Too much private debt caused the last 43 crises.
https://www.ineteconomics.org/perspectives/videos/a-brief-history-of-doom
In this interview, Richard Vague discusses his 200 year research into financial crises - investigating every one of the 43 major financial crises in 6 countries. Every one of them has been "caused" by too much private debt. And it is always private sector debt .... never government debt in developed countries.
Key common symptoms across these 43 financial crises:
Excessive private debt/GDP (in excess of a 150% threshold) PLUS
Private debt/GDP growing more than 20% over a 5 year period. Australia gets a special mention.
This combination is the key warning - the key finding of this research.
This research has just been published in Richard Vague's new book. "A Brief History of Doom". Two Hundred Years of Financial Crises" http://www.upenn.edu/pennpress/book/15996.html
Note: In the 4 years from 2011 to 2015, Australia's private DEBT/GDP rose from 183% to 209% of GDP ( https://tradingeconomics.com/australia/private-debt-to-gdp ) - an increase of 14%, but well in excess of the threshold of 150% private Debt/GDP - so clearly Australia is vulnerable to a financial crisis. Household debt of course, is the lion's share of Australia's current private debt at 128%.