In the early morning hours of Saturday, September 2nd, hundreds of people throughout Adelaide in South Australia were awoken by a loud boom and a pair of powerful ground tremors. Geoscience Australia, a governmental agency which monitors seismic activity, initially reported a 1.4-magnitude earthquake in the area. However, after a few hours, those reports were taken down off of their website with no explanation.

Rattled Adelaide residents took to the internet to share their experiences and seek an explanation for the tremors and noises. One such report details how even house pets were terrified by the incident:

Yep. Definitely heard it. Woke first at 2am, 2nd not long after. Was a strange rumbling noise with shaking windows. Cat went crazy. Never heard anything like it before. Freaked me out!!!

Geoscience Australia seismologist David Love told Australia’s ABC News that some “unknown meteorological disturbance” could be the cause and that Geoscience Australia is still investigating the event:

I can confirm that is definitely not an earthquake; exactly what it is, I don’t know but we have recorded it on quite a lot of our instruments

No injuries were reported during the tremors. Some government agencies explained the event away as thunder, but many residents aren’t buying it, noting that thunder doesn’t usually rattle windows the way these mystery booms did. The usual anomalous weather phenomena such as temperature inversions have been cited, but for now there is no official explanation.

With North Korea testing nuclear weapons technology not entirely far from the Australian mainland, could these tremors have a basis in the aftereffects of underground nuclear detonations? Could that be why Geoscience Australia is so hush-hush about the anomalous tremors? Who knows. With the way things are going with North Best Korea, we’ll likely soon find out. Remember: uncooked white rice has an indefinite shelf life if kept in cool, dry conditions. Like a bunker. Start digging.