Heat flow is inevitably accompanied by temperature change,thus,the water temperature coseismic response during earthquake activity should also obey the laws of thermodynamics.Taking the M S8.0 Wenchuan,Sichuan,China e...Heat flow is inevitably accompanied by temperature change,thus,the water temperature coseismic response during earthquake activity should also obey the laws of thermodynamics.Taking the M S8.0 Wenchuan,Sichuan,China earthquake and the M9.0Tohoku,Japan earthquake as an example,and based on the data of water temperature coseismic responses observed in well ZK26 in Haikou,Hainan Province,China,we investigate the relationship between well water temperature change and heat transfer in the coseismic response process and the relevant thermodynamic mechanism by using the numerical simulation method for thermodynamic equations.Then,through forward modeling,we obtain several simulation curves of water temperature change in response to earthquakes along the well depth at different times.The simulated curves of water temperature change approximately fit the observed curves.Consequently,based on the variation of temperature,we find that the modes of well water temperature coseismic response( ascending,descending or stable) are related to factors such as the location of sensors,distribution and location of heat sources,the span between sensors and heat sources.展开更多
We systematically analyze coseismic responses and post-seismic characteristics of groundwater levels in the Three Gorges well-network to the Ms8.0 Wenchuan earthquake on 12 May 2008. The results indicate that these ch...We systematically analyze coseismic responses and post-seismic characteristics of groundwater levels in the Three Gorges well-network to the Ms8.0 Wenchuan earthquake on 12 May 2008. The results indicate that these characteristics differ among wells. On the conditions of similar borehole configurations, the differences are associated with geological structural sites of wells, burial types of aquifers monitored, and transmissivities of aquifer systems. We explored coseismic and post-seismic step-rise and step-drop mechanical mechanisms and their implication to earthquake prediction. We validated the inference that the residual step-rise zone is a possible earthquake risk zone based on recent seismic activity on the Xiannüshan fault in the area.展开更多
Vertical coseismic deformation on non-causative fault caused by remote strong earthquakes （epicentral distance ≥1 500 km, Ms≥7.0） are observed by fault-monitoring instruments of new type during recent two years. T...Vertical coseismic deformation on non-causative fault caused by remote strong earthquakes （epicentral distance ≥1 500 km, Ms≥7.0） are observed by fault-monitoring instruments of new type during recent two years. The monitoring result shows, delay time, maximum amplitude and duration of vertical deformation on the non-causative fault have remarkable close relationship with earthquakes magnitude and epicentral distance. The delay time of vertical coseismic deformation have positive linear relationship with epicentral distance. The velocity of coseismic deformation is 5.5 km/s, close to the velocity of surface wave in granite. The logarithms of maximum amplitude of coseismic deformation and epicentral distance have remarkable linear relationship with magnitude. The greater the magnitude and the closer the epicentral distance are, the bigger the maximum amplitude of coseismic deformation on non-causative fault will be. Relative to the epicentral distance, the magnitude is the most important factor to the duration of coseismic vertical deformation on the non-causative fault. Stronger earthquake causes longer vibration duration of coseismic deformation. The experiential equation of co-seismic deformation faults obtained by this work is significant on the coseismic deformation research.展开更多
As an achievement of the cooperation with Japan,TOA electromagnetic observation station was established with an 800 m borehole antenna and put into service in 1992 in Dali,Yunnan province,China.Li Wuxian et al.(2003)s...As an achievement of the cooperation with Japan,TOA electromagnetic observation station was established with an 800 m borehole antenna and put into service in 1992 in Dali,Yunnan province,China.Li Wuxian et al.(2003)summarized main anomalous variation characters by analyzing 23 strong earthquakes with magnitudes more than 5.0 recorded in the first ten years.This work mainly presents the electromagnetic changes prior to the last Mojiang MS5.9 earthquake on September 8,2018.First of all,the initial weak signals appeared in two ULF channels out of three observing channels(CH10.01-0.10 Hz,CH20.1-1.0 Hz and CH31-9 kHz)on May 30,2018 at Dali TOA electromagnetic station.The information recorded was characterized by wave-like changes with magnitudes of ACH1≤0.26 mV in CH1 and pulse-like impulses of ACH2≤0.6 mV in CH2,respectively.Then,abnormal information gradually enhanced either in magnitudes or in occurrence frequency.Pulse-like signals were full of lattices of recording paper for CH2 during June24-25 and slopped over the recording paper during June 28-29,with the magnitudes being greater than or equal to 10 mV.At the same time,the clear wave-like signals also appeared in CH1 with a maximum magnitude of^0.6 mV on June 28 and reached its climax.From then on,the information started to decrease from the end of July and only weak signals occasionally occurred till the end of August 2018,when obvious anomaly was recorded again in two ULF channels with maximum magnitudes of ACH1~0.2 mV and ACH2~0.3 mV respectively.Generally,these signals did not appear continuously but group by group and accumulated intensively only in ULF band instead of VLF band during the total period.10 days later,the Mojiang MS5.9 earthquake occurred on September 8,2018,300 km away from Dali TOA station,and a coseismic response was also recorded at this time.Thus,these ULF electromagnetic abnormities could be probably attributed to the Mojiang event.展开更多
In this paper, electromagnetic emissions recorded by a borehole TOA installment with three observing channels of CH1 (0.01 - 0.1 Hz), CH2 (0.1 - 1.0 Hz) and CH3 (1 - 9 kHz) before four large earthquakes with magnitude...In this paper, electromagnetic emissions recorded by a borehole TOA installment with three observing channels of CH1 (0.01 - 0.1 Hz), CH2 (0.1 - 1.0 Hz) and CH3 (1 - 9 kHz) before four large earthquakes with magnitudes more than 8.0 have been depicted. These abnormities present different fluctuating processes from one another. For the Wenchuan MS 8.0 earthquake on 12 May 2008, the nearest one among these four events and only 660 km from the TOA station, electromagnetic information appeared at least 5 months ago in two low frequency bands of CH1 and CH2 and it was subjected to an obvious fluctuating process with several developing stages: initial information, intensive anomaly and large amplitude signals. The typical pulse-like emissions in CH2 happened group by group with large various magnitudes, which can be of 10 mV in the climax period. While during this period, compatible wave-like information with little magnitudes also happened in CH1 channel and a few pulses in CH3. Anomalous emissions occurred about 4 months prior to the 25 April 2015 Nepal MS 8.1 event, 1560 km away from the TOA station. The abnormal information in CH2 also appeared group by group but with small various magnitudes, more than 2 mV during their climax. This process is also effective for the Sumatra MS 8.9 earthquake on 26 December 2004, 2500 km from the borehole TOA, only with a different duration of 2 months and less magnitudes of 0.1 mV in CH1 and 1 mV in CH2 in this case. However, there is no obvious fluctuation and only small constant amplitude signals being ~0.15 mV appeared during 2 weeks before the Japan MS 9.0 earthquake on 11 March 2011. It is the farthest one among these four events and beyond 4000 km from the observing station. So, we can make a conclusion that there is a near relationship between the properties of the abnormities associated with these four earthquakes, such as amplitudes, duration and signal types, and the distances from TOA station: on one hand, the amplitude and duration decreases as the distance increases;on the other hand, there is an evolution for emission properties from complex various magnitude signals to single equal magnitude ones as the distance changes to be far. However, one common feature of the anomalous information related to these four events is that almost electromagnetic emissions were collected in two low frequency bands of CH2 and CH1 instead of CH3 band, which means ULF band (0.01 - 1.0 Hz) is more sensitive than VLF band (1 - 9 kHz) at this TOA station.展开更多
基金sponsored by the Spark Program of 2011,China Earthquake Administration(XH1020)the Basic Research Program of the Hainan Province(ZDXM20110107)
文摘Heat flow is inevitably accompanied by temperature change,thus,the water temperature coseismic response during earthquake activity should also obey the laws of thermodynamics.Taking the M S8.0 Wenchuan,Sichuan,China earthquake and the M9.0Tohoku,Japan earthquake as an example,and based on the data of water temperature coseismic responses observed in well ZK26 in Haikou,Hainan Province,China,we investigate the relationship between well water temperature change and heat transfer in the coseismic response process and the relevant thermodynamic mechanism by using the numerical simulation method for thermodynamic equations.Then,through forward modeling,we obtain several simulation curves of water temperature change in response to earthquakes along the well depth at different times.The simulated curves of water temperature change approximately fit the observed curves.Consequently,based on the variation of temperature,we find that the modes of well water temperature coseismic response( ascending,descending or stable) are related to factors such as the location of sensors,distribution and location of heat sources,the span between sensors and heat sources.
基金supportedby Basic Science Research Special Item of the Institute of Geology, China Earthquake Administration (NoDF-IGCEA-0608-2-10)Special Research Program of China Earthquake Administration (No. 200808079).
文摘We systematically analyze coseismic responses and post-seismic characteristics of groundwater levels in the Three Gorges well-network to the Ms8.0 Wenchuan earthquake on 12 May 2008. The results indicate that these characteristics differ among wells. On the conditions of similar borehole configurations, the differences are associated with geological structural sites of wells, burial types of aquifers monitored, and transmissivities of aquifer systems. We explored coseismic and post-seismic step-rise and step-drop mechanical mechanisms and their implication to earthquake prediction. We validated the inference that the residual step-rise zone is a possible earthquake risk zone based on recent seismic activity on the Xiannüshan fault in the area.
文摘Vertical coseismic deformation on non-causative fault caused by remote strong earthquakes （epicentral distance ≥1 500 km, Ms≥7.0） are observed by fault-monitoring instruments of new type during recent two years. The monitoring result shows, delay time, maximum amplitude and duration of vertical deformation on the non-causative fault have remarkable close relationship with earthquakes magnitude and epicentral distance. The delay time of vertical coseismic deformation have positive linear relationship with epicentral distance. The velocity of coseismic deformation is 5.5 km/s, close to the velocity of surface wave in granite. The logarithms of maximum amplitude of coseismic deformation and epicentral distance have remarkable linear relationship with magnitude. The greater the magnitude and the closer the epicentral distance are, the bigger the maximum amplitude of coseismic deformation on non-causative fault will be. Relative to the epicentral distance, the magnitude is the most important factor to the duration of coseismic vertical deformation on the non-causative fault. Stronger earthquake causes longer vibration duration of coseismic deformation. The experiential equation of co-seismic deformation faults obtained by this work is significant on the coseismic deformation research.
基金the National Natural Science Foundation of China(41774084)
文摘As an achievement of the cooperation with Japan,TOA electromagnetic observation station was established with an 800 m borehole antenna and put into service in 1992 in Dali,Yunnan province,China.Li Wuxian et al.(2003)summarized main anomalous variation characters by analyzing 23 strong earthquakes with magnitudes more than 5.0 recorded in the first ten years.This work mainly presents the electromagnetic changes prior to the last Mojiang MS5.9 earthquake on September 8,2018.First of all,the initial weak signals appeared in two ULF channels out of three observing channels(CH10.01-0.10 Hz,CH20.1-1.0 Hz and CH31-9 kHz)on May 30,2018 at Dali TOA electromagnetic station.The information recorded was characterized by wave-like changes with magnitudes of ACH1≤0.26 mV in CH1 and pulse-like impulses of ACH2≤0.6 mV in CH2,respectively.Then,abnormal information gradually enhanced either in magnitudes or in occurrence frequency.Pulse-like signals were full of lattices of recording paper for CH2 during June24-25 and slopped over the recording paper during June 28-29,with the magnitudes being greater than or equal to 10 mV.At the same time,the clear wave-like signals also appeared in CH1 with a maximum magnitude of^0.6 mV on June 28 and reached its climax.From then on,the information started to decrease from the end of July and only weak signals occasionally occurred till the end of August 2018,when obvious anomaly was recorded again in two ULF channels with maximum magnitudes of ACH1~0.2 mV and ACH2~0.3 mV respectively.Generally,these signals did not appear continuously but group by group and accumulated intensively only in ULF band instead of VLF band during the total period.10 days later,the Mojiang MS5.9 earthquake occurred on September 8,2018,300 km away from Dali TOA station,and a coseismic response was also recorded at this time.Thus,these ULF electromagnetic abnormities could be probably attributed to the Mojiang event.
文摘In this paper, electromagnetic emissions recorded by a borehole TOA installment with three observing channels of CH1 (0.01 - 0.1 Hz), CH2 (0.1 - 1.0 Hz) and CH3 (1 - 9 kHz) before four large earthquakes with magnitudes more than 8.0 have been depicted. These abnormities present different fluctuating processes from one another. For the Wenchuan MS 8.0 earthquake on 12 May 2008, the nearest one among these four events and only 660 km from the TOA station, electromagnetic information appeared at least 5 months ago in two low frequency bands of CH1 and CH2 and it was subjected to an obvious fluctuating process with several developing stages: initial information, intensive anomaly and large amplitude signals. The typical pulse-like emissions in CH2 happened group by group with large various magnitudes, which can be of 10 mV in the climax period. While during this period, compatible wave-like information with little magnitudes also happened in CH1 channel and a few pulses in CH3. Anomalous emissions occurred about 4 months prior to the 25 April 2015 Nepal MS 8.1 event, 1560 km away from the TOA station. The abnormal information in CH2 also appeared group by group but with small various magnitudes, more than 2 mV during their climax. This process is also effective for the Sumatra MS 8.9 earthquake on 26 December 2004, 2500 km from the borehole TOA, only with a different duration of 2 months and less magnitudes of 0.1 mV in CH1 and 1 mV in CH2 in this case. However, there is no obvious fluctuation and only small constant amplitude signals being ~0.15 mV appeared during 2 weeks before the Japan MS 9.0 earthquake on 11 March 2011. It is the farthest one among these four events and beyond 4000 km from the observing station. So, we can make a conclusion that there is a near relationship between the properties of the abnormities associated with these four earthquakes, such as amplitudes, duration and signal types, and the distances from TOA station: on one hand, the amplitude and duration decreases as the distance increases;on the other hand, there is an evolution for emission properties from complex various magnitude signals to single equal magnitude ones as the distance changes to be far. However, one common feature of the anomalous information related to these four events is that almost electromagnetic emissions were collected in two low frequency bands of CH2 and CH1 instead of CH3 band, which means ULF band (0.01 - 1.0 Hz) is more sensitive than VLF band (1 - 9 kHz) at this TOA station.
