very hot, undersea geysers

produced when seawater goes down through cracks and gets superheated

color: from iron sulfide minerals

non explosive eruption of basalt lava flow

i.e. Hawaiian volcanoes (intraplate type of volcano) 

one of the most throughly studied volcanoes because it is extremely active and almost alwayss quiet outpourings of lava that can be destructive

type: shield volcano 

consists entirely of pyroclastic debris of all shapes + sizes

(no lava flow)

small, symmetrical cones + usually with short lifespans

rare, but violent eruption that produces huge crater

start as composite cone 

SW Oregen

created Crater Lake 

dangerous for obvious reasons

(kills crops, livestock, ruins buildings) 

magma eruptiong explosively will be sent vertically and flows down the side of the volcano with great speed

 also common during caldera forming eruptions

water is major gas release during eruptions

sulfer bearing gases can be oxidized to sulfuric acid and ve highly corrosive 

flow: turbulent movement of sediment

slide/slip: earth material moves as coherent block in contact with slope.

fall: earth material moves as free fall (out of contact with slope)

flow:Speed ranges from imperceptibly slow (creep) to extremely fast (avalanche). Creep is very slow (few mm per year), continuous downslope movement of rock or sediment. Process involves outward expansion of earth + downward contraction of earth.

complex: Slumps/rotational slide/earthflow have combinations of different characteristics. Upslope portion moves as coherent mass (i.e., slide) + produces cliff. Downslope portion flows + has rolling surface. Failure surface is curved in cross-section + spoon-shaped in map view

What factors lead to slope stability or instability?

Slope weight - instability can result from either natural processes or human-induced processes that add "driving mass" to slope

Slope angle - > slope angle = less stable slope. Slope angle can change from human intervention

Geologic material - earth materials with low shear strength are susceptible to failure. Sediment is generally weaker than rock + clay is typically very weak

Water - important factor in nearly all landslides. > weight (driving force) by filling pore space

Vegetation - plant roots > soil cohesion (+ therefore > shear strength), making slope more stable.

Volcanic eruptions or earthquakes

Mapping + Zoning (by engineering geologist) - need detailed maps of known landslide areas

Building Codes - Regulations to ensure good construction practice, such as requirements for drainage, soil compaction, slope angle (< 27°), + dealing with planes of weakness.

involve < driving force (<slope weight) or > resisting force (strengthening rock/soil) or both.

Water drainage - don't allow water to build up within slope (< weight + > shear strength); install horizontal plastic pipes that drain water from within slope, surface drains, or impermeable seals on top of slope (prevent infiltration).


Proper grading of slope - remove material from top of landslide (< driving force) + place it at toe of landslide (> resisting force).

Retaining walls - steel-reinforced concrete wall at vertical face to strengthen slope (> resisting force); need holes in wall for drainage;

Regrowing vegetation

Slow - involves gradual compaction of sediment caused by withdrawal of subsurface fluid (groundwater or oil); usually affects large areas + is entirely human-induced process; usually recognized only after reaches advanced stage (due to gradual nature of its effects)

Rapid - involves abrupt lowering of more localized land area; commonly associated with collapse of land over underground cavity. 

Coal mining - involves human-constructed cavity (underground coal mine)

Sinkholes circular depressions (commonly water-filled) usually in limestone (dolomite, less commonly) bedrock + in other soluble bedrock such as marble, gypsum + halite (geologically uncommon)

troposphere where all weather phenomena occur

stratosphere which contains ozone (O₃) layer