SHANGHAI — Chinese scientists say that even before a final accounting can be made in last month’s earthquake in Sichuan Province, one thing is painfully evident: The huge death toll stems partly from a failure to heed clear warnings of a devastating earthquake in the area.

For decades, Chinese scientists say, they have known of the risk of a potentially catastrophic earthquake along the Longmenshan belt, the area where the Wenchuan earthquake struck, and repeatedly raised their concerns with government authorities. But they say preparations for a quake there were cursory at best, and building codes remained well short of the codes that have become standard in other well-known earthquake zones, including Beijing itself.

The ruling Communist Party has hailed its own vigorous response to the quake as evidence of its concern for human life, and has generally received positive reviews at home and abroad for its rescue efforts after the quake. To date, however, China’s state-run news media have paid little attention to the fact that government officials apparently did little to shore up structures, limit urban growth or even conduct basic safety drills that might have reduced the death toll.

“Chinese people have a saying, that you learn a fence needs mending after the sheep have run away,” said Gao Jianguo, a researcher with the China Earthquake Administration, in Beijing. “In this case, people wouldn’t recognize the danger until the sheep actually died. We tried to lay out the reasons beforehand, but people wouldn’t listen.”

One after another, Chinese experts have emphasized that they are unable to predict the timing of an event like the one May 12, which left about 87,000 people dead or missing. But they say the general danger to this region has been known since at least 1933, when a major quake struck Wenchuan, and has been studied fairly intensively since the 1970s.

“The line of the middle fault is as clear as a string,” said Li Yong, a geological expert at Chengdu University of Technology. “It suggests continuous and strong movement. Such a long and clear lineament should trigger a big quake. Other scientists have had similar ideas.”

In July, a paper by Mr. Li and another scientist raised the likelihood of a 7.0 magnitude earthquake along the Longmenshan belt, and spoke again of the dangers there at a conference in China a month before the disaster.

While many say scientists advocated stronger precautionary measures for years, some also expressed a deep sense of failure for not having warned the government in stronger terms that seismic danger there was being underestimated. The Longmenshan belt did not appear, for example, on a recent priority watch list of likely trouble spots.

“Beyond the pain felt by ordinary Chinese, we in earthquake science are guilty beyond description,” said Ma Shengli, deputy director of the Institute of Geology of the Chinese Earthquake Administration. “Our ability fell far short of what was needed, and we can’t help but cry.”

Some seismologists also say that the earthquake agency, based in Beijing, did not press the government to impose tougher building codes in the region. So even if most buildings there had been built to code — many appeared to fall far short — they might well have failed to withstand the May quake, which the Chinese government says had a magnitude of 8.0, the most powerful in China in modern times.

“The earthquake administration didn’t warn the government enough,” said Mr. Gao, the researcher with the earthquake agency. “We told them things should be built to withstand seventh-degree crack resistance, but we should have insisted on ninth degree, just as experts from the Soviet Union advised us back in the 1950s.”

Mr. Gao referred to an earthquake building code standard used in China. A building would have required construction to an 11th-degree standard to have escaped damage in last month’s earthquake. Many Chinese experts invoked the high cost of building structures to withstand major earthquakes as a rationale for the failure to do so.

Earthquake-related building codes exist throughout China, but experts say they have been applied spottily. In Beijing, where the earthquake risk is high, more strenuous efforts have been made to enforce strict building codes. In many other high-risk areas, this has not been the case.

“Standards are one thing, and the implementation is another,” said Liu Hang, a professor and senior engineer at the Beijing Construction Engineering Research Institute. “The quake-proof level for Wenchuan’s local buildings is rated Degree 7, but based on what I’ve seen on-site, the buildings there are far from reaching this standard. Let’s not talk about whether the degree of quake-proofing is high enough; the buildings in the affected areas just have no quake-proof protection at all.”

Speaking of the capital, Mr. Liu said, “Unless the epicenter of an earthquake like this occurred right in Tiananmen Square, central Beijing would not be seriously damaged.”

Officials at China’s Ministry of Housing and Urban-Rural Development did not respond to a request for an interview. An official at Sichuan Province’s construction department who identified himself only as Lu denied there were widespread problems of enforcing building standards, but declined to say more.

In light of the huge loss of life, many said that whatever the rationale, the failure to enforce adequate building standards in Sichuan was unacceptable.

Hu Xingdou, a professor at the Beijing Institute of Technology, called the failure to enforce adequate building standards a case of “serious malfeasance” on the part of local governments.

“One of their basic responsibilities is to ensure people’s safety, which means supervising the quality of people’s homes, and making sure that new houses comply with standards,” Professor Hu said. “Even if they haven’t made the effort to cover all rural housing, initially they should make sure public buildings, such as schools and hospitals, are safe and compliant.”

China has long pushed major infrastructure and even military developments in the area despite the quake risk. The mountainous region outside Chengdu became a major military production base in the 1960s, when China feared the possibility of an attack from the Soviet Union or the United States. Nuclear design, plutonium and fighter jet production facilities were located not far from the Longmenshan belt, largely because the region, deep in central China, was far from the country’s borders and considered relatively safe from aerial assault.

Under Mao’s Third Front policy, major industrial and military facilities were located in the Chinese heartland rather than in coastal areas viewed as more vulnerable. “The awareness of earthquake risk has been a gradual process, while the construction of the Third Front was primarily a political decision,” said Ma Dingsheng, a military expert and commentator on Phoenix TV, based in Hong Kong. He said that even after the quake risk was better understood, military facilities there continued to expand.

There is no evidence of serious damage to military facilities, though information about them is highly classified in China.

On Wednesday, China’s State Council passed a draft regulation on post-quake restoration and reconstruction at an executive meeting, the official Xinhua news agency reported Thursday. It introduced special requirements on earthquake-resistance levels of infrastructure construction in the quake-hit regions, including schools and hospitals.

Local governments must organize personnel to conduct safety appraisals of all school buildings as soon as possible to ensure the safety of students as they return to school, according to the statement.

A disproportionately large number of the earthquake’s victims were children crushed when thousands of classrooms crumbled or collapsed. Facing pressure from parents over the loss of their children, this week the Sichuan Education Bureau published a list of five reasons school-related deaths were so high. The reasons included the timing of the quake, while classes were in session, and the age of school buildings. No mention was made of government failure to enforce standards, or of corruption, which are taboo subjects.

Treading carefully around a politically delicate subject, Mr. Li, the co-author of last year’s paper warning of the danger to this region, said, “Many experts have provided their knowledge and suggestions, but how much of it became a reality in these towns and villages isn’t something that’s convenient for me to say.”

Some scientists said that given the known risk, the areas with the worst damage should never have been settled. “How could a populous city be built in such a risky area, particularly right at the foot of mountains?” said Liu Jingbo, a professor at the Construction Institute of Disaster Preparation and Relief at Tsinghua University, in Beijing. “When an earthquake occurs, it’s not just the collapse of buildings that buries people, but boulders and huge rocks and mud flows follow on immediately.”

More than 15,000 people died in Beichuan, or about one-tenth of the city’s population. “The ignorance of the local government or the lack of attention to implementation of the departments with real power contributed to this tragedy,” Professor Liu said.

Beichuan, a county capital, was moved in 1952 to its present site at the foot of three mountains, from a nearby site that was prone to flooding. But concerns about the risk of a major earthquake have been voiced almost continuously since the relocation.

“Ever since I was small,” said Sun Xiaotao, director of the general office of Beichuan County’s fiscal bureau, “I’ve heard talk about how if an earthquake happened, we’d be wrapped in, just like a dumpling.”

Copyright 2008 The New York Times Company