Here we report two cases of coseismic ionospheric disturbances observed through a GPS network in China after the great Wenchuan earthquake at 06：28 UT on 12 May, 2008. One is detected 7.9 rain after the earthquake an...Here we report two cases of coseismic ionospheric disturbances observed through a GPS network in China after the great Wenchuan earthquake at 06：28 UT on 12 May, 2008. One is detected 7.9 rain after the earthquake and had an intensive ＂N＂ shape oscillated waveform with a pronounced amplitude of about 1 TECU, which propagates approximately southward to the distance about 1000 km with the horizontal phase velocity of 600±84 m/s and the period of 9.5±1.3 min. The other is detected 8.5 min after the earthquake and has an oscillated waveform more like a positive pulse with an amplitude of about 0.5 TECU, which propagates eastward to the distance about 800 km with the horizontal phase velocity of 720＋59 m/s and the period of 7.4±0.8 min. These two coseismic ionospheric disturbances are caused by the acoustic gravity waves excited by partial trans-formation of the acoustic waves originated from the energy release of the earthquake, somewhere near the epicenter. The directional preferences of these two coseismic ionospheric disturbances may be associated with the oblique geomagnetic field lines and the background winds filtering effect.展开更多
Ionospheric disturbances caused by acoustic waves emitted during earthquakes were studied using the Global Navigation Satellite System(GNSS)to analyze the changes in total electron content(TEC)values.GNSS signals norm...Ionospheric disturbances caused by acoustic waves emitted during earthquakes were studied using the Global Navigation Satellite System(GNSS)to analyze the changes in total electron content(TEC)values.GNSS signals normally propagate from satellites to receivers through the ionosphere layer.The delayed signals can be used to obtain TEC values by passing through the layer.Therefore,this study aims to analyze Coseismic Ionospheric Disturbances(CIDs)in six earthquakes,including 2016 M7.8 New Zealand(about 0.49 TECU),2018 M7.9 Alaska(about 0.20 TECU),2005 M7.2 California(about 0.29 TECU),2023 M7.5 Turkey(about 0.49 TECU),2012 M8.6 Sumatra(about 2.98 TECU),and 2012 M8.2 Sumatra(about 1.49 TECU)earthquakes.The propagation speed of the wave from the earthquake epicenter,identified as an acoustic wave,was estimated to be between 0.6 and 1.0 km/s.The 3D tomography modeling was performed to analyze the TEC height variations in the ionosphere to obtain a more accurate spatial analysis of TEC due to earthquakes.Moreover,checkerboard accuracy tests were applied to test the resolution of the 3D tomography model.The maximum ionization correlation test was also conducted for the six earthquakes to determine variations in the maximum ionization height of the ionosphere.The correlation test results between magnitude and maximum CID height produced a moderate correlation.The greater the earthquake magnitude,the higher the maximum CID detected.This is because greater earthquake produces compressed energy,which reduces the ionospheric density and reaches the maximum height.In addition,the maximum CID height is higher at night than in the afternoon because the E layer disappears at night.展开更多
By inverting GPS data recorded at stations of the Crustal Movement Observation Network of China （CMONOC） near the 2013 Lushan Ms7.0 earthquake, we found a horizontal displacement of 22 mm at a site about 32 kin SW o...By inverting GPS data recorded at stations of the Crustal Movement Observation Network of China （CMONOC） near the 2013 Lushan Ms7.0 earthquake, we found a horizontal displacement of 22 mm at a site about 32 kin SW of the epicenter and vertical displacements of as much as 12.4 mm at several sites. The vertical displacements were generally uplift on the west side of the nearby Longmenshan fault zone and subsidence on the east side. We also found coseismic ionospheric disturbances about 0.5 to 0.9 TECU in amplitude that lasted for about one hour.展开更多
基金supported by the Chinese Academy of Sciences(Grant No.KZZDEW-01-2)the National Natural Science Foundation of China(Grant Nos.41274162,41131066,41304126)the National Basic Research Program of China(Grant No.2011CB811405)
文摘Here we report two cases of coseismic ionospheric disturbances observed through a GPS network in China after the great Wenchuan earthquake at 06：28 UT on 12 May, 2008. One is detected 7.9 rain after the earthquake and had an intensive ＂N＂ shape oscillated waveform with a pronounced amplitude of about 1 TECU, which propagates approximately southward to the distance about 1000 km with the horizontal phase velocity of 600±84 m/s and the period of 9.5±1.3 min. The other is detected 8.5 min after the earthquake and has an oscillated waveform more like a positive pulse with an amplitude of about 0.5 TECU, which propagates eastward to the distance about 800 km with the horizontal phase velocity of 720＋59 m/s and the period of 7.4±0.8 min. These two coseismic ionospheric disturbances are caused by the acoustic gravity waves excited by partial trans-formation of the acoustic waves originated from the energy release of the earthquake, somewhere near the epicenter. The directional preferences of these two coseismic ionospheric disturbances may be associated with the oblique geomagnetic field lines and the background winds filtering effect.
基金supported by the Master's Thesis Research Program of the Ministry of Education and Culture of the Republic of Indonesia,Sepuluh Nopember Institute of Technology with grant number 2002/PKS/ITS/2023 contract number 112/E5/PG.02.00.PL/2023.
文摘Ionospheric disturbances caused by acoustic waves emitted during earthquakes were studied using the Global Navigation Satellite System(GNSS)to analyze the changes in total electron content(TEC)values.GNSS signals normally propagate from satellites to receivers through the ionosphere layer.The delayed signals can be used to obtain TEC values by passing through the layer.Therefore,this study aims to analyze Coseismic Ionospheric Disturbances(CIDs)in six earthquakes,including 2016 M7.8 New Zealand(about 0.49 TECU),2018 M7.9 Alaska(about 0.20 TECU),2005 M7.2 California(about 0.29 TECU),2023 M7.5 Turkey(about 0.49 TECU),2012 M8.6 Sumatra(about 2.98 TECU),and 2012 M8.2 Sumatra(about 1.49 TECU)earthquakes.The propagation speed of the wave from the earthquake epicenter,identified as an acoustic wave,was estimated to be between 0.6 and 1.0 km/s.The 3D tomography modeling was performed to analyze the TEC height variations in the ionosphere to obtain a more accurate spatial analysis of TEC due to earthquakes.Moreover,checkerboard accuracy tests were applied to test the resolution of the 3D tomography model.The maximum ionization correlation test was also conducted for the six earthquakes to determine variations in the maximum ionization height of the ionosphere.The correlation test results between magnitude and maximum CID height produced a moderate correlation.The greater the earthquake magnitude,the higher the maximum CID detected.This is because greater earthquake produces compressed energy,which reduces the ionospheric density and reaches the maximum height.In addition,the maximum CID height is higher at night than in the afternoon because the E layer disappears at night.
文摘By inverting GPS data recorded at stations of the Crustal Movement Observation Network of China （CMONOC） near the 2013 Lushan Ms7.0 earthquake, we found a horizontal displacement of 22 mm at a site about 32 kin SW of the epicenter and vertical displacements of as much as 12.4 mm at several sites. The vertical displacements were generally uplift on the west side of the nearby Longmenshan fault zone and subsidence on the east side. We also found coseismic ionospheric disturbances about 0.5 to 0.9 TECU in amplitude that lasted for about one hour.
