Migration is a process that reconstructs an image of the earth's reflecting structure from elastic wavefield energy recorded at the surface in seismic traces. In seismic imaging, conventional processing is concentrates on producing a stacked section from common mid point gathers and is followed by a poststack migration, while in a prestack migration, first the events are migrated one by one, then those are stacked and the energy the common reflection point gathers goes to the surface of the earth. In this paper the effects of both post-and pre-stack time migration methods are compared by use of the Kirchhoff summation method on a seismic line in the central Iran area. The method of data collection is offend and the foldage is 48. The source of energy in acquisition is dynamite. The work is implemented by using PROMAX 6.0 software on ULTRA SUN system. The results are as follows: Continuity of reflectors will be improved after prestack migration. Velocity analysis after prestack migration is improved and provides a better harmony of the velocities. Because of the increasing of the reflector's amplitudes continuity, some geology structures appeared after prestack migration.      

PSPC or split step Fourier migration is a method based on downward continuation of seismic wave field in frequency space and frequency-wave number domains. Compared with the phase shift method, this method is a superior algorithm with the ability to handle lateral variations in the velocity field. Therefore, the method is a depth migration, which works in the post stack domain. In this study, the ability, precision and validity of PSPC migration in the processing of real data sets with strong lateral velocity variations is verified. In order to achieve this objective, the velocity section used by migration algorithms has been improved in different steps by the iterative method of residual move-out analysis through applying pre stack Kirchhoff time migration. The improved velocity section was then used to apply pre stack Kirchhoff depth migration to original CMP gathers and PSPC migration to the stack section and the results were compared.    

Though in most of the countries such as Iran the emphasis has been on rural-urban emigration, the result of censuses show emergence of new current of internal migration with the form of reverse migration or counter-urbanization in recent years in Iran. For recognition and best analysis of reverse migration, 12100 reverse migrants in demographic and economic characteristics, determinants and reason of migration with 23700 metropolis migrants as a result of two percent sample of 1390 census have been studies comparatively. Findings show that in demographic-economic characteristics, age-sex combination, marriage state and head of household, education, and the kind of employment, there is significant difference between reverse and metropolis migrants, the most affective of these differences is migrants’ employment. The superiority of skillful migrants in agriculture and ordinary labor in reverse migration and other professions in metropolis migration has caused migrants’ jobs explain two of three of occurrence changes in under-analyzed migrations. Natural and bio-environmental features of rural and deep structure, economic, commercial, political of metropolis have caused the reverse migrants who entered rural of diverse states and migrants who entered metropolis (Tehran, Mashhad, Isfahan, Karaj, Tabriz, Shiraz, Ahvaz and Ghom) have diverse social, economic features and reasons for this migration

Background and Aim: Migration has been a historical phenomenon that reflects and affects social changes in societies. In recent decades, the growing scale and complexity of international migration have raised concerns among policymakers and planners in developing (or migrant-sending) countries, who face the challenges of human capital loss and development delay in their own countries. This study examines the question of whether these migrations can be seen as a facilitator of development course or as a reducer of human capital in the long run for the countries of origin?   Methods and Data: The present study is a narrative review that analyzes relevant literature from 2000 to 2022 using a descriptive-analytical approach.   Findings: Results show that international migration follows have individual and collective benefits for migrants, their families, and their origin countries. Depending on how the capacities of the migrants are utilized, these migrations may also have negative impacts or challenges for development. In other word, as litrature suggests, international migration does not necessarily reduce human capital, but depending on the way of using its capacities, it can facilitate development for the origin countries.   Conclusion: The phenomenon of international migration, which reflects the freedom of choice and the common right of individuals and communities to benefit from this option in their lives, requires careful attention from policymakers and planners. Governments should adopt policies that increase the benefits and reduce the risks of migration for their communities.   Key Message: Governments of migration-sending countries should change their attitude towards international migration from a merely threat to a possible opportunity in their population planning and take necessary steps to benefit from the potentials of these immigrants in the direction of their own country's development.