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Midterm

ATS1310 Study Guide - Midterm Guide: Types Of Volcanic Eruptions, Soil Contamination, Volcanic Bomb

3 pages75 viewsFall 2018

Department
Arts - ATS
Course Code
ATS1310
Professor
Megan Farrelly
Study Guide
Midterm

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VOLCANOES, EARTHQUAKES, TSUNAMIS
KEY DEFINITIONS
Earthquake: caused when the earth’s crust is flexed and eventually fractured which releases built-up energy through violent shaking of ground
Tsunami: set of ocean waves caused by a large, abrupt disturbance of the sea surface
Volcano: formed from molten material (magma) within earth’s crust
Secondary hazard: generated by primary geo-physical force (e.g. tsunami triggered by earthquake)
TYPES
Tsunami
- Slower as approaches shore (shallow) and then wave height increases
- Collect debris & can flow inland for kms with significant force
Volcanic hazards
Primary (associated directly with eruption)
- Lava flows
- Pyroclastic flows (clouds of hot gas & ash)
- Ash & cinders
- Toxic gases
- Ground motion & earthquakes
Secondary (follows after eruption)
- Lahars (ash & rain, may carry large boulders, trees…)
- Landslides
- Tsunami
- Toxic chemicals
- Collapse of lava tubes
- Climate effects
- Effects on crops (yields, food supply)
Range from:
Effusive fluid lava streams, reduced hazard (predictable in its path and have warning before lava stream arrives)
To highly explosive dominated by clouds of hot ash, cinders, and volcanic bombs, travels too fast to escape highly dangerous
Patterns/distributions of earthquake & volcanic activity plate boundaries/tectonics
- Crust of earth composed of several tectonic plates (movement occurs at boundaries between plates & on the surface)
- Four basic types of plate boundaries: divergent (plates splitting apart rift valleys), convergent (plates colliding one dips beneath other mountains &
volcanoes), transform (plates sliding against crust neither destroyed/created), plate boundary zones (zigzagged/erratic)
FACTORS/CAUSES
Tsunami
- Mainly from the abrupt movement on the seafloor resulting from brittle failure of crust beneath the ocean (tectonic displacement of sea-bed)
- Significant vertical displacement of coastal floor generates series of ocean waves and carry large masses of water
- Volcanic eruption
- Major landslides
- Meteorite impact (in ocean –‘super waves’)
Earthquakes
- When accumulated stress exceeds resisting strength of fault (zone of pre-existing geological weakness) fracture of brittle crust ground shaking
Destruction dependent on:
- Duration of shaking (longer - more damage for the same magnitude of an event)
- Distance from fault (further lower levels (energy reduces with distance))
- Local conditions (soil & rock properties, topographic effects)
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