Pacific Ocean

Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. When the rocks break, the earthquake occurs.

The “Ring of Fire”, also called the Circum-Pacific belt, is the zone of earthquakes surrounding the Pacific Ocean- about 90% of the world’s earthquakes occur there.

5 Main Causes of Earthquakes

• Volcanic Eruptions. The main cause of the earthquake is volcanic eruptions.
• Tectonic Movements. The surface of the earth consists of some plates, comprising of the upper mantle.
• Geological Faults.
• Man-Made.
• Minor Causes.

Things that cause earthquakes

• Groundwater extraction – decrease in pore pressure.
• Groundwater – increase in pore pressure.
• Heavy rain.
• Pore fluid flow.
• High CO2 pressure.
• Building dams.
• Earthquakes.
• No earthquakes (Seismic quiescence)

We cannot prevent natural earthquakes from occurring but we can significantly mitigate their effects by identifying hazards, building safer structures, and providing education on earthquake safety. By preparing for natural earthquakes we can also reduce the risk from human induced earthquakes.

What’s the main cause of most earthquakes? tectonic plates? You just studied 9 terms!

The following are the cities which experts believe are the most likely to experience a major earthquake.

• Manila, Philippines.
• Los Angeles, California.
• Quito, Ecuador.
• Osaka, Japan.
• San Francisco, California.
• Lima, Peru.
• Tehran, Iran.
• Istanbul, Turkey. Istanbul is positioned near the center of the North Anatolian fault zone.

Earthquakes occur when energy stored in elastically strained rocks is suddenly released. This release of energy causes intense ground shaking in the area near the source of the earthquake and sends waves of elastic energy, called seismic waves, throughout the Earth.

Earthquakes are caused by the release of built-up pressure inside the Earth’s crust. The point inside the crust where the pressure is released is called the focus. The point on the Earth’s surface above the focus is called the epicentre. Earthquake energy is released in seismic waves.

Seismic Waves – The source of an earthquake is called the focus, which is an exact location within the Earth were seismic waves are generated by sudden release of stored elastic energy. The epicenter is the point on the surface of the Earth directly above the focus.

The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth’s crust and cause the shaking that we feel.

Most volcanoes, mountains, and earthquakes occur where plates meet. Places where plates meet are called plate boundaries. There are seven major plates along with countless minor plates. You can see that a plate can be made of both oceanic crust and continental crust.

But the Earth isn’t getting any bigger. In locations around the world, ocean crust subducts, or slides under, other pieces of Earth’s crust. The boundary where the two plates meet is called a convergent boundary. Deep trenches appear at these boundaries, caused by the oceanic plate bending downward into the Earth.

If the continents were eroded completely into the oceans there would be no continents and no land left. The continents are being eroded. Without plate tectonics that push the continents up the erosion would result in the continents disappearing under the surface of the oceans.

Without volcanoes, most of Earth’s water would still be trapped in the crust and mantle. Early volcanic eruptions led to the Earth’s second atmosphere, which led to Earth’s modern atmosphere. Besides water and air, volcanoes are responsible for land, another necessity for many life forms.

They move at a rate of one to two inches (three to five centimeters) per year.

Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again.

When the plates move they collide or spread apart allowing the very hot molten material called lava to escape from the mantle. When collisions occur they produce mountains, deep underwater valleys called trenches, and volcanoes. The Earth is producing “new” crust where two plates are diverging or spreading apart.

If two tectonic plates collide, they form a convergent plate boundary. Usually, one of the converging plates will move beneath the other, a process known as subduction. The new magma (molten rock) rises and may erupt violently to form volcanoes, often building arcs of islands along the convergent boundary.

In this lesson, we explore the causes of plate movement, including thermal convection, ridge push and slab pull.

Plate tectonics affects humans in several important ways. What would Earth be like without plate tectonics? We’d have many fewer earthquakes and much less volcanism, fewer mountains, and probably no deep-sea trenches. In other words, the Earth would be a much different place.

Mountains, earthquakes, and volcanoes form where plates collide. If we choose to live near convergent plate boundaries, we can build buildings that can resist earthquakes, and we can evacuate areas around volcanoes when they threaten to erupt.

Life needs more than water alone. Recent discoveries suggest that plate tectonics has played a critical role in nourishing life on Earth. The findings carry major consequences for the search for life elsewhere in the universe.

Three good things that plate tectonics provide for humans are: fertile soils, ore deposits and fossil fuels.

Mars, however, doesn’t have plate tectonics. After its formation, the planet was a searing mass of molten rock that eventually cooled to form a static crust around a rocky mantle, yet it’s unclear how hot the planet’s insides are today.

Without plate tectonics, Earth would not have its diverse geography, which provides a wide range of habitats. Plate tectonics is also responsible for hydrothermal vents on the ocean floor.