HR: 1330h
AN: G32A-0733    [PDF]
TI: Satellites Seek Gravity Signals for Remote Sensing the Seismotectonic Stresses in Earth
AU: * Liu, H
EM: Han-Shou.Liu-1@nasa.gov
AF: NASA Goddard Space Flight Center, Code 921, Greenbelt, MD 20771 United States
AU: Chen, J
EM: chenj@pop900.gsfc.nasa.gov
AF: Sigma Space Corporation, Code 924, NASA/Goddard, Greenbelt, MD 20771 United States
AU: Li, J
EM: jll@center.shao.ac.cn
AF: Shanghai Astronomical Observatory National Academy of Sciences, 80 Nandan Road, Shanghai, 200030 China
AB: The ability of the mantle to withstand stress-difference due to superimposed loads would appear to argue against flow in the Earth$'$s mantle, but the ironic fact is that the satellite determined gravity variations are the evidence of density differences associated with mantle flow. The type of flow which is most likely to be involved concerns convection currents. For the past 4 decades, models of mantle convection have made remarkable advancements. Although a large body of evidence regarding the seafloor depth, heat flow, lithospheric strength and forces of slab-pull and swell-push has been obtained, the global seismotectonic stresses in the Earth are yet to be determined. The problem is that no one has been able to come up with a satisfactory scenario that must characterize the stresses in the Earth which cause earthquakes and create tectonic features. The stress generated by mantle convection under the crust are inferable from high degree (n$\geq$13) spherical harmonics of the geopotential. Therefore, satellite gravity missions may be able to seek the Earth's gravity signals for investigating the seismotectonic effect of these subcrustal stresses. It is well known that subcrustal stress patterns for (13$\leq$n$\leq$25) are applicable to identify the forcing mechanisms for uplift, depression, rifting, volcanism, seismicity, plate motion, kimberlite magmatism, ore formation and hot spots distributions on the surface of the Earth. However, in order to provide significant insights into the origin of earthquakes and the formation of tectonic features, subcrustal stress patterns for (13$\leq$n$\leq$150) are required. To meet this requirement, satellite gravity missions during the past 40 years have improved and extended the spherical harmonic model of the Earth's gravitational potential up to degree and order 360. This gravity model can be used to compute the stresses under the crust accurate enough to identify stress concentrations for earthquakes and realize tectonic features in the crust. In this paper, we have stiched together the satellite gravity data with a single thread of mantle convection. In this way, we have obtained a series of subcrustal stress patterns up to harmonic degree 150 from which 10 stress patterns are selected and displayed. Subcrustal stress maps for n=13 through n=150 illustrate the recognition progress of the modern world. A map of earthquakes for Ms$>$7.0 from 1976 to 2000 is also given for reference. The intense seismicity in the subcrustal stress concentration belt (the ring of fire around the Pacific) is expected. A broad band of seismicity extends from southern Europe to southeast Europe to southeast Asia; this is associated with the subcrustal stress concentration belts in Europe, Africa, Arabian, and Asia. These results seem to provide significant insights into the origin of the earthquakes and formation of the world.
DE: 1214 Geopotential theory and determination
DE: 1242 Seismic deformations (7205)
DE: 1645 Solid Earth
DE: 7230 Seismicity and seismotectonics
DE: 8166 Stresses--deep-seated
SC: Geodesy [G]
MN: 2003 Fall Meeting