earthquake and its hazards
TRANSCRIPT
BABY JANE T. PUNONGBAYANBABY JANE T. PUNONGBAYANSeismological Observation and Earthquake Prediction DivisionSeismological Observation and Earthquake Prediction Division
Philippine Institute of Volcanology and SeismologyPhilippine Institute of Volcanology and SeismologyPHIVOLCS PHIVOLCS -- DOSTDOST
UNDERSTANDING UNDERSTANDING
EARTHQUAKES AND EARTHQUAKES AND
EARTHQUAKE HAZARDSEARTHQUAKE HAZARDS
�� 30 unmanned stations: 30 unmanned stations: 1 in 1 in OrmocOrmoc
1 in 1 in MaasinMaasin
�� 29 manned stations29 manned stations
1 in Palo1 in Palo
�� 5 5 seismoseismo--volcanologicalvolcanologicalobservatoriesobservatories
�� Metro Manila Metro Manila micronetworkmicronetwork with 5 with 5 telemeteredtelemetered
seismic stationsseismic stations
�� Temporary Temporary HinunanganHinunangan NetworkNetwork
5 stations5 stations
Network of Earthquake Monitoring Stations in
the Philippines
Seismic monitoring station in El Nido, Palawan
PHIVOLCS seismologists: PHIVOLCS seismologists: earthquake huntersearthquake hunters
4,000th quake in 4 days!
PHIVOLCS: Source of earthquake information in the PhilippinesPHIVOLCS: Source of earthquake information in the Philippines
�� Details of earthquake location: Details of earthquake location:
�� Origin time, coordinates, depth, Origin time, coordinates, depth,
source (tectonic or volcanic), source (tectonic or volcanic),
generatorgenerator
�� Intensities of affected areas Intensities of affected areas
�� Tsunami bulletins and warningsTsunami bulletins and warnings
�� Advisory in times of necessary Advisory in times of necessary
evacuationevacuation
Information transmitted by tri-media (tv,
radio and print)
What have we learned?What have we learned?
�� PHIVOLCS is the agency mandated to PHIVOLCS is the agency mandated to
monitor earthquakes in the Philippinesmonitor earthquakes in the Philippines
�� A seismically active area may produce A seismically active area may produce
hundreds to thousands of earthquakes in a hundreds to thousands of earthquakes in a
brief span of time (hours to several weeks)brief span of time (hours to several weeks)
EarthEarth
Our planet is dynamic
The outermost layer is broken into pieces
These pieces called “plates” are moving, away or toward each other
Mantle convection is driving the earth’s tectonic platesMantle convection is driving the earth’s tectonic plates
The Earth is dynamic: Plate TectonicsThe Earth is dynamic: Plate Tectonics
The Philippines is a region between tectonic plates
EQUATOR
FaultFault
-- form in rocks when the stresses overcome the form in rocks when the stresses overcome the internal strength of the rock resulting in a fracture internal strength of the rock resulting in a fracture
THE CRUST IS FRAGMENTED
�Tectonic plates
Earthquakes are found along plate boundaries
What have we learned?What have we learned?
�� Earthquakes are natural phenomena Earthquakes are natural phenomena brought about by slow but powerful motions brought about by slow but powerful motions within the earthwithin the earth
�� The internal motion within the Earth The internal motion within the Earth induces deformation along the fragile induces deformation along the fragile surface of the planetsurface of the planet
�� Sudden ground deformation produces Sudden ground deformation produces seismic waves or earthquakesseismic waves or earthquakes
A weak to violent shaking A weak to violent shaking
of the ground produced by of the ground produced by
the sudden movement of the sudden movement of
rock materials below the rock materials below the
earth’s surface.earth’s surface.
2. Volcanic- earthquakes produced
by movement of magma beneath volcanoes
1. Tectonic- earthquakes produced
by sudden movement along faults and plate boundaries
TYPES OF NATURAL EARTHQUAKESTYPES OF NATURAL EARTHQUAKESTYPES OF NATURAL EARTHQUAKESTYPES OF NATURAL EARTHQUAKES
Particle Motion upon
passage of different
types of seismic waves
P – primary wave;
displacement of media along
direction of propagation
(up-down)
S – secondary;
displacement of media
perpendicular to direction of
wave propagation (sideways)
Surface waves:
1. Love waves
2. Rayleigh waves (rotational)
SeismogramSeismogram
Distance of point of observation from earthquake source is determined using
the arrival times of different seismic waves, usually P and S waves
Locating the Epicenter
�� Travel Time and earth structure Travel Time and earth structure
�� Velocity ModelsVelocity Models
�� Refracted and Reflected PhasesRefracted and Reflected Phases
FAULT
FOCUS vs. EPICENTERFOCUS vs. EPICENTER
• at least 20 earthquakes are recorded per day
• 4 – 5 earthquakes are felt per week
Instrumental Data (ISC) 1964-1999
Philippines is an earthquake country !
M7.5 01 Apr 1955 Lanao(291/713)
M7.3 02 Aug 1968 Casiguran(270/600)
M7.3 07 Apr 1970 Baler (15/200)
17 Aug 1976 Moro Gulf (3,739/8,000)
16 July 1990 Luzon (1,283/2,786)
15 November 1994 Mindoro(78)
Fact:
The Philippine Archipelago
has a complex tectonic setting
with several trenches and
many active faults
perceived strength of an earthquake based on relative effect to people and structures; generally higher near the epicenter
based on instrumentally
derived information and
correlates strength with the amount of total energy
released at the earthquake’s
point of origin
Two ways of describing the strength of an earthquakeTwo ways of describing the strength of an earthquakeTwo ways of describing the strength of an earthquakeTwo ways of describing the strength of an earthquake
1. . . . Intensity 2. 2. 2. 2. Magnitude
Magnitude Magnitude <energy><energy>
�� Compares logarithmic of amplitude with Compares logarithmic of amplitude with distance from epicenterdistance from epicenter
�� Types depending on instrumentation:Types depending on instrumentation:
Period (s)Period (s)DescriptionDescriptionNameName
Moment Moment
MagnitudeMagnitude
Surface Surface
MagnitudeMagnitude
Body Body
MagnitudeMagnitude
Local Local
MagnitudeMagnitude
MwMw
MsMs
MbMb
MlMl
> 200> 200
2020
1.0 1.0 –– 5.05.0
0.1 0.1 –– 1.01.0
WoodWood--
Anderson type Anderson type
seismographseismograph
RICHTER MAGNITUDE SCALERICHTER MAGNITUDE SCALE
Earthquakes with M over 9 have never occurred since the data based on the
seismographic observations became available.1010
M over 9 have never occurred since the data based on the seismographic observations
became available.99
M 8 to 9 are the "great earthquakes" occurring once or twice a year. When in land areas,
damages affect wide areas. When under the sea, considerable tsunamis are produced.
Many aftershocks occur in areas approximately 100 to 1,000 kilometers in diameter.
88
M 7 to 8 are the "major earthquakes“; can cause considerable damages near epicenters;
may generate tsunamis. 77
M 6 to 7 are "strong earthquakes“; accompanied by local damages near epicenters.66
M 5 to 6 are "earthquakes with moderate strength“; felt over the wide areas; some of
them cause small local damages near the epicenter.55
M 4 to 5 are "feeble shocks" where damages are not usually reported.44
M 3 to 4 are "very feeble shocks" and only felt near the epicenter.33
M below 3 are "hardly perceptible shocks" and are not felt. 22
magnitude below 1 are only detectable when an ultra sensitive seismometer is operated
under favorable conditions.11
• There are different types of magnitude depending on type of seismograph used: Ml, mb, Ms, Mw, Mwp, etc.
• Magnitude scale is open ended (no limit)
1960 Chile earthquake (strongest 1960 Chile earthquake (strongest
recorded earthquake)recorded earthquake)9.5
estimate for a 2 km rocky meteorite impacting at 25
km/s1 teraton10.0
Catastrophic to whole earthCatastrophic to whole earth12.0
2004 Indian Ocean earthquake32 gigatons9.3
1990 Baguio (Luzon) earthquake(67,000x hiroshima)
1 gigaton7.8
Nagasaki atomic bomb32 kiloton5.0
Small atomic bomb1 kiloton4.0
Construction site blast32 kg (70 lb)1.0
large Hand grenade5.6 kg (12.4 lb)
0.5
ExampleApproximate TNT for
Seismic Energy Yield
Richter Approximate
Magnitude (Ml)00
Indonesia 2004
INTENSITY• Decreases with distance
from source
• can be gauged by Assumption
students!! Very easy…
INTENSITY VIII
INTENSITY IX
INTENSITY VIII
INTENSITY VII
What have we learned?What have we learned?
�� Magnitude = instrumentsMagnitude = instruments
�� Intensity = personal observationsIntensity = personal observations
�� An increase of one unit on the Richter Scale corresponds to An increase of one unit on the Richter Scale corresponds to approximately a 30approximately a 30--fold increase in the total energy released. fold increase in the total energy released.
�� Large magnitude earthquakes have occurred in the Large magnitude earthquakes have occurred in the Philippines in the pastPhilippines in the past
�� Large magnitude earthquakes are inevitable in the Philippines Large magnitude earthquakes are inevitable in the Philippines because of its geodynamic setting and the presence of faultsbecause of its geodynamic setting and the presence of faults
�� YOU and your class may contribute in intensity reporting!YOU and your class may contribute in intensity reporting!
�� Basic seismology deciphers information about the earth and Basic seismology deciphers information about the earth and its movements using the imprint of the passing of seismic its movements using the imprint of the passing of seismic waveswaves
Basic TermsBasic Terms
�� Seismology Seismology -- sciencescience
�� Seismic Seismic -- pertaining to earthquakepertaining to earthquake
�� Seismograph Seismograph -- instrumentinstrument
�� Seismogram Seismogram –– record of earthquakerecord of earthquake
�� Aftershock Aftershock -- following the following the mainshockmainshock
�� Foreshock Foreshock ––before a before a mainshockmainshock
Seismic Hazards:Seismic Hazards:
dangers posed by large earthquakesdangers posed by large earthquakes
• Ground Shaking - shake
• Ground Rupture - cut
• Liquefaction - very soft soil
• Landslides - slope failure
• Tsunami - waves
Secondary Hazards:•Fire•Lateral spreading, etc.
Intense shaking, earthquake of Kobe, Japan 1995Intense shaking, earthquake of Kobe, Japan 1995
intense shaking + weak structure = building damage or collapse
Ex. Hyatt Hotel in Baguio City after the magnitude 7.8 earthquake of July 16, 1990
USA
INDIA
Ground rupture with vertical displacementGround rupture with vertical displacement
Intense shaking + loosely hanged objects = Intense shaking + loosely hanged objects =
falling objectsfalling objects
Hazard 2:Hazard 2: GROUND RUPTUREGROUND RUPTURE
�� fissuringfissuring or faulting along the surface
� The creation of new or the renewal of movements of old fractures, oftentimes with the two blocks on both sides moving in opposite directions
Groundrupture
Seismic Seismic
HazardsHazards
•• Reverse FaultReverse Fault
Photo of Nojima Fault in Japan, fissured during the M=7.2 1995 Kobe earthquake
Ground rupture and fissuringTaiwan Earthquake, 1999
Active Fault: trace certain
Active Fault: trace approximate
Offset stream
Legend:
Faulted outcrop (Brgy. Salog, Leyte)
Salog Elementary School, Leyte
Hazard 3: LiquefactionHazard 3: Liquefaction
-- a process that transforms the behavior of a body of sediment from that of a solid to that of a liquid
Liquefaction in Hinunangan, Southern Leyte July 19, 2007
Photo courtesy of PHIVOLCS HINUNANGAN JULY 2007 QRT Team
Brgy. Badiangon
Brgy. Das-ay
Liquefaction: Liquefaction: The ground loses strength and structures The ground loses strength and structures
built on top of it may sink and tilt...built on top of it may sink and tilt...
EarthquakeEarthquake--induced Landslidesinduced Landslides
��Occurrence of a strong earthquakeOccurrence of a strong earthquake
�� Elevated areas:Elevated areas: steeper slopes, more pronesteeper slopes, more prone
��Thick soil cover:Thick soil cover: more loose materials to fallmore loose materials to fall
��Proximity to fault:Proximity to fault: stronger shaking in areas stronger shaking in areas
near the earthquakenear the earthquake--generating faultgenerating fault
��Water saturation of materials:Water saturation of materials: wet slopes wet slopes
easier to landslideeasier to landslide
READY MAPPING 2007: Dr. Arturo Daag and Ms. Angela Montes
LandslideLandslide
Hazard 4:Hazard 4: Landslides and Landslides and RockfallsRockfalls
HinunanganHinunangan, Southern , Southern LeyteLeyte July 19, 2007 11:10 PM July 19, 2007 11:10 PM
Magnitude 5.5 EarthquakeMagnitude 5.5 Earthquake
Intensity VII in Hinunangan
Landslide in Brgy.
Biasong
Photo: Punongbayan, BJT 2007
Tension cracks in Tension cracks in BrgyBrgy. . ManalogManalog July 19, 2007 July 19, 2007
(Intensity VII in (Intensity VII in HinunanganHinunangan))
Ground Failure Ground Failure -- LandslideLandslideINTENSE shaking +INTENSE shaking +
�� SlopeSlope
�� VegetationVegetation
�� Water contentWater content
�� PrePre--existingexistingstructuresstructures
Secondary Hazard: FireSecondary Hazard: Fire
COMMON QUESTIONS:COMMON QUESTIONS:
��Can earthquakes be predicted? Can earthquakes be predicted?
�� Is there a fault passing through your Is there a fault passing through your school?school?
��Where is the Where is the MarikinaMarikina Fault? Fault?
�� Is there a risk of tsunami in Is there a risk of tsunami in MetroManilaMetroManila??
��Who are at risk?Who are at risk?
~3 km
WVFWVF
Maximum 4mMaximum 4m
average 2m average 2m
alongside alongside
Manila BayManila Bay
Will not Will not
occur occur
TsunamiTsunami
Seismic Seismic
Intensity Intensity
(PEIS)(PEIS)
Fault Fault
MechanismMechanism
MagnitudeMagnitude
ModelModel
Almost VIII, Almost VIII,
IX alongside IX alongside
MarikinaMarikina
River and River and
Manila BayManila Bay
Inland FaultInland Fault
7.27.2
ModelModel 0808
VIII at West of VIII at West of
Metropolitan Metropolitan
Mania, VII at Mania, VII at
other areaother area
SubductionSubduction
7.97.9
ModelModel 1313
Is there a possibility of a big earthquake in Is there a possibility of a big earthquake in MetroManilaMetroManila??The The MetroManilaMetroManila Earthquake Impact Reduction Study (MMEIRS)Earthquake Impact Reduction Study (MMEIRS)
Some Earthquake Models/Scenario for Metro ManilaSome Earthquake Models/Scenario for Metro Manila
HAZARD MAPPINGEx. Groundshaking for West Valley Fault
Mag=7.2 Scenario 08
INVENTORY OF CRITICAL FACILITIESEx. Schools
PEIS Intensity VIII PEIS Intensity VIII –– Very DestructiveVery Destructive�� People are panicky and find it difficult to stand even outdoorsPeople are panicky and find it difficult to stand even outdoors
�� Many wellMany well--built buildings are considerably damagedbuilt buildings are considerably damaged
�� Concrete dikes and foundations of bridges destroyed by ground Concrete dikes and foundations of bridges destroyed by ground settlingsettling
�� Railway tracks may be broken; tombstones may be displaced, Railway tracks may be broken; tombstones may be displaced, twisted or overturnedtwisted or overturned
�� Utility posts, towers and monuments may tilt or toppleUtility posts, towers and monuments may tilt or topple
�� Water and sewer pipes may be bent, twisted or brokenWater and sewer pipes may be bent, twisted or broken
�� Sinking or titling of structures due to liquefactionSinking or titling of structures due to liquefaction
�� Landslides and Landslides and rockfallsrockfalls; Boulders thrown out near epicenter; Boulders thrown out near epicenter
�� Fissures or rupture observedFissures or rupture observed
�� Water splashes over dikes or Water splashes over dikes or oror riverbanksriverbanks
August 2, 1968 (Ms 7.3); Casiguran
Fault-East Luzon Trench region
The Ruby Tower in Binondo,
Manila, a large six-storey
building containing 38
commercial units in its first two
floors and 76 residential units
in its upper four floors; Most of
the building collapsed except
for a part of the northern end
of its first and second floors.
268 persons died and 260 were
injured.
ESTIMATED IMPACTS OF WORST CASE SCENARIO EARTHQUAKE ESTIMATED IMPACTS OF WORST CASE SCENARIO EARTHQUAKE
(Magnitude=7.2 West Valley Fault)(Magnitude=7.2 West Valley Fault)
13%13%
170,000170,000
heavily damaged heavily damaged
or collapsedor collapsedResidential buildingsResidential buildings
25.6% or25.6% or
350,000 350,000
moderately moderately
damageddamaged
34,000, 34,000,
90% from pressure of 90% from pressure of
collapsed buildingcollapsed building
deaddeadHuman LossHuman Loss
With population of 9,932,560 With population of 9,932,560
120,000120,000injuredinjured
20 20 –– 25 %25 %Partly DamagedPartly Damaged
8 8 -- 10 %10 %Heavily DamagedHeavily DamagedPublic Purpose Buildings: Public Purpose Buildings:
Schools 1412, Hospitals 177, Fire Schools 1412, Hospitals 177, Fire
Fighting 124, Police 43, MMDCC Fighting 124, Police 43, MMDCC
Organizations and 17 LGU City Organizations and 17 LGU City
and Municipal Halls 53and Municipal Halls 53
Four out of ten buildings and houses will be damaged
PHIVOLCS has the knowledge, it is our PHIVOLCS has the knowledge, it is our
mission to prepare the public.mission to prepare the public.
Some of our information and Some of our information and
earthquake campaigns:earthquake campaigns:
�� Nationwide lectures and seminarsNationwide lectures and seminars
��Earthquake drillsEarthquake drills
�� Tsunami warning systemsTsunami warning systems
�� Tsunami warning signageTsunami warning signage
�� Tsunami drillsTsunami drills
Make the drill a nice learning experience …
http://www.phivolcs.dost.gov.ph
For requests/inquiries:
Director Renato U. Solidum, Jr.PHIVOLCS Bldg., C.P. Garcia Ave.
U.P. Diliman, Q.C. 1101
Tel: 426-1468 loc. 112 or 124 or 125
Fax: 927-8366