Yushu earthquake of magnitude 7.1 in Qinghai on April 14, 2010 and Ning'er
earthquake of magnitude 6.4 in Yunnan on June 3, 2007, both are moderately
strong earthquakes near the town at the epicenter.
Table 2-3 Comparison earthquakes of Yushu and Ning'er in Qinghai and Yunnan
|Ning'er earthquake of magnitude 6.4
|Yushu earthquake of magnitude 7.1
5:34 am on June 3 2007
7:49 am on April 14, 2010
North latitude 23.0 ° and East longitude 101.1 °
North latitude 33.1 ° and East longitude 96.7 °
Intensity of meizoseismal area
Ning'er county town was 8 degrees, the intensity of a few villages nearby county town reached 9 degrees
Yushu county town, a strong earthquake of 9 degrees
Similarities between the two earthquakes:
Time: Both earthquakes occurred in the small hours of the
morning, and most residents were sleeping.
Place:The epicenter of both earthquakes were near the county
town. The epicenter of Ning'er earthquake was only 2km away
from the county town. Although the epicenter of Yushu earthquake
was 39 km away from Jiegu town, but the causative fault of Yushu
earthquake extended to the vicinity of the county town.
Area:The areas where the earthquake occurred were all ethnic
minority areas. Ning'er County was Hani and Yi Autonomous County,
while Yushu was a Tibetan Autonomous Prefecture.
Earthquake damage:Both earthquakes caused serious damage to
county town buildings and urban infrastructures, all the phenomena
of water supply, power supply and communication interruption occurred.
Differences between the two earthquakes:
Casualties:Casualties caused by the two earthquakes were quite
different. Up to April 25 2010, 5:00pm, 2220 people died, 70 were
missing and more than 12135 were injured in the Yushu earthquake.
3 people died and 313 were injured in the Ning'er earthquake. The
magnitude of Yushu earthquake was 7.1, and Ning'er was 6.4, with a
difference of 0.7, the seismic wave energy released by Yushu earthquake
was about 13 times than Ning'er.
The dwellings structure of Yushu are mostly composed of adobe structure
and hollow brick structure, and Ning'er is wooden frame tile-roofed house
structure mostly. Comparing with the two earthquakes in Ning'er and Yushu,
besides the magnitude of earthquake destructive force, there are also
differences in earthquake prevention and disaster mitigation consciousness,
architectural structure form and traditional habits of the residents in
the two places. Analysis and study of these differences have reference
significance to other counties for how to carry out earthquake prevention
and disaster reduction work.
Residential buildings and structure forms
Yushu County is located in the eastern part of the Qinghai-Tibet Plateau,
with an average altitude of 4493.4m and cold climate, which is a Tibetan
Autonomous County with animal husbandry as master, combining agriculture
with animal husbandry, the Tibetan population accounts for over 96% of
the total population of the county. Most of the houses in Yushu rural
areas are adobe and hollow brick structures, the roof is generally heavier,
which belongs to the worst type of aseismic performance in China. According
to the preliminary investigation by the on-site emergency team of the
Seismological Bureau of China, almost all of these structure houses collapsed
or seriously damaged in Jiegu Town, an extreme disaster area.
Ning'er County is the hometown of Pu'er Tea, the starting point of the
ancient tea-horse road, rich in forest resources, high vegetation coverage,
hotter climate. The houses of Ning'er Hani nationality are generally 2-storey
wooden frame tile-roofed house structure with brick walls or adobe outer walls.
Compared with the dwellings in Yushu, the houses of wooden frame structure in
Ning'er area have good aseismic performance. When Ning'er Earthquake occurred
in 2007, the main structure wooden frame of this kind of house basically keeps
standing, main earthquake damage were roof tiles sliding and adobe wall collapse.
Due to the protective function of the wooden frame, adobe walls had collapsed
to outside the house, avoiding the inward collapse and hurting people. Roof tiles
fell mainly on the second floor, whereas local residents were used to sleep
downstairs (the first floor was cool), and the second floor was only a pile of
debris, which were the objective reasons for less casualties in Ning'er earthquake.
Disaster prevention awareness and earthquake drill
Ning'er County belongs to the area where earthquakes are relatively active，on average, an earthquake of magnitude 5 to 6 or so will occur every 10 years.
Frequent seismic activities have greatly enhanced the awareness of earthquake
prevention for local residents. Six months before the magnitude of 6.4 Ning'er
earthquake, local earthquake drills were held, especially in primary and secondary
schools. For example, the Tongxin Township Middle School of Ning'er County,
after the earthquake, students living in school withdrew to school playground
orderly according to the drill plan without the guidance of teachers. None of
the students was injured by the earthquake, and no more crowding caused by
panic of the earthquake.
In contrast, the awareness of earthquake prevention and disaster reduction in
Yushu residents was relatively weak, especially in rural areas. Local housing
structure rarely adopted aseismic measures. Take the hollow brick structure as
an example，this building should be used as temporary housing only. If as a
housing, which need to add core columns and other aseismic measures. Unfortunately,
most local residents didn't take notice when they built their houses. It was
relieved that the lessons learned from Wenchuan earthquake played an important
role in this earthquake. Take the Nationality No.1 Middle School of Yushu as an
example, the first earthquake of magnitude 4.7 occurred at 5:39 am on April 14,
the leaders and teachers on duty at school felt that the situation was not right，they organized students to evacuate to the playground and eluded the main earthquake
2 hours later successfully. It was inseparable that the school usually payed
attention to the safety education, often organized students to conduct earthquake
Comparison of earthquakes in Yushu and Ning’er, we can find that the strong and
weak consciousness of earthquake disaster prevention and mitigation has a decisive
influence on the degree of earthquake damage. The stronger awareness of earthquake
prevention and disaster mitigation, the stronger ability to resist earthquake
disasters, disaster losses may be less, otherwise earthquake disasters will
inevitably aggravate. The persistent awareness of disaster prevention is a prerequisite
for earthquake disasters mitigation.
(Excerpts from Aiwen Liu《Comparison earthquakes of Yushu and Ning'er, a brief discussion
on the disaster reduction measures of the medium and strong earthquakes in nearby towns》)