerical results show that co-seismic and post-seismic deformation information about-20-10 cm equivalent water thickness from large earthquake can be detected by GRACE satellite gravity surveying.

Detection of Co-seismic and Post-seismic Deformation Caused by the Sumatra-Andaman Earthquake Using GRACE

The Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-on (GRACE-FO) satellites are important for studying regional gravitational field changes caused by strong earthquakes. In this study, we chose Chile, one of Earth’s most active seismic zones to explore the co-seismic and post-seismic gravitational field changes of the 2010 Mw 8.8 Maule earthquake based on longer-term GRACE and the newest GRACE-FO data. We calculated the first-order co-seismic gravity gradient changes (GGCs) and probed the geodynamic characteristics of the earthquake. The earthquake caused significant positive gravity change on the footwall and negative gravity changes on the hanging wall of the seismogenic fault. The time series of gravity changes at typical points all clearly revealed an abrupt change caused by the earthquake. The first-order northern co-seismic GGCs had a strong suppressive effect on the north-south strip error. GRACE-FO results showed that the latest post-seismic gravity changes had obvious inherited development characteristics, and that the west coast of Chile maybe still affected by the post-seismic effect. The cumulative gravity changes simulated based on viscoelastic dislocation model is approximately consistent with the longer-term GRACE and the newest GRACE-FO observations. Our results provide important reference for understanding temporal and spatial gravity variations associated with the co-seismic and post-seismic processes of the 2010 Maule earthquake.

https://www.mdpi.com/2072-4292/12/17/2768/pdf

Co-Seismic and Post-Seismic Temporal and Spatial Gravity Changes of the 2010 Mw 8.8 Maule Chile Earthquake Observed by GRACE and GRACE Follow-on

The invention provides a self-adaptive Kalman filtering landslide prediction method taking many factors into account. According to the method, a Kalman filtering state equation and observation equation are firstly built, a multiple factor-based Kalman filtering recursion equation group is built, weighted attenuation memory Kalman filtering is performed by introducing an index type attenuation factor, and finally landslide prediction is realized. The method takes random disturbance of external inducers of landslide into consideration, thereby reducing error generated in linearization of a landslide deformation model; since the attenuation factor is introduced, the problem that classic Kalman filtering is liable to divergence is solved and the filtering accuracy and the filtering precision are greatly improved, so that the reliability of using the self-adaptive Kalman filtering landslide prediction method taking many factors into account to predict landslide disaster is further guaranteed.

An Dongdong

Papers

Co-Seismic and Post-Seismic Temporal and Spatial Gravity Changes of the 2010 Mw 8.8 Maule Chile Earthquake Observed by GRACE and GRACE Follow-on

A self-adaptive Kalman filtering landslide prediction method taking many factors into account