Volcanoes, Earthquakes and Mass Wasting Essay
Volcanoes, Earthquakes and Mass Wasting
Formation of volcanoes is often found where several large pieces of Earth’s lithosphere participate in plate tectonics, either converging or diverging underwater bodies. Volcano refers to a vent or fissure on a planet’s surface (usually in a mountainous form) with a magma chamber attached to a planet or moon’s mantle, periodically erupting forth hot lava, volcanic gases, and ash onto the atmosphere surface. The topic aims to explore how volcanoes occur onto the Earth’s surface, causes of short-term climatic cooling effects, and how volcanism leads to global warming of the atmosphere.
Volcano begins with Magma’s formation, which rises towards the Earth’s surface through its crust from the mantle under very great pressure. When Magma reaches the Earth’s surface, it depends on its state of being viscous from the constituent’s molten rocks (Sigurdsson et al., 2015). The thick viscous Magma erupts as explosive eruptions while non-viscous Magma erupts as effusive eruptions produce large volcanic ash and gases onto the Earth’s surface, accumulating to form a landform or a mountain as molten rocks tend to open downwards to a layer underneath the surface.
The diverging boundaries plates occur when two plate tectonics separate from each other, making hot lava mantle rock creep above the ocean’s thinned crust. The rise of the mantle rock due to pressure differences causes partial melting and adiabatic expansion of the rocks, forming volcanoes and new oceanic crust. Faulting and folding occur, causing fractures or cranks of the rocks to appear. Furthermore, as pressure increases, it tends to travels towards the vent with a tremendous hitting force of the molten rocks, creating a passage of Magma to the Earth’s surface (Sigurdsson at el, 2015). When the Magma reaches the atmosphere, it changes its form and becomes lava, an ejected molten rock by a volcano from its crater or fissured sides.
Figure 1: The eruption of the Magma due to the divergence of the molten rocks.
Converging boundaries plates occur where two tectonic plates collide, forming an ocean trench offshore, which is slightly deep. Water produced by the subduction plates creates Magma by lowering the overlying mantle melting temperatures, known as flux melting (Sigurdsson et al., 2015). Due to the silica content present in the Magma, it produces viscous eruptions as it solidifies and cools below the molten rocks, altering it from reaching the Earth’s surface, causing a volcano to occur. Moreover, the volcanic arcs border the subduction zones by forming chains of volcanoes around the molten rocks. Typical examples are cascade volcanoes of the Sunda Arc and the pacific ring of fire.
Figure 2: The converging boundary plate formation due to the colliding of the plates.
Volcanoes tend to occur at different stages to form a conical shape depending upon the type of material erupted and the type of eruption, either effusive or explosive eruptions (Sigurdsson et al., 2015). They are grouped into three different categories according to the nature in which they repeatedly occur. This classification includes active volcanoes which are expected to erupt, or its eruption is already taking place, dormant volcanoes which are not expected or predictable to erupt in the future, and lastly, extinct volcanoes which have ever occurred once in a lifetime, and no one expects that it will erupt again.
Classification of Volcanoes
Volcanoes are classified into four different types according to how and form each occurs, such as shield volcanoes, cinder cones volcanoes, lava volcanoes, and composite volcanoes.
Composite volcanoes: they employ multiple exposures of a single plate to create an average view of faces informing fluid lava flows. They are entirely made up of symmetrical cones of very large dimensions of alternating layers of volcanic ash, lava flows, bombs, and blocks which may rise upwards in the atmosphere as much as 9,000 feet above their molten base. Composite volcanoes occur in the Earth’s grandest mountain, referred to as Stratovolcanoes (Albert et al., 2019). Composite volcano magma contains minerals rich in andesite, dacite and rhyolite inform of silicate layers.
Stratovolcanoes or composite volcanoes’ formation occurs as one plate in the tectonic boundary is pushed against the other underneath it at subduction zones. This may be evident in the way the oceanic crust lies or is drawn below the continental plates. Water under the continental plate is trapped in minerals and porous basalt. Pressure and temperatures rise into greater depths as the molten rock plate sinks through a process known as dewatering. The hydrates produced due to the instantaneous release of water lowers the molten rock’s melting point in the mantle because it’s denser than the solid rock, thus forming Magma (Albert et al., 2019). Meanwhile, as the magma deposits rise upwards, the vent pops open, it lessens the pressure difference allowing the escape of volatile compounds from the solution of carbon dioxide, water, chlorine gas, and sulfur dioxide into the atmosphere in an explosive eruption.
Figure 3: The formation of the stratovolcano as it erupts.
Figure 4: A typical pictorial view of a composite volcanic mountain.
The composite volcano magma does not flow inform of fluid, and it rather escapes as a river of lava in its eruption, causing sudden destruction due to the formation of the lava bombs as molten chunks build up to form small stones up in the atmosphere (Albert at el, 2019). These bombs don’t explode into the atmosphere, causing a mixture of volcanic debris and water referred to as lahars. Lahars are volcanic landslides that travel faster down the slope, making them unable to escape. They cause major negative effects, as it erupts, it causes death to millions of people since the 16th century.
Lava volcanoes: they are composed of tiny stature in their compounds. They occur as the viscous lava flows at a great distance, making its surface harder and cools within its constituent structure. Eventually, loose fragments spill down due to the internal pressure present inside its sides, resulting in the outer surface’s shattering. Lava occurs due to collisions caused by hot heat present in the mantle as it is trapped on the Earth’s surface (Sigl at el, 2015). The heat present is produced by the radioactive decaying element concentrations, which partially melt the mantle’s mantle underneath the surface.
Figure 5: A typical pictorial example of a lava volcano.
Lava volcanoes result in numerous hazards on Earth’s surface, like tsunamis, mudflows, toxic clouds, gases, explosions, and lava flows, which causes secondary effects like changes to climate and weather loss of crops and property damage diminishing the economic growth of the world. The massive lava volcanic explosions are produced by the rapid expansion of gases, triggered by the sudden depressurization of a hydrothermal gas-charged Magma between the molten plates (Sigl et al., 2015). The hot fragments and ash are the most observable products of lava volcanic eruption in the world. When it gets exposed to the atmosphere, the toxic cloud gases combine with the explosive products, causing people to suffocate, scorching vegetation, and death to Animals. The common volcanic gases are sulfur dioxide, water vapor, hydrogen sulfide, and carbon dioxide.
Cinder cones volcanoes: they occur when lava particles are ejected upwards from the volcanic vent, as the lava pieces rain down due to violently blown air around the vent surface (Sigl et al., 2015). The lava ejection momentarily builds up in an oval-shaped or circular cone, with a crater at its top. They take place at about 1100 feet below their surface. It solidifies over time and hits the ground losing its particle compositions. However, cinder cones are rough, and their particles tend to clog together, causing the pile to stable for repose, and rather supports the flow of lava out underneath the cinder base to form a smooth pad on its sit. Cinder cones grow abundantly onto the atmosphere and piggyback 100 meters high on larger volcanoes.
Figure 6: An example of a typical pictorial view of cinder cone volcanic, forming a crater on the top of the surface.
The great danger produced by the cinder cones volcanoes is the lava flow, which causes the breaching of crater walls. They expose crosscutting Road cuts into different locations along the surface of the Earth. Cinder cones are evident to produce a dramatic and beautiful scene in the atmosphere as they erupt (Sigl et al., 2015). It affects environmental conditions due to emissions of hot lava gases, causing climatic and weather conditions changes.
Shield volcanoes: they entirely occur as the fluid flow of lava horizontally in the slopes of the molten plates. They erupt as effusive eruptions in all directions as they tend to flow out. Shield volcanoes are formed as spots on the Earth’s surface in which Magma settles underneath the rock plates and ascends as lava, leaving the magma chamber below empty. The Magma transforms into ash when reaching the Earth’s surface, producing volcanic gases. The basaltic flow of lava in a shield volcano covers a wider area due to its low viscosity. The lava’s eruption depends on each other as it flows hardens on top of the previous plate.
Figure 7: A typical example of the Mauna Loa shield volcano on the island of Hawaii.
This process creates an elevation over time, resulting in a gradual increase in shield volcanic formation as lava hardens and flows out underneath it as runny and non-acidic. They are experienced in shorter periods less violently in their eruptions and explosions, causing widespread global warming of the atmosphere (Trenberth et al., 2014). It increases greenhouse effects in large amounts caused by gases produced by the volcanic eruptions, but the sulfuric dioxide present onto the surface has a fine cooling effect that encounters the greenhouse warming effects.
Causes of Volcanic Eruption
Magma buoyancy: the rocks underneath the Earth’s surface increase in volume as their mass remains the same due to the rocks’ melting. The lighter Magma then ejects upwards towards the surface, producing lava, hot gases and ash in the atmosphere that pops up like an inflated balloon. The magma buoyancy creates heat between flexible walls, expanding them as new Magma flows in, blowing their top surface. The eruptions of these type cause major destruction to living organisms in the vicinity.
Absolved gases pressure: the eruption of thick Magma towards the surface makes bubbles of gases harder to escape creating more pressure within the plates underneath the surface. The accumulation of more bubbles of gases creates more intense pressure than the buildup to strained stored energy, which produces an upward thrust towards the Earth’s crust. The pressure difference created by frictional stresses of the tectonic plates melts the underlying rocks, making Magma rise into the Earth’s crust.
Hot lava rises through the gap created when two tectonic plates move away from each other, resulting in volcanic eruption into the atmosphere. This kind of volcanic eruption takes place on the ocean beds and rises above to form an island.
Effects of Volcanic Eruption
The volcanic eruption has major effects on the environment since it is already known that it causes cooling effects on the Earth’s atmosphere by throwing droplets of sulfuric acid, gases, and ash particles that block the sunlight from reaching the Earth into the required intensity due to formation of volcanic winter on the ozone layer. The volcanic eruptions cause major threats to millions of people, dangerously impacting their health, environment, and climatic changes. These impacts are detrimental to social and economic growth and hazardous to human survival (Trenberth et al., 2014). The harmful gases present in the atmosphere, such as methane, hydrogen chloride, Magma, carbon dioxide, sulfur dioxide, and other organic elements, cause an unconducive environment to live in. Harmful impacts like tsunamis are experienced widely depending on the distance on which volcanoes are located and the magma viscosity and gas concentration.
The major problems associated with volcanic eruptions are death, eye problems, psychological effects, respiratory problems, injuries, destruction in transport and communication system, human displacement, sewage disposal, and power outage. A volcanic eruption may also lead to other negatives impacts on the Earth’s surface, such as the unsafe water quality, damage of crops, severe lack of rainfall, and climatic weather change conditions causing destructions on the world economy in the regions impacted. Eventually, lack of rainfall leads to severe drought and famine, causing more deaths to people and Animals at large. However, safety measures may be employed promptly to counter the unfavorable impacts on human health.
Large-scale volcanic eruptions lead to short-term climatic cooling as a huge ton of sulfur and outpouring of ash particles are deposited and blown into the Earth’s atmosphere (Trenberth et al., 2014). Harmful gases and solid particles are blown into the stratosphere around the Earth for a couple of days, leading to global climate, which minimizes the intensity of solar radiation that could reach Earth’s surface. These effects alter the circulation in which the patterns of the atmospheric conditions occur, reducing its temperatures. Volcanic eruptions may lead to long and short-term climatic changes on the Earth for a great period. For instance, there was experienced global warming in temperatures reduction for about three and half years as Mount Pinatubo in 1991 erupted.
Volcanic eruption leads to a release of sulfur elements such as sulfur oxide in huge amounts causes a stronger climatic change than dust particles present in the atmosphere. The sulfuric elements move into the dry upper part above the troposphere mixing with the moisture content present in the atmosphere to form sulfuric acid visible as very small light droplets particles reflecting the sun’s radiation. Such droplets accumulate in the atmosphere in large amounts, which eventually spreads and grows bigger (Gudmundsson, 2016). Over a certain period of about two to four years, the droplets fall on Earth due to their heavyweight onto the atmosphere. The cooling effects experienced in the atmosphere are due to sulfur droplets present since the last time the volcanic eruption took place. Furthermore, when Mount Pinatubo erupted, a satellite traced the presence of sulfur hazes produced by its eruption causing global cooling effects.
The instantaneous rise of outpouring gases and dust particles increases the effects of global warming in the atmosphere as it acidifies within water bodies like seas or oceans that causes the enormous release of hot gases that trap heat in the entire atmosphere (Trenberth et al., 2014). Since 9191, more than 20 volcanic eruptions have erupted, including Nabco (Eritrea), Merapi (Indonesia), and many more others have produced Sulphur that leads to global cooling effect for a period of more years. Volcanic eruptions can’t be predetermined nor predicted for future occurrence, which blocks the solar radiations for several years when they took place. The release of hot greenhouse gases leads to an increase in temperatures in the atmosphere.
In conclusion, the volcanic eruption enhances climatic effects such as global warming, ozone layer depletion, and greenhouse cooling effect. The volcanoes occur in the regions where mountains are causing environmental impacts that are hazardous for human beings’ survival due to emission of the hot lava gases and ash in the atmosphere, affecting the ozone layer. It evidenced that volcanic eruption occurs as the magma deposits from underneath the molten rock plates rise upwards towards the Earth’s surface through its crust from the mantle under great pressure under folding and faulting processes. The release of volcanic gases and particles causes long and short-term cooling effects as it tends to block the sunlight radiations from reaching the Earth’s surface. Global warming is triggered by the composition of the carbon dioxide present in the atmosphere, causing a greenhouse effect. The two phenomena have a greater impact on climatic and weather changes, though they aren’t major causes of climatic change.
The release of energy by an Earthquake is in seismic waves, which spread out towards the Earth’s surface above the focus, causing Earth’s trembling. Earthquake is defined as the shaking or trembling of the Earth’s surface caused by volcanic activities or movement around geologic faults. These topic aims to examine how Earthquakes are formed, environmental impacts on the Earth’s surface, and focus on what triggers Earthquakes to occur.
An earthquake occurs due to the tectonic plates’ movement in the crust of the Earth’s surface. They mainly occur when frictional stress of the plate boundaries combines, causing fault line failure. Eventually, in an Earthquake formation, the elastic strain release of energy and waves radiate, disrupting the ground. Earthquakes actually can range from those that are violent enough to displace people, Animals, and other objects in the air and environmental destructions compared to those which are too weak to be felt or noticed as they take place. The smaller Earthquakes takes places in the same place for a while before major large Earthquake takes places are referred to as foreshocks. Furthermore, one can’t tell whether Earthquake’s occurrence is a foreshock until a larger Earthquake occurs, causing major destruction (Scholz, 2019). The largest Earthquake is referred to as the main-shock, which follows after foreshock occurrence.
The seismic wave has a high frequency that spreads in a wide area of the Earth experienced over a longer period resulting in the ground’s tremor. The attenuation of the waves past a molten rock establishes high–frequency limits to moderate Earthquakes. The seismic waves are classified into love and Rayleigh waves, primary and secondary waves that propagate on the Earth’s surface. The seismic waves’ existence was predicted mathematically in a modern comparison in the 19th century that showed a great close correspondence with actual measurements and theoretical calculations. The primary seismic waves are longitudinal waves with elastic motion transmitted in the Earth’s interior by both liquid and solid materials at a higher speed. The primary wave particles vibrate and expand at a higher rate that makes it possible to reach the Earth’s surface first, and they originate from the focus point of the Earthquake (Scholz, 2019). Secondary seismic waves are transverse motion because of the shearing of the transmitting rock in the direction of travel.
Love and Rayleigh seismic waves follow the primary and secondary waves’ traces as they travel in the horizontal displacement of particles in motion. They are responsible for strong shaking of the ground during an Earthquake occurrence as they travel and disperse as longwave trains at substantial distances (Woodward et al., 2018). When Love and Rayleigh’s waves encounter separation of the boundary rocks due to a difference in their properties, it goes through refraction and reflection. These complications are observed during an occurrence of earthquakes as the ground move. The actual ground motion of the Earthquake is measured by two instruments referred to as Seismographs and Accelerometers. The initial point of Earthquake rupture is referred to as a hypocenter or point of focus, and the point just directly above the hypocenter at the ground level is referred to as epicenter where frictional stresses of the plates are much felt.
Figure 8: Earthquake epicenter
A global dynamic model theory of tectonics plates holds that the Earth’s lithosphere is made up of large dozen quasi slabs referred to as rock plates, which move relative to each other in a horizontal direction at a rate of 3 to 9cm annually over a magnitude of the lesser shell. The edges of the fault plates combated along with the adjoining plates, causing chemical and physical changes of the tectonic plate boundaries due to frictional stresses between them. The oceanic ridges generated by the Magma’s cooling and upwelling toward the Earth’s surface mantle’s crust forms a lithosphere underneath the interior ground (Woodward et al., 2018). The Earthquake belt’s major concentration is along the oceanic ridges that correspond to the divergent boundary plates. Meanwhile, the lithosphere slab’s location is associated with the deep and intermediate focus of the Earthquake mark on the upper convergent boundary plates at the subduction zone, which aligns the lithosphere below the island arc.
Plate’s tectonic Earthquakes occur anywhere along the Earth’s surface, where much strain energy is stored to accelerate the propagation of the fracture along a fault boundary. Most sides of the fault plane slide seismically past each other smoothly if there are no asperities that could cause an increase of frictional resistance along the fault plane surface. When the fault plane has locked, it creates a large volume of stored energy around the fault due to the increased stress triggered by the plates’ continued relative motion (Woodward et al., 2018). The plates’ continued relative motion rises the stress into sufficient volume to break the irregularities that create frictional resistance, allowing the locked fault to slide over each other, freely releasing the strain energy stored. The released stored energy comprises radiated seismic waves, which are elastic, fractures of the rock, and frictional stresses of the fault plane that results in an Earthquake occurrence.
The gradual formation of the frictional stress and strain energy accelerated by the Earthquake’s occasional sudden failure is known as Elastic rebound. The energy stored is used to provide thrust in the generation of the Earthquake’s fracture growth or provide heat created by friction stresses. Therefore, the lowering of the Earth’s surface’s potential energy is caused by Earthquake occurrence, raising the temperatures in the atmosphere due to heat produced out by the Earth interior. Since the plate edges are rough, they stuck together, restricting further movement, while the rest parts of the plates keep moving freely enough to unstuck the edges on one of the faults planes, enabling an occurrence of an Earthquake (Rijsingen et al., 2018). The Earth shakes as the energy radiated outwards in all directions in the form of seismic waves ripples on a pond shaking the ground and everything above it due to the buildup of the stored energy that unsticks the fault edges to overcome friction stresses.
Scientists’ records and measures the size of Earthquakes using an instrument referred to as seismographs. The records they make during an Earthquake occurrence are referred to as seismograms (Nievas et al., 2020). The seismograph base is stable, which sits firmly on the ground; it shakes as the ground shakes to enable the heavyweight that hangs freely records all the movements absorbed by the spring. The heavyweight does not shake as the base of the seismograph shakes. The differential position of the motionless part and shaking part of the seismograph is determined and recorded.
Figure 9: A simple diagram of a seismograph measuring device.
Figure 10: Illustration showing types of earthquakes
Tectonic Earthquake: the strained stored energy causes the movement of unevenly shaped slabs of rocks referred to as tectonic plates that slide or collide against each other due to the buildup of intense pressure between plates. The waves of the energy trace the faults formed by high pressure as plates move or push over each other towards the Earth surface, shaking it.
Volcanic Earthquake: the frictional stresses between the rocks causes the injection of Magma towards the crust of the Earth surface, exerting more pressure on the plates breaking the rocks. However, the space magma ejection has to be filled by rocks that move in a relative motion, resulting in a tremor of low magnitude.
Explosive Earthquake: during detonation of the nuclear weapons, there is the vast release of energy in a large amount that blast into the atmosphere resulting in an earthquake. Nuclear weapon testing has led to earth vibrations that distrust the pattern of tectonic plates, creating faults.
Explosion such as natural as explosion produces intense pressure into the Earth surface that propagates as acoustic waves in the air that triggers the tectonic plates’ relative motion, resulting in an earthquake.
Collapse Earthquake: the collapse of mines produces seismic waves that cause the ground shaking as they travel between the faults underneath the Earth surface, resulting in a major earthquake ever experienced in the world.
Impacts of Earthquakes
An occurrence of an Earthquake leads to major effects such as ground rupture and shaking, soil liquefaction, human impacts, landslides, floods, fires, and tsunamis that affect the world’s economic growth and environmental destruction of buildings, vegetation, and other major impacts on human beings such as death.
The ground rupture and shaking: these results from;
- Complex magnitude combination of the Earthquake
- Geological conditions of the plates
- The epicenter distances
Ground rupture and shaking causes major effects created by an earthquake, resulting in severe damage to rigid structures and buildings. Ground rupture results from the displacement and breaking of the ground surface as an Earthquake tries to trace the fault spots (Fan et al., 2019). They cause major risks on the rigid structures such as bridges, power stations, and dams, which are more prone to the existence of faults breaking the structure’s life within the ground surface.
Soil Liquefaction: An Earthquake’s occurrence leads to the soil’s liquefaction, making it lose its strength and stiffness due to vibration of the ground surface. The soil structure becomes substantially destroyed and starts to flow in a liquid form. However, this happens because seismic wave increases water molecules pressure, present in the space between particles at the Earth’s crust.
The existence of soil liquefaction makes buildings tilt and sink into the ground surface, resulting in loss of properties and resources (Fan et al., 2019). The collapse of the buildings due to soil liquefaction was experienced in Alaska in 1964 when the occurrence of the Earthquake took place. Soil liquefaction makes the unstable to withhold the structural forces between its geologic patterns, making it lose and allowing faults at ease.
Human Impacts: Earthquakes are capable of causing catastrophic damages, wreaking havoc on everything nearby, and putting all life at risk (Fan et al., 2019). Many forms of damages may have resulted from earth tremors, such as the collapse of buildings leading to massive deaths and property damage due to destabilization. Similarly, there might be corresponding health damages due to the aftermath of diseases and mental instabilities due to depression and panic.
The destruction of factories, schools, buildings, shops, and roads render millions of people homeless and increase street children. For instance, the Haiti 2010 earthquake left over 1.6 million people homeless, which lasted for 6 years. It also led to the death of more than 230,000 lives, and others became injured. Therefore, homelessness leads to isolation, shame, and stigma due to society’s division.
The Earthquake causes psychological/ mental effects as some of the survivors become traumatized after the incident resulting in post-traumatic stress disorders such as nightmares, anxiety, flashbacks, and intense fear. Besides, it is terrible for the Rescue teams of survivors to located different dead bodies in case a building collapse causing traumas. Besides, Earthquake creates a natural disaster in need of help in distributing foods, medicine, and security to the victims.
Tsunami: The abrupt movement of large volumes of water due to earth tremors (Fan et al., 2019). A tsunami wave’s height and speed determine the power contained within its structure, as it can travel at speeds of 600- 1100 km/hr. Tsunami causes mass destruction of properties and mass casualties, making it a natural disaster to the government in overwhelming post-disaster implementation development due to lack of funds to cater to the expenses needed.
Poverty among the people who lost everything as the tsunami took place increases, leading to insecurities among the other people who were not affected. Moreover, evacuation of people occurs due to the destruction of homes or intense fear of what might arise if they remain in the incidents’ location.
Figure 11: A typical pictorial view of the 2004 Indian Ocean tsunami.
Landslides: it occurs due to the plate tectonics’ quake movements underneath the crust of the Earth’s surface. During an earthquake in mountainous areas, the Earth’s surface’s vibration causes the heavy molten rocks to slide over each other (Fan et al., 2019). Landslides are triggered by the Earthquake’s occurrence, causing catastrophic destruction of buildings along the Earthquake’s induced landslide path.
Figure 12: Photograph showing landslide
Flood and fires: the earthquake occurrence may cause landslips which collapses the dam river walls resulting in floods. The flood destroys all the crops and other vegetation in the region, leading to severe famine and drought. Floods have major effects on humans, such as loss of lives, displacement, increased poverty level, and unemployment in the affected regions.
Earthquakes damage the electrical power or gas stations, resulting in fire, which spread within minutes due to the vibration of the earth that produces electric arc on the power stations (Fan et al., 2019). Fire leads to loss of lives, destruction of properties and buildings, causing major displacement of people in the region of the incident. The pictorial below shows the San Francisco fire.
Figure 13: The pictorial above shows the San Francisco fire as a result of an Earthquake.
The causes of earthquakes
Volcanic Eruptions: the boiling of lava as it tries to break towards the crust of the Earth’s surface creates a fault due to increased hot lava gases and ash present beneath the Earth’s surface, which destroys the molten rock pattern formation (Hardebeck & Okada, 2018). This destruction of the faults sends shockwaves from underneath the Earth’s ground surface, causing the Magma’s upward movement, causing damage. The volcanic eruption of the mountains causes the Earth’s surface to tremble as Magma ejects onto the atmosphere.
The Earth is made up of irregular-shapes of molten rock plates that collide and slide over each other due to the accumulation of pressure underneath the Magma composition, release stored energy at a higher speed, causing an occurrence of earthquakes. Similarly, a divergent boundary plate causes volcanic lifts enlarging the faults present on the molten rocks as Magma ejects upwards, leading to the Earthquake’s volcanic type.
Tectonic movement of plates: the plate of the molten rocks moves in a relative motion towards each other, affecting the Earth’s surface. They move in a constructive horizontal movement away from each other, resulting in mild earthquakes (Hardebeck & Okada, 2018). The plates’ colliding as they move towards each other forms a destructive boundary plate generating much heat underneath the Earth’s surface, causing fractures of the molten rock leading to the Earthquake.
Geological Faults: this refers to the dislocation of the plates from their usual original plane. The planes develop slowly over a long period, spreading vertically and horizontally in all directions, causing the rocks’ movements as they develop, resulting in tectonic earthquakes. The faults and the rock structure result from the impact of geological forces between the plates (Hardebeck & Okada, 2018). The dislocation/ displacement of the plate creates fractures on the rock’s surface, which releases strain energy resulting in an earthquake.
Human-made activities: man’s interferences with nature cause crustal unbalance due to heavy clubbing of water molecules seas, dams, or oceans leads to an occurrence of Earthquake in that region (Hardebeck & Okada, 2018). The bombing of nuclear weapons sends shockwaves along the Earth’s surface, disturbing the natural pattern alignment of tectonic plates, resulting in an Earthquake explosive type.
Fracking for gas and oil as the initial drilling imposes stress on the Earth surface. It exerts more pressure between subterranean rock opening existing fissures, causing an earthquake occurrence. The franking process disposes of wastewater produce that fracture hydrocarbons patterns from the rock. The wastewater produces the by-products of water, chemicals and sand, which come out under high pressure lubricating the existing faults and fractured molten rocks, triggering earthquakes.
Mining activities causes instability in the ground as mining companies dig deeper into the Earth’s crust, triggering Earthquake due to mining machines’ vibrations. For instance, the Crandall Canyon coal mine in the northern Emery, collapsed leading to many loss of lives inside the mine, as it caused vibrations of the tectonic plates on the Earth surface.
In conclusion, the world has incurred numerous occurrences of earthquakes in the past years. For instance, it has occurred in Japan, Chile, New Zealand, Haiti, and many other countries leading to the catastrophic destruction of properties, buildings, loss of lives, affecting at large people’s life emotionally, environmentally, economically, and socially. Also, earthquakes are mainly caused by volcanic eruptions, geological faults, tectonic movements of the plates, and human-made activities. Safety measures may be employed to counter the effects caused by earthquakes occurrence by building safer structures, identifying hazards, and providing basic education on safety during an earthquake.
Everything that is on the Earth’s surface is pulled towards the Earth by the force of gravity. That include all earth materials, rock and regolith, which forms the basis of mass wasting. Mass wasting is a type of erosions caused by gravity, glaciers caused by ice, river erosion caused by running water and groundwater, and wave erosion caused by winds and currents in the seas or land. Mass wasting processes are very varied in three very key respects: the mass of material involved, the speed of the movement, and the materials’ nature. Thus, we can say that mass wasting is a type of erosion that plays a significant role in shaping the landscape. Though mass wasting is not as dramatic as volcanic eruption and earthquakes, they are extremely vital in shaping the Earth’s surface. They do not act alone but in conjunction with other erosional processes, especially streams and lakes. Mass wasting processes operate without human intervention, but human activities affect it.WEATHERING AND MASS WASTING
The mass of materials that are involved in mass wasting will vary from tiny mineral grains tumbling downslope to enormous mass that contain huge volumes of rock and mineral materials that may be as great as thousands of cubic kilometers. Mass wasting speed may range from unnoticeably slow, less a meter per year, to hundreds of meters per second. Mass movement’s nature will range from intact masses, which retain their original structure, to those that become thoroughly mixed and homogenized during the movement (Easterbrook, 1999).
Mass wasting that involves the transfer of rocks and social downslope due to gravity is known as a mass movement. Mass movement may be triggered by saturation of the ground surface with water, overly steep slope and ground gradient, absence of vegetation on the ground and earthquakes.
The force of gravity is responsible for the downslope transportation of weathered and loosened materials allowing them to move without needing lubrication by water or agents such as ice or water. The movement of materials by the force of gravity may be abrupt, or it may be slow depending on the involved factors. The force of gravity about erosion can be coherent or incoherent. The erosion of consolidated mater that move as a single unit is known as the coherence of matter. On the other hand, incoherence is the movement or erosion of materials of unconsolidated fragments of materials.
Figure 14: A photograph showing the effects of gravity on the sloping landmass.
Types of Mass Movement
Geologists classify mass movement based on the kind of material that moves, how it moves and the speed with which the material moves.
Rockfall is the mass movement that is very rapid and involves rocks falling from higher grounds like cliffs. In rockfall, rock fragments can break with relative ease down steep bedrock slopes due to frost ice that gets trapped inside rock crevices. Once the liquid water gets frozen, it expands within the rock space, causing the rock’s weathering that falls down the cliff or mountain slope.
Figure 15: Rockfall keeps Highway 133 to one lane south of Carbondale in Crystal Valley
Rockslide: It is a type of mass movement that involves rock and soil materials sliding down a slope. In the process, a block of material moves suddenly along a flat, inclined surface. In most cases, the movement is parallel to the fracture, bedding, or metamorphic foliation plane, and it can change from very slow to moderate fast. Sackung is the term used to describe a slope that slow down the motion of the rock as they slide down the slope. Rockfall leads to the formation of a talus or a talus slope that is simply a pile of debris. It occurs when rock fragments break off relatively easily from steep bedrock slopes, most commonly due to frosts-wedging in areas where there are diverse freeze and thaw cycle per year. One can have heard the occasional fall of rock fragments onto a talus slope when hiking along a steep mountain slope on a cold morning. The occurrence is due to water that is trapped between cracks, freeze and expand overnight (Martini, Brookfield & Sadura, 2001).
Figure 16: Rockslide closes part of the highway in Menifee County (Gamel, 2019).
Rock avalanche: If a rock slides and starts moving quickly, the rock has a very high probability of breaking into many small pieces, turning into a rock avalanche where small and large fragments of rock moving in a fluid manner aided by air cushions beneath and within the moving mass of soil matter.
Figure 17: Avalanche
The downward movement of a mass of soil matter along a curved surface. The material slips backwards, leading to a curve shapes feature where the ground and soil material are removed.
Flow is another form of mass movement involving the movement of materials containing a large amount of water that moves down a slope as a thick liquid. The movement involved a thick mixture of soil mixed with water that moves down a slope. The two types of flow in the mass movement are mudflow and earth flow. Mudflow is different from Earth flowing in that it consists of water, soils and rock mixed and having a consistency of wet concrete. Earth flow moves slowly and usually carries clay-rich sediments.
Creep or Solifluction
Creep is another example of a mass wasting process. Solid creep is the most common type of creep that involves slow, downhill soil and regolith movement. Soil creed happens at a very slow speed travelling only a few centimeters or even millimeters per years, and thus is it not easy to observe the movement. It is the slowest type of mass wasting where soil particles take a very long time to move a very short distance. However, the effects of the movement can be seen after a long period of times, as demonstrated by the movement of structures downhill or the presence of soil deposited behind buildings.
Creep is considered as a very slow process, as over time we observe the slow downslope movement it engenders, but it is the small and discrete movement of the slope mantling regolith classic creep is not brought about by the bodily movement of the surface layer above a plane of failure, but the individual cyclic movement of the material. In this process, particles or small masses of material at or near the Earth’s surface are lifted upwards perpendicularly to the surface by any of several cyclic processes involving lifting of material perpendicularly to the surface the lowering of those materials in a much more nearly vertical direction. Creep can only be noted on steep or moderate slopes: tress, grave markers, or fence posts consistently leaning in a downslope direction. Tree, which is in constant growth, will tend to correct the bending as they grow upright, leading to curving in their lower section of the trunk. Creep can take place to some extent in almost all hillslope due to the effects of gravity. Saturated conditions and freeze-thaw cycles may accelerate the creep process for a limited period (Plummer, Carlson & Hammersley, 2013). Solifluction is a type of creep where froze tundra solid matter thaws and started a slow movement downslope.
Figure 18: The photograph illustrates a bending tree at the lower end due to soil creep effects.
The soil beneath the tree roots is slowing creed downhill, leading to the curving of the trees lower ends as they try to remain upright.
A slump is a type of slide that takes place within thick unconsolidated deposits. Slump involves movement along one or more curved failure surfaces, with downward motion near the bottom and outwards motion towards the bottom. Slumps are typically caused by an excess of water within these soil matter located on a slope. A slump is a form of mass wasting that is particularly common in areas where soil or rocks collapse, breaking off from the upslope, rotating at a low speed as it moves down the slope. If a slump occurs as a large consolidated mass of soil matter, it is considered as coherent and incoherent if it moves as unconsolidated soil matter or sediments. Slump causes damages to roads, infrastructure and houses (Watkins & Hargitai, 2014). An example of a slump is in Alberta’s Lethbridge area, as illustrated in the figure below.
Figure 19: Slump
From the diagram, the feature is likely to have been in existence for many years, with just small movements in seasons of snowmelt and large spring rains runoff the bottom of the slump as small streams of water downstream erodes it. The erosion contributes to continues slump. The basal materials from the support for the overlying mass of soil matter down the slope, and if the support is removed, there is likely to be slumping.
Mudflow and Debris Flow
When a mass of sediment becomes saturated with water, the mass loses strength, to the extent that grains are pushed apart, and it flows even on a gentle slope. The process can happen during rapid spring snowmelt or heavy rains and is also relatively common doing volcanic eruptions due to the rapid melting of snow and ice. A mudflow or debris flow on a volcanic or during a volcanic eruption is larger. If the material involved is primarily sand-sized or smaller, it is known as a mudflow. However, if the materials involved are gravel or a mixture of larger soil particles, it is known as a debris flow. The debris flow typically forms in areas with steeper slopes and more water than mudflow, and thus it requires more gravitational energy to move the particles that have a huge mass. In many cases, debris flow occurs within a steep stream channel and is triggered by the collapse of bank materials into the stream. The process leads to creating a temporary and significant flow of debris mixed with water when the dam breaks.
Mudflows and debris flow have the capacity of carrying particles of different sizes, such as a saturated mixture of soil and water, to large social particles and boulders. However, the two mass wasting processes differ by the size of the particles that transport downhill. The consistency of mudflow represents a thick, muddy sludge that carries branches, twigs and rocks, and other particles of soil. Mudflow and debris flow poses a natural hazard as their sudden movement are a threat to human life, and human structure builds in their paths.
Figure 20: Mudflow in Southern California triggered by fire and rain (Left). Debris flow (right).
Landslide: Landslide is another example of a mass wasting process that occurs when gravity overcomes the frictional forces that hold the layer of rocks in place on a slope. The rocks and the ground are made of the layer, which is of varying strength. A weak geological layer forms a failure plane on a slope making the slope unstable. The mass of material previously held by friction undergoes a disturbance once there is a force that upsets their balance, causing the upper layer to slide away. Landslide is caused by heavy rains that lubricate the upper layer, reducing the amount of friction and the layer below it, causing the land to slide. The water added to the soil layer as the mud formed to act as a lubricant. The extra weight and reduced friction cause the upper layer to slide away. Deforestation is another contributor to landslides as it weakens the root structure and increases the risk of landslides. Earthquakes are another trigger of a landslide where the ground shakes; the ground’s upper layers may become dislodged. One way to prevent the occurrence of landslides is to drill large bolts to secure the upper layers of the ground materials in place.
Figure 21: A land slide in Papua New Guinea. At least 12 people died as a result of the land slide.
In a landslide, a huge amount of weathered rock material moves down a mountain slope mainly due to erosion that is aided by gravity. Landslides take place within a very short time, moving at a very high speed and leaving destruction on their trail as they remove or cove everything on their path. Almost all landslides are triggered by earth movements such as earthquakes or lubrication agents such as snow, ice, melted water or rainfall. In high-intensity rainfall, weathered rocks and soil matter become loosened and unstable from saturated conditions leading to the separation of individual grains and other soil material fragments. The loosened soil matter, coupled with increased fluid pressure, succumbs to gravity and erosion that plunge materials downslope as a strong landslide. The landslide has the potential of causing huge natural hazards as they cause damage to human structures and other resources on their path.
Glacier and Periglacial
Glacier and periglacial, and periglacial are forms of mass wasting in the areas that have ice. The glacial erosion processes occur when soil particles are incorporated in the glacial ice through plucking from where they are transported down as slope within the glacier. Abrasion and friction involved in ice and rock moving across the bedrock erode the rock’s surface, leaving scrapes, striae, gloves and polished rock surfaces. Glacier and periglacial erosion within the mountain environment produce various common glacial landforms such as the hanging and the U-shaped valleys. In the below photograph, this landscape’s glacial reason hassled to the carving of several distinct landforms, such as the aretes and glacier U-shaped valleys forming ridges between the U shapes valleys (Martini, Brookfield & Sadura, 2001).
Figure 22: Glacier
A deposition is a constructive mass wasting process that involves the placing or the laying down of eroded and soil materials in a location that is different from their origin. It is not specific to a single process or event as it occurs following erosion, weathering and mass wasting taking place to nay consolidated or unconsolidated soil matter that has accumulated due to certain natural processes or agents. The deposition of materials can be due to chemical, mechanical or biological weathering and erosion processes caused by ice, wind or water. The accumulation of deposited materials leads to the building up of landform features, effectively altering the landscape’s terrain. Some of the depositional landforms include floodplains which are large depositional features resulting from the accumulation of fluvial deposits. Others include the dunes, which are depositional features that are built as a result of wind-related activities.
Water is a very significant agent of erosion ass it erodes rocks and soils matter, transports the weathered materials from their sources to other locations where they are deposited. The wind is the other erosion agent that involves material being picked and being temporarily transported from their source to a different location where they are deposited, either stored permanently or later moved to another location. Erosion by ice is a process where soil particles are picked and incorporated into moving ice such as glacier, from where they are later transported downslope, or when friction between bedrock and ice destroys bedrock materials that are later transported downslope. Gravity is very vital in the downward movement of the weathered, loosened material enabling them to move without the aid of ice, water or wind. Gravity, as about erosion, has a very significant role in mass wasting processes (Toy, Foster & Renard, 2002).
Figure 23: Aftermath of erosion
From the diagram, the basin and range landscape is influenced by several depositional processed. The mountains in the background have been impacted by fluvial erosion such as water, with the sandstorm leading to aeolian erosion. The other types of mass wasting that are likely to be taking place within the mountain region include landslides and rockfall due to gravity and the steep terrain of the region.
Water is an agent of erosion that affects rocks affecting their shapes and the nature of the landscape as it removes and transport weathered soil matter to different locations. Fluvial erosion can be categorized into sheet erosion, gully erosion and rain splash erosion. Sheet erosion occurs when soil particles are loosened by raindrops and then transported by the runoff downslope. Gully erosion occurs when water concentration during sheet erosions causes small gullies and rills as water flows downstream. The splashing of rain is another form of erosion when the impact raindrops loosen and mobilize soil particles (Toy, Foster & Renard, 2002).
Fluvial erosion is a form of erosion that occurs during the effects of rain, meltwater runoff and percolation of groundwater. The eroded soil matter is transported either as a suspension in water, bounced by saltation, or dragged along the ground surface by traction. The accumulation of fluvial over an extended region for a pathway for groundwater flow continues to erode, transport, and deposit weathered soil materials along the ground surface.
The illustration on the right side illustrates the effect of rainwater splashing on the ground and its impact on the soil. It leads to the disintegration of individual grains of soils exposing the soil to erosion and mass wasting processes. The image on the right side shows the landscape effect of fluvial erosion.
Wind/ Aeolian Erosion
Wind erosion is another method through which soil material are removed, transported and deposited to other regions. Erosions by wind can be through deflation and abrasion. Deflation is the wind erosion process that involves particles’ transportation by air currents along the ground surface. Abrasion is a winding process that takes as wind transport particles within the landscape through a “sandblasting” process. Wind erosion and deposition lead to diverse landforms that include loess deposits, yardang, and dunes.
The image shows a satellite image showing regional clouds of dust storm transporting aeolian sediments from South and Africa over the Red Sea. In the arid, desert climates, wind erosions are very prevalent and can transport soil sediments thousands of miles before they are deposited.
Mass wasting can be prevented by restricting walls that would prevent the movement of debris down the slopes. One must be aware of land’s susceptibility to mass wasting before building a road or any other structure.
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