996

NEWS>>THIS WEEK A flood of lawsuits The skinny on

microbes

1000 1001

CHENGDU, CHINA—Wei Fangqiang knows

what it’s like when a mountain crumbles:

The Longmenshan, or Dragon’s Gate

Mountains, are prone to landslides. But

when the physical geographer and seven

colleagues with the Chinese Academy of

Sciences’ Institute of Mountain Hazards

and Environment (IMHE) in Chengdu

trekked into the area devastated by the

Sichuan earthquake, they were stunned. It

looked as though the hills had been blown

apart. Landslides had flattened several-

story buildings in the town of Beichuan and

annihilated villages that clung to the steep

slopes. In Wenchuan, Wei and his comrades

picked their way across a 70-meter-high,

300-meter-wide rubble pile that had

crushed a hydropower station and blocked

the Chaping River. If an aftershock had

struck, it could have spawned a new land-

slide where they were walking. “It was very,

very dangerous,” Wei says.

Landslides unleashed by the rupture of a

more than 200-kilometer section of the

Longmenshan fault, followed by powerful

aftershocks, dammed parts of nine rivers,

creating 24 new lakes. The biggest and most

threatening is 3.5 kilometers upstream of

Beichuan. If the debris dam were to break,

the resulting flood would threaten relief

workers and researchers in Beichuan.

“We’re worried about another catastrophe,”

says Wei. As Science went to press, experts

with the Ministry of Water Conservation

were weighing options for how to relieve

pressure building up behind the dam.

They had at most a week to act , said

Cheng Genwei, IMHE’s vice director.

Down the road from IMHE, researchers

with the Chengdu Institute of Biology (CIB)

were in mourning. Three senior staff mem-

bers died when the wall of a hostel in the

mountains collapsed as they were dashing

out of the door for safety. (IMHE lost one

staffer in Beichuan.) After a 20 May memo-

rial service, CIB scientists were hoping to

return to work with an ambitious research

agenda, including an examination of habitat

fragmentation and ecological succession in

landslide areas. “The earthquake will be a

big driver for research,” says CIB ecologist

Bao Weikai. He and colleagues will also be

alert to a grave threat to Sichuan’s famed

giant pandas: the possibility of a massive

die-off of bamboo, the panda’s staple, like

one recorded in a quake 30 years ago.

At 2:28 p.m. local time on 12 May, the

Sichuan earthquake struck with a magni-

tude of 7.9. It “was not a total surprise to

geophysicists,” says Mian Liu, a geo-

physicist at the University of Missouri,

Columbia. It occurred on a well-known,

active fault system, he notes, which in 1933

produced a magnitude-7.5 quake that killed

about 9000 people.

But the death toll of the Sichuan earth-

quake is horrific. As of 20 May, more than

40,000 people are known to have perished,

including thousands of children. Experts are

asking whether better construction, espe-

cially at schools, could have prevented

many deaths. “Earthquakes themselves do

not kill people,” says Liu. The biggest killer,

he says, is structural collapse—“a point so

sadly illustrated by this earthquake.” It

appears that many wrecked buildings were

not reinforced. “One hardly sees steel CR

ED

ITS

(T

OP

TO

BO

TT

OM

): C

OU

RT

ES

Y O

F W

EI FA

NG

QIA

NG

/IM

HE

; U

SG

S

23 MAY 2008 VOL 320 SCIENCE www.sciencemag.org

Landslides, Flooding Pose ThreatsAs Experts Survey Quake’s Impact

SICHUAN DISASTER

Chengdu

Mianyang

Guangyuan

Beichuan

WENCHUAN

On the fault. A massive

landslide crushed some

buildings in Beichuan.

Shake map. The magnitude-7.9 earthquake cen-tered in Wenchuan brought devastation to the severeshock zone (red) on the Longmenshan fault.

Published by AAAS

on

Aug

ust 2

1, 2

015

ww

w.s

cien

cem

ag.o

rgD

ownl

oade

d fr

om

on

Aug

ust 2

1, 2

015

ww

w.s

cien

cem

ag.o

rgD

ownl

oade

d fr

om

www.sciencemag.org SCIENCE VOL 320 23 MAY 2008 997

FOCUS Five-way symbiosis

1006

Gamma ray vision

1008

beams extruding from the collapsed build-

ings,” Liu says. “When they are seen, they

are so thin that they bent with the debris like

overcooked noodles.”

Under a makeshift canopy next to a swim-

ming pool at a community center in the hard-

hit historic town of Dujiangyan, west of the

epicenter, geophysicist Miao Chong-Gang

points to a map on his laptop overlain with

seven circles in a line on the Longmenshan

fault. It’s the latest data from China’s seismic

monitoring network showing that the

Sichuan earthquake was composed of seven

powerful sequential ruptures unleashed

when the fault ruptured southwest to north-

east. “Several years ago, we could not do an

analysis like this,” says Miao. But with more

than 1000 seismometers now in a digital

network, China can now parse data like this

in a few hours.

Within 30 minutes after the quake hit, the

China Earthquake Administration (CEA) in

Beijing had crunched the numbers and issued

a preliminary forecast of at least 7000 deaths.

Their assessment would prove to be an under-

estimate, but it was alarming enough to

prompt CEA to mount a full-scale response.

Miao, vice-director of CEA’s Earthquake

Emergency Management Department

Response Command Center, led a 230-

person team to Dujiangyan late in the evening

on 12 May. His group, one of 187 rescue

teams in the disaster area, has saved 48 people;

in the morning of 19 May, they were elated to

have saved a 61-year-old woman who had

survived 163 hours in the rubble.

Miao’s team was about to switch from

rescue to recovery. Among their tasks over

the next 2 months, Miao says, is to ground-

truth the computer-generated data. That will

mean conducting seismic, strong-motion,

and geologic surveys and running tests on

everything from geomagnetism to water

chemistry. Such research must wait until the

aftershocks have subsided. Several CEA

volunteers who were ferrying food and

water on foot into the disaster zone were

among more than 150 relief workers known

to have died in aftershock-induced land-

slides. The slides also claimed the lives of

two Sichuan Earthquake Administration

researchers who were measuring crust

deformation. “We have almost no experi-

ence in responding to an earthquake in a

mountainous area,” says Miao.

Back in Chengdu, CIB scientists are itch-

ing to get out into the field. A week after the

quake, 10 of their colleagues were alive but

stranded at CIB’s Maoxian Mountain Ecosys-

tem Research Station in a pine forest 220

kilometers northwest of Chengdu. The insti-

tute had a couple of dozen long-term projects

in the disaster area, a biodiversity hot spot

that encompasses 22 nature reserves. They’ll

have to write a new research plan. “The earth-

quake has dramatically changed the land-

scape,” says CIB ecologist Luo Peng.

One urgent task is to monitor bamboo.

The plant flowers once every 70 years or so.

Shortly after a powerful earthquake in the

1970s, large swaths of bamboo suddenly

flowered and died, says CIB ecologist Pan

Kai-Wen. How a quake might trigger flower-

ing is a mystery, but a large-scale die-off, he

says, could pose a big threat to China’s

endangered giant pandas.

To map the landslides, Wei and his

IMHE colleagues ventured into the danger

zone on 15 May. They had to abandon their

car where a landslide had blocked the high-

way and head toward Beichuan on foot.

Traveling in the other direction was a

ragged stream of refugees. When the

researchers reached Beichuan the next day,

they found that although many buildings

had collapsed from the shaking, many oth-

ers were demolished by massive boulders.

“In some places, the landslides did more

damage than the earthquake,” Wei says.

“We know the rock is very loose here. But

still I was surprised that the landslides were

so severe.” In a nearby village, a woman was

on top of a pancaked building. “She was

calling her son’s name, trying to wake him

up.” There was no one else around.

Wei and his colleagues could not get past

a blocked mountain pass leading to the

biggest landslide, a 2-kilometer-long debris

flow that had clogged the Qingjiang River. To

ward off a catastrophic breach, Cheng says,

the preferred option is to dig a canal that

drains the lake gradually. If that’s impossible,

he says, they’ll have to blast the dam and

allow a more chaotic release. Sichuan’s rainy

season starts in late June; if the rains start

early, before the problem is dealt with, the

situation could be very dangerous, says Wei.

The IMHE researchers plan to head into

the f ield as early as next week to sample

landslide material and draw topographic

maps. A future task is to advise authorities

on a safe place to rebuild Beichuan city. The

original site will almost surely be aban-

doned. “It should be a memorial to the earth-

quake victims—and a reserve for seismic

research,” says Miao. CIB scientists hope to

turn the disaster into an opportunity to

advise Longmenshan residents about more

sustainable livelihoods in the fragile moun-

tain ecosystem. One practice they want to

see ended is farming on the steep slopes.

Better forest cover could reduce the land-

slide risk, says Luo: “We need a new strategy

of mountain development.”

Others say the Sichuan disaster should

stimulate China to rethink its entire

approach to earthquake research. “In recent

decades, geophysicists have spent too much

energy and funding on research on deep-

earth structure or tectonics,” says Zhou

Shiyong, a geophysicist at Peking Univer-

sity. He argues that more attention should be

devoted to earthquake prediction. “We could

f ind some precursors,” he says, such as

abnormal patterns in seismic stress or under-

water variation before a huge quake occurs.

Miao counters that any precursors of the

Sichuan quake were minimal. “They could

not have given us any warning,” he says.

One thing that will surely come under

scrutiny is China’s construction standards.

“More effort should be devoted to earth-

quake hazards analysis and management,

including developing and enforcing proper

building codes, especially for schools, hos-

pitals, and other public buildings,” Liu says.

For thousands of victims in Sichuan, that

lesson came too late. –RICHARD STONE

With reporting by Chen Xi and Hao Xin.CR

ED

IT: C

OU

RT

ES

Y O

F W

EI FA

NG

QIA

NG

/IM

HE

Risky research. IMHE scientists

assess a landslide that has

dammed a river.

Published by AAAS