[5] **viXra:1905.0511 [pdf]**
*submitted on 2019-05-26 13:08:57*

**Authors:** Abdelmajid Ben Hadj Salem

**Comments:** 7 Pages.

Using the geodetic coordinates $(\varphi,\lambda,h)$, we give the expression of the laplacian $\Delta V=\ds \frac{\partial^2 V}{\partial x ^2}+\frac{\partial^2 V}{\partial y ^2}+\frac{\partial^2 V}{\partial z ^2}$ in these coordinates. A solution of $\Delta V=0$ of type $V=f(\lambda).g(\varphi,h)$ is given. The partial differential equation satisfied by $g(\varphi,h)$ is transformed in an ordinary differential equation of a new variable $u=u(\varphi,h)$.

**Category:** Geophysics

[4] **viXra:1905.0423 [pdf]**
*submitted on 2019-05-21 10:18:35*

**Authors:** A.M.Eigenson, I.B.Bazylevych, M.S.Shevchenko

**Comments:** 1 Page.

Recently we have made the prognosis of such terrestrial events for the period between April 22 and May 2, 2019. This forecasting is confirmed. Now we do the same prognosis for the next 2 weeks, from May 19 until June 2, 2019. During this period new great catastrophes are expected to occur on our Earth. In our days, we see from Fig. 1 that the dangerous area lies between May 19 and June 2, 2019. (Addition: earthquakes 6+ are noted as circle’s, earthquakes 7+ as ellipsis and volcanic eruptions as crosses). So, the people of seismic zones: BE CAREFUL!

**Category:** Geophysics

[3] **viXra:1905.0249 [pdf]**
*submitted on 2019-05-16 19:31:34*

**Authors:** Abdelmajid Ben Hadj Salem

**Comments:** 7 Pages. In French.

This note concerns the international cartographic division. It gives how is organized the numbering of sheets at different scales ranging from 1/500 to 1/50000 and their sizes and surfaces.

**Category:** Geophysics

[2] **viXra:1905.0200 [pdf]**
*replaced on 2019-05-14 08:30:24*

**Authors:** Henri Marcel Dufour, Abdelmajid Ben Hadj Salem

**Comments:** 27 Pages. In French. It is an-update version of a paper dated 1979 with comments of the second author.

Many geodetic works currently exist on the surface of the globe, which have developed through regional networks, usually each having a fundamental point, where the astronomical data (\phi= latitude,\lambda=longitude,Az=azimuth) of a reference are confused with the counterparts geodetic data. The comparison of 2 networks, and, step by step, of all the connectable networks, can be done by the analysis of the coordinates of their common points. To this end, we can use 3 types of coordinates:
- Geographical coordinates = simple method, but not very convenient for different ellipsoids.
- Three-dimensional cartesian coordinates, the most rigorous method in the case where the so-called geoid correction has been made.
- Coordinates in conformal projection.
An analysis of the main formulas that can be used is studied by the first author in this article.

**Category:** Geophysics

[1] **viXra:1905.0115 [pdf]**
*submitted on 2019-05-07 18:41:22*

**Authors:** Abdelmajid Ben Hadj Salem

**Comments:** 7 Pages. In French.

In this note, we review the Dufour-Fezzani formula concerning the comparison of two geodetic networks. This formula is developed for ellipsoidal models.

**Category:** Geophysics