The Motley Fool offers our deepest sympathies and best wishes to all those who have been and will continue to be affected by the terrible tragedy in Japan. There are no words to describe the shock and horror we've all no doubt felt by seeing events unfold there. 

Despite this disaster of unimaginable proportion, the Tokyo stock exchange opened today, reflecting Japan's firm resolve to carry forward and onward as quickly as possible. The large sell-off that occurred today is an obvious indicator that the global economy will need to adjust to profound economic ramifications from the damage inflicted upon Japan, a nation that produced $5.4 trillion in GDP last year, accounting for 8.7% of global GDP. With that in mind, let's take a cursory look at what companies may be in for hard times ahead, and those that might see some benefit in the post-disaster global economy.

Potential setback
As with any natural disaster, the first sector to usually be picked apart by traders is insurance. Aflac appears to have dodged a bullet because it does not engage in property and casualty underwriting in Japan, but does derive the majority of its revenue within the country. AIG (NYSE: AIG) may not be so lucky. The company’s Chartis division insures 8% of the property and casualty market in Japan. The impending loss payouts, which will undoubtedly be a large number, are the last thing shareholders needed after the insurer relied on $180 billion in government loans just to stay afloat a little over two years ago.

The automotive sector could be driving down a slippery path considering many of Japan’s auto manufacturers have reduced production or closed their plants entirely. One of the hardest hit Japanese companies listed in the U.S. is Toyota Motor (NYSE: TM). Toyota closed all 12 domestic plants today and the immediate future of two of its plants in Northern Japan still remains in question. A more immediate issue will be when Toyota expects its parts suppliers to be back to full operation. Ford or General Motors may or may not pick up market share in the wake of this disaster, but the possibility is certainly there.

Technology stocks however may face the most immediate impact, particularly those based in Taiwan that rely on Japanese parts in the manufacturing process. AU Optronics (NYSE: AUO), the fourth largest provider of flat-panel displays worldwide, may suffer supply-chain problems despite word from the company that its Japan facility appears to be operational. In Japan, Panasonic and Sony could see an immediate negative impact to their bottom-line figures as both struggle to get the parts required to manufacture their electronic products.

Moving forward
Construction-related companies are likely the most logical choice to benefit from Japan’s rebuilding process. Heavy machinery provider Caterpillar (NYSE: CAT) and Japan-based Komatsu should see increased demand for years to come. Going hand in hand with heavy machinery are steel, copper, iron and wood providers, which make construction possible. South Korean-based Posco (NYSE: PKX) appears to be in great shape to provide steel to Japan, while the U.S.' lumber giant Weyerhaeuser (NYSE: WY) could be in line to benefit greatly, especially in the considerably more rural areas of Northern Japan.

Energy providers are a mixed bag, but overall the outlook for the sector appears bullish. Nuclear power accounts for nearly one-third of all power generation, so it appears that nuclear operators and alternative energy providers may both benefit. Japan-based Hitachi (NYSE: HIT) designs and constructs nuclear generation systems, but is also involved in hydroelectric and wind power generation. Wind turbine provider General Electric or even solar cell manufacturer First Solar could see a jump in production if Japan looks for more eco-friendly energy alternatives.

Short-term winners can also be found locally. Refiners in general could oddly benefit from this tragedy. Refiners had been facing considerable oversupply problems in Cushing, Okla., but those problems seem to be lifting after many of Japan’s refineries have been shut down. Valero Energy, Tesoro, and Western Refining are three names that could directly see an uptick in earnings based on this slowdown in output.

Don't discount the impact environmental cleanup companies could have as well. It remains to be seen who may step up to fill this role in Japan, but I wouldn’t be surprised to see a company like Clean Harbors, who played a critical role in cleanup efforts in 2005 after Hurricane Katrina, trend higher in the interim.

Finally, it pays to note just how important of a role social media played in getting news and information out of Japan when standard telephone and Internet access was nonfunctional. Facebook, Twitter, Google’s YouTube, and to a lesser extent Skype, have played a tremendous role over the past few days in connecting families and providing first-hand accounts of conditions in Japan that simply dwarfed the coverage of larger media networks. It appears Goldman Sachs’ investment in Facebook is looking a lot smarter than I initially thought.

The big picture
The big picture here remains cloudy because Japan is still dealing with countless humanitarian issues and the aftereffects of the disaster, including a potentially grave nuclear crisis -- its future prospects could change dramatically over the next few months. These scenarios can at least serve as a starting point for further research into the companies mentioned here, and provide some analysis of how this event could affect your portfolio.

What’s your take on Japan’s economy going forward? Will it be able to recover quickly or could this earthquake cripple the economy? Share your thoughts on this and the companies mentioned above in the comments section below and consider tracking these stocks, along with your own portfolio with My Watchlist.

Add Caterpillar, Posco, Weyerhaeuser, Hitachi, AIG, Toyota Motor, and AU Optronics to My Watchlist.

Ford Motor and Aflac are Motley Fool Stock Advisor picks. Google and First Solar are Motley Fool Rule Breakers selections. General Motors and Google are Motley Fool Inside Value picks. The Fool owns shares of Ford, Aflac and Google.

Fool contributor Sean Williams does not own shares in any companies mentioned in this article. He urges those who want to help in the relief effort to donate to the American Red Cross. You can follow him on CAPS under the screen name TMFUltraLong. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.