Re-insurance companies, which back up insurers and are among those hit early by catastrophes, stressed it was too soon to estimate the final cost, but "it will be an expensive event," said Christian Muschick at the private German bank Silvia Quandt.
The cost in human life has already reached 90, public broadcaster NHK said, after the massive 8.9-magnitude earthquake, the biggest ever recorded in Japan, was followed by huge aftershocks and tsunamis along the nation's Pacific coast.
A tsunami warning was issued for the entire Pacific Ocean, including Alaska, Australia, Antarctica, Hawaii and South America.
In Paris, a sector analyst who asked to remain anonymous told AFP: "After the floods in Australia, the quake in New Zealand and now the one in Japan, the bill for re-insurers is already looking expensive this year."
The Italian investment bank Mediobanca agreed, saying: "We expect the reinsurance sector to be significantly affected."
Swiss Re spokesman Tom Armitage told AFP in Switzerland: "It is too soon to consider the financial consequences, whether for the sector or for a company like Swiss Re," the second-biggest re-insurance group after German Munich Re.
Muschick said the massive Japanese quake that struck Kobe in 1995 and killed 6,400 people cost a total of six billion dollars, a figure that does not account for inflation.
He and others said insurers would now raise their premiums but that the Sendai quake, as the latest was called, would cause less damage because its epicenter was deeper and well off the coast of less populated areas.
Although media reported widespread damage and fires in the world's third largest economy, J.P. Morgan Cazenove estimated the quake would cost European re-insurers "a loss in the $1-$2 billion scale, no more."
On Thursday, Munich Re said it expected to pay about one billion Australian dollars (726 million euros, $1.0 billion) for the Christchurch earthquake in New Zealand on February 22.
Munich Re then warned it would only achieve this year's profit target if "random major losses" remained below the average expected level.
Muschick said that "Munich Re can most probably forget about its net profit guidance."
J.P. Morgan Cazenove analyst Michael Huttner added that insurance premiums would probably rise, remarking that "historically big events are a net positive in that they are associated with stronger earnings one and two years later."
On Friday, shares in European re-insurance groups showed heavy losses in afternoon trading, with Munich Re off by 5.44 percent at 110.4 euros, while Frankfurt's DAX index was 0.88 percent lower overall.
Swiss Re showed a loss of 5.32 percent at 50.75 Swiss francs, meanwhile.
Hannover Re, which says it is the world's third biggest re-insurance group showed a loss of 4.53 percent at 38.95 euros and shares in French re-insurer SCOR had lost 7.61 percent to 18.76 euros.