They form in the ocean where undersea volcanoes are errupting. The magma turning into lava piles up on top of itself over lots of time to form land.
Trenches are formed by subduction, a geophysical process in which two or more of Earth's tectonic plates converge and the older, denser plate is pushed beneath the lighter plate and deep into the mantle, causing the seafloor and outermost crust (the lithosphere) to bend and form a steep, V-shaped depression.
At divergent plate boundaries, earthquakes tend to be weak and shallow. Transform plate boundaries, have shallow, but very powerful earthquakes. At convergent plate boundaries, where two continental plates collide earthquakes are deep and also very powerful.
Recall that there are three types of plate boundaries: convergent, divergent, and transform. Volcanism occurs at convergent boundaries (subduction zones) and at divergent boundaries (mid-ocean ridges, continental rifts), but not commonly at transform boundaries.
Hope this helps :)
<span>Converting a sphere to a flat surface results in distortion. This is the most profound single fact about map projections</span>
I would say the answers are the world's largest plain ie it is the largest lowland mostly around only 100m elevation and also, being in Siberia, in winter it is a very harsh environment.