ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

CHUAN TANG 1 & JORG GRUNERT 2
Landslides from the February 3, 1996,
Lijiang earthquake in China
1 Yunnan Provincial Institute of Geography, Jiaochang East Road 28,
650223 Kunming, China
2Institut fur Geograpie, Universitat Bonn, Meckenheimer Allee 166,
53115 Bonn, Germany
A strong earthquake occurred on 3 February 1996 with its
epicenter located 40 km north of Lijiang City in Yunnan
Province, southwestern China. The magnitude of 7.0 on
the Richter-scale placed this event among the strongest
that have occurred in densely populated areas in China during
the 1990's. 385 people were killed by the earthquake.
The epicenter was determined to be at 27.18 Nand 100.13
E, where is located the seismically active region of the
Hengduan Mountains, which belong to the Alpine-Himalaya
seismic belt. The earthquake triggered more than 140
small to moderate-scale landslides (less than 10,000 m')
and 96 large-scale landslides throughout an area of 12,000
km 2 based on an intensive field investigation taken a few
days after the earthquake. The mass movements induced
by this earthquake caused extensive damage to settlements
and farmlands; blocked or destroyed roads and bridges;
isolated the city of Lijiang and other towns; and hampered
rescue and relief efforts. The investigation has been made
for mapping the distribution of landslides triggered by this
earthquake and for determining the mechanisms of their
formation in order to lend technical assisstance to Yunnan
Government in assessing the future hazard to people and
property in areas where apparent landslide hazards remain.
Because of the widespread landslides distribution, the 1996
Lijiang earthquake has provided a great deal of information
and insight regarding seismically induced landslides.
This study lead us to the following generalization:
1. The earthquake triggered-landslides were concentrated
south-southeast of the epicenter of the main shock, adjacent
to the area of tectonic rupture at the surface and
within the area of principal aftershock. The regional distribution
of landslides has a coincidence with seismic intensity.
The landslides distributed mostly within the modified
Mercalli intensity VI.
2. The predominant types of landslides induced by this
earthquake were rockfalls, debris slides, and slumps ( classification
after Varnes,1978). Rockfalls were commen on
steep-walled canyon faces cut in well-fractured basement
rock, easpecially along major dainages-Baishui and Hutiao
Canyons. Debris slides occurred mainly at the free face of
recent stream terrace deposits and intensely weathered sedimentary
rock. Slumping was found largely on reactivated,
preexisting landslides. Incipient slumps were also numerous.
3. Topography was a key factor in controlling the location
and extent of landslides in all affected areas. Rockfalls occurred
on very steep (steeper than 60°) canyon slopes and
ridges, and largely initiated in the upper parts of slopes.
Debris slides and slumps occurred on gentler (approximately
25°-45°) slopes. Topographic amplification of seismic
ground motion appears to have been another important
factor influencing on the distribution of landslides.
4. The presence of preearthquake landslides also contribute
to slope instability during the 1996 earthquake, which
showed obviously reactivation, in the sence that they were
generally characterized by many new open cracks or fissures.
5. Most incipient and reactivated landslides have the potential
for further failure if they receive sufficient rainfall in
the affected areas. Widespread ground fracturing throughout
much of the area is closely related to landsliding.
This fracturing appears to be most pronounced along ridge
tops and road cut slopes, where, given sufficient moisure,
the highly fractured surficial mass rock may give rise to as
many as or even more landslides as were triggered during
the earthquake.
KHALID E. TANRYVERDIYEV & A.S. SAFAROV
Development of relief of the Lowerkiir
depression (Azerbaijan) in connection with neotectonics
Institute of Geography, Azerbaijan Academy of Sciences, Azerbaijan
The latest tectonic movements beginning from the Early
Pliocene (age of productive rock mass) predetermined in
large way the plan of development and formation of present
appearance of the relief adjoining to the Caspian of
the Lowerkur oil-gas bearing depression. At that time the
mentioned territory was subjected to the greatest depression
(Kargalin sinclinal - more than 4,200 m, Alat, Kharamin,
Kiirovdag and oth. anticlinals - up to 1,600-2,200 m).
The beginning of foldness which later caused the formation
of morphostructure is clearly see. The beginning of
formation of Alat, Kharamin, Mishovdag, Kiirovdag and
other folds refer to this time. The intensive depression, sedimentation
and fold formation taking place in the early
pliocene illustrate the inseparable link between them. Beside
that, connected with neotectonics of transgression and
regression of sea basins exerted a great influence on the
development of relief of the given territory which experienced
mainly submarine development. In Akchagyl period
all mentioned territory was covered by sea water
which was experienced relatively weak latest movements
(maximum thickness up to 600-700 m). The increase of
folds slowed down at this time. In Absheron, especially at
its end, the neotectonic movements intensified, which immediately
exerted influence on the development of relief
of the territory at that time. Ihe Kargalin and N avagin depressions
began to take shape in their present boundaries.
The formation of the present morphostructural plan is
connected mainly with Pleistocene. At the beginning of the
Bakuian age the relief of the territory was partly experienced
the constant continental development, covering the
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