What is a volcano & how does one form? 4/27/17

volcano= a weak spot in the crust, usually a mountain, created through plate tectonics @ subduction zones that explodes lava to the surface

a lot of them in Hawaii b/c Hawaii is made of volcanoes

magma=molten rock INSIDE the volcano lava= molten rock OUTSIDE the volcano Ancient Greeks thought Hephaestus,

God of fire & forge, lived in volcanoes; eruption meant he was working at the forge...Roman God Vulcan, which gives the word volcano

Ancient Polynesians/Hawaiians believed in Pele, Goddess of Fire

All volcanoes have the same key structure

Most explosive landform on Earth Can go extinct…never erupt again! Formed the first atmosphere by

releasing CO2 Main vent lets magma escape

Subsequent eruptions build up the volcano

Pressure build up causes the eruption Beautiful but dangerous & deadly! Nature’s fireworks show! PT causes volcanoes by creating

weakness in the crust where magma can escape…divergent & subduction zones

NOT @ transform or C VS C boundary b/c an opening in the crust is NOT formed @ these boundaries

Subduction zone volcanoes are the strongest/biggest boomers!

Found on all continents except Australia Ring of Fire=lg volcanic belt

outlining the Pacific Ocean; most volcanoes are here

Island arc= arc of volcanoes formed along a deep ocean trench @ OvsO boundary: Japan

Volcanic arc= arc of volcanoes formed along a CvsO boundary: Andes Mts in South America &

Cascade Range of North America (Oregon & Washington)

Hot spot volcanoes=volcano found in the middle of a plate rather than on a boundary: Hawaii & Yellowstone National Park

What do volcanoes look like on the inside? 5/3/17 (structure)

No matter the outside, ALL volcanoes have the SAME internal structure

1) crater= bowl shaped area @ the top of the volcano surrounding the vent

2) central vent= opening allowing magma to escape in the crater @ the top

3) pipe= long tube connecting the magma chamber to the vent… “straw”

4) magma chamber= pocket/pool of magma under the volcano

5) side vent= opening on the side that allows magma to escape

6) lava flow= area covered in lava which spewed from the vent

Why does a volcano erupt & what happens during an eruption? 5/9/17

dissolved gases in the magma expand (bubbles) as it rises in the pipe

less rock pressure allows gases to expand as magma rises

dissolved gases push magma farther up the pipe

eruptions differ depending on amt of silica in the magma (SiO2):

1) quiet eruption =low silica magma is thin & runny so flows easily & gently…BLUB-BLUB! low viscosity…viscous=thickness*pahoehoe lava is HOT!!!, runny & fast moving*aa lava is hot!, slow moving, thicker* lava flows/oozing, lava rivers, lava burps*Hawaiian Islands

2) explosive eruption = high silica magma which is viscous/thick & chunky! so plugs up the vent like a cork causing ++++++++ pressure…BOOMERS!*pyroclastic flow= “cloud” of explosive eruption made of ash, cinders, bombs, poisonous gases & is HOT!

What did I learn from the video: Eyewitness Volcano 5/12/17

What are the different forms of volcanic mountain? 5/15/17

(glue chart)

three stages of volcanic activity:-active=is erupting right now-dormant= “sleeping”-may erupt in the future-extinct= will never erupt again…DEAD!

What other landforms are created by volcanic activity? 5/18/17

book page 232-235, 228 caldera= collapsed volcanic mtn

formed when the magma chambers empties after a huge eruption (Crater Lake)…huge hole/crater shape

volcanic soil=rich in nutrients b/c of the ash, ++++fertile & holds water well

dike=magma forced across rock layers & hardened…vertical or diagonal (II)

sill=a horizontal dike but btwn rock layers (II)

volcanic neck= magma hardened in the pipe, softer surrounding rock wears away, looks like a “big tooth mountain” (Ship Rock) (II)

batholith=massive rock formed by hardened magma (Sierra Nevada Mtns) (II)

geysers= spout of HOT! water and steam erupting out of the ground (Old Faithful)

hot spring= geothermal activity= igneous intrusion (II)=volcanic rock

forced in among other types of rock