PartnerRe Ltd has increased its loss estimate for the Japanese earthquake and tsunami by another $230 million.The re/insurer announced initial loss estimates of approximately $500 million last month.PartnerRe president and CEO Costas Miranthis said: “We recently received new information from a long standing large cedant in the region for whom we underwrite several treaties, including some underwritten on an exclusive basis at pricing not available to the broader market. While this information remains limited, we believe it is prudent to increase our loss estimate at this time, including reserving the full limit of our exclusive arrangements.Although the Tohoku earthquake loss is a significant one for PartnerRe, we continue to believe in the value of diversification in a catastrophe portfolio, and we will continue to pursue transactions which optimize our long-term risk adjusted returns.”PartnerRe now estimates that the total net impact of these events will result in a loss of approximately $730 million.