Earthquake 2021 - Mansfield |
A 5.8 magnitude earthquake was one of four that rocked Melbourne on Wednesday 22nd September 2021.
The earthquake centred below Mansfield shook Melbourne, regional Victoria, southern NSW, Sydney, Canberra, Adelaide and Launceston
Just about every Victoria felt the massive quake descriving it like "a bomb went off".
Geoscience Australia said the first magnitude 5.8 earthquake was detected in the Alpine National Park south-east of Mansfield around 9:15am and was 10 kilometres deep. It also says the quake is one of the largest earthquakes in eastern Australia since European settlement.
Acting Premier James Merlino said the initial quake was followed by a 5.5-magnitude quake at 9:40am, a 4.0 quake at 9:55am and a 3.1-magnitude quake at 10.15am. "Buildings have been damaged in the Mansfield township, no reports of injury at this stage," he said.
The four quakes measured 5.8, 5.5, 4.0 and 3.1 in magnitude Tremors were felt across much of south-eastern Australia including South Australia, Tasmania and New South Wales Experts say smaller aftershocks may continue to occurHOW THE EARTHQUAKE HAPPENED
The earthquake was likely a thrust quake, which occurs when the pressure building up between two rock formations that are being pressed together suddenly releases.
This can happen with one rock formation suddenly thrusting upwards and the other suddenly thrusting downwards, but the movement can also be side-to-side and forwards-and-backwards, and in a combination of directions at the same time.
The pressures are usually released along pre-existing fault lines. While the Moyston Fault is regarded as the most significant fault line in Victoria, Wednesday's disturbance happened near the Governor Fault.
The Australian continental plate is moving north at about 7cm per year, and this motion builds up stress in different areas of the plate.
Best thing to do in an earthquake
Geoscience Australia senior seismologist Trevor Allen said the official advice when someone was in an earthquake was to "drop, cover and hold on". Standing in a door frame was not recommended, as the door may swing shut and injure a person standing there during the quake.
❊ Web Links ❊
➼ Earthquake 2021 - Mansfield
➼ GeoScience Australia - www.ga.gov.au
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