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Landslide
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The
term landslide includes a wide range of ground movements, such as rock falls,
deep failure of slopes and shallow debris- or mudflows. Although some landslides
move slowly and cause damage gradually, others move so rapidly that they can
destroy property and take lives suddenly and unexpectedly.
Gravity is the prime reason for a landslide, but there are other factors that
may trigger its occurrence:
| o | Heavy rainfalls that saturate the soil and underlying geologic formation with water, |
| o | steep slopes (very often increased due to constructions), |
| o | earthquake shaking |
| o | volcanic eruptions deposing thick layers of instable ashes. |
Also
the commonly used practice to burn agricultural areas before seeding may reduce
water holding capacity and soil stability and thereby increase the risk of
landslides.
This very serious geologic hazard is common to almost every mountainous area
in Indonesia. Because of very high population densities in some parts, many
settlements are located on very steep slopes and therefore are often affected
by landslides.
The following examples of recent disasters give an impression about the threat
they pose to local population:
| 2003/04/01 |
Heavy rainfalls caused floods and several landslides on the island of Flores. There were at least 27 casualties and a serious destruction of infrastructure. |
| 2003/01/29 |
A mudslide in West Java province killed at least 20 people, 263 families had to be evacuated. |
| 2003/01/11 |
10 people were killed in a landslide in a remote part of Kalimantan. |
| 2002/12/27 |
At least 11 people were killed during heavy rainfalls causing floods and landslides in a hilly area of southern Sumatra. |
| 2002/12/11 |
Days of heavy rainfall triggered a mudslide in East Java, killing at least 22 people. |
| (Source: Asian Disaster Reduction Center - ARDC) | |
In
Indonesia much research has been done on the physical mechanism of landslides.
But although there are quiet good synoptic maps for Java, many other Indonesian
regions still lack a sufficient database for landside mitigation.
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