EARTH QUAKES AND FAULTING Flashcards
1
Q
BROAD-BANDED VIBRATORY GROUND MOTIONS, RESULTING FROM A N UMBER OF CAUSES INCLUDING TECTONIC GROUND MOTIONS, VOLCANISM, LANDSLIDES, ROCKBURSTS, AND MANMADE EXPLOSIONS
A
EARTHQUAKE
2
Q
These are caused by the fracture and sliding of rock along faults within the earth crust
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EARTHQUAKE
3
Q
Seismic hazards
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fault rapture
vibratory ground motion
inundation
ground failure
fire
hazardous materials release
4
Q
caus eo f earthquake that produced by sudden movement along faults and plate boundaries
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Tectonic plate movements
5
Q
cause of earthquakes that can occur in volcanic regions due to the movement of magma within the earth
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volcanic activity
6
Q
causes of earthquakes
A
tectonic plate movements
volcanic activity
human activity
fault slippage
Isostatic Rebound
7
Q
When the stresses exceeds the friction holding the rocks together, the faults slips, releasing energy as an earthquake
A
FAULT SLIPPAGE
8
Q
this occurs when the earth crust adjust the changes in surface load, such as the melting of glaciers
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Isostatic rebound
9
Q
it is also called focus or first location of dynamic rupture.
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Hypocenter
10
Q
The projection on the surface of the earth directly above the hypocenter
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EPICENTER
11
Q
The region close to the Earthquakes epicenter
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NEAR-FIELD
12
Q
the region farther away from the earthquake epicenter
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FAR-FIELD
13
Q
the region of strong shaking and damage
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MEIZOSEISMAL
14
Q
It travels through the interior of the earth and are further divided into two waves : P-WAVES & S-WAVES
A
BODY WAVES
14
Q
travel along the earth surface and typically cause ,more damage than body waves due to their larger amplitude and slower speed. They are divided into two : LOVE WAVES AND RAYLEIGH WAVES
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SURFACE WAVES
15
Q
TYPES OF SEISMIC WAVES
A
PRIMARY WAVES (PWAVES)
SECONDARY WAVES (SWAVES),
LOVE WAVES
RAYLEIGH WAVES
15
Q
compressional waves
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P WAVES OR PRIMARY WAVES
16
Q
waves that travels through solid, liquid, and gases
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P WAVES OR PRIMARY WAVES
17
Q
fastest seismic waves that moving in PUSH-PULL manner
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P WAVES OR PRIMARY WAVES
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Q
often first to be felt during an earthquake and first to be detected by seismograph
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P WAVES OR PRIMARY WAVES
19
Q
shear waves
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S WAVES OR SECONDARY WAVES
20
Q
waves that travels in solids only
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S WAVES OR SECONDARY WAVES
21
Q
waves that create side to side or up and down motions
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S WAVES OR SECONDARY WAVES
22
Q
waves that is more responsible for the majority of damage during an earthquake
A
S WAVES OR SECONDARY WAVES
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it is Horizontal shear waves
LOVE WAVES
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it is wave that move side to side in horizontal motion
LOVE WAVES
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it travels slower than P an S waves
LOVE WAVES
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rolling or elliptical waves
RAYLEIGH WAVES
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It moves in a rolling motion, similar to ocean waves, causing both vertical and horizontal ground movements
RAYLEIGH WAVES
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slowest seismic waves but can cause significant surface damage due to their large amplitude
RAYLEIGH WAVES
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is the rigid outer part of the Earth.
Lithosphere
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Its thickness varies between 10-200 km. It comprises the crust and the upper part of the mantle.
Lithosphere
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a portion of the Earth's mantle that flows like molten plastic
despite being solid.
Asthenosphere
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is a type of earth movement resulting from the horizontal compression of rock layers by internal forces of the earth along plate boundaries.
FOLDING
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Six type of folds:
* Anticline,
* Syncline
* Monocline
* Plunging Anticline
* Dome
* Basin
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a fold that is convex.
* Anticline
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is a fold that is concave.
* Syncline
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is a special type of fold in which both
limbs are para lel but offset to each other.
* Monocline
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has a tilted hinge
* Plunging Anticline
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has a shape of an overturned bowl
* Dome
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has a shape of an upright bowl
* Basin
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occurs when tension and compression associated with plate movement and it is so great that blocks of rock fracture or break apart
FAULTING
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This process can occur rapidly which causes the ground to shake and vibrate resulting in earthquakes.
FAULTING
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are the physical expression of plate boundaries.
FAULT
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The longer the ________, the larger the earthquake it can generate
FAULT
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7 MAJOR TECTONIC PLATES
* Pacific Plate
* North American Plate
* Eurasian Plate
* African Plate
* Antarctic Plate
* Indo-Australian Plate
* South American Plate.
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MINOR TECTONIC PLATES
* Arabian Plate.
* Caribbean Plate.
* Cocos Plate.
* Juan de Fuca Plate.
* Nazca Plate.
* Philippine Sea Plate.
* Scotia Plate.
* Somali Plate.
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Four types of Faulting:
* Normal fault
* Reverse fault
* Transform or Strike Slip fault
* Oblique fault
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dip-slip motion, two sides in tension, move away from each other
* Normal fault
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dip-slip, two sides in compression, move toward each other
* Reverse fault
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relative fault motion occurs in the horizontal plane, para lel to the strike of the fault
* Transform or Strike Slip fault
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is a fault similar to both a strike-slip and a dip-slip fault.
* Oblique fault
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are faults at depth occurring under anticlinal folds — since they have only subtle surface expression, their seismogenic potential can only be evaluated by indirect means (Greenwood 1995).
Blind Thrust Faults
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- are particularly worrisome because they are hidden, are associated with folded topography in general, including areas of lower and infrequent seismicity, and, therefore, result in a situation where the potential for an earthquake exists in any area of anticlinal geology, even if there are few or no earthquakes in the historic record.
Blind Thrust Faults
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- refers to the direction of slip in an earthquake and the orientation of the fault on which it occurs.
FOCAL MECHANISM
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- are determined from seismograms and typicaly displayed on maps as a black and white ‘beach bal’ symbol.
FOCAL MECHANISM
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. Focal mechanisms are shown by what classical representation?
‘beach ball’
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refers to the plunging of one plate (e.g., the Pacific) beneath another, into the mantle, due to convergent motion.
Subduction
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are typicaly characterized by volcanism, as a portion of the plate (melting in the lower mantle) re-emerges as volcanic lava.
Subduction zone
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are where cold oceanic lithosphere sinks back into the mantle and is recycled
Subduction zone
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They are found at convergent plate boundaries, where the heavier oceanic lithosphere of one plate is overridden by the leading edge of another, less-dense plate.
Subduction zone
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German Climatologist and Geologist
Proposed Continental Drift Theory
(1912)
Author of the book “The Origin of Continents and Oceans”
Alfred Lothar Wegener (1880-1930)
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American Geologist and U.S Navy Officer
Proposed Seafloor Spreading Theory
(1960)
Author of the “The History of Ocean Basins”
Harry Hammond Hess (1906-1969)
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theory That continents were once joined together in a supercontinent and have since drifted apart.
theory of continental drift
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theory that explains how new oceanic crust is formed at mid-ocean ridges and slowly moves away as magma rises and solidifies.
Seafloor Spreading Theory
(1960)
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is a scientific theory that explains how major landforms are created as a result of Earth’s subterranean movements.
PLATE TECTONIC THEORY
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LAYERS OF EARTH
inner and outer core
mantle
crust
sublayer: lithosphere and asthenosphere
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two plates move APART each other.
DIVERGENT BOUNDARY
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movements within the Earth's mantle caused by the heat from the core, driving the movement of tectonic plates.
convection currents
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two plates move TOWARDS each other.
CONVERGENT BOUNDARY
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- Plates that SLIDE past each other horizontally
TRANSFORM BOUNDARY
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types of plate boundary
convergent, divergent, transform boundary
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What are the four main types of faults?
Normal fault, Reverse fault, Strike-slip fault, and Oblique fault.
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faults occurs when the hanging wall moves downward relative to the footwall due to tensional forces.
normal fault
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fault occurs when the hanging wall moves upward relative to the footwall due to compressional forces.
reverse fault
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fault involves horizontal movement of the Earth's crust, with little to no vertical motion.
strike-slip fault
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is a fault that has experienced movement within the last 10,000 years and is considered capable of generating future earthquakes.
ACTIVE FAULT
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It is a crack in the crust that was formed when the crust shifted. When two sides of the fault move past one another, seismic waves are generated and therefore the earthquake is generated
FAULT LINE
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average slip rate per year
1.5 to 3.6 cm/year
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The movement of the Philippines Plate, Eurasian Plate,
and Indo-Australian Plate has resulted in the formation
of the Philippine fault zone.
Left-lateral stike- slip
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how long is the fault system that transects the whole
Philippine archipelago from northwestern Luzon to
southeastern Mindanao.
1200 km
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originally the Marikina Fault System, consists of
West Valley Fault and East Valley Fault that
forms the Marikina River Valley and transects the
eastern margins of Metro Manila.
VALLEY FAULT SYSTEM
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Zone where the Philippine Sea Plate
subducts beneath the Philippine Mobile Belt
between offshore Bicol Peninsula and
Southeast Mindanao.
The Philippine
Trench
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PH TRENCH CONVERGENCE RATE
8 cms/year
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Zone where the Philippine Sea
Plate subducts beneath the Philippine Mobile Belt offshore of
Northeastern Luzon. The depth of the trough is 5,700 meters.
EAST LUZON THROUGH
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Zone where the South China Sea
Plate subducts beneath the
Philippine Mobile Belt between
Taiwan and west of the islands of
Luzon and Mindoro. The depth of
the trench is 5,400 meters.
MANILA TRENCH
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Zone where the Sulu Sea -Plate
subducts beneath the Philippine
Mobile Belt offshore of Panay and
Negros Island. The depth of the
trench is 4,400 meters.
NEGROS TRENCH
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Zone where the Sulu Sea Plate
subducts beneath the Philippine
Mobile Belt offshore of
Zamboanga Peninsula and Sulu
Archipelago. The depth of the
trench is 5,600 meters.
SULU TRENCH
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Zone where the Celebes Sea Plate subducts
beneath the Philippine Mobile Belt offshore
of Cotabato and Sarangani Provinces. The
depth of the trench is 5,395 meters.
COTABATO TRENCH
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An application capable to do proximity
searches to active faults.
PHIVOLCS FaultFinder
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is a region of the Earth's surface that is
prone to earthquakes. T
SEISMIC ZONE
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SEISMIC ZONE CLASSIFICATION
»
* Zone0-Noriskofseismicactivity.
*
* Zone1-Verylowrisk.
* Zone 2 - Low to moderate risk.
»
* Zone 3 - Moderate to high risk.
»
* Zone4-Highrisk.
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The National Structural Code of the Philippines 2010
(NSCP 2010) divided the Philippines into two seismic
zones only
Zone 2 and Zone 4 (Association of Structural
Engineers of the Philippines)
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zone that have low to moderate probability of damaging ground motion
zone 2
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refers to earthquakes triggered by human activities, such as mining, reservoir filling, or geothermal energy extraction.
induced seismicity
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describes the relationship between the magnitude and total number of earthquakes in a region over time.
Gutenberg-Richter law
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What is the difference between the hypocenter and epicenter?
The hypocenter is the underground point where an earthquake originates, while the epicenter is directly above it on the surface.
96
involves strengthening existing structures to make them more resistant to seismic activity.
earthquake retrofitting
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device that measures the strength and duration of an earthquake by recording ground motion.
seismograph
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What is the difference between dip-slip and strike-slip faults?
Dip-slip faults involve vertical motion (normal or reverse), while strike-slip faults involve horizontal motion along the fault plane.
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visible displacement or breaking of the ground surface caused by movement along a fault during an earthquake.
fault rupture
100
type of reverse fault with a low-angle fault plane, typically occurring in compressional tectonic environments.
thrust fault
101
is a region around the edges of the Pacific Ocean known for frequent earthquakes and volcanic eruptions due to active tectonic plate boundaries.
Ring of Fire
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