Every country's population growth is adapted to natural constraining factors such as earthquakes and floods. These constraining events occur periodically and offset the excess population. If the natural periodic controlling mechanism misses the date, it results in exponential growth of population. It has happened in earthquake prone countries like Japan, China, and India etc. These countries have become very dense in population because the controlling events haven't happened for a very long time and have been long overdue. Once the natural events like earthquake and floods become regular, the population densities of these regions will be normal again.

Russia never/rarely has earthquakes. Hence Russia's population growth has not developed resilience to natural calamities like earthquakes. In general, during calamities, all over the world, communities just survive. During other times, it's population swells. Earthquakes are completely absent in Russia. So no question of relief periods (relief from periodic earthquakes) during which time the earthquake resistant population would surge abnormally in favourable conditions. Russia's population density remains low even without earthquake. Hence Russia is sparsely populated.