How close a person can go towards volcano| Will it hurt or kill me?

How close you can get depends on what kind of lava flow it is, and whether you are upwind or downwind.

The safe distance from an active volcano is generally 5kms or it may be more but you should check for the latest CDEM information. Beyond this distance the major hazards will be ashfall and volcanic gas. Breathing in small amounts of ash particles may only cause discomfort rather than pose a health hazard.

Volcanoes are inherently beautiful places where forces of nature combine to produce awesome events and spectacular landscapes. For volcanologists, they're FUN to work on! Safety is, however, always the primary concern because volcanoes can be dangerous places. USGS scientists try hard to understand the risk inherent in any situation, then train and equip themselves with the tools and support necessary to provide a comfortable margin of safety. Such training involves learning the past and current activity of the volcano, first aid, helicopter safety procedures, and wilderness survival techniques. When working around non-explosive volcanoes in places like Hawaii, USGS scientists go through training to wear gas masks and use heat-resistant gear as needed.

How close can I get to lava

For example, the most approachable lava is Pahoehoe.  This is because each toe forms an insulating skin seconds after emerging on the surface. This skin is at first flexible and then hardens, but even when flexible it is a good insulator. This serves to keep the interior of an active pahoehoe toe hot and fluid but also prevents you from getting burned by the radiant heat. If the wind is at your back, you can easily approach long enough and close enough to get a sample with a hammer. It is still hot, and unless you are well-protected you can only be that close for a minute or so. You also notice that as soon as you peel the skin off to get at the molten interior, the heat goes way up. This is heat that you can't stand, you have to get back otherwise blisters start to form. It is hot enough that you can't accidentally step on active lava. 

Skylights into lava tubes on pahoehoe flows are quite hot, and have to be approached from upwind. They are so hot that the air shimmers over them so they are hard to miss. They are dangerous not as much because of the radiant heat from the lava inside but because of the super-heated plume of air coming out. You have to be really careful that the wind doesn't shift, and many a volcanologist has gotten singed skin and hair when the wind changed.

How do scientists predict eruptions?

Earthquakes may take place every day near a volcano. But before an eruption, the number and size of earthquakes increases. This is the result of magma pushing upward into the magma chamber. This motion causes stresses on neighboring rock to build up. Eventually the ground shakes. A continuous string of earthquakes may indicate that a volcano is about to erupt. Scientists use seismographs to record the length and strength of each earthquake. All that magma and gas pushing upward can make the volcano’s slope begin to swell. Ground swelling may change the shape of a volcano or cause rock falls and landslides. Most of the time, the ground tilting is not visible. Scientists detect it by using tiltmeters, which are instruments that measure the angle of the slope of a volcano.

 Scientists measure the gases that escape from a volcano to predict eruptions. Gases like sulfur dioxide (SO₂), carbon dioxide (CO₂), hydrochloric acid (HCl), and water vapor can be measured at the site. Gases may also be measured from satellites. The amounts of gases and the ratios of gases are calculated to help predict eruptions. Satellites can be used to monitor more than just gases. Satellites can look for high temperature spots or areas where the volcano surface is changing. This allows scientists to detect changes accurately and safely.

Can a volcanic eruption be stopped?

One of the most successful lava stops came in the 1970s on the Icelandic island of Haimey. Lava from the Eldfell volcano threatened the island's harbour and the town of Vestmannaeyjar. For almost five months in 1973, frigid sea water was blasted through cannons towards the advancing lava. As the water hit the superheated rock, it turned into steam, allowing the lava's heat to dissipate. A fifth of Vestmannaeyjar was destroyed before larger cannons were brought in, but enough of the lava flow was slowed and redirected to save the harbour. Around 1.5 billion gallons (6.8 billion litres) of water were used.

Back at Mount Etna, an eruption in March 1983 threatened three towns. Barriers of rock and ash were constructed in an attempt to divert the lava. "They were trying to slow it down and direct it downhill," One of the first barriers, 18m high and 10m wide, was overrun, but a second barrier blocked lava from moving further west. Two other major barriers kept the flow from reaching the main tourist area of Etna on the eastern side of a valley. The lava missed buildings by metres. One of the barriers, known as Sapienza, had six feet added to it by the lava. But Sapienza and the others held until the eruption ended in August.

Almost 10 years later, Etna erupted again, and Italian officials used the lessons of the earlier eruption to save the town of Zafferana. In addition to barriers, workers created an artificial trench to catch lava redirected from a breach made with explosives. That only pushed away part of the lava, so concrete blocks were dumped into the remaining flow, fully diverting its path.

Are Volcanoes Dangerous When They’re Not Erupting? 

Almost everyone knows to avoid an erupting volcano, due to its hot lava, flying debris, and its suffocating ash. But, with volcano tourism being on the rise, it’s time to ask: are volcanoes still safe when they’re not erupting? Extinct volcanoes have almost no danger, but dormant and active ones aren’t so safe (because, again, they may erupt at any time). But, in general, it’s true that even minor volcanic activity can cause dangerous earthquakes and mudslides. So yes, even when they’re not erupting, volcanoes are pretty dangerous.

Many stratovolcanoes have a plumbing system of hot acid water that progressively breaks down hard rock to soft, clay-rich material. The volcano is gradually weakened, and large parts may suddenly fail. Resulting water-rich landslides are especially dangerous because they can occur without any volcanic or seismic warning.

The risk of mudflows [lahars] formed this way is especially high along rivers downstream from Mount Rainier, because of the large population on floodplains, the huge weakened edifice of the volcano, and a long history of large flows that occurred when the volcano was otherwise dormant."

Safety precautions to take when visiting active/dormant volcanoes

There are around 1,500 potentially active volcanoes around the world, many of which are on the ocean floor. The most active region in the world is the Ring of Fire; a major area in the basin of the Pacific Ocean. The Ring of Fire is responsible for 81% of the largest earthquakes recorded and 22 of the largest volcanic eruptions of the past 11,700 years. Some of the most affected countries include the Philippines, Japan, New Zealand and the west coast of the US. One of the problems facing volcanologists is that volcanoes are unpredictable. Even with the complete eruption history of a volcano, experts can only offer possibilities as opposed to specific dates and times. Some eruptions in history have also been completely out of the blue.

Before an Eruption

• Follow any evacuation orders issued by authorities, and put your emergency plan into action. Although it may seem safe to stay at home and wait out an eruption, if you are in a hazard zone, doing so could be very dangerous.

• If indoors, close all window, doors, and dampers to keep volcanic ash from entering.

• Put all machinery inside a garage or barn to protect it from volcanic ash. If buildings are not available, cover machinery with large tarps.

• Bring animals and livestock into closed shelters to protect them from breathing volcanic ash.

• Stay out of designated restricted zones. Effects of a volcanic eruption can be experienced many miles from a volcano.

• Avoid low-lying areas, areas downwind of the volcano, and river valleys downstream of the volcano. Debris and ash will be carried by wind and gravity. Stay in areas where you will not be further exposed to volcanic eruption hazards. Trying to watch an erupting volcano up close is a deadly idea.

After an Eruption

• If you have been evacuated return when the authorities tell you

• Never return to your home unless instructed

• Let friends and family know your safe

• Ensure your family and friends are also safe

• Continue to stay tuned in to local alerts and information

Do volcanoes affect the climate? 

When Mount Pinatubo erupted in the Philippines June 15, 1991, an estimated 20 million tons of sulfur dioxide and ash particles blasted more than 12 miles (20 km) high into the atmosphere. The eruption caused widespread destruction and loss of human life. Gases and solids injected into the stratosphere circled the globe for three weeks. Volcanic eruptions of this magnitude can impact global climate, reducing the amount of solar radiation reaching the Earth's surface, lowering temperatures in the troposphere, and changing atmospheric circulation patterns. The extent to which this occurs is an ongoing debate.

Large-scale volcanic activity may last only a few days, but the massive outpouring of gases and ash can influence climate patterns for years. Sulfuric gases convert to sulfate aerosols, sub-micron droplets containing about 75 percent sulfuric acid. Following eruptions, these aerosol particles can linger as long as three to four years in the stratosphere. Major eruptions alter the Earth's radiative balance because volcanic aerosol clouds absorb terrestrial radiation, and scatter a significant amount of the incoming solar radiation, an effect known as "radiative forcing" that can last from two to three years following a volcanic eruption.

The cooling influence is particularly marked in the case of large eruptions able to blast sun-blocking particles all the way up to the stratosphere such as Mount Pinatubo in 1991, which caused a significant dip in global temperatures in the following year or two. It's difficult to know for sure that the cooling observed after a particular eruption is definitely the result of that eruption, but examining the average global temperature change after multiple eruptions proves a strong link.

As for greenhouse gases, underwater and land-based volcanoes are estimated to release, in total, around 100–300 million tones of CO2 each year, according to the British Geological Survey and the US Geological Survey. That's a large quantity, but only around 1% of the amount that humans release from burning fossil fuel alone.

What are volcanoes like on other planets? 

There is plenty of hot stuff in our solar system, even in the outer frozen realms; so much that planetary scientists have found evidence of volcanism on every terrestrial planet and on many of the moons and even some asteroids.

The Moon and Mercury have thick volcanic flows on their surfaces, erupted long ago from fissures in their crusts. While the Moon and Mercury have relatively small volcanoes, those on Venus, Earth and Mars are large and numerous. We know that Earth's volcanoes are still active and Venus' may be, but scientists debate whether Mars' volcanic activity has finished or not. Jupiter's moon holds the record for the most volcanically active body in the solar system.

Volcanologists on Earth have applied their knowledge to these other places in our solar system. Volcanic activity acts as a window to a planet's interior. The type of volcanism and the composition of the lava give scientists a peak underneath the crust. The very presence of volcanic features tells scientists that a planet's interior is hot enough to form magma that erupted at its surface.

Most volcanism outside Earth seems to have occurred in the early ages of the Solar System, when the planets were still hotter: our moon had volcanic activity in the remote geologic past, between 3-4 billion years ago, when it still was hot enough to allow basaltic lava flows to erupt through the broken crust of impact craters, the maars.

Mount Olympus on Mars is the largest known volcano in the entire Solar System, Venus is dotted with thousands of volcanic features, and Io is the volcanically most active place in the System.
Most of the knowledge of volcanic activity outside Earth comes from recent space research using modern telescopes and space craft.