Waltemath described one of the proposed moons as being 1,030,000 km (640,000 mi) from Earth, with a diameter of 700 km (430 mi), a 119-day orbital period, and a 177-day synodic period.
A subduction zone is formed at a convergent plate boundary when one or both of the tectonic plates is composed of oceanic crust. The denser plate, made of oceanic crust, is subducted underneath the less dense plate, which can be either continental or oceanic crust.s a result of pressure, friction, and plate material melting in the mantle, earthquakes and volcanoes are common near convergent boundaries. When two plates move towards one another, they form either a subduction zone or a continental collision. This depends on the nature of the plates involved.
1 At other convergent boundaries, oceanic plate meets other oceanic plate. 2  This results in an oceanic trench and a chain of volcanic islands known as an island arc. Japan, the Philippines and the Aleutians are examples of island arcs.3  At some convergent boundaries, two continents collide. At some convergent boundaries, oceanic plate meets continental plate. 2  An example of this is the west coast of southern Mexico, Central America and South America. 3  An oceanic trench forms offshore, and a chain of volcanic mountains forms just inland of the coast.