scone.com.auTell Seismologists What You Felt
GEOSCIENCE Australia encourages people to lodge a a “felt report” with them on the magnitude 3.2 earthquake which occurred approximately 13 kilometres south of Muswellbrook at 3:44pm today.
Andrea Thom, duty seismologist at Geoscience Australia is currently analysing the earthquake and said the reports from on the ground are invaluable.
Seismological device for measuring earthquakes. Seismological activity live on the sheet of measuring paper.
“We received quite a few felt reports for this event all of the 35 we received came from Muswellbrook,” said Ms Thom.
“It is very helpful to us because we can use it to produce maps and learn about earthquakes, because for example this one did not register automatically and so sometimes this is our first notification of an earth quake if someone gives us a felt report,” she said.
“In this case I had seen the seismic waves on our screens, but it is a great confirmation if you receive feedback from the public,” she said.
“This is very preliminary and it is very difficult to constrain the depths of an earthquake accurately so quickly, it is more of an after event analysis, but at the moment it is definitely shallow all of our continental earthquakes here are shallow and this one sits at about 12 kilometres at the moment, but it might be shallower when it is reviewed by our analysts.
“Deeper ones are not felt as much as shallow ones and it also depends on the substrait and the houses, but people felt it quite a bit.
“It is also an area that is used to seismicity, so people there know about these things and know what it is; some people said it felt different from a mine blast and that’s the first thing that springs to mind for me, so it is very helpful when people know and live in that area,” she said.
“It is definitely nothing to worry about it is nature’s way of relieving pressure which builds up in the earth’s crust and this happens in the form of an earthquake,” Andrea Thom said.
There are 400 to 600 earthquakes a year on Australia and in a search area of 150 kilometres in the Hunter there have been 65 earthquakes in the last 10 years.
During the last 12 months there have been eight earthquakes, with the last one also being in Muswellbrook on July 18 measuring 2.6 in magnitude.
Large earthquakes measuring a magnitude five are fairly rare in Australia.
“Of course there was the 5.4 in Newcastle in 1989 and Ellalong, near Cessnock, had a 5.3 in 1994,” said Ms Thom.
“We can never predict it you could have one tomorrow, but usually we only have a magnitude five once per year in Australia,” she said.
“We are becoming more effective in analysing smaller events and therefore people may think the activity is increasing, but it’s really due to the better technology and having more seismometres, so our coverage is better,” she said.
“We are fairly lucky in Australia, unlike places in the world like Indonesia,” Andrea Thom said.
Help piece together information on the earthquake, if you felt something: Lodge a Felt Report.
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