Good Morning Oz! - A mysterious, terrifying, and truly giant explosion rocks China - Greek police trap thousands of migrants in a stadium with no food and water - Boko Haram's boisterous leader has reportedly been replaced - And more in your CareerSpot World News Briefs:

A series of massive explosions rattled China's fourth largest city Tianjin, southeast of Beijing.  Mobile video from quite a distance shows a giant fireball rising up and dwarfing the city's skyline, followed by a shockwave and an incredibly tall mushroom cloud.  Tianjin is an industrial city with several big corporations and manufacturing plants.  The BBC is reporting that hospitals are overwhelmed with "hundreds" of casualities, Chinese state TV says 400 are hurt - but that's going to change as the day progresses.

United Nations Secretary General Ban Ki-moon has demanded and received the resignation of the UN Envoy to the Central African Republic.  This, after the rights group Amnesty International alleged that a peacekeepes had raped a twelve-year old girl in the capital Bangui.  There are also questions about the killing of a teenage boy and his father.  Last year, the UN denied allegations it covered up child abuse by French troops serving in CAR.

Boko Haram apparently has a new leader.  Chadian Presidnet Idriss Deby says it's not clear what happened to the former leader often seen giving highly animated addresses in propaganda videos, Abubakar Shekau.  But he's been replaced by Mahamat Daoud, who authorites have not heard of before.  The most recent Boko Haram video was a confusing jumble, with an unidentified young man claiming to speak for Islamic State in the local Hausa language, with the same tribal accent as the missing Shekau.

An Islamic State affiliate group in Egypt claims to have beheaded a Croatian man kidnapped by militants last month, according to the SITE Intelligence Group.  Tomislav Salopek, a father of two, was a surveyor working in Egypt for a French company involved in the oil and gas industry. 

How messed up is Islamic State if the freakin' Taliban says they've gone too far?  The Afghanistan Taliban is condemning IS for strapping explosives to bound and blindfolded prisoners and blowing them up.  IS claims the victims were apostates.  The Taliban says they were civilians.

The Indian government is suing Nestle for more than A$135 Million over food safety.  Earlier this year, India ordered Nestle's Maggi Instant Noodles off of store shelves after lab tests showed them containing unsafe levels of lead.  The swiss food giant denied this.  "Our complaint is over their unfair trade practices and the court will now issue them notices to hear their response," saod G. Gurcharan, additional secretary at the Ministry of Consumer Affairs.

Overwhelmed and undertrained Greek cops on the resort island of Kos routed thousands of migrants into a stadium, ostensibly to register their paperwork - but then locked the refugees in the stadium for 24 hours, without any food, little water, and no protection from the midday summer sun.  Aid workers said the migrants were fainting at a rate of four per hour:  "We have unconscious people coming out of the playground area, being carried by their friends and family, every 15 minutes," said Constance Theisen, a team leader for Medecins sans Frontieres.  "It is absolutely out of control," she added, "Nobody understands the sense behind it, or if there is any (sense) at all."  A day earlier, cops and migrants clashed over the paperwork issue.  More than 120,000 immigrants from the Middle East and sub-Saharan Africa have shown up on Greece's islands so far this year, compared to 30,000 for the whole of last year.

And the waves of migration from Libya's lawless shore continues unabated:  Italy's Navy rescued about 50 migrants from a sinking rubber dinghy on Wednesday.  It's just a fraction of the more than 1,700 migrants picked up from the sea in the past couple of days.

Sweden is dropping the sexual assault investigation against WikiLeaks founder Julian Assange, because the statute of limitations has passed.  An official announcement is expected on Thursday.  The more serious investigation of rape is continuing - that doesn't expire until 2020.  Julian denies the charges, and has taken shelter in the Ecuadorian Embassy in London to avoid extradition, saying he fears he will be bundled up and sent to the US to be tried for releasing secret and embarrassing American documents.