China on Thursday moved to clamp down on any unauthorized reporting of the earthquake in its southwestern Sichuan province, ordering news outlets to stick to the official line.
The ruling Chinese Communist Party's propaganda officials have issued a ban on any individual reporting of the quake, a leaked directive to media editors showed.
"Regarding the earthquake in Jiuzhaigou, Ngaba prefecture, Sichuan province, all outlets must stick to official copy from Xinhua news agency," an order from the party's propaganda ministry posted online by the U.S.-based China Digital Times website said.
Horrifying photos and video are forbidden, and outlets must stay on top of changes in online public comments. Be prepared to delete harmful information in a timely manner," it said.
Thousands of rescuers have poured into the scenic tourist region worst-hit by Tuesday night's 7.0 magnitude quake that killed 20 people and injured hundreds, with 16 tourists reported stranded near a lake in the Jiuzhaigou national park.
Local residents and tourists are sleeping outside, some in relief tents, for fear of further aftershocks and building collapses, with many of them clustered in the county town in Sichuan's Jiuzhaigou county.
As temperatures fall, many are at risk of illness, including colds and flu, sources said.
"There are around 10,000 people on the main square in the Jiuzhaigou county town right now, tourists," a source in the area told RFA. "There's no hope of transportation, because nothing can get in."
Damage to roads
"There is serious damage to many of the local roads, with massive rockfalls and landslides every kilometer or so," she said. "We have to rely on rescuers going to search each of the villages, and there are still many places that they haven't managed to reach yet."
She said some vehicles have managed to leave the area: "But there are too few, and they move too slowly. People are afraid to drive because of all the landslides."
"Only one bus has arrived here so far today, a bus which took away more than 20 people," she said, adding that a small number of people had been airlifted out by helicopter.
A business owner in Jiuzhaigou confirmed her account.
"For the time being, nobody can get into the area; they have to clear the roads first ... because some of the mountainside has likely tumbled down," he said. "They will only let people in when they can guarantee their safety."
Calls to Wang Zhongchen, spokesman for the Sichuan provincial government, rang unanswered during office hours on Thursday.
Tourism industry hit
A Chinese journalist in the quake-hit area said the quake has done huge and immediate damage to tourism in the area.
"Everyone has fled, except for the ones who are still waiting for transportation," he said. "And when they're gone, they'll leave a ghost town behind them."
"There is geological instability now, and it'll take time to recover."
Hong Kong's tourist industry association said all tours to the quake-hit area have been canceled, with more than 300 tourists in 20 tour groups run by its members currently affected by the quake.
"There is no way that we will get any more tourists this year, or for who knows how long," a Jiuzhaigou resident told RFA. "Just as business was looking up, we get this earthquake. There's no way we can recover from this in a couple of months."
"Will people want to come to Jiuzhaigou, one month from now? I think it'll take at least six months."
An employee who answered the phone at the Sichuan Tourism Association declined to comment when contacted by RFA on Thursday.
"Only official websites are allowed to put out news about this stuff, so there will be only one announcement," she said.
Death toll unclear
Beijing economics professor Hu Xingdou said he believes the authorities may be covering up the true extent of the death toll.
"I think it's likely that the toll of deaths and injuries from this earthquake was very serious, although it's not very high in the official media reports," Hu said.
"There are probably a lot that haven't been counted yet, and then there's the massive, even disastrous impact on the local economy, on society, and on people's livelihoods."
State media said that 47,000 tourists had been transferred to safer places as of 6 p.m on Thursday, while the ministry of transport in Beijing has initiated emergency response procedures in response to the damage to roads.
The Global Times newspaper said four foreign nationals were injured in the quake, out of more than 1,000 in the area.
Chinese seismologists warned that there might be more aftershocks in the coming days, the paper, which has close ties to the ruling Chinese Communist Party, reported.
Link to dams
However, some experts told RFA that the recent earthquake and the devastating 2008 earthquake that left tens of thousands dead are likely linked to a massive program of dam-building in the region in recent years.
"Actually, the  earthquake and the Jiuzhaigou earthquake are in the same region, and these are reservoir-induced earthquakes," Germany-based hydrologist Wang Weiluo said in an interview on Thursday.
"A lot of scholars in China don't agree with this view."
"But the 2008 earthquake was clearly and directly linked to the Zipingpu reservoir," he said. "There have in fact been a number of earthquakes linked to hydropower projects in China's southwest."
In 2014, experts called for further research into reservoir-triggered quakes after a powerful earthquake left nearly 600 people dead in the southwestern Chinese province of Yunnan.
According to Yang Yong, a senior researcher in the seismology team at the Sichuan provincial land and mining bureau in Chengdu, the quake came just months after authorities in Yunnan's worst-hit Ludian county filled up a brand new 23 million cubic-meter (812 million cubic-foot) capacity reservoir.
Yang's colleague Fan Xiao told RFA on Thursday that the link between earthquakes and hydroelectric dams can't be ignored.
"Overdevelopment exacerbates local geological disasters," Fan said. "They have now built so many dams in that area that they can't find room to build any more."
"A lot of this is government-led, because they can extract a lot of income from selling water resources [for development]."
Reservoirs at fault
Fan and Yang told reporters in 2008 that pressure from the water in reservoirs contributed to the break-up of the earth's crust along the fault line, a claim that has also been made by other international seismology experts.
Reservoir-triggered seismicity is the term used by experts to describe the triggering of earthquakes by the physical processes that accompany the filling of large reservoirs.
Harsh K. Gupta, a top international expert on the subject, defined this in 2002 as "earthquakes occurring in the vicinity of artificial water reservoirs as a consequence of impoundment [i.e., the collection and confining of water]."
According to Gupta, more than 90 earthquakes are known to have been triggered by the filling of water reservoirs, including the 1967 Koyna earthquake in India, which measured 6.3 on the Richter scale.
Reported by Wong Lok-to, Wong Siu-san, Lam Kwok-lap, Ng Yik-tung and Sing Man for RFA's Cantonese Service, and by Yang Fan for the Mandarin Service. Translated and edited by Luisetta Mudie.