"Just a little shaking to keep us all awake!" tweeted Service Central Chip Ganassi Racing's Graham Rahal late on Wednesday night, after the Tokyo region was hit by a 6.2 magnitude 'quake.
It was an aftershock from the massive 9.0 earthquake that hit the region in March, triggering a devastating tsunami and causing problems with the Fukushima nuclear power plants, the consequences of both of which are still being felt - including forcing IndyCar to have to switch from the structurally-compromised speedway oval to the road course circuit for this weekend's Indy Japan event.
While a 6.2 might sound serious, it was practically not even worth talking about to the locals, who have endured some 1538 'quakes since the big one on March 11 caused such catastrophic damage. This latest aftershock was centered about 137 miles east of Tokyo and was still very much felt in Motegi, which is about 86 miles north of the capital, but for the IndyCar entourage it was a bit of a jolting experience nonetheless.
"Interesting to sit in your hotel room and see your TV walk across the desk!" said Rahal, who quickly reassured people that everything was "all good here."
"Just had a pretty good tremor here in Motegi!!" tweeted Ryan Hunter-Reay. "Wow, that's a first for me! No more please!"
"It was fun for like 3 secs until you realize is not stopping is not stopping is not ..." quipped Oriol Servia.
"Forgot to mention nearly being trampled by a herd of elephants stampeding because of the 'quake," tweeted JR Hildebrand, who as a native of California would have more experience of 'quakes than most in the IndyCar paddock. "Was pretty sure the world was ending actually."
The aftershock did not damage the race facilities at Motegi, and didn't get in the way of preparations for the weekend's race activity. Nearly 200,000kg of equipment had already flown in on two Nippon Cargo Airlines 747s earlier in the week to deliver the IndyCar roadshow to Japan - and that doesn't include 1,526 Firestone Firehawk tyres arriving at the Port of Tokyo after a 16-day sea voyage from Long Beach, California.
Wednesday saw the drivers take to the circuit for their first walkthrough of the 2.983-mile, 14-turn clockwise natural-terrain road course - the longest track on the 2011 calendar - which will be new to practically everyone on the grid.
One of the few drivers with some very useful pre-knowledge of the track configuration is Brazil's Joao Paulo de Oliveira, an IndyCar rookie racing for the first time for Conquest who just happens to be the 2010 Formula Nippon champion. During that championship season he won at Motegi in the May event and could prove to be a strong challenge to the IndyCar regulars. It will be interesting to compare the IndyCar times with the most recent pole position lap of 1:35.012s that de Oliveira set.
Former IndyCar regular Hideki Mutoh, driving this weekend with AFS/Sam Schmidt Motorsports, is another driver with experience of the road course having two victories in Japanese F3 here in 2005 - but that was a long time ago. Last year's winner from pole position, Helio Castroneves, has meanwhile only run on the oval circuit: Motegi marks a year since Helio's last IndyCar series victory and he's hungry to get back to victory lane again.