Volcanic Gases Flashcards
Where is lake Nyos?
Cameroon. Oku volcanic field
What gas suffocated the villagers?
Carbon dioxide
What was original source of gas?
Lake Nyos sits on top of a mountain, magma releases gas. Underground magma has gases that travel up cracks.
What triggered release of gas from lake?
A landslide that went into the lake, and the trapped CO2 at the bottom got released. CO2 rich water rose, mixed up the stratification.
Why was gas-rich water at the bottom of lake?
CO2 rich water is denser than regular lake water
Why was gas white?
condensation of water droplets. water droplets formed on surface of gas.
Was there any warning for villagers?
No, the gas was silent and odourless
how many people died?
1800 people
How are future disasters like this being prevented?
Pipes going down to vent out CO2 and not build up at the bottom
Describe process
- CO2 from underground volcanic chimneys is dissolved and concentrated at bottom of lake
- Earthquake triggers landslide, water layers disrupted
- Deepest water rise to surface and CO2 bursts out
- CO2 is heavier than air, so flows down to valleys and side of volacno
What is Mazuku?
Lake Nyos is an example
- a pocket of CO2 rich air that can be lethal to humans when accumulated at pockets low at the ground
what are fault lines?
can help magma travel since there are cracks here
what is volcanism?
crust moving apart causing magma to be released
Where is mammoth mountain?
California, there is a horseshoe lake there. It lies on the edge of Long Valley Caldera.
What gas killed trees north of Horseshoe lake?
Carbon dioxide
how much gas escapes horseshoe lake each day?
100 tons
What is usual concentration of CO2 in air?
0.035%
What cocentration of CO2 causes headaches and dizziness
1%
What does horseshoe lake have so much CO2 released?
Because snow covers the vents on the volcanic mountain, and when snow collapses, a dangerous level of CO2 vents out.
Exposure to CO2 in horseshoe lake
- by laying directly on floor
- digging pits
What is mammoth mountain made of?
Silica-rich lava formed from 110,000 to 57,000 years ago
Is mammoth moutain still active?
Yes with minor phreatic/ steam eruptions.
What is a caldera?
A large depression that forms when a volcano erupts and collapses. When magma chamber is empty, this happens.
USGS volcano monitoring program
Real time monitoring of ground movements
