You’ll probably remember back in September when the Rainbow Beach sinkhole opened up at a popular Inskip Point campsite, claiming a vehicle, a caravan and forcing the evacuation of 140 campers.
Interestingly, there have been 15 earthquakes or tremors in the Fraser Coast and Sunshine Coast region since July when a 5.4 magnitude quake occurred just off Fraser Island, with the most recent aftershock measuring 3.3 on September 17. Geologists are to employ underwater sonar surveys of the erosion-prone beach where the sinkhole is located to see if the spectacular collapse was linked to these earthquakes.
A preliminary report submitted to Queensland National Parks and Wildlife Service describes the collapse at MV Beagle campground as a “near-shore landslide”, triggered by erosion and strong tides, but it was not initially linked to the recent earthquake activity.
However a new report is currently being put together after hydrographic and side-sonar surveys were completed in late October. The geotechnical report will be available this month and will outline if the earthquakes actually did have an impact and whether further geotechnical studies are needed. QPWS will make decisions on the future management of this area based off this report, which is due any time now.
Since the incident, there has been no further erosion of the area around the sinkhole and the tidal action is expected to gradually return the sand to the hole, making it more stable over time. With that said, the MV Beagle and eastern section of the Sarawak campgrounds remain closed with barricades in place to prevent anyone venturing too close, but a spokesperson assured us that all of the other camping areas in the Inskip Peninsula Recreation Area remain open, so there’s still plenty of space to head over there for a couple of days (or weeks).
We’ll keep you up to date as further news develops.
4 comments
If the sediment is already water filled, then an earthquake can produce liquefaction, where water moves upwards through the shaking sediment to the surface and the sediment flows like a liquid at the surface. Look up video of Christchurch earthquakes and liquefaction to see what happens. Any heavy mass on the sediment will sink as the sediment loses solidity. Given that this may have partially happened and then natural tides and currents may have contributed to sediment removal, then it is a recipe for this type of collapse.
I remember back in the late 80s – early 90s there was a similar episode on the eastern side of Fraser Island where some fishermen returned by boat to where they had left their 4wds and boat trailers, only to find they had vanished. They had parked well above the high tide mark on the beach and at first, thought that the vehicles had been stolen. As they walked to where the 4wds were parked they found them right where they had parked them only at the bottom of a 8 metre sinkhole, still upright and in shallow water, the hole had shere sides and the recovery took a lot of heavy machinery and time. Turns out that the ocean had undermined the beach forming a sand cave and they were unlucky enough to have parked where they did when the roof of the sand cave collapsed while they were in the boat fishing. Very possible that this may have occurred at Rainbow Beach too. I guess at least they were lucky not to of been in there cars when it collapsed.
We have been camping at Beagle for quite a few years now and although this sink hole seems a fair bit larger, this seems to be something which happens in the same area every year or so. it is a shame if the whole of Beagle is closed as we reckon it has the best sites under the shady trees along the beach.
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