“The land movement is in form of land cracking and found 73 points in hilly areas and could develop becoming debris slide,” says the Head of Center for Vulcanology and Geological Hazard Mitigation (PVMBG), Surono.
The land cracking, according to Surono, threaten settlement close to the land cracking and settlement close to the river. Surono explained the condition of land movement areas, generally the land cracking areas and surroundings are hilly areas and settlement with slope of steep and very steep slope. “The land movement areas are predicted in form of volcanic breccias rocks at the top and tuff rock or lava at the bottom.
Based on Assumption Map of Land Movement Potential Area East Java Province on October 2011 (Geological Agency, PVMBG), those area include in potential area of middle to high land movement. Middle potency means land movement may happen in this zone if rainfall is above the normal, especially to areas adjacent to river valley, escarpment, cliff road or disturbed slope. The area having high potency of land movement means land movement may happen if rainfall is above the normal, while the old land movement could be active again.
Surono predicted the cause of landslide is because of high and long rainfall during and before the land cracking. Besides, it is because of erosion of the river or river basin and lamah areas between bedrock contact and weathering soil composing the rock in the area.
“Emergency Response Group of land movement from PVMBG will be immediately sent the location of land cracking to investigate and research,” says Surono.
Next he gave recommendation of temporary mitigation is by avoiding the entrance of the water into the cracking land, so the slope does not become saturated-water area. Citizens doing activity in the area have to be alert especially during or after the heavy rain and long duration. “Attach a warning sign in the land movement-prone areas,” he says. (AK)
Land Movement Potential Areas in East Java Province
| NO PROVINCE DISTRICT SUB-DISTRICT LAND MOVEMENT POTENCY |
| Jember PANTI Middle - High flash flood potency |
| KALIWATES Middle |
| WULUHAN Middle |
| MAYANG Middle |
| AMBULU Middle |
| TANGGUL Middle |
| PAKUSARI Middle - High |
| RAMBIPUJI Middle |
| PATRANG Middle |
| BANGSAL SARI Middle - High flash flood potency |
| JEBLUK Middle |
| ARJASA Middle - High |
| SUKORAMBI Middle - High |
| SUMBER JAMBE Middle |
| LEDOK KOMBO Middle - flash flood potency |
| SILO Middle |
| KALISAT Middle - High |
| TEMPUREJO Middle |
| MUMBULSARI Middle |
