The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-bas...The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.展开更多
The existence of a detectable precursory phase of fault slip preceding major earthquakes has been a subject of ongoing debate for decades.A recent study(Bletery and Nocquet,2023)demonstrated exponential acceleration o...The existence of a detectable precursory phase of fault slip preceding major earthquakes has been a subject of ongoing debate for decades.A recent study(Bletery and Nocquet,2023)demonstrated exponential acceleration of fault slip prior to large earthquakes.Conversely,(Hirose et al.,2024)reported no such phenomenon when analyzing tiltmeter data.Furthermore,their analysis focused predominantly on subduction zone earthquakes,with limited consideration of intraplate earthquake scenarios.In this study,we examined 15 M≥6.5 intraplate earthquakes in China from 2010 to 2024 and found no clear evidence of deformation acceleration prior to these events.We also investigated several key factors contributing to uncertainties in this approach.Our findings suggest that the exponential acceleration phenomenon is associated with specific earthquake characteristics and is influenced by the spatial distribution of proximal seismic signals.展开更多
基金supported by the CAS Pioneer Hundred Talents Program and Second Tibetan Plateau Scientific Expedition Research Program(2019QZKK0708)as well as the Basic Research Program of Qinghai Province:Lithospheric Geomagnetic Field of the Qinghai-Tibet Plateau and the Relationship with Strong Earthquakes(2021-ZJ-969Q).
文摘The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.
基金funded by the National Natural Science Foundation of China(Nos.42274068,U2039204,and U2139205)the Special Fund of the Institute of Geophysics,China Earthquake Administration(No.DQJB25Z03)the Shanghai Sheshan National Geophysical Observatory(No.SSOP202207).
文摘The existence of a detectable precursory phase of fault slip preceding major earthquakes has been a subject of ongoing debate for decades.A recent study(Bletery and Nocquet,2023)demonstrated exponential acceleration of fault slip prior to large earthquakes.Conversely,(Hirose et al.,2024)reported no such phenomenon when analyzing tiltmeter data.Furthermore,their analysis focused predominantly on subduction zone earthquakes,with limited consideration of intraplate earthquake scenarios.In this study,we examined 15 M≥6.5 intraplate earthquakes in China from 2010 to 2024 and found no clear evidence of deformation acceleration prior to these events.We also investigated several key factors contributing to uncertainties in this approach.Our findings suggest that the exponential acceleration phenomenon is associated with specific earthquake characteristics and is influenced by the spatial distribution of proximal seismic signals.
