Noah Ryan Geology

An Earthquake is defined as a sudden movement of a block of Earth's crust along a geologic fault; the movement releases accumulated strain in the rocks.   A Fault is where earthquakes occur along a plane of weakness in Earth's crust. This seismicity map of Australia shows quakes from 1836-2010 Earthquakes in Australia are caused by horizontal compression producing reverse faults. A reverse fault is a generally steep fracture or fracture system in which the hanging wall has moved up relative to the foot wall in a direction opposite to the direction of the fault dip.  Australia has large earthquakes, but the occur infrequently  Which means Australia has a low seismicity but does not mean weak ground motion. It means that strong earthquake motion happens less often.  The largest earthquake ever recorded in Australia occurred in Tennant Creek, Northern Territory in January 1988 a 6.6 on the richter scale.  Three quakes of greater than magnitude 6 hit

Definitions from Natural Hazards 4th edition. Plate Tectonics: process associated with the creation, movement, and destruction of these plates.    Australia is surrounded on all sides by both convergent and divergent boundaries and plates.  Convergent: occur where plates move toward each other. Ocean-Continent where the oceanic plate sinks beneath continental plate Volcanic continental arc is formed (Earthquakes and Volcanic Activity) Great Earthquakes, explosive volcanoes, tsunamis, flooding, mass wasting Divergent: occurs where neighboring parts of plates are moving away from each other. Ocean-Ocean spreading of two plates and molten rock (lava) rises up to fill the gaps.   Divergent zone along the Antarctic Plate to the SW and E. Slight Convergent zone along the SE toward New Zealand.  Mid-Ocean ridge forms, new volcanic lithosphere is created.  Light to moderate earthquakes, nonexplosive volcanic eruptions Convergent zone and the site of

Definitions from "Natural Hazards 4th edition" Keller and DeVecchio Natural Hazard: A potential danger that poses a threat to people or property the exists or is caused by nature; generally one that is not made or caused by humans. Disasters: One possible effect of a hazard on society. Usually a sudden event that causes great damage or loss of life during a limited time in a limited geographic area. Catastrophes: An event or situation causing sufficient damage to people, property, or society that recovery or rehab is long and complex; natural processes most likely produce a catastrophe include floods, hurricanes, tornadoes, volcanoes, tsunamis, and large fires. Black Saturday Brushfires Newcastle Earthquake 1989