TECTONICS Flashcards
TECTONIC HAZARDS - WHAT ARE THEY ???
EARTHQUAKES AND VOLCANIC ERUPTIONS
PLUS SECONDARY HAZARDS
SUCH AS TSUNAMI
CAN BE CLASSIFIED AS EITHER ??
SEISMIC OR VOLCANIC
GLOBAL DISTRIBUITON OF TECTONIC HAZARDS - EARTHQUAKES
FAR FROM RANDOM !
MAIN EARTHQUAKE ZONES FOUND ALONG PLATE BOUNDARIES.
ABOUT 70% OF ALL EARTHQUAKES ARE FOUND IN THE “RING OF FIRE” IN THE PACIFIC OCEAN
SEISMIC HAZARDS - DESCRIBE ??
GENERATED WHEN ROCKS WITHIN 700 KM OF THE EARTHS SURFACE COME UNDER SUCH STRESS THAT THEY BREAK AND BECOME DISPLACED
VOLCANIC HAZARDS - DESCRIBE ??
ASSOCIATED WITH THE ACTUAL ERUPTION EVENTS
VOLCANO - WHAT IS THIS ??
A LANDFORD THAT DEVELOPS AROUND A WEAKNESS IN THE EARTH’S CRUST FROM WHICH MOLTEN MAGMA, DISRUPTED FROM PRE-EXISTING VOLCANIC ROCK AND GASES ARE EJECTED OR EXTRUDED
INTRA PLATE EARTHQUAKES
OCCUR IN THE MIDDLE OR INTERIOR OF TECTONIC PLATES AND ARE MUCH RARER THAN BOUNDARY EARTHQUAKES
GLOBAL DISTRIBUTION OF TECTONICS HAZARDS : VOLCANOES
THE VIOLENCE OF A VOLCANIC ERUPTION IS DETERMINED BY
THE AMOUNT OF DISSOLVED GASES IN THE MAGMA AND HOW EASILY THE GASES CAN ESCAPE
ABOUT 500 ACTIVE VOLCANOES THROUOUT THE WORLD
ON AVERAGE AROUND 50 ERUPT EACH YEAR
PLATE BOUNDARY - 3 TYPES
DIVERGENT
CONVERGENT
CONSERVATIVE
PLATE TECTONICS - WHAT IS THIS ??
A THEORY DEVELOPED > 60 YEARS AGO TO EXPLAIN THE LARGE-SCALE MOVEMENTS OF THE LITHOSPHERE (OUTERMOST LAYER OF THE EARTH)
LITHOSPHERE - WHAT IS THIS ??
OUTERMOST LAYER OF THE EARTH
DIVERGENT PLATE BOUNDARY - DESCRIBE
CONSTRUCTIVE MARGINS
MOST CLEARLY DISPLAYED AT MID-OCEAN RIDGES.
LARGE NUMBERS OF SHALLOW FORCES
GENERALLY LOW MAGNITUDE
MOST ARE SUBMARINE(UNDER THE SEA)
CONVERGENT PLATES - DESCRIBE
PLATES MOVE TOGETHER
ACTIVELY DEFORMING COLLISION LOCATIONS WITH PLATE MATERIAL MELTING THE MANTLE,
CAUSING FREQUENT EARTHQUAKES AND VOLCANOES
CONSERVATIVE PLATES - DESCRIBE
OBLIQUE-SLIP,SLIDING OR TRANSFORM
MARGINS WHERE ONE PLATE SLIDES AGAINST ANOTHER
RELATIVE MOVEMENT IS HORIZONTAL AND CLASSIFIED AS EITHER
SINISTRAL (TO THE LEFT)
OR
DEXTRAL (TO THE RIGHT)
LITHOSPHERE IS NEITHER CREATED NOR SUBDUCTED
DO NOT RESULT IN VOLCANIC ACTIVIITY
THEY ARE THE SITES OF EXTENSIVE SHALLOW FOCUS EARTHQUAKES
OCCASIONALLY OF CONSIDERABLE MAGNITUDE
CONTINENTAL INTERIORS
SCATTERED EARTHQUAKES
ALONG OLD FAULT LINES AND IS ASSOCIATED WITH THE REACTIVATION OF THIS WEAKNESS EG CHURCH STRETTON FAULT IN SHROPSHIRE
EARTHQUAKES -
ARE A COMMON HAZARD
PRIMARY HAZARDS (GROUND MOVEMENT AND GROUND SHAKING)
SECONDARY HAZARDS LIKE LANDSLIDES AND TSUNAMIS CAN BE DEVELOP FROM THE EARTHQUAKE
CAN DEVELOP INTO A DISASTER ESPECIALLY WHEN THE EARTHQUAKES HAVE BOTH -
HIGH MAGNITUDE AND
OCCUR IN DENSELY POPULATED AREAS
WAYS OF PLATES MOVEMENT - X3
PULL AWAY FROM EACH OTHER
SLIDE PAST EACH OTHER
CRUNCH INTO EACH OTHER
PLATE MOVEMENT AND EARTHQUAKE TYPE
WAYS OF MOVEMENT - X3
PULL AWAY FROM EACH OTHER
SLIDE PAST EACH OTHER
CRUNCH INTO EACH OTHER
PLATE MOVEMENT AND EARTHQUAKE TYPE
WAYS OF MOVEMENT - X3
PULL AWAY FROM EACH OTHER ( DIVERGENT)
SLIDE PAST EACH OTHER (COVERGENT)
CRUNCH INTO EACH OTHER (CONSERVATIVE)
DIVERGENT PLATES (MOVE AWAY FROM EACH OTHER )
IMPACTS ??
DIVERGENT “SPREADING RIDGES” IN THE OCEANS
NEW OCEANIC CRUST = THINNER AND DENSER THAN THE CONTINENTAL CRUST IS CREATED.
FREQUENT SMALL EARTHQUAKES
TYPICALLY LOW HAZARD RISK, AS OCEAN BASED
DO NOT TYPICALLY TRIGGER TSUNAMIS
SLIDE PAST EACH OTHER
PRESENTS MORE RISK SAN ANDREAS FAULT, CALIFORNIA PACIFIC PLATE (MOVING NORTH) ZONE OF FRICTION AGAINST THE NORTH ATLANTIC PLATE (MOVING NORTH ALSO BUT AT A DIFFERENT SPEED )
CRUNCH INTO EACH OTHER OR MOVING TOWARDS EACH OTHER (SUBDUCTION)
GENERATES THE LARGEST AND MOST DAMAGING EARTHQUAKES AND CAUSES THE EMERGENCE OF MOUNTAINS/MOUNTAIN RANGES LIKE THE HIMALAYAS AND
The friction of the movement can also melt rocks and produce volcanoes.
This is also part of the rock cycle, because the plate that dives under the other one becomes part of the mantle and emerges much later from volcanoes and in seafloor spreading.
sometimes bends the other down into a deep seafloor trench.
DESTRUCTIVE PLATE BOUNDARIES - WHAT HAPPENS HERE ??
Sometimes called convergent or tensional plate margin.
Occurs when oceanic and continental plates move together.
The oceanic plate is forced under the lighter continental plate.
Friction causes melting of the oceanic plate and may trigger earthquakes.
CONSTRUCTIVE PLATE BOUNDARIES - WHAT HAPPENS HERE ??
SOMETIMES CALLED DIVERGENT PLATE MARGIN
AT OCEANIC RIDGES AND FORMS young fold mountains, rift valleys, ocean ridges, deep sea trenches and island arcs
