Below the lithosphere the upper mantle becomes more plastic in its rheology. In some regions below the lithosphere, the seismic velocity is reduced. This low velocity zone extends down to a depth of several hundred km. The bottom of the upper mantle – it is a transition zone. The transition zone (located at a depth of 400 - 650 km) is an area of great complexity; it physically separates the upper and lower mantle. The processes occurring in the upper mantle have a great impact on many natural phenomena observed on the surface of the Earth.
In the middle of last century was built by the generalized one-dimensional physical model of the Earth - Jeffreys – Bullen Model
This model so far is a standard/reference model for studying the internal structure of the Earth as a whole and its individual areas, including the Upper mantle.
Typically, the study of the structure of the upper mantle is performed for same regions of the Earth.
And the results are presented as quantitative differences between the propagation velocity of seismic waves from the reference model of the Earth in one direction or another percentage or other relative values.
Achievements of modern structural seismology and the latest information technologies have enabled us to set a problem - creation a Virtual model of Earth's upper mantle, which a decade ago would have seemed impossible.
Not only to set a problem, but be sure that it can be solved by the Internet - community in the foreseeable future.
We have in mind that the results of solving the problem will be of practical use.
The objective of the project "Virtual upper mantle of the Earth
" is the construction of the 3D velocity model Earth's upper mantle. Technology - åđó methods of seismic tomography for the body teleseismic waves from long distant earthquakes.
We use the earthquake of such magnitude that the body waves from these earthquakes were registered to practically all of seismological stations of the Earth. The waves from these earthquakes penetrate the Earth's mantle and refracted in the mantle, or mantle boundary - outer core. These earthquakes are of magnitude, typically exceeding 4.0.
The distribution of epicenters of the earthquakes on the Earth's surface is uneven (irregular)Earthquakes are clustered in the seismic zones. Nevertheless, this distribution allows building a reliable monitoring system (seismic stations - centers of the earthquakes) for tomographic reconstruction of the upper mantle in many regions of Earth.
Many hundreds of earthquakes with a magnitude of 4.0 or higher reliably recorded global network of stations every year.
The current global seismic network was formed over 100 years. Currently, the Global Network consists of several thousands of seismological stations.
Global Network records the seismic waves from distant earthquakes in continuous operation. Seismic stations are distributed unevenly on the Earth's surface. The global network of seismic stations is composed of regional groups.
Seismograms are stored in the regional archives. Some of the information transmitted to the central seismological archives. International Seismological Center (ISC, UK) is one of the largest centralized archives. The International Seismological Center publishes Seismic Bulletins and Regional Catalogues of earthquakes in paper and digital forms.
One of the objectives of the project is the development of the Application Program Interface (API) to digital catalogs and bulletins.
Digital seismic bulletins and catalogs are accompanied by a small number of functions written in C language, to the lowest level of access to these data.
The project envisages the creation of the program and user interface at a higher level, which allows us to extract all necessary information from the bulletins and catalogs and store it in the database. When you create interfaces will use native C function supplied in conjunction with digital bulletins and catalogs
If we have a programming access to digital bulletins and catalogues of earthquakes recorded during the last century, we can, as necessary, extract it from the ones and stored in the database. For all the earthquakes recorded over a century, and at all stations of the global network!
These data will be used to restore the image of inland area of the upper mantle of the Earth. To restore the image of inland area of the upper mantle of the Earth will use the methods of computer tomography.
We engage the Internet - community to solve this problem. Internet - Community will include researchers, graduate students, students, school children, all who are interested in the internal structure of the Earth.
One of the objectives of the project is the creation of Web tools, which will be used by members of the Internet - community in the reconstruction of images of internal areas of the upper mantle of the Earth.