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WorksheetsLandslide and Sinkhole
Total questions: 20
Worksheet time: 12mins
What is rainfall-induced landslides?
These are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them.
Prolonged intense rainfall can often cause rainfall-induced landslides. The geological hazard occurs when water from rainfall seeps into the ground at a rate faster than the soil can drain it. As the spaces become filled up with water, the underlying ground material can no longer support the weight of the surface material, thereby resulting in a landslide.
A form of mass wasting involving "very rapid to extremely rapid surging flow"[a] of debris that has become partially or fully liquified by the addition of significant amounts of water to the source material.[1]
Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows; thus, they are able to travel farther and across lower slope angles. Both types are generally mixtures of various kinds of materials of different sizes, which are typically sorted by size upon deposition.[2]
It is what happens when two blocks of the earth suddenly slip past one another.
The landslide movement is marked by high speed due to the fluidity and consistency of the material. One type is debris flow containing loose soil, rock, organic matter, air, and water. Another type is called mudflow, whose composition is at least 50% sand, silt, and clay. A combination of debris flow and mudflow is referred to as mudslide.
Flow
Topple
Slump
Slide
Free-falling of the materials that includes bouncing or rolling happens in this type of landslide movement. As a result, the rock and debris are heaped at the base of the slope.
Creep
Fall
Slide
Slump
Flow
. Similar to a falling domino, the landslide movement is characterized by the tumbling over of a blocked unit or units due to gravity, the added force exerted by neighboring units, and water in the fissures.
Flow
Topple
Slump
Slide
Creep
The unnoticeable gradual motion of materials characterizes the type of landslide movement. An area has to be monitored over a long period of time to detect its occurrence.
Topple
Slump
Slide
Creep
Fall
The landslide movement happens along weak portions of the slope such as fault, joint, or bedding plane. The motion is usually parallel to the slope.
Flow
Topple
Slump
Fall
Slide
The landslide movement is characteristic of the sliding mass movement of materials along an arched portion of the slope.
Flow
Topple
Slump
Slide
Creep
What to do BEFORE a landslide?
. Evacuate immediately when local authorities give the signal.
Stay informed on the current news and warnings about the landslide.
Assist if possible, in the rescue operation to search for casualties and missing people.
Create and develop a household emergency plan for the family. Include the location of where to meet in case there is a need to leave the house immediately.
What to do BEFORE a landslide?
Observe the conditions and monitor warning signs in the environment, which include unusual sounds from trees cracking or boulders knocking each other.
. Stay in the part of the house that is farthest from the approaching landslide if caught indoors and take cover under a sturdy table or bench. Firmly hold on to the furniture until the tremors stop.
Move quickly to a higher area when there is either a sudden increase or decrease of water flow, or a clear water turning murky.
Assist if possible, in the rescue operation to search for casualties and missing people.
What to do AFTER a landslide?
Keep clear of structures that may fall such as trees, power lines, and poles.
Avoid immediately returning to the areas prone to landslides, unless the local authorities announce it is safe.
Contact the local authorities to find out if there is a threat of a landslide in the area.
Practice the evacuation plan with the family members.
What to do AFTER a landslide?
Observe the conditions and monitor warning signs in the environment, which include unusual sounds from trees cracking or boulders knocking each other.
Move quickly to a higher area when there is either a sudden increase or decrease of water flow, or a clear water turning murky.
Assist if possible, in the rescue operation to search for casualties and missing people.
Practice the evacuation plan with the family members.
What to do DURING a landslide?
. Keep updated about the weather conditions through the radio, television, and newspapers. Remember that heavy rainfall can induce landslides.
Avoid immediately returning to the areas prone to landslides, unless the local authorities announce it is safe.
Stay in the part of the house that is farthest from the approaching landslide if caught indoors and take cover under a sturdy table or bench. Firmly hold on to the furniture until the tremors stop.
Stay informed on the current news and warnings about the landslide
What to do DURING a landslide?
. Move quickly to a higher area when there is either a sudden increase or decrease of water flow, or a clear water turning murky.
Observe the conditions and monitor warning signs in the environment, which include unusual sounds from trees cracking or boulders knocking each other
Avoid immediately returning to the areas prone to landslides, unless the local authorities announce it is safe.
Assist if possible, in the rescue operation to search for casualties and missing people.
A geological hazard characterized as an opening in the ground that is a result of the dissolving of rocks beneath the surface of the land or the collapse of underground caves is called sinkhole. Sinkholes vary in size and depth, which may be very shallow to hundreds of feet deep. Their formation may be sudden or gradual.
Landslide
Sinkhole
Mudflow
Flood
Liquefaction
A type of sinkhole...
Sediments like sand lying on the bedrock fill in the cavities within the bedrock, which slowly sinks the surface and creates the cover-subsidence sinkhole. The sunken area continues to become enlarged due to its constant exposure to erosion.
Dissolution sinkhole
Cover-subsidence sinkhole
Cover-collapse sinkhole
A type of sinkhole...
Since a thin layer of soil or vegetation covers the limestone bedrock (i.e., consolidated solid rock deposits that are mainly composed of calcium carbonate and found underneath the soil and other debris), rainwater finds its way into the spaces within the bedrock and dissolves the rocks, gradually forming the dissolution sinkhole, which is also called limestone-solution sinkhole.
Dissolution sinkhole
Cover-subsidence sinkhole
Cover-collapse sinkhole
A type of sinkhole...
Deep in the ground is an underground cavern that is exposed to dissolution. Sediments eventually reach the bottom of the cavern. Crumbling of the ground does on until the top layer of the cavern becomes too thin. Consequently, the layer collapses, creating the sinkhole, which can cause the structures on top of it to topple down.
Dissolution sinkhole
Cover-subsidence sinkhole
Cover-collapse sinkhole
What to do before a sinkhole happens?
Select 3 answers.
Get information about the soil geology of the residential area to know its susceptibility to a sinkhole. Check soil maps and coordinate with the nearest local officials.
Be alert during heavy rainfall that may induce the formation of sinkholes
Refrain from throwing trash or dirt in the sinkhole because it will contaminate the groundwater
Observe signs of water loss from nearby small bodies of water such as ponds.
Barricade the area where there is traffic coming from vehicles and people to keep them away from the sinkhole. Do the same in a place where there are livestock and pets.
What to do AFTER a sinkhole happened?
Select 4 answers.
Refrain from throwing trash or dirt in the sinkhole because it will contaminate the groundwater.
Stay away from the sinkhole.
Perform the necessary preparations to the house and property like securing the durability of the foundations.
Report the sinkhole to the local officials and concerned professionals to determine the conditions below the surface.
Barricade the area where there is traffic coming from vehicles and people to keep them away from the sinkhole. Do the same in a place where there are livestock and pets.
Is Philippines exposed to hazards like sinkhole and landslides?
Yes
No
