The internet is aflame with rumors, launched by Chinese micro-blog users, that North Korean leader Kim Jong-un was assassinated in Beijing this morning. We believe we've figured out what's behind the rumor, and it has more to do with a birthday celebration for Kim Jong-un's dead dad than a violent coup.

The rumor appears to have started with a user of the Chinese Twitter-clone Weibo named Hucaihe, a Beijing venture capitalist. Hucaihe's office is near the North Korean embassy, and yesterday he noticed some unusual activity downstairs.

At 12:19 February 10th, China time, Hucaihe posted this message to Weibo:

downstairs of the office, the cars for the Korean embassy is increasing rapidly, now it's over 30 cars. It's the first time I've seen this situation, did something happen in Korea?

Thanks to its ominous tone and first-hand reporting, the post took off. It's been "forwarded" (retweeted) 11,968 times. Another Weibo user, Fan Jing, soon posted a picture that purported to show the embassy parking lot filled with cars. That photo's been forwarded almost 5,000 times.

These posts, and chatter about them, launched a wave of speculation about a potential coup or assassination. (There has been some anxiety about Kim Jong-un's ability to consolidate power.) Through the inborn truth-distortion field of microblogs, this turned into the fact, confirmed by "reliable sources," that Kim Jong-un had been shot to death early this morning at the embassy. That rumor bounced among Twitter and Weibo users, who each fed on increasing chatter on the other's service, creating a crazy Kim Jong-un death rumor vortex. The tweets I saw all cited the Weibo rumors, but a popular Weibo post began "According to the most accurate twitter."

But why was there so much activity at the embassy? It may have been part of an extended birthday celebration for the late Kim Jong-il, whose 70th birthday will be lavishly celebrated by North Korea on February 16th. In a Weibo post on the rumors about the activity at the embassy, the Chinese news agency Phoenix pointed out that a "Conference of Remembering the 70th Anniversary of Kim Jong Il's Birthday" was scheduled to have begun on February 8th in Beijing. Trips and tours have been planned to China and North Korea by travelers from all over the world to mark the anniversary.

However, Phoenix adds: "So far there is no way to confirm if the actions of the North Korean Embassy today were related to the celebrations of Kim Jong Il's 70th birthday." No mention of any assassinations.

So: Kim Jong-un is probably not dead. The ruckus yesterday that prompted rumors of his demise was probably just a killer birthday party for his dad.

Update: just a minute ago, reader Jeremy S. emailed with a report that "all's quiet at the DPRK embassy":

I live really close by the embassy, and happen to have just gotten off work (night shift at a large media company). Rode my bike out there and even circled the place and as of around 7:30 am local time there was absolutely nothing unusual.

Update 2: U.S. officials tell ABC the rumors are untrue. There.