Economic losses from natural catastrophes in 2011 were the highest on record, according to global reinsurers.

A greater spread of geophysical events and a rise in the number of catastrophes in Asia pushed global economic losses to $US350-435 billion ($329-$409 billion), about two thirds higher than the previous record set in 2005.

Only low insurance penetration for earthquakes in Japan kept insured losses below 2005 levels at between $US105 billion ($98 billion) and $US108 billion ($101 billion).

While last year’s catalogue of 820 events was not unusual in number – it was in line with the 10-year average – location and cost set 2011 apart from previous years.

Aon Benfield says insured losses were 280% higher than in 2010, which in turn were double those recorded in 2009.

Earthquakes caused the most devastation, a change from previous years where weather-related catastrophes such as floods generated the greatest losses.

The Tohoku earthquake off the east coast of Japan and subsequent tsunami was the costliest single 2011 event at $US35 billion ($32 billion) in insured losses, followed by earthquakes in Christchurch at about $US12 billion ($11.3 billion).

Munich Re board member Torsten Jeworrek says many of last year’s events have been calculated at a frequency of once every 1000 years.

“Thankfully, a sequence of severe natural catastrophes like last year’s is a very rare occurrence,” Mr Jeworrek said.

Swiss Re Chief Economist Kurt Karl says earthquake insurance coverage is still low, including in industrialised countries with high seismic risk.

All but two of the 10 most costly events struck in the first half of 2011.

Flooding in Thailand, which began in July and is ongoing, and Hurricane Irene in the US caused a combined $US17 billion ($15.9 billion) in insured losses in the second half, or about 16% of total losses.