Perhaps the Kobe disaster in 1995 is a better comparison than Chernobyl because the USSR was not economically integrated in world trade back then (communist countries traded with each other but had little to sell to the west except some basic materials such as oil perhaps, although they were a major market for our wool exports). Very little investment in USSR by outsiders (if any), maybe some loans to them.
Chernobyl was probably seen as a USSR/communist failure so why would the US market tank, whereas the Japan disaster is in part more about the failure of market economics (unsafe and maybe poorly manned nuclear reactors still in operation). Back then oil was cheap and US exports and imports only represented about 10% of their GDP - the US was the world's manufacturing powerhouse and at the forefront of most technologies, and was still a net creditor nation. On the other hand I wonder how the US market reacted when they had the Three Mile Island disaster in 1979, which was an era of economic woes including stagflation (perhaps an era closer to current conditions).
Japan is 8% or the world economy (was larger back in 1995 when the world economy was smaller) and is central to world investment and capital flows. I have seen a suggestion that the impact of the present disaster could involve a 0.4% reduction in US growth over 1 year, and that this translates into $3 in lost earnings by the S&P500 countries (about 42 points on the S&P assuming a PE ratio of 14).
I think Japan is the largest importer of Australian goods and services and we have a trade surplus with them (China is our biggest trading partner and the two way trade is fairly evenly balanced) so maybe there will be some impact here both in trade and capital flows.
I also imagine the Kobe disaster had little impact on the USA market because they were far more dominant back then and trade as proportion of their economy was lower than it is now. Also the 1990s were the boom times for the US sharemarket, so Kobe may not even have registered on their market.
This disaster will have a short-medium term economic impact on Japan, not long term. The market has been looking for a reason for tanking, and there are many. As I wrote earlier, company earnings were already being revised down (because of higher energy costs etc).
Anyway, this is not the end of the world (unless HJ stops clapping).
loki (making a poor attempt at two handed economic analysis)
(20min delay)