If a huge inland earthquake occurs in the Tokyo Metropolitan Area, it would cause economic losses topping ¥1 quadrillion, the Japan Society of Civil Engineers (JSCE) said Thursday.

The government has already forecast an asset loss of ¥47 trillion as direct damage from such a quake based on a scenario presented in 2013 by its Central Disaster Management Council.

This time, the JSCE figured out that indirect losses, including from suspended production activities due to broken roads and bridges, will reach ¥954 trillion in a post-quake period of 20 years or so.

In addition to the direct and indirect losses, the JSCE predicted that the central and local governments will see their tax revenues decline by a combined ¥36 trillion and that they will need ¥353 trillion for reconstruction work.

But the society also said economic damage could be reduced by 39%, or ¥369 trillion, if ¥21 trillion or more is invested in advance to make roads, ports and buildings more quake proof.

"Reconstruction would be delayed in areas where roads and bridges are severely damaged," Satoshi Fujii, head of a JSCE subcommittee and professor at Kyoto University, said at a news conference.

"If nothing is done, the consequences will be really terrible," he stressed.

In its 2018 report, the JSCE projected that losses from a Tokyo inland quake will total ¥731 trillion, based on data from the 1995 Great Hanshin Earthquake in western Japan.

But the group of civil engineering experts revised the loss forecast significantly upward after analyzing tremendous damage from the Great East Japan Earthquake 13 years ago.

It also plans to update its loss estimates regarding a possible massive quake in the Nankai Trough off the Pacific coast of the country after the central government reviews its damage projections.