EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION
According to the steady state of fault and energy balance, we provided a new idea to observe the precursors for a stressed fault. The meta-instability (or sub-instability) state of a fault is defined as the transition phase from peak stress to critical stress of fast instability (earthquake generati...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust
2020-06-01
|
| Series: | Геодинамика и тектонофизика |
| Subjects: | |
| Online Access: | https://www.gt-crust.ru/jour/article/view/1041 |
| _version_ | 1797855723264147456 |
|---|---|
| author | Yanshuang Guo Yanqun Zhuo Peixun Liu Shunyun Chen Jin Ma |
| author_facet | Yanshuang Guo Yanqun Zhuo Peixun Liu Shunyun Chen Jin Ma |
| author_sort | Yanshuang Guo |
| collection | DOAJ |
| description | According to the steady state of fault and energy balance, we provided a new idea to observe the precursors for a stressed fault. The meta-instability (or sub-instability) state of a fault is defined as the transition phase from peak stress to critical stress of fast instability (earthquake generation) during a full period of slow loading and fast unloading. The accumulative deformation energy begins to release in this stage. Identifying its deformation before fast instability would be beneficial to obtain premonitory information, and to evaluate the seismic risks of tectonic regions. In this study, we emphasized to analyze deformation process of the meta-instable stage with stain tensor data from a straight precut fault in granite at a slow loading rate, and observed the tempo-spatial features during the full deformation process of the fault. Two types of tectonic zones and instabilities occur on the stick-slip fault. The low- and high-value segments in the volume strain component appear along the fault strike with a load increment. The former first weakens and then becomes initial energy release segments; the latter forms strong stress-interlocking areas and finally turns into the initial region of fast instability. And there are two stages in the entire instable process of the fault: the initial stage is associated with the release of the low volume strain segments, which means fault pre-slips, slow earthquakes or weak earthquakes. The second one characterizes a strong earthquake through the release of high volume strain parts. The rupture acceleration in the first stage promotes the generation of the second. Moreover, fault instability contains two types of strain adjustments along the fault: the front-like strain change along the transition segments from low- to high- strain portions with volume strain release, and the compressive strain pulse of fault instability after the volume strain release extends to a certain range with loading increment. In laboratory experiments, the front-type strain occurs about 12 seconds before fast fault instability; the compressive pulse initiates within less than 0.1 second, and then the fault turns quickly into a dynamic strain adjustment, which appears quasi-synchronously between different measurement points, and, finally, an earthquake is generated. |
| first_indexed | 2024-04-09T20:27:42Z |
| format | Article |
| id | doaj.art-75908071000a480fb794c07847ed957c |
| institution | Directory Open Access Journal |
| issn | 2078-502X |
| language | English |
| last_indexed | 2024-04-09T20:27:42Z |
| publishDate | 2020-06-01 |
| publisher | Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust |
| record_format | Article |
| series | Геодинамика и тектонофизика |
| spelling | doaj.art-75908071000a480fb794c07847ed957c2023-03-30T20:08:04ZengRussian Academy of Sciences, Siberian Branch, Institute of the Earth's crustГеодинамика и тектонофизика2078-502X2020-06-0111241743010.5800/GT-2020-11-2-0483481EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATIONYanshuang Guo0Yanqun Zhuo1Peixun Liu2Shunyun Chen3Jin Ma4State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake AdministrationState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake AdministrationState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake AdministrationState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake AdministrationState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake AdministrationAccording to the steady state of fault and energy balance, we provided a new idea to observe the precursors for a stressed fault. The meta-instability (or sub-instability) state of a fault is defined as the transition phase from peak stress to critical stress of fast instability (earthquake generation) during a full period of slow loading and fast unloading. The accumulative deformation energy begins to release in this stage. Identifying its deformation before fast instability would be beneficial to obtain premonitory information, and to evaluate the seismic risks of tectonic regions. In this study, we emphasized to analyze deformation process of the meta-instable stage with stain tensor data from a straight precut fault in granite at a slow loading rate, and observed the tempo-spatial features during the full deformation process of the fault. Two types of tectonic zones and instabilities occur on the stick-slip fault. The low- and high-value segments in the volume strain component appear along the fault strike with a load increment. The former first weakens and then becomes initial energy release segments; the latter forms strong stress-interlocking areas and finally turns into the initial region of fast instability. And there are two stages in the entire instable process of the fault: the initial stage is associated with the release of the low volume strain segments, which means fault pre-slips, slow earthquakes or weak earthquakes. The second one characterizes a strong earthquake through the release of high volume strain parts. The rupture acceleration in the first stage promotes the generation of the second. Moreover, fault instability contains two types of strain adjustments along the fault: the front-like strain change along the transition segments from low- to high- strain portions with volume strain release, and the compressive strain pulse of fault instability after the volume strain release extends to a certain range with loading increment. In laboratory experiments, the front-type strain occurs about 12 seconds before fast fault instability; the compressive pulse initiates within less than 0.1 second, and then the fault turns quickly into a dynamic strain adjustment, which appears quasi-synchronously between different measurement points, and, finally, an earthquake is generated.https://www.gt-crust.ru/jour/article/view/1041fault meta-instabilitydeformation processstrain tensorprecursory information |
| spellingShingle | Yanshuang Guo Yanqun Zhuo Peixun Liu Shunyun Chen Jin Ma EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION Геодинамика и тектонофизика fault meta-instability deformation process strain tensor precursory information |
| title | EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION |
| title_full | EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION |
| title_fullStr | EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION |
| title_full_unstemmed | EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION |
| title_short | EXPERIMENTAL STUDY OF OBSERVABLE DEFORMATION PROCESS IN FAULT META-INSTABILITY STATE BEFORE EARTHQUAKE GENERATION |
| title_sort | experimental study of observable deformation process in fault meta instability state before earthquake generation |
| topic | fault meta-instability deformation process strain tensor precursory information |
| url | https://www.gt-crust.ru/jour/article/view/1041 |
| work_keys_str_mv | AT yanshuangguo experimentalstudyofobservabledeformationprocessinfaultmetainstabilitystatebeforeearthquakegeneration AT yanqunzhuo experimentalstudyofobservabledeformationprocessinfaultmetainstabilitystatebeforeearthquakegeneration AT peixunliu experimentalstudyofobservabledeformationprocessinfaultmetainstabilitystatebeforeearthquakegeneration AT shunyunchen experimentalstudyofobservabledeformationprocessinfaultmetainstabilitystatebeforeearthquakegeneration AT jinma experimentalstudyofobservabledeformationprocessinfaultmetainstabilitystatebeforeearthquakegeneration |