volcanoes Flashcards
what is the distribution of shield volcanoes?
near divergent plate boundaries where magma can rise directly from the mantle.
what is the distribution of stratovolcanoes?
near convergent plate boundaries where there is subduction and build-up of pressure.
what is the gradient of stratovolcanoes?
steeply-sloping sides
what is the gradient of shield volcanoes?
gently-sloping sides
what type of summit shield volcanoes have?
broad summit
what is the summit of stratovolcanoes?
steep summit
what is the base of stratovolcanoes?
gentler base
what is the base of shield volcanoes?
increases in size as lava accumulates after successive eruptions.
which volcanoes has a secondary cone?
stratovolcanoes. May develop as magma from the vent seeps into the sides of the cone and erupts
what are the materials erupted from shield volcanoes?
lava and ash
what are the materials erupted from stratovolcanoes?
lava, ash,pyroclastic flow and lahars
what type of lava does shield volcanoes contains?
low-silica lava that flows easily and spreads out over a large area before solidifying.
what type of lava does stratovolcanoes have?
they contain high-silica lava that flows slowly and spreads out over a small area before solidifying.
what type of eruption does shield volcanoes have?and their characteristics?
non-explosive eruption due to low silica lava that does not trap gas.The gases will be able to escape easily as magma reaches the earth´s surface,causing an outward explosion
what type of eruption does stratovolcanoes have?and its characteristics?
explosive eruption due to high-silica lava that traps gases.these gases will expand as the magma reaches the earth´s surface,causing an outward explosion.
Describe the steps the students should take to collect the wind speed data.
Stand at an open area where wind flows freely. [1]
Read the wind speed off the display on the anemometer. [1]
describe the formation of sea breeze.
During the day, the land heats up faster than the sea. [1]
Over land, warmer air expands & rises, creating an area of low pressure. [1]
As a result, air pressure over land is lower than the sea. [1]
Thus, wind blows from sea (high pressure) to land (low pressure), lowering the temperature of coastal areas. [1]
One programme to reduce climate change
plant a tree programme that maintain Singapore’s status as a Garden City
Residents donate money to buy a tree or take part in tree planting events
limitations : Trees take many years to mature, it takes time to materialise
E.g. Fast-growing trees like angsanas, raintrees planted by Nparks took 25 years to reach full height
