1. What is a volcano?

a. Types of lava A-a, Hawaiian term for lava flows that have a rough rubbly surface composed of broken lava blocks. Sharp clinker block, slower moving and cool in temp.

pahoehoe Pahoehoe is a Hawaiian term for basaltic lava that has a smooth, hummocky, or ropy surface. A pahoehoe flow typically advances as a series of small lobes and toes that continually break out from a cooled crust. The surface texture of pahoehoe displaying all kinds of bizarre shapes often referred to as lava sculpture

The Ring Of FIRE Borders plate edges Borders plate edges Mainly in Pacific Ocean as that is where subduction is occurring the most Mainly in Pacific Ocean as that is where subduction is occurring the most Most volcano’s are at DIVERGING BOUDARIES OR CONVERGING Most volcano’s are at DIVERGING BOUDARIES OR CONVERGING Some are HOT SPOTS Some are HOT SPOTS

Tuff Ring: Diamond Head, Hawaii

Divergent boundary volcano’s Mostly underwater Emit gasses and pillow lava do break surface in Iceland and east Africa

Divergent usually are rift eruptions or cinder cones

Convergent Boundaries Due to subduction and crust recycling We get more gas and silica More explosive cones Form Island arc’s- Sumatra

Island arc system ocean-ocean plate collisions forms volcanic island arc shape chain of islands Japan, Aleutians in Alaska

Hot spot volcanoes Can be EXPLOSIVE like convergent boundaries (yellowstone) Or VERY mild like Hawaii Hotspot is an area that has excess heat, the plate moves over it and creates volcano’s

Usually for Shield Cones

Section 3-2 VOLCANIC ACTIVITY

1. How Magma reaches the Surface Less Dense than surroundings Low density RISES Still hot so find weak spot melts thru Pressure builds As pressure rises TEMP rises (BOYLE’s LAW) Eruption!!

. Eruption Magma is now lava- – Flows and projectiles Ash into atmosphere Gasses ejected – WATER,N, O, C, S, Hydrogen sulfide others – Early atmosphere???

Inside the volcano Magma chamber is the pocket of magma Vent is escape route. Main is largest side are lateral vents Pipe is neck to chamber Crater is top of vent Magma is liquid rocks and hot gasses Draw pg 95

Batholith-large body of igneous rock formed beneath the Earth’s surface by the intrusion and solidification of magma) with a surface exposure of 100 square km (40 square miles) or larger.igneous rock Stock-is a discordant igneous intrusion having a surface exposure of less than 40 sq mi (100 km 2 ), differing from batholiths only in being smaller. FLAT BASEigneousintrusionbatholiths

Laccolith a type of igneous intrusion that has split apart two strata, resulting in a domelike structure; the floor of the structure is usually horizontal. A laccolith is often smaller than a stock

Batholith Sill runs ---- Dike runs up and down

Evolution of Volcanoes An active volcanic landscape

Evolution of Volcanoes A volcanic landscape after a million years or so so

Types of volcanic eruptions Quiet- mainly slow flow lava, some gas Pahoe-hoe and a-a lava Lava Tubes- cooled and hard on top but still flowing below

Explosive eruptions Thick, high silica magma Lots of gas Pressure builds Explosion produces ash and BOMBS

Pyroclastic Flows Ash, gas and cinders thrown with force, flows like a river, DEADLY

Products of Eruptions Lava Flows Pyroclastic Debris Bombs Lapilli Ash Mudflows Landslides Gases Steam Carbon Dioxide H 2 S SO 2 HCl HF

Types of Volcano’s Extinct- Not active Dormant-Sleeping, not active in recent history Active- Live has erupted, will erupt

Other activity Geothermal- as magma or REMNANT heat heats water it rises (that density thing again) it can then form hot springs and geysers Geyser is when it is forced out when the water reaches Boiling point. This energy can be used for electricity

Caldera Formation