EARTH CAUSATIVE FACTORS

Causative Factors in Earthquakes

• Earthquakes, abrupt and often intense vibrations of the Earth's surface, are mainly induced by the dynamic motion of tectonic plates. 
• Plate boundaries: The majority of earthquakes take place along the periphery of tectonic plates, where they interface with one another.
• At convergent boundaries, the collision of two plates typically results in one subducting under the other. Such phenomena may give rise to profound oceanic trenches and volcanic arcs.
• Friction between tectonic plates may result in seismic activity.
• Divergent boundaries result in the formation of fresh oceanic crust as plates separate. This phenomenon, often linked to volcanic eruptions, may also induce seismic events.
• Transform boundaries: The horizontal movement of plates past one another may result in substantial earthquakes. An example of this is the San Andreas Fault, located in California.
• Structural stress and strain accumulate along fault lines when plates undergo movement.
• When the tension surpasses the geological strength of the rocks, the fault breaks, liberating energy in the form of seismic waves.

Other Factors

• The flow of magma inside volcanoes has the potential to initiate earthquakes.
• Furthermore, seismic events may be triggered by the collapse of volcanic structures.
• Human Activity: Although less often, human activity may trigger earthquakes, including:
  High-pressure injection of fluid into the subsurface, known as hydraulic fracturing (fracking), may increase seismic activity.
• Dam Construction: The substantial mass of a dam may exacerbate the strain on the underlying faults.
• Excavating substantial quantities of material from the earth via mining may cause ground instability.

Types of earthquakes

• Tectonic earthquakes are the predominant kind of seismic activity resulting from the displacement of tectonic plates.
• Volcanic earthquakes pertain to seismic events that are linked to volcanic activity, resulting from either the flow of magma or the collapse of volcanic formations.
• Induced earthquakes are seismic events that are triggered by human actions. Although they are often smaller in size, they may still result in substantial destruction.

Seismic waves

• Body Waves: These waves propagate throughout the earthly interior.
• Primary waves, often known as P-waves, are compressional waves capable of propagating in both solid and liquid systems.
• Secondary waves, often known as S-waves, are shear waves that are limited to propagating through solid materials.
• The propagation of surface waves along the Earth's surface is the primary source of the majority of the destruction resulting from earthquakes.

IMAGE SOURCE (THUMBNAIL)