1. 1. Discuss the different geological hazards 2. Analyze the causes of geological hazards 3. Recognize signs of impending geological hazards 4. Interpret different geological maps 5. Apply mitigation strategies to prevent loss of lives and properties 1. Discuss the different geological hazards 2. Analyze the causes of geological hazards 3. Recognize signs of impending geological hazards 4. Interpret different geological maps 5. Apply mitigation strategies to prevent loss of lives and properties

3.  Rainfall-Induced Landslide  Sinkholes

6. Rainfall-Induced Landslide Landslide  is a massive outward and downward movement of slope- forming materials.  the term "landslide" is restricted to movements of rocks and soil masses, these masses may range in size up to entire mountainsides.  it is initiated when a section of hill slope or sloping section of a sea bed is rendered too weak to support its own weight.  Landslide as a geological hazard is caused by earthquake or volcanic eruption.

7. NATURAL CAUSES OF LANDSLIDE ground water (pore water) pressure acting to destabilize the slope loss or absence of vertical vegetative structure, soil nutrients, and soil structure ( ex. wildfire) erosion of the toe of a slope by rivers or ocean waves weakening of a slope through saturation by snow, glaciers, melting or heavy rains earthquakes adding loads to barely stable slope earthquake-caused liquefaction destabilizing slopes volcanic eruptions

8. LANDSLIDES ARE ALSO AGGRAVATED BY HUMAN ACTIVITIES, SUCH AS:  deforestation, cultivation and construction which destabilize the already fragile slopes  vibrations from machinery or traffic  blasting ( as miners normally do)

9.  earthwork which alters the shape of the slope, or which imposes new loads on an existing slope  in shallow soils, the removal of deep-rooted vegetation that binds colluviums to bedrock (ex. Kaingin farming system)  construction works, agricultural or forestry activities (ex. Logging) which change the amount of water infiltrating the soil.

10. EFFECTS OF LANDSLIDES Property damage, injury and death and adversely a variety of resources Ex: water supplies, fisheries, sewage disposal systems, forests, dams and roadways can be affected for years after a slide event The negative economic effects of landslides include the cost to repair structures, loss of property value, disruption of transportation routes, medical costs in the event of injury, and indirect costs such as lost timber and lost fish stocks. Water availability, quantity and quality can be affected by landslides.

11. Search and read the account on two major landslides that occurred in the Philippines, namely the 1999 Cherry Hill Subdivision Landslide and the 2006 Southern Leyte Mudslide. Analyze the causes and effects of these two landslides and make a report of your analysis.

14. MUDSLIDE. The entire village of Guinsaugon in St. Bernard, Southern Leyte was buried after a portion of a nearby mountain collapsed. Photo by AFP/Jay Directo

15. 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.

16. TYPES OF SINKHOLES Dissolution Sinkholes Cover-subsidence Sinkholes Cover-collapse Sinkholes

17. DISSOLUTION SINKHOLES Dissolution of the limestone or dolomite is most intensive where the water first contacts the rock surface. Aggressive dissolution also occurs where flow is focused in pre-existing openings in the rock, such as along joints, fractures, and bedding planes, and in the zone of water-table fluctuation where groundwater is in contact with the atmosphere.

18. COVER- SUBSIDENCE SINKHOLES Cover-subsidence sinkholes tend to develop gradually where the covering sediments are permeable and contain sand. In areas where cover material is thicker, or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods.

19. COVER- COLLAPSE SINKHOLES Cover-collapse sinkholes may develop abruptly (over a period of hours) and cause catastrophic damages. They occur where the covering sediments contain a significant amount of clay. Over time, surface drainage, erosion, and deposition of sinkhole into a shallower bowl-shaped depression.

20. Sinkholes can be human-induced groundwater pumping construction and development practices when natural water-drainage patterns are changed and new water-diversion systems are developed when the land surface is changed, such as when industrial and runoff-storage ponds are created. The substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole.

21. SIGNS OF IMPENDING GEOLOGICAL HAZARDS LANDSLIDE Earlier Landslide as an Indicator Tension Cracks Things Moving Water Doing Something Different

22. SIGNS OF IMPENDING GEOLOGICAL HAZARDS 1. trees or fence posts that tilt or fall9. sinkholes in the neighborhood 2. foundation that slants10. wilted vegetation in a limited area 3. new small ponds that appear after rain11. well water that is discolored or contaminated with debris 4. cracks in the ground12. cracking or buckling of home's concrete slab 5. sudden drainage of a pond13. presence of odd bugs like slugs and centipedes in the home 6. rapid appearance of a hole in the ground14. earthy odor in home after rain 7. dips, depression, slopes that appear in the yard 15. new or widening cracks 8. dead patches of grass or plants16. separation between walls and ceiling or floors

23. 17. cracks in interior walls 18. cracks around door and window frames 19. cracked grout between tiles 20. cracked tiles 21. stair step cracks in blocks or bricks 22. uneven floors, warping of hardwood, bulging or sagging sections 23. doors or windows that don't open or close easily 24. cracks in sheetrock near doors or windows SIGNS OF IMPENDING GEOLOGICAL HAZARDS