Is the San Andreas Fracture a bayonet-shaped fracture as inferred from the acoustic body waves in the SAFOD Pilot hole ?

The method using the propagation of acoustic body waves within the stress modified areas around a vertical borehole has been applied to the granitic formation penetrated by the SAFOD Pilot hole near the San Andreas Fault trace. This method allows us investigating the horizontal in situ stresses. Only P waves supplied useful and surprising information. A depth of 1270 m separates an upper region of uniform thickness of stress modified areas, possibly corresponding to a shear domain, and a lower region where there are simultaneously two values of the thicknesses of the stress modified areas (particularly between 1500 and 1600 m of depth) possibly corresponding to a compressive and a shear domain. In order to integrate the contradictory effects of the simultaneity of shear and compressive domains at some depths, as well as the presence of three shear zones at particular depths, we propose that the San Andreas Fault could be bayonet-shaped instead of planar. Other recent available information in the literature about this fault, such as the presence of a fault zone of low shear wave velocity, stress rotation measured with depth, and the large angles of the frictional coefficients, can be logically explained by this kind of fault geometry

A New Global Theory of the Earth's Dynamics : a Single Cause Can Explain All the Geophysical and Geological Phenomena

After describing all the contradictions associated with the current Plate Tectonics theory, this paper proposes a model where a single cause can explain all geophysical and geological phenomena. The source of the Earth's activity lies in the difference of the angular velocities of the mantle and of the solid inner core. The friction between both spheres infers heat, which is the cause of the melted iron which constitutes most of the liquid outer core, as well as the source of the global heat flow. The solid inner core angular velocity is supposed to remain steady, while the mantle angular velocity depends on gyroscopic forces (involving acceleration) and slowing down due to external attractions and, principally the motions of mantle plates 2900 km thick. The variations of the geomagnetic field are therefore the direct consequence of the variations of the angular velocity of the mantle relative to that of the inner core. As a result, the biological and tectonic evolutions during geological times are due to those phenomena. So, the limits of eras coincide exactly with the passage to zero of the geomagnetic field. Here we show that cycles of about 230-250 millions years, which exhibit the correlation between the mantle angular velocity variations, the geomagnetic variations, and therefore the climate, allow us to predict future events : the current global warming which parallels the Earth's magnetic field decrease

Model of horizontal stress in the Aigion10 well (Corinth) calculated from acoustic body waves

In this paper we try to deduce the in situ stresses from the monopole acoustic waves of the well AIG10 between 689 and 1004 meters in depth (Corinth Golf). This borehole crosses competent sedimentary formations (mainly limestone), and the active Aigion fault between 769 and 780 meters in depth. This study is the application of two methods previously described by the author who shows the relationships between in situ horizontal stresses, and (i) the presence or absence of double body waves, (ii) the amplitude ratios between S and P waves (Rousseau, 2005a,b). The full waveforms of this well exhibit two distinct domains separated by the Aigion fault. Within the upper area the three typical waves (P, S and Stoneley) may appear, but the S waves are not numerous, and there is no double body wave, whereas within the lower area there are sometimes double P waves, but no S waves. From those observations, we conclude that the stress domain is isotropic above the Aigion fault, and anisotropic below, which is consistent with conclusions drawn by authors from other kinds of data. The calculation applied to the characteristics of the double P waves suggests that this horizontal stress anisotropy is very high, up to 190 % with the maximum horizontal stress superior to 100 MPa and the minimum horizontal stress close to zero at 939 meters in depth. The amplitude ratios between the S and P wave indicate a very strong compression - which is isotropic - above the Aigion fault.Comment: 7 page

Le tribunal du travail

L'auteur étudie les dispositions nouvelles relatives au tribunal du travall dans le Code du travail du Québec.The Province of Quebec has launched a major experiment by creating a Labour Court, constituted by Bill 50 (as revised by Bill 65). The Court's jurisdiction was defined by these two measures and is set out in Section 103 of the Quebec Labour Code.The whole area of labour relations is marked increasingly by a collective approach, emphasizing collective bargaining. On the other hand, the Civil Code still prevails and civil courts remain the main recourse for non-unionized workers. The latter cannot take advantage of the new legislation, which protects only those who are in, or covered by labour organizations.Even in union-organized sectors, we still note the necessity to maintain some recourse to common law tribunals; such recourse, dealing with the individual contract of employment and violations of criminal and statutory laws, is the only one available to workers in marginal and unorganized sectors, who still make up the majority of our labour force.This paper proposes the creation of a Labour Court that would replace all the present dispute settlement procedures. This body would be competent to hear and decide : civil action between workers and employers; civil and criminal cases under statutory legislation in labour matters; injunctions and special writs in the field of labour law; action now before the labour Court; arbitration of disputes and grievances.A Labour Court, under this very broad concept, would offer the following advantages: single and integrated jurisdiction, intervention by the interested parties, settlement at a higher level, uniform, rules of interpretation, of evidence and procedure, and easier access to all workers anxious to use its facilities.We realize that such a proposal and such a transformation in our institutional structure would not be easy. The main objections to be encountered would appear to be : the fact that our economic and institutional structures are oriented towards the entreprise; the need for human resources, in order to provide all the specialistsrequired by such a Labour Court; the statuory character of the Court, as against a contractual type of machinery which might be preferred by the parties; the lack, at the present time, of a unified body of laws, in the field of labour relations; the low industrial concentration, inview of the number of Courts to be created.In conclusion, the principal advantage stressed is the possibility, through such a Labour Court, of changing the scope and level of decision-making. At the present time, the approach to labour problems is very specific and loealized; the presence of the parties and the vast jurisdiction of a Labour Court would make it possible to take into consideration the problems of an entire industry, union or economic sector

Comparative study of P and S wave amplitudes of acoustic logging through solid formations : contribution to the knowledge of in situ stresses and fractures

In order to compare the ratios between the amplitudes of P and S acoustic waves drawn from various boreholes, we have defined a specific wave parameter called magnitude : for each shot, we have added the maximum positive amplitude values and the absolute values of the minimum negative amplitudes of a given wave recorded at different depths. In compact formations, the difference between the logarithms of the magnitudes of S and P waves provides a value that appears to be characteristic of the state of stress of the domain where a borehole is drilled. Accidents between those formations, such as fractures or sedimentary joints can be determined, and breakouts well distinguished

Relationship between acoustic body waves and in situ stresses around a borehole

This paper shows that there are three types of shape of acoustic body waves propagating inside competent and homogeneous formations penetrated by a borehole : simple, double, and resonant. This fact is connected to the modifications undergone by the area located around a well after drilling in relation to in situ state of stress. There are overstressed and understressed vertical cylindrical zones with "bubble-shaped" cross-sections, in which acoustic body waves are supposed to reflect. The horizontal size and the shape of the stress modified areas depend on the values of (K1+K2)/2 - with K1=SH/Sv (the overburden pressure) and K2=Sh/Sv -, that is to say on the in situ horizontal stress and the anisotropy of this stress. The calculation of the velocities of the P and S double waves allows us to evaluate the radial thicknesses of these stress modified areas. As their values are different according to whether they result from P or S waves, we propose an explanation based on their wavelengths. The comparisons with other works on the in situ stress of the studied boreholes allow us to propose a method for evaluating the horizontal stress and its anisotropy, thanks to the estimation of the value (K1+K2)/2

Employee ownership as a signal of management quality

The employees' decision to become shareholder of the company they work for can be a consequence of employers' matching contribution in company stock. From a behavioral perspective, employees would regard these contributions as an implicit investment advice made by their employer. This paper adopts another viewpoint. Since employee ownership can be used as an entrenchment mechanism, we suggest that employer's matching policy can be considered as an imperfect signal of management quality. This paper suggests that employee ownership can be used by managers to compensate their management skills to the market. It recommends that employee ownership policy should not be influenced by the managers.Employee ownership ; corporate governance ; management entrenchment

Employee ownership as a signal of management quality

The employees' decision to become shareholder of the company they work for can be a consequence of employers' matching contribution in company stock. From a behavioral perspective, employees would regard these contributions as an implicit investment advice made by their employer. This paper adopts another viewpoint. Since employee ownership can be used as an entrenchment mechanism, we suggest that employer's matching policy can be considered as an imperfect signal of management quality. This paper suggests that employee ownership can be used by managers to compensate their management skills to the market. It recommends that employee ownership policy should not be influenced by the managers