Pyroclastic flows often follow the path of least resistance, such as valleys. The images below show the impact of a pyroclastic flow from the Fuego volcano on the town of San Miguel Los Lotes, Guatemala in Flows of volcanic ash, mud, rock and water, known as lahars, are a deadly after-effect of volcanic eruptions.
In , lahars contributed to the 25 death-toll following the eruption of the Nevado del Ruiz volcano in Colombia. Despite their hazardous nature, many people live in areas that are likely to experience volcanic eruptions.
They do so for several reasons, including:. If you've found the resources on this page useful please consider making a secure donation via PayPal to support the development of the site. The site is self-funded and your support is really appreciated. If you've found the resources on this site useful please consider making a secure donation via PayPal to support the development of the site. Effects of earthquakes and volcanoes on people and the environment. Effects of earthquakes and volcanoes on people and the environment The effects of earthquakes and volcanoes are typically classified as being either primary or secondary.
Impacts of earthquakes and volcanoes on people The impacts of volcanoes and earthquakes will vary depending on a range of factors at any particular place, however, earthquakes and volcanoes have a similar range of hazardous results. Previous Next. Loss of life Loss of life occurs in a many ways including collapsing buildings, bridges and elevated roads, disease and fire. Cutting basic amenities The loss of basic ammenities such as fresh water, gas and electricity due to damage to power lines, gas pipelines, water and sewage pipes.
Collapse of buildings Earthquakes can lead to the destruction of buildings. Damage to transport infrastructure Damage to transport infrastruture, such as roads, rail and airports can make access to earthquake affected areas very difficult. Death of fish Ashfall can lead to the death of fish in rivers, lakes and hatcheries. Spread of disease Due to the lack of clean water, poor access to medicine, overcrowding in temporary camps and lack of sanitation disease can easily spread.
Loss of jobs and business The loss of factories and offices when earthquakes and volcanoes occur can lead to the loss of businesses and jobs. Even though volcanoes can be dangerous, there are lots of reasons why people live alongside them.
There can be emotional, societal and economic benefits. For those living alongside volcanoes, knowing about volcanic hazards is just one way that people can reduce their risk. Volcanic products are typically named according to clast particle size, which can range from metres down to microns in size. During an eruption, most tephra will fall to the ground around the volcano. The loading of tephra on leaves can lead to the burial of plants or the stripping of branches from trees, resulting in a significant impact on agriculture.
The fine-grained nature of volcanic ash means it is easily transported by winds to distance of hundreds to thousands of kilometres away from the volcano. It may also be sent up high into the air, sometimes reaching the stratosphere. Ash is made up of small, sharp, angular fragments of glass and other volcanic rock; due to its abrasive nature, volcanic ash can cause damage to aircraft.
Many buildings with galvanised corrugated steel roofs and cars were badly damaged by acid rain, which was produced when rain mixed with volcanic gases and ash. The eruption emitted large amounts of gas and ash that changed the colour of the sky worldwide. Various gases can be emitted by active volcanoes before, during or after an eruptive event and can cause various health hazards locally, but also have the potential to affect the climate globally.
The five main gases that pose a threat to health are:. People can be exposed to harmful volcanic gases by breathing them in or through contact with the skin and eyes. The health effects range from mild to serious, with occasional deadly exposures. After exposure, people may report difficulty breathing and itchy skin. High concentrations of volcanic gas may also be a health hazard inside planes.
Sulphur gases convert to sulphate aerosols mainly sulphuric acid which, if they reach the stratosphere, may remain there for years, causing short-term climate changes. Lava flows are flows of magma extruded onto the surface of a volcano. In general, it is rare for lava to cause the direct loss of life, because it usually flows slowly, allowing sufficient time for people to be evacuated.
It does, however, destroy everything in its path by a combination of burial, crushing and heat. Such eruptions are also associated with emission of volcanic gases and aerosols. The viscosity — how easily a fluid can flow — of lava flows generally increases with silica content and decreases with a rise in temperature and water content. They can flow relatively long distances. The rate of movement of lavas typically ranges from a few metres per hour for high-silica, andesitic lavas to several kilometres per hour for fluid basalts.
Lava domes form when high-viscosity lava is slowly erupted from a volcano. Positively charged particles meet up with negatively charged particles, either in the cooler atmosphere or in the volcanic debris itself. Lightning bolts then occur as a means of balancing these charge distributions.
The eruption of Mount Tambora, Indonesia, the largest eruption in recorded history, ejected an estimated cubic kilometers 36 cubic miles of debris into the air. This year was characterize d by widespread crop failure, deadly famine , and disease. Airborne volcanic ash is especially dangerous to moving aircraft.
The small, abrasive particles of rock and glass can melt inside an airplane engine and solidify on the turbine blades—causing the engine to stall. Air traffic controller s take special precaution s when volcanic ash is present. Volcanic ash can impact the infrastructure of entire communities and regions. Ash can enter and disrupt the functioning of machinery found in power supply, water supply, sewage treatment , and communication facilities.
Heavy ash fall can also inhibit road and rail traffic and damage vehicles. When mixed with rainfall, volcanic ash turns into a heavy, cement -like sludge that is able to collapse roofs.
In , Mount Pinatubo erupted in the Philippines at the same time that a massive tropical storm wreak ed havoc in the area. Heavy rains mixed with the ash fall, collapsing the roofs of houses, schools, businesses, and hospitals in three different provinces. Ash also poses a threat to ecosystem s, including people and animals. Carbon dioxide and fluorine, gases that can be toxic to humans, can collect in volcanic ash. The resulting ash fall can lead to crop failure, animal death and deform ity, and human illness.
If inhale d, volcanic ash can cause breathing problems and damage the lungs. Inhaling large amounts of ash and volcanic gases can cause a person to suffocate. Suffocation is the most common cause of death from a volcano.
Volcanic ash is very difficult to clean up. Its tiny, dust -sized particles can enter into practically everything—from car engines, to office building air vents, to personal computer s. It can severely erode anything that it contacts, often causing machinery to fail.
When dry, ash can be blown by the wind , spreading into and polluting previously unaffected areas. Meanwhile, wet ash bind s to surfaces like cement and removing it often means stripping away what is found underneath.
Cleaning up volcanic ash is a costly and time-consuming procedure. Communities must make coordinate d efforts to dispose of ash while ensuring the safety of their residents. The eruption of Mount St. Helens covered the city of Yakima, Washington, in tons of volcanic ash. Declaring a state of emergency , Yakima received donated maintenance equipment and workers, who were then dispatch ed throughout the city in a grid pattern. Citizens also helped with a block-by-block cleanup effort.
Sulfur dioxide can cause breathing problems in both healthy people and people with asthma and other respiratory problems. Other volcanic gases include hydrogen chloride, carbon monoxide, and hydrogen fluoride. Amounts of these gases vary widely from one volcanic eruption to the next. Although gases usually blow away rapidly, it is possible that people who are close to the volcano or who are in the low-lying areas downwind may be exposed to levels that may affect health.
At low levels, gases can irritate the eyes, nose, and throat. At higher levels, gases can cause rapid breathing, headache, dizziness, swelling and spasm of the throat, and suffocation.
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