Disaster Readiness and Risk Redu ction

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1. DISASTER READINESS
AND RISK REDUCTION
MIKO ANSELM A. GALLON SST I
PPT #1

2. Most Essential
Learning
Competencies
Discuss the different
geological hazards.
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Analyze the causes of
geological hazards.
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Recognize signs of impending
geological hazards.
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3. ANALYZE THE
PICTURE
This is a before and after
illustration of a debris
avalanche of Mount Pinatubo
located on the tripoint
boundary of the Philippine
provinces of Zambales, Tarlac
and Pampanga, all in Central
Luzon on the northern part of
Luzon.

4. ANALYZE THE
PICTURE

5. ANALYZE THE
PICTURE
1.What happened to the
appearance of the crater after
the volcanic eruption?
2. What happened to the
portions of the volcano that
were removed?
3. What geologic hazard could
be responsible for the
movement of the soil?

7. DIFFERENT
GEOLOGICAL
HAZARDS

8. LANDSLIDES
Alandslideisaground
movementonaslopingterrain.
Itdoesnothappenonflat
groundbecauseoftheangleon
theground,gravityinducesthe
landtomovedownward.Itis
aggravatedbyrainbecause
waterisanaturalagentfor
erosion.

9. LANDSLIDES
Ifrainoranysourceof
waterfrequentlyflows
downaslopingarea,the
gravitationaldescentof
loosenedsoilmakesit
possibleforlandslideto
occur.

10. TYPES OF
LANDSLIDES
1.SoilCreepLandslideisa
very slow downslope
movementofparticlesthat
occursineveryslope
covered with loose,
weathered material
(Britannicadictionary).

11. TYPES OF
LANDSLIDES

12. TYPES OF
LANDSLIDES
2.SlumpingLandslideisa
downwardmovementofrock
debris, usually the
consequenceofremovalof
buttressingearthatthefoot
ofaslopeofunconsolidated
material (Britannica
dictionary).

13. TYPES OF
LANDSLIDES

14. TYPES OF
LANDSLIDES
3.DebrisFlowLandslide
happenswhentheslope
becomessaturatedwith
water,thisthentriggersa
landslideofwater-soaked
massofrockandsoilthat
slidesdowntheslope.

15. TYPES OF
LANDSLIDES

16. TYPES OF
LANDSLIDES
4.RockFalllandslides
aresuddenslidescaused
byheavyraintherockon
theslopeloosensandthen
slidesdowntheslope.

17. TYPES OF
LANDSLIDES

18. SINKHOLES
A sinkholeisa
topographicdepression
created when
groundwaterdissolvesthe
underlying limestone
bedrock.Oftenknownas
"sink"or"doline,".

19. SINKHOLES
Characteristics
occurinareaswherethesoil
foundationismadeofsoft
mineralsandrockssuchas
limestone,saltbeds,orany
acidicrocks.
Thedepthofsinkholes
rangesfromacoupleof
meterstoseveralmiledeep.

22. How it
occurs:
Waterfromtherainfallseeps
underneaththesoilthroughthe
cracksandfissures.Aswater
passesthroughthesecracksand
fissures,iterodesthesoiland
formsaconduitsystem,these
undergroundwatersystems
increaseinsizeasthesoilis
carriedbythewaterthrough
internalerosion.

23. How it
occurs:
Thiscaneitherformavoidfilled
withairwithanunderground
drainage.Ifthevoidisclogged
withclay,thenitformsa
depression which then
accumulateswaterandformsa
pond.Otherwiseitformsahole
oncethecovercollapsesintothe
voidwhichcanbeeitherfilled
withairorwater.

25. Types of
Sinkholes
1. Cover Collapse Sinkhole
Itdevelopssuddenly(over
anhourperiod)thus,causing
catastrophicdamage.
2. Cover Subsidence Sinkhole
Itgraduallygrowswherethe
sedimentcoversarepermeable
andcontainsand.

28. Types of
Sinkholes
3. Dissolution Sinkhole
Itoccursinareaswherecalcareousis
exposedonthegroundorwherethinlayers
ofsoilandpermeablesandarealso
covered.Limestoneordolomitedissolution
ismostintensewhenthewaterfirstreaches
therocksurface.
4. Artificial Sinkhole
Suchtypesofsinksmaybecausedby
varioushuman activities,including
groundwaterpumpingandbuilding.

30. LANDSLIDES

31. Natural
Causes of
Landslides
Climate
Long-termclimaticchanges
cansignificantlyimpactsoil
stability.Ageneralreductionin
precipitationleadstoloweringof
watertableandreductionin
overallweightofsoilmass,
reducedsolutionofmaterialsand
lesspowerfulfreeze-thawactivity.

32. Natural
Causes of
Landslides
Earthquakes
Seismicactivitieshave,fora
longtime,contributedtolandslides
acrosstheglobe.Anymoment
tectonicplatesmove,thesoil
coveringthemalsomovesalong.
Whenearthquakesstrikeareaswith
steepslopes,onnumerous
occasion,thesoilslipsleadingto
landslides.

33. Natural
Causes of
Landslides
Weathering
Itisthenaturalprocedureof
rockdeteriorationthatleadsto
weak, landslide-susceptive
materials.Itisbroughtaboutbythe
chemicalactionofwater,air,plants
andbacteria.Whentherocksare
weakenough,theyslipaway
causinglandslides.

34. Natural
Causes of
Landslides
Erosion
Erosioncausedbysporadic
runningwatersuchasstreams,
rivers,wind,currents,iceand
waveswipesoutlatentandlateral
slopesupportenablinglandslides
tooccureasily.

35. Natural
Causes of
Landslides
VolcanicEruption
Ifaneruptionoccursinawet
condition,thesoilwillstartto
movedownhillinstigatinga
landslide.Volcanicgasespartially
dissolveingroundwaterwhich
turnsintoacidichydrothermal
systemsthatweakensrockby
alteringmineralstoclay.

36. Natural
Causes of
Landslides
ForestFires
Burnsvegetationthatholds
soilinplace.Wildfireremovesthe
protectiveabilityofvegetation
whichincreasesrunoff,erosion,
anddebrisflowbecausethe
watercannotpenetratethrough
thesoilthuscarryingthedebris
downslope.

37. Natural
Causes of
Landslides
Gravity
Steeperslopescoupledwith
gravitationalforcecantriggera
massivelandslide.Steeperslopes
canalsocausethedebristomove
fartherfromthefootofthearea.

38. Human
Causes of
Landslides
Mining
Miningactivitiesthatutilize
blastingtechniquescontribute
mightilytolandslides.Vibrations
emanatingfromtheblastscan
weakensoilsinotherareas
susceptibletolandslides.The
weakeningofsoilmeansa
landslidecanoccuranytime.

39. Human
Causes of
Landslides
ClearCutting
Clearcuttingisatechnique
oftimberharvestingthat
eliminatesalloldtreesfromthe
area.Thistechniqueisdangerous
sinceitdecimatestheexisting
mechanicalrootstructureofthe
area.Itchangestheamountof
waterinfiltratingthesoil.

40. Rainfall-
induced
Landslides
Rainfall-Inducedlandslides
arethemostcommon and
widespreaddamaginglandslides
inthePhilippines,withan
averageof20typhoonseachyear
duetoprolongedorheavy
rainfall.Mostrainfall-induced
landslidesareshallow(lessthana
fewmetersdeep),thin,andmove
quickly.

42. The impending
signs of a
rainfall-
induced
landslide
Rainfall-induced landslide
canhappenanytimeduringa
heavyandprolongedrainfall.We
cannottellwhenexactlyitwill
happenbuttherearesomesigns
thatmayindicateso:

43. The impending
signs of a
rainfall-
induced
landslide
Unusualnoises,suchasbreaking
trees,orknockingboulders
together,canmeanmoving
debris.
Asthelandslidenears,aslight
rumblingsoundthatrisesin
amplitudeisnoticeable.
Rapidriseinwaterlevelsofthe
creeks,likelyfollowedby
increasedturbidity(soilcontent).

44. The impending
signs of a
rainfall-
induced
landslide
TheEarlyWarningSystem(EWS)of
thePhilippineInstituteofVolcanology
andSeismology(PHILVOCS)and
PhilippineAtmospheric,Geophysical
and Astronomical Services
Administration (PAGASA) are
monitoringsystemsdesignedto
forecastevents accompanying
landslidesinordertoprovidea
warningabouthazards.Byreducing
theimpact,itmitigatesrisk.

45. SINKHOLES

46. Sinkholes
NATURAL CAUSES OF
SINKHOLE
–Dissolutionofsedimentary
rocks
Sinkholesoccur when
sedimentaryrocksaredissolved.
Whentheserocksaredissolved,
itcaneitherformavoidofwater
orair.

47. Sinkholes
HUMANCAUSESOFSINKHOLE
–Undergroundwaterpumping
Pumpingwaterunderneath
thegroundcausesdrainageto
altertheirflowwhichcausesthe
soiltobeerodedbywater.

48. The impending
signs of a
sinkhole
Sinkholeseitherman-made
ornaturalcanoccuranytime.We
cannottellwhenwillthehole
emergebuttherearesomesigns
thatmayindicateanimpending
disaster.

49. The impending
signs of a
sinkhole
Newcracksatthefoundationsof
buildingsandhouses
Cracksinanarea
Depressionsatgroundlevel
Rapidappearanceofacraterin
theground