Earthquakes and volcanoes are interrelated to each other as both are caused by the release of heat and energy from the core of the Earth. They can trigger volcanic eruptions causing movements in the tectonic plates. Similarly, volcanoes trigger earthquakes through the movement of magma within them causing various changes in the physical geography. The main reason for the occurrence of earthquakes and volcanoes includes the movement of plates as these plates meet with the edges and boundaries.

 Earthquakes 

Earthquakes refer to the shaking and vibration of the Earth’s crust due to the movement of the tectonic plates. It is an intense shaking of the earth’s surface that may occur when tension is released from the earth’s crust. It is identified by the jerks that steadily build up pressure on both sides of the rock strata causing changes in the physical geography. The tectonic plates that make up the surface of the earth lie beneath the land and oceans. The movement of these plates can cause the volcanoes to erupt and mountains to form, also leading to surface shakes. The intensity of vibrations is sometimes so much that it results in great devastation. It may cause heavy shakings and vibrations and sometimes can bring tsunamis in oceans, which is equally destructive. Earthquakes are not random; however, the main causes of the earthquakes include the following categories

• Volcanic Eruptions- One of the main causes of earthquakes is Volcanic Eruptions and the area having active volcanoes is greatly devastated. However, these earthquakes are mild and the range is also limited. In rare cases, earthquakes due to volcanic eruptions bring destruction to life and property. On the other hand, volcanic eruptions in themselves are great disasters causing damage to life and property.
• Movement in the Tectonic plates: It is the most common cause for earthquakes as these are always moving and therefore affects the earth’s crust. The movement and collision of these plates are very destructive and the earthquakes caused by this have varying intensities. The movements of the earthquakes are again divided further into three categories namely constructive, destructive and conservative. 
• Geological Faults- The faults or diseases of the lakes from their original place is the main reason that results in slow improvement over a long period. These faults are also due to most of the geological forces that cause fracturing of the rocks and release a good amount of energy.
• Man-Made- The interference of man with geographical environment and nature also creates a disturbance in the crustal balance. Examples of human activities causing earthquakes are using nuclear bombs and nuclear weapons, which in itself is destructive. Along with these mining areas also causes the threat to this. 
• Minor causes- Minor cases like landslides, avalanches and falls of heavy rocks can cause shaking of the earth’s surface.  

Volcanoes 

A volcano is an opening in the crust of the Earth through which lava escapes along with volcanic gas and ashes. Volcanic eruptions are considered an awesome display of the destructive power of the earth. However, these eruptions in the later years resulted in the formation of soil by the magma which is left out. Volcanoes can broadly be divided into three categories as listed below

• Active Volcanoes- Active volcanoes are the ones that are frequently erupted and have a long history of frequent eruptions. This causes a change in the physical geography and most of these are located along the “Ring of Fire” located in the Pacific Rim.
• Dormant volcanoes These volcanoes are not frequent with their eruptions but have a history of eruption and can erupt in future. 
• Extinct volcanoes These volcanoes are often considered dead volcanoes and are not prone to erupt in the near future. These volcanoes are the ones that erupted several years ago and there are a few or no possibilities left for its future explosion. 

Volcanoes are an important part of physical geography and the three main causes of volcanic eruptions are listed as follows:

• Heat and pressure inside the earth
• Plate tectonics
• Magma chamber

However, the volcanoes also have some importance in maintaining the physical geography of the earth with the following constructive effects

• They lead to the formation of landforms, plateaus, plains and volcanic mountains.
• The volcanic eruption has also led to the formation of beautiful Caldera Lake in the United States of America.
• Hot Springs and natural geysers are also formed due to volcanic eruptions that have caused the formation of artistic beauty.

 Volcanoes causing earthquakes

The molten magma and volcanic fluids present in the volcanoes are responsible for earthquakes. These Occur in swarms during the eruption and are usually caused by the lipid magma and the hot fluids and glasses. This also leads to force in the crust reaching the surface. Mostly the active volcanoes are responsible for frequent triggers as discussed above but sometimes even the dormant ones are responsible for the cause in the physical geography.

Conclusion 

The earthquakes and volcanic eruptions are both useful and destructive causing both harm and usefulness to the physical geography. The main similarity between the two is that they both are unpredictable and are prone to cause changes in the physical conditions of the earth. Volcanic eruptions are responsible for the formation of soil and its layers and earthquakes are responsible for the formation of mountains and beautiful sceneries as well.