Transcript 四川(Sichuan)

人口（2004） 87,250,000
四川(Sichuan)
四川省，簡稱川或蜀，是中國西南
地區的一個省，省會位於成都。四
川自古被譽為「天府之國」。北宋
將原位於四川一帶的川峽路一分為
四，設立益州路、梓州路、利州路
和夔州路，合稱為「川峽四路」，
簡稱「四川路」，四川由此得名。
四川位於長江上游，是中國內陸腹地省份之一，全省東西長1075公里，南北寬
921公里，面積48.41萬平方公里。四川西部地區是青藏高原的一部分，東部地區
則大都位於四川盆地內。四川與重慶、陝西、甘肅、青海、雲南、貴州和西藏自
治區接壤。
以龍門山-大涼山一線為界，四川大致可分為東部四川盆地及盆緣山地區，以及
西部川西高山高原及川西南山地區。四川地形複雜多樣，包含四川盆地、青藏高
原、橫斷山脈、雲貴高原、秦嶺-大巴山山地等幾大地貌單元，地跨中國地勢第
一及第二階梯，西高東低，由西北向東南傾斜。全省最高點是川西的大雪山主峰
貢嘎山，海拔7556米。
Page created by W. G. Huang
Earthquake Information
European-Mediterranean Seismological Centre
Summary:
Magnitude
Mw 7.9
Region
EASTERN SICHUAN,
CHINA
Date time
2008-05-12 at 06:27:59.0
UTC
Location
31.12 N ; 103.24 E
Depth
10 km
Distances
94 km NW Chengdu (pop
3,950,437 ; local time
14:27 2008-05-12)
39 km W Guangkou (pop
65,379 ; local time 14:27
2008-05-12)
Credit EMSC
200805120627
Mw=7.9, D=10 km
Page created by W. G. Huang
The rugged Sichuan
Tarim
Tibetan Plateau
Credit DigitalGlobe
Page created by W. G. Huang
Tibetan Plateau
The Himalayan Mountain Range runs a curving path from west to east in this true-color
image. In this image, the Range separates southeastern China from India, and runs through
(from left to right) northwestern India, Nepal, a small bit of northeastern India, and Bhutan.
Credit
NASA
Page created by W. G. Huang
Tibetan Plateau
Epicenter
India
Burma
Laos
Credit INGV
Vietnam
Epicenter
Page created by W. G. Huang
Earthquake Near Chengdu, China (as of May 2008)
This elevation map
shows the region
where the
earthquake struck.
Elevations—green
indicating the
lowest, and beige
indicating the
highest—are based
on data collected
by NASA’s Shuttle
Radar Topography
Mission (SRTM)
flown in 2000.
Page created by W. G. Huang
Page created by W. G. Huang
Regional seismicity before the main shock
From 12/05/2006 to 12/05/2008
2 events with magnitude <=5.2
Credit EMSC
Page created by W. G. Huang
Aftershocks distribution (From main shock to 15/05/2008)
72 events with magnitude M>=4.5; None with M>6
MOMENT TENSORS
SOLUTIONS
CreditEMSC
EMSC
Credit
The aftershocks are
distributed along an approx.
300 km long North-East
direction which is consistent
with the mechanisms
reported by Harvard and
the USGS as well as with the
regional topography. As the
main shock epicentre is
located at the South-West
end of the aftershock
distribution, the main shock
rupture propagated towards
the North-East.
Page created by W. G. Huang
Aftershock Animation
蘭州
九寨溝
汶川
都江堰
綿陽
成都
重慶
昆明
Credit GFZ Potsdam
Page created by W. G. Huang
Affected Areas (受地震影響的範圍)
2008 Sichuan earthquake
Page created by W. G. Huang
China: Mapping the earthquake zone
北川
汶川
綿竹
映秀
都江堰
綿陽
德陽
什邡
成都
Credit BBC
Page created by W. G. Huang
川西鎖鑰
Page created by W. G. Huang
臥龍保護區
Page created by W. G. Huang
8000 feared dead
20,000 injured
China: Earthquake (as of 12 May 2008) - Situation Map
Epicentre
Mw=7.9
Time 2:28 (local time)
Communication facilities,
roads, houses damaged
Areas unreachable
Landslides reported
Credit ReliefWeb
80% of houses
destroyed
Beichuan
Wenchuan
Middle school collapsed
And over 50 students
Reported dead
900 student buried
Page created by W. G. Huangc
15,000 dead
64,746 injured
25,000 buried
14,000 missing
80% of houses
destroyed
Beichuan
 Communication facilities,
roads, houses damaged
 Troops reached epicentre
by parachute
Mianyang (7,395 dead)
Wenchuan
Middle school collapsed
And over 50 students
Reported dead
900 student buried
Chengdu
959 dead
Rescue teams tricking into
worst hit area north of
Chengduc
China: Earthquake (as of 14 May 2008) - Situation Map
Credit ReliefWeb
Page created by W. G. Huangc
189 deads
China: Earthquake
(as of 16 May 2008) - Situation Map
 Communication facilities,
roads, houses damaged
 Troops reached epicentre
by parachute
Wenchuan
Chengdu
959 dead
Rescue teams tricking into
worst hit area north of
Chengduc
Credit ReliefWeb
21,500 dead
150,000 injured
14,000 buried
13,400 pulled out alive from debris
571,400 houses collapsed
279,900 houses destroyed
5.7 million people evaccuated
Page created by W. G. Huangc
Credit ReliefWeb
67,183 dead
361,822 injured
20,790 missing
45.61 million affected
5.9 million homes damaged
5.46 million homes destroyed
15
million
relocated
Credit
ReliefWeb
Page created by W. G. Huangc
Detected radar anomalies
(possible damages to
buildings infrastructures)
都江堰
Credit ReliefWeb
Page created by W. G. Huang
Page created by W. G. Huang
Landslide
Road damaged by landslide
Flooded area
Buildings destoryed
Buildings and roads destoryed
Page created by W. G. Huang
Page created by W. G. Huang
Road damaged by landslide
Buildings destoryed
Flooded area
Buildings destoryed
Landslide
Page created by W. G. Huang
Tectonics of the May 12 Sichuan earthquake
Credit GFZ
Page created by W. G. Huang
中評社香港5月17日電／台灣“中央大
學”地球科學系教授王乾盈說，四川強
震成因被認為“漸歸沉寂”的龍門山斷
層“復活”發生錯動，這個斷層自明朝
以來錄得震動的數據不多；本月12日的
錯動使當地地殼抬升九公尺，“喜馬拉
雅山也隨之長高好幾公尺”。
王乾盈說，四川過去百年來發生的大小
地震，只有少數跟龍門山斷層有關，規
模不大，“以前長時間地震釋放的能量，
幾乎都被同在四川的鮮水河斷層消耗
掉”，地震專家都以為龍門山斷層的傷
口癒合，不可能再動了。
每秒裂3公里 裂動一百秒
三板塊夾擠 地殼抬升9米
王乾盈分析，龍門斷層破裂面，從震央
汶川縣往北東方向以每秒3公里速度裂
向廣元，足足花一百秒裂完，震災範圍
長240公里、寬30公里，尤其以破裂至
北川縣時錯動得特別厲害。
王乾盈認為，四川地震是因夾在西藏地塊、崑崙地塊、揚子地塊，這三個地塊間的松潘甘孜地塊，
向揚子地塊逆衝而上，“年輕的蓋在老的上面”，龍門山斷層要幾千年才會有這麼大的錯動，這次
錯動使地殼抬升九公尺，“喜馬拉雅山至少因此長高幾公尺”。
Page created by W. G. Huang
POSTED BY KIM AT 8:27 PM
KIM HANNULA
I'm a forty-something tenured geology professor at a small public
college in the Rockies. I love mountains - hiking in them, looking
at them, studying them. You can reach me at shear sensibility at
gmail dot com. My opinions are my own - not my employer's, not
my students', not my spouse's, not my graduate advisor's... just
mine.
By KIM HANNULA
Page created by W. G. Huang
MIT's tectonicist Clark Burchfield is quoted in the NY Times as being
surprised that an earthquake of that magnitude (which requires a lot of
fault to have moved at once) occurred in this particular spot. But although
the size might be larger than one would expect, the type of earthquake isn't.
This isn't a classic plate boundary earthquake, but it's part of the way that
continents respond to continent-continent collisions.
In the big picture, India is moving northward and colliding with Asia. That's
what created the immense mountains of the Himalayas, and the highlands of
the Tibetan Plateau, in the first place. This earthquake, however, was not on
the plate boundary itself. It was off on the eastern edge of the Himalayas,
on the boundary between the high country and the Sichuan basin.
Here's the USGS earthquake location map. The pink lines represent the
collisional plate boundaries - the boundary between India and geologic Asia
runs along the southern end of the Himalayas. This earthquake was within
Asia proper.
By KIM HANNULA
Page created by W. G. Huang
By KIM HANNULA
Page created by W. G. Huang
But continents are... well, continents are kind of wimpy, actually, in terms of
deformation. They're made of rock that's easier to break than oceanic crust is.
And on top of that, they're thick. And when they run into one another, the
continental crust gets even thicker. And that thick, weak crust can break within
itself - it doesn't behave like the classic rigid plates that "plate tectonics" is
named for.
The crust of Asia breaks in a number of different ways. Parts of it are
squeezed out, especially to the east, where it can run over the subducting
Pacific plate like a semi over a squirrel. Parts of it actually stretch east-west,
creating features like Lake Baikal up in Russia. Parts are pushed over each
other, making the height of the Himalayas and Tibet possible. And parts are
squeezed over other parts of Asia. And that's what's happening on the
northwestern side of the Sichuan basin - the edge of the Tibetan Plateau is
running over eastern Asia, in this case, along a classic thrust fault, sloping
about 30 degrees down into the ground beneath the edge of the mountains.
You can also see the movement of Tibet in this map of GPS velocities:
By KIM HANNULA
Page created by W. G. Huang
The map of GPS velocities (From Gan,
Zhang, Sun, and Sun, 2006)
Each of the arrows represents the
movement of a GPS monitoring
site compared to the rest of
Eurasia. The southern Himalayas
are moving north; the Tien Shan
mountains, north of the Tarim
basin (white, north of the
Himalayas) are moving much
more slowly, and the eastern
Himalayas... are moving east. Or
even south.
And at the Sichuan basin, that
green blob east of the Himalayas,
the GPS velocities drop.
There's a change in movement.
And that M 7.9 earthquake took
place where the change occurs.
By KIM HANNULA
Page created by W. G. Huang
The Google earth image
(from the USGS Google
earth KML) of the
earthquake and its
aftershocks shows the
setting closer-up:
It looks like the earthquake was on the basin-bounding fault. It looks like there are ridges in
the basin running parallel to the fault, too - ridges that are cut by rivers. They are probably
actively growing folds... which means there are probably active thrust faults running
underneath the basin itself, not just under the mountains. Those faults, at least, don't
seem to have moved.
By KIM HANNULA
Page created by W. G. Huang
PRESS RELEASE
16th May 2008
Scientists identified earthquake faults in Sichuan, China
Only last summer research published by earth scientists in the international
journal Tectonics concluded that geological faults in the Sichuan Basin, China
“are sufficiently long to sustain a strong ground-shaking earthquake, making them
potentially serious sources of regional seismic hazard."
An international team of scientists including Dr. Alexander Densmore (Durham University),
Dr. Mike Ellis (British Geological Survey) and colleagues from research institutes in Chengdu,
carefully mapped and analysed a series of geologically young faults that cross Sichuan
Province like recently healed scars.
The team mapped the densely populated Sichuan Basin and adjacent mountains using what is
known as ‘tectonic geomorphology’. This technique can demonstrate significant changes in
ground movement over time, such as observations of offset river channels, disrupted
floodplains, abnormally shaped valleys and uplifted landscape features. These subtle signals of
deformation, when combined with the ability to measure the age of the disfigured landscapes
(using cosmogenic nuclides that bombard the Earth from all corners of the universe), produced
surprising results.
Credit BGS
Page created by W. G. Huang
The recent earthquake in Sichuan occurred under some of the steepest and most rugged
mountains in the world, the Longmen Shan: the Dragon's Gate Mountains. This dramatic
range, steeper than the Himalayas, is the upturned rim of the eastern edge of Tibet, a plateau that
has risen to 5 km in response to the slow but unstoppable collision of India with Asia that began
about 55 million years ago and which continues unabated today.
Two long faults in particular, running almost the entire length of the Longmen Shan, showed
clear evidence of slip during the last few thousands, and in some cases hundreds, of years. The
rates of slip varied between fractions of mm per year to possibly many mm per year. Millimetre
by millimetre, the Longmen Shan are being sliced and displaced much like salami. One of
these faults is likely to be the one that gave rise to the 7.9 magnitude earthquake that has now
caused 22,069 fatalities. Exactly why the Longmen Shan are here is a mystery. Unlike the
Himalaya, which form the southern boundary of Tibet and whose faults chatter continuously with
small earthquakes, faults in the Longmen Shan, remnants perhaps of geological events hundreds
of millions of years ago, have historically only produced earthquakes up to magnitude 6.
Geomorphological evidence suggests that the mapped faults are very steep with dominantly
lateral or strike-slip displacements taking place over time scales of thousands to hundreds of
thousands of years. This contrasts with shorter-term measurements using GPS which suggest a
greater proportion of thrust or shortening displacement than lateral displacement. The
observations of seismologists at the BGS suggest both things: more thrust in the SW, nearer
the epicentre, and more strike-slip toward its direction of propagation, the NE.
Credit BGS
Page created by W. G. Huang
Map showing
seismicity and
faulting in the eastern
Tibetan plateau
region (magnitudes
7.0 and greater
labelled).
Credit BGS
1718 7.5
1654 8.0
1879 8.0
1976 7.2
1933 7.5
Credit BGS
Map showing the
distribution of aftershocks
following the magnitude 7.9
Mw in Eastern Sichuan on
12 May 2008 (magnitudes
4.5 and greater).
Credit BGS
Credit BGS
Coulomb Failure Stress variation & Vertical displacement
by José A. Álvarez Gómez (Instituto Geografico Nacional, Madrid, Spain)
Page created by W. G. Huang
Thanks to the finite fault model provided by the USGS, the author computed the
Stress variations and the vertical deformation at the surface promoted by the fault
rupture. The equations of Okada (1992), which describe the deformation in a
homogeneous elastic half-space due to a rectangular dislocation, and Hooke's law
were used to compute the stress tensor. The Coulomb Failure Stress variation (DCFS)
was calculated on fault planes equal to the one of the main shock, at a depth of 10 km,
that could rupture in the future and is defined as DCFS=T-m'(Sn), where T and Sn are
the shear and normal stresses acting on the dislocation respectively, and m' is the
assumed apparent friction coefficient of the fault plane (in this case 0.5).
by José A. Álvarez Gómez (Instituto Geografico Nacional, Madrid, Spain)
Page created by W. G. Huang
Rupture model of Mw=7.9
08/05/12 Sichuan earthquake
Page created by W. G. Huang
Earthquake Research Institute, Univ. of Tokyo
The Eastern Sichuan Earthquake
(preliminary finite fault model)
Teleseismic stations used in inversion.
The star represents the epicenter of
the main-shock
Comparison of the observed waveform (Black) with the
calculated waveform (Red). The numbers below the station
code indicate maximum amplitude in microns.
（Analyzed by KazutoHikima, Earthquake Research Institute, Univ. of Tokyo）
Page created by W. G. Huang
Surface projection of the slip distribution
（Analyzed by KazutoHikima, Earthquake Research Institute, Univ. of Tokyo）
Page created by W. G. Huang
Slip distribution on the fault
The largest slip occurred at 40 to 60 km north from the hypocenter, and
some more asperities (i.e. local maxima of slip) can be also seen. The
length and width of the fault are presumed to be 230 km and 40 km,
respectively, according to the slip distribution. (For the analyses, we
assumed 320 km and 40 km from the aftershock distribution.) The
duration time (i.e. time to complete the rupture on the fault) is estimated
to be 100 to 120 sec.
（Analyzed by KazutoHikima, Earthquake Research Institute, Univ. of Tokyo）
Page created by W. G. Huang
Kunlun earthquake in 2001
Longmenshan thrust zone
Adapted from He and Tsukuda, 2003
Page created by W. G. Huang
The Longmenshan thrust zone is approximately 60 km wide, and
constitutes the topographic boundary between the eastern Tibetan
Plateau and the Sichuan basin. The total vertical slip rate is about 1-2
mm/yr, and thus the convergence rate across the thrust zone is inferred
to be 4-6 mm/yr.
The northward indentation of the Indian plate into the Tibetan crust after
the collision between the Indian and Eurasian plates induced uplift and
deformation of the Tibetan Plateau. The continental crust of China, thus,
is highly active tectonic area.
This continuing northward indentation resulted in three types of tectonic
deformation: convergence zones surrounding the plateau, strike-slip
fault zones associated with the laterally extruding crustal blocks in the
eastern plateau (i.e. Kunlun earthquake in 2001), and extensional basins
in the southern plateau on which the Longmenshan fault is located.
（Analyzed by KazutoHikima, Earthquake Research Institute, Univ. of Tokyo）
Page created by W. G. Huang
Waveforms Recorded at Taipei Basin Downhole Seismic Network
The locations of the downhole arrays and their relationships to the faults around the Taipei metropolitan
area. The accelerographic arrays with pink-square are in operation. The broadband arrays are triangulated.
Page created by W. G. Huang
The particle velocities recorded at SNJB at level -100 meters.
E
Installation of SNJB was completed in November 2007.
N
Z
10 min.
Page created by W. G. Huang
200805122008
Mw=5.5
200805120628
Mw=7.9
200805121111
mb=5.7
The particle velocities of EW
component recorded at
DANB at level -90 meters.
P
S
Sichuan Earthquake’s Devastation
More than 90,000 people are dead, missing or buried under rubble
following the devastating earthquake that hit China's Sichuan province last
Monday.
Credit BBC
Page created by W. G. Huang
May 14, 2006
Images captured by Taiwan’s Formosat-2 satellite
the left image shows the region under normal springtime conditions. Two tiny villages flank the river, the
man-made surfaces regularly shaped and bright. The
towns are connected by light-colored roads, which line
the river on both sides and merge at a bridge where the
river narrows on the right.
May 15, 2006
three days after the initial earthquake, both the
bridge and the roads it connected have disappeared
under murky water. Some sections of the villages
remain above the waterline, as do portions of the
roads leading to the villages. The tops of trees,
perhaps on slightly higher ground, form tiny islands
near the shores of the growing lake.
May 19, 2006
Formosat-2 took the final image on May 19, 2008.
By this time, water levels in the earthquake lake
had risen enough to immerse both villages and
the entire road network. Tan debris floats on the
surface of the water, concentrated over the
locations of the villages.
Yansai Lake in Beichuan County
Page created by W. G. Huang
before
before
after
after
Page created by W. G. Huang
In the February 19, 2003, image (bottom)
the terrain seems more rugged because the
Sun’s low angle cast long shadows at that
time of year. Likewise, the brighter red hues
in the May 23, 2008, image (top) may result
in part from more robust vegetation
growing in late spring.
The most dramatic difference between the
images, however, is the abundance of bareground areas along mountain ridges. Many,
if not most, of these areas result from
landslides triggered by the May 12
earthquake, and potentially by some of the
aftershocks. According to David Petley of
Durham University, topographic
amplification strengthens an earthquake’s
effects on a mountaintop where the shaking
is maximized. This leads to landslides that
start near the top of a ridge and travel all or
most of the way to the valley below.
after
before
Page created by W. G. Huang
Thousands are under threat if the water spills over from the 'quake lake‘
About 200,000 people have now been evacuated to higher ground from an area at
risk of flooding from a lake formed after the Sichuan earthquake.
Residents around the city of Mianyang are being moved as troops dig diversion
channels to relieve pressure on the lake, made by landslide-blocked rivers.
But there are fears that the dam could burst before they finish.
Yingxiu: epicentre of the earthquake
(ghost of town)
Page created by W. G. Huang
Street view of Yingxiu, July 2005.
Rubble on both sides of the street
in Yingxiu. Photograph: Jonathan
Watts
Page created by W. G. Huang
Rescuers walk through a section of the
elevated expressway brought to earth
Photograph: Jonathan Watts
The devastated town of Yingxiu, the rubble
is all that is left of the infant school
Photograph: Jonathan Watts
Page created by W. G. Huang
Troops navigate the speedboats taking
people to safety along the Min river
Photograph: Jonathan Watts
A motorway tunnel entrance - the road is
blocked by a landslide on the other side
Photograph: Jonathan Watts
Page created by W. G. Huang
A aerial view of the badly
stricken town of Yingxiu in
Wenchuan County of southwest
China's Sichuan Province, two
days after a massive
earthquake. (May 14, 2008
Xinhua Photo)
Photo taken on May 14, 2008 shows an aerial view of the
badly stricken town of Yingxiu in Wenchuan County of
southwest China's Sichuan Province, two days after a
massive earthquake. (Xinhua Photo)
Page created by W. G. Huang
Photo taken on May 14, 2008 shows an aerial
view of the badly stricken town of Yingxiu in
Wenchuan County of southwest China’s
Sichuan Province, two days after a massive
earthquake.
Photo taken on May 14, 2008 shows an aerial
view of the badly stricken town of Yingxiu in
Wenchuan County of southwest China's
Sichuan Province, two days after a massive
earthquake. (Xinhua Photo)
Page created by W. G. Huang
An aerial photo taken on May 14 shows the
road from Dujiangyan city to Wenchuan
County in southwest China's Sichuan
Province is destroyed by landslide caused
by Monday's earthquake. The serious
devastation of the road affected the
transportation of rescue teams and relief
materials to the disaster areas. (Xinhua
Photo)
These 10 soldiers have just one mission:
deliver food and medicines to several towns
in Wenchuan county.
Page created by W. G. Huang
An aerial view of the remains of
the town of Yingxiu
Aerial view of damage of Yingxiu
town, Wenchuan
Page created by W. G. Huang
Beichuan: a vision of hell
The day before the earthquake in Beichuan
The last entry on a blog called TGP1963 was posted at 7:49am on May
12. According to Hecaitou the blogger is a science teacher at Beichuan
Middle School called Tang Guoping. On May 11, teachers and final
year students held a sports fun event. Here are some of the pictures
taken that afternoon.
Page created by W. G. Huang
Page created by W. G. Huang
The next day, 80% of the buildings in Beichuan county were
destroyed. A thousand children were buried in the middle school.
Page created by W. G. Huang
Earthquake-affected Beichuan County.
before
after
The devastation is seen in earthquakeaffected Beichuan County in Sichuan
province
Credit BGS
Page created by W. G. Huang
Residents look for survivors among the
ruins of collapsed apartment blocks in
Beichuan
woman cries after she realised a survivor who has
just been rescued from a collapsed building is not
her husband, in the old city district near a mountain
at the earthquake-hit Beichuan county, Sichuan
province, May 15, 2008
Page created by W. G. Huang
Residents look for survivors amongst the ruins of collapsed apartment
blocks in the city of Beichuan
Page created by W. G. Huang
Page created by W. G. Huang
Page created by W. G. Huang
Page created by W. G. Huang