Chapter 3 Earthquakes
- 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.
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| This seismicity map of Australia shows quakes from 1836-2010 |
- 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 Tennant Creek in one day, each about half an hour apart. At magnitude 6.6, the largest of these is considered Australia’s biggest quake. Considering the intensity, damage was small. Tremors warped the natural gas pipeline and opened a 35km-long fault scarp, with a step of 2m. Two buildings and three other structures – including the hospital – were damaged, with a total cost of $2.5 million. No injuries were reported.
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| The warped gas line. |
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| The location of Tennant Creek. |
Safety in Australia
- Geoscience Australia monitors seismic data from more than 60 stations on the Australian National Seismograph Network and in excess of 300 stations worldwide in near real-time, 24 hours a day, seven days a week. Most of the 40 samples per second data are delivered within 30 seconds of being recorded at the seismometer to Geoscience Australia’s central processing facility in Canberra through various digital satellite and broadband communication systems.
- https://www.ses.vic.gov.au/documents/112015/0/State+Emergency+Response+Plan+-+Earthquake+Sub-plan+-+Edition+1.pdf/f2dd5a2e-4aec-2fc2-f981-52aa1f1436ed This is a link to the emergency response plan in place for Australia
Sources:
All definitions from Natural Hazards 4th edition.
Pictures:
Good Morning Noah!
ReplyDeleteI thoroughly enjoyed your post for this week's topic. Thank you for expanding my knowledge on Australia's earthquakes and it's seismic data. The pictures that you included throughout your post were really helpful in understanding the severity of the largest earthquake that occurred in Tennant Creek. Great job, and have a wonderful rest of your weekend!
I would also like to add, I noticed the magnitude of the largest earthquake in Australia was fairly similar to the country I chose to analyze in my blog, Bangladesh. With that being said, Bangladesh is expecting an earthquake in the near future, while their frequency has been a bit higher in comparison to Australia's, although both have had extremely horrific consequences. Again, a very thorough job on your post this week, have a great night!
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