all right so now that we understand a little bit about the processes associated with these volcanic eruptions and where they occur and why let's start taking a look at the effects of these volcanic eruptions starting with the ones that directly impact us with primary effects so these are the many effects and these are by no means all of the effects of volcanic hazards we have our primary effects which are the main objective of this video with our lava flows our pyrolastic flows and new ardantes our volcanic bombs and ash and finally poisonous gas but those aren't the only ways you can be taken out by a volcano um there are also secondary effects which include laahars and landslides and avalanches floods fires contamination of soil surface water and groundwater acid rain tsunami weather and climate change just to name a few and those secondary effects will be the topic of our next video but in this video we're going to focus on those many primary effects how the volcano can directly impact you and some of these you have to be quite close to the volcano in order to to be impacted by a primary effect but not all of them ash can travel great distances and can impact communities that are hundreds of miles away from the volcano so these are still important to understand we'll start with our lava flows because I think for most of us when we think about a volcano our mind goes to these beautiful lava flows the lava flows are hazardous and they can flow tens of kilometers from their source especially those basaltic lavas those ausive eruptions are still hazardous because those lavas can flow pretty far and sometimes these lavas can move at pretty high speeds up to 19 miles hour down a steep slope although usually they're much slower than that and we can predict their path so usually we don't see a lot of loss of life from lava flows it's usually going to be a lot of economic loss property loss the immovable things that end up being destroyed in these lava flows now I have some videos that's going to describe these hazards that's just going to do a nicer job than me talking to you or putting words at a screen so here are some videos from W film um that we're going to watch for most of our hazards that are just going to show them in action many volcanoes erupt molten rock called lava lava is extremely hot much hotter than an oven or boiling water some eruptions produce runny lavas that can form flows like red hot rivers which can travel many kilometers in other eruptions the lavas ooze slowly out of the volcanoes to form piles of lava called domes or short thick flows lava is dangerous to approach because of its intense heat blocks of lava can roll off the front of flows buildings and vegetation can be set on fire generating smoke and poor air quality explosions can occur when lava comes into contact with fuel in 2002 a lava flow traveled through the city of GMA in the Democratic Republic of Congo many people were killed or injured in an explosion of a gas station other violent explosions can occur when lava interacts with water snow or vegetation the heat of lava can melt snow or ice and cause flooding and mud flows which can be widespread and destructive some lavas can flow faster than a person can run but normally lava travels slowly enough for people to move out of its way sometimes there's time to remove possessions in 2014 lava threatened a wine business in Fogo Cabo Verde but the equipment and the wine was moved before the lava's arrival heed the authorities advice on when to evacuate and whether there's time to take belongings lava can bury roads and cut off escape routes making it important to evacuate in good time farmland buried under lava can be unproductive for years decades or longer in some cases lava flows around buildings or even through them but some lava flows are so powerful they can knock buildings down the sticky slowmoving lavas that form domes can be very dangerous as they can suddenly collapse to form deadly avalanches of hot rock gas and ash called pyrolastic flows lavas can take months to cool sometimes a fragile cooled crust can form over a molten interior so people should not attempt to cross recent flows lava deltas can suddenly collapse and trigger explosions and scalding waves scientists can often successfully forecast the direction of the lavas if you're advised to evacuate do not return until you're told it's safe although dangerous lava eruptions can be beautiful so they can attract spectators heed the advice of local authorities to avoid dangers and view lavas safely all right and that brings us to my most terrifying volcanic hazard pyrolastic flows a pyrolastic flow is a mixture of hot gases infused with incandescent ash and larger lava fragments and they're also called new ardantes because at night they're they they glow and pyrolastic flows are propelled by gravity and they move very similarly to how snow avalanche moves except for this stuff is not cold at all and the materials being propelled from the volcanic vent at extremely high speeds they can exceed 100 km an hour that's 60 m hour so definitely not something that you could even try to outrun pyrolastic flows are typically generated by the collapse of tall eruption columns but there are other ways that you can get it as well with the collapse of lava domes like we just saw in that last video now a surge is a small amount of ash that separates from the main body of the pyrolastic flow but is just as destructive because these surges have enough force to knock over buildings and move automobiles and in 1902 the town of St pierre was destroyed by a pyrolastic flow from a volcano called Mount Ple pompei which is a really famous example some of you probably heard about that um that that whole city was in tuned beneath a layer of volcanic ash and pummus where some of it was provided by these surges and pyrolastic flows now you definitely can't outrun these things they're moving at 60 mph but you really can't outdrive them either unless your road's going to continue in a straight path which we know that doesn't always happen so it's very unclear as if this vehicle actually made it out okay now let's take a look at that 1902 Mount Ple eruption mount Ple erupted and produced a massive pyrolastic flow and this pyrolastic flow killed 30,000 people almost the entire village only three known survivors made it out of that event and here's a picture of of Mount Ple before the eruption a coastal city and after everything completely covered and destroyed now this is a direct quote from one of the three survivors from that Mount Ple eruption Leon Compre Leandre he was a local shoemaker and and this is a direct quote from him this is what he says i felt a terrible wind blowing the earth began to tremble and the sky suddenly became dark i turned to go into the house with great difficulty climbed the three or four steps that separated me from my room and felt my arms and legs burning also my body i dropped upon a table at this moment four others sought refuge in my room crying and withering with pain although their garments showed no sign of being touched by flame at the end of 10 minutes one of these the young Delivow girl aged about 10 years fell dead the others left i got up and went to another room where I found the father deod still clothed and lying on the bed dead he was purple and inflated but the clothing was intact crazed and almost overcome I threw myself on a bed inert and awaited death my senses returned to me in perhaps an hour when I beheld the roof burning with sufficient strength left my legs bleeding and covered with burns i ran to fawn Saint Denise six kilometers from St pierre that quote gives me chills every time I read it but look at this people were just killed and caught off guard by this but their clothes were not burned even though they appeared to have been burned to death now these pyrolastic flows are super hot incandescent gas and ash so this is similar to being steamed alive boiled alive just like you were to put something in a pot of boiling water it doesn't burn it doesn't catch fire but it gets cooked and that's unfortunately what happens to victims in a pyrolastic flow here's another video from Vool Films that explores those pyrolastic flows pyrolastic flows are one of the most deadly of volcanic hazards they are rapidly moving avalanches of hot rock dust and gas that flow down the sides of a volcano and into surrounding valleys they can climb up and over ridges and high ground they are dangerous because they flow much faster than a person can run and often faster than a car so for those in their path there's little chance of escape what makes them especially lethal and devastating is that they're extremely hot during the day they appear gray and ashy but at night they can be seen glowing red hot they destroy and burn anything in their way death or severe injury is certain for those caught by a pyrolastic flow there are two main ways pyrolastic flows may form sometimes a volcano explodes and forms a fountain of hot pulverized rock and gas that first rapidly rises into the sky and then falls back forming pyrolastic flows which race down the sides of the volcano other times instead of an explosion sticky lava oozes out of a volcano and piles up around the summit pyrolastic flows can then form by parts of the lava collapsing although pyrolastic flows normally move down valleys extremely hot fast-moving billowing clouds form above them which can spill out of valleys this means that even people on high ground are not safe pyrolastic flows normally travel to distances of 5 to 10 km from the volcano summit but in the biggest eruptions we reach much more than 20 km volcanoes that haven't erupted for many decades or even centuries may appear peaceful but when they awaken the eruptions are often very large and explosive scientists can detect that a volcano is reawakening and are able to provide some warning or advice to evacuate which is the only protection from pyrolastic flows next is another primary effect called volcanic bombs now bombs are ejected from a volcano as hot lava that are greater than 2 and 1/2 in in diameter so they're these big blobs of lava that can be thrown many meters to kilometers away from an erupting vent now they can explode as they cool which is why they get the name bomb however that's not actually very common but it does happen most of the damage from volcanic bombs actually comes from their direct impact or the subsequent fires they cause now these can cause severe injury and death to those near an eruption some examples of where volcanic bombs became a problem was in 1993 the Galaris volcano in Colombia six people were killed and several others were severely injured by these lava bombs when a volcano erupted very suddenly without warning and a more recent example Mount Kilawea in 2018 even though that's an ausive erupting volcano sometimes we do get explosive episodes such as 2018 when 23 people ended up being injured on a tourbo when they were hit with a basketball-sized lava bomb so when you go do these tours they make you sign a waiver for a reason folks they might not appear to be hazardous or dangerous in that moment but they can always change in a blink of an eye now volcanic ash is probably the most extensive primary effect of a volcanic eruption that can impact people many miles away for many years to come and they are especially hazardous to airplanes jet engines can be completely damaged when they're flying through a cloud of volcanic ash that's why it's so important that we monitor not just the volcanoes that are near population centers but all of the volcanoes on Earth because we fly over some of the ones that are in inhibited and and at remote islands it's still important we understand this because we don't want to have um a jet failure in 2010 the eruption of Iceland's volcano which again usually are ausive eruptions but there's a lot of ice and water that gets added to these lava sometimes that can cause some explosions and an eruption in 2010 actually caused a very thick plume of ash over Europe that ended up stranding hundreds of thousands of travelers now most of you are probably too young to remember this event um but I remember this event very very clearly it got a lot of media attention and it really did strand a lot of people all over the globe now ash can also bury landscapes and they kill crops making farmland unusable for not just the years following an eruption but sometimes many years after an eruption so these are some secondary and tertiary effects as well um but ash is also heavy and when it accumulates on top of roofs it's just kind of like snow and it can cause roof collapse if it gets too heavy especially if it gets wet and ash is super harmful to breathe in remember those cinder cones I showed those are just gravel sized pieces of ash the microscopic pieces of ash that you breathe in are just as sharp and rough and these ash particles can be ejected really high into the atmosphere which can also reflect sunlight back to space and produce a temporary atmospheric cooling so again more secondary tertiary effects and this actually happened in 1815 with Mount Tambora's eruption that produced a year without a summer now again important to remember ash can impact locations hundreds of miles away from a volcano for many years after an eruption so ash can lead to primary effects it can also lead to secondary and tertiary effects but it is the direct result of the volcanic eruption itself so that's why we're including it in our primary effects now here's another video from V Films that explores just how extensive volcanic ash can be [Music] explosive volcanic eruptions send clouds full of rock and fine grained ash to great heights in the atmosphere ash is spread over large areas by the wind gradually the rocks and ash fall to the ground with the largest material falling closest to the volcano near the vent falling rocks can cause death and injury people caught in a shower of rock should protect their heads and seek refuge indoors but the largest rocks can break through roofs and hot rocks can cause fires people for kilometers to hundreds of kilometers downwind of an eruption are at risk from volcanic ash both during the eruption and when ash is stirred up by the wind or human activities for months or even years later volcanic ash is an irritant to the skin eyes and lungs and can affect breathing children the elderly and those with chronic heart or lung conditions are especially vulnerable and should avoid exposure as it may trigger conditions such as asthma layers of ash can bury land and buildings roofs may collapse under thick layers of ash especially if the ash gets wet the safest option is to evacuate areas near the volcano but if caught seek shelter in sturdy buildings avoiding those with flat roofs agriculture can be impacted through damage and burial of crops and machinery and injury or death of livestock through ingestion of ash and restricted access to clean food and water water supplies and wastewater systems can be disrupted through damage blockage or contamination all forms of transportation may be disrupted or stopped during an ashall and for days afterwards heavy ash falls can reduce visibility and make roads slippery vehicles can break down as engines are clogged with ash airports railways and ports are commonly shut flights may be cancelled because airborne ash can cause catastrophic damage to aircraft scientists and authorities can provide information on what areas will be most affected by volcanic ashfall for those who live near a volcano having an emergency kit will help in the event of an eruption if outdoors or if your indoor environment is ashy wear a face mask designed to block fine particles holding cloth over your nose and mouth will provide limited protection skin should be covered contact lenses removed and eyes protected if advised to evacuate follow all instructions and do not return until advised that it's safe take care when cleaning up ash as deaths and injury due to heart attacks and falls are possible thick deposits can be heavy and ash can easily become airborne making breathing difficult many people live in areas frequently impacted by ashfall preparation and coordinated organized cleanup operations can help you live alongside volcanoes and finally we get to our volcanic gases which are also ejected from volcanic eruptions during an eruption and even can be ejected during volcanoes when not during an eruption so these things can escape volcanoes at any point and volcanic gases are also a respiratory health hazard and not all gases are poisonous but some of the gases they emit are poisonous and endanger humans and livestock and wildlife nearby water vapor is another gas that's commonly erupted and it's not necessarily harmful to breathe but water vapor is usually released as extremely hot steam and can be deadly if if you come into uh direct contact with it now carbon dioxide and sulfur dioxide are the most toxic gases released one example was Lake Nyos in Cameroon in 1986 carbon dioxide suffocated 1,746 people and 3500 livestock in nearby towns and villages and this happened when the volcano wasn't even erupting it silently released this carbon dioxide and suffocated these people without any warning and here's another video of why it's so important to understand volcanic gases this is also from Wolf the molten rock stored beneath volcanoes called magma contains dissolved gases which are released during eruptions or emitted when the volcano is quiet escaping through the soil hot springs lakes and gas vents called fummeralss there are several types of volcanic gas some form a cloud that looks like fog known as vogue other times the gases are invisible the most common gas is water vapor or steam steam plumes can often be seen reaching high into the atmosphere above volcanoes there can be substantial amounts of other gases which can sometimes be toxic to people and animals and damage crops and property carbon dioxide is colorless and odorless this means you can't see it or smell it it's heavier than air so can collect in low-lying areas lakes and confined spaces even short exposure to too much carbon dioxide can cause unconsciousness and death other gases contain sulfur these are colorless but some have a strong smell like rotten eggs sulfurous gases irritate your skin eyes nose and throat the smell can act as a warning but it disappears at high concentrations where it becomes highly toxic causing unconsciousness and death long range hazards can form when gases react with rain water to form acid rain and sunlight in the atmosphere to create particles which can cause health impacts even hundreds of kilometers from the volcano large eruptions can produce such enormous amounts of gas that the world's climate can be affected for years as the gas acts to block out some of the sun's energy persistent plumes of volcanic gas may cause long-term damage to agriculture and to people's health however normally volcanic gases become harmless as they are diluted quickly in the air scientists monitor volcanic gases during and between eruptions monitoring can allow for warnings when gas levels are potentially hazardous