do volcanoes and earthquakes occur in the same time???why?

Answer 1

Some, but not all, earthquakes are related to volcanoes. For example, most earthquakes are along the edges of tectonic plates. This is where most volcanoes are too. However, most earthquakes are caused by the interaction of the plates not the movement of magma.

Most earthquakes directly beneath a volcano are caused by the movement of magma. The magma exerts pressure on the rocks until it cracks the rock. Then the magma squirts into the crack and starts building pressure again. Every time the rock cracks it makes a small earthquake. These earthquakes are usually too weak to be felt but can be detected and recorded by sensitive instruments. Once the plumbing system of the volcano is open and magma is flowing through it, constant earthquake waves, called harmonic tremor, are recorded (but not felt).

There is a general relationship, in that volcanic eruptions and earthquakes occur along the same major areas of the world. . .because both occur most often at plate boundaries. . .such as around the edge of the Pacific Ocean.

Answer 2

Volcanoes occur due to pressure and friction of molten rock, which finds an escape hatch for that energy. Earth is made of sliding Rock plates which grind and slide against each other, kind of like a RAVE. This sliding causes friction which generates heat. This intense heat melts the rock and may cause volcanoes. Earthquakes occur due to pressure of sliding rock on solid faces. Usually the stoppage of the sliding , for whatever reason, increases the pressure and after it builds so much, the tektonik plates will snap, causing an earthquake.
An actual "quake" is the seismic waves travelling along the Earth's crust. This may be caused by anything which impacts the crust. Meteors, volcanic explosions, nuclear explosions, and unfortunately, even huge mining collapses. WIKIPEDIA...BaYbEE!