DRRR VOLCANIC

dynamic

our planet is

plates

The outermost layer of the earth is broken into pieces. These pieces called____are moving, away or toward each other.

thin

New parts of a plate rise because they are warm and the plate is

ridge push

As hot magma rises to the surface at spreading ridges and forms new crust, the new crust pushes the rest of a plate out of its way. This is called

convection

Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a

tectonic and volcanic

types of natural earthquakes

tectonic

Earthquake produces by sudden movement along faults and plate boundaries.

volcanic

Earthquakes produced by the movement of magma beneath volcanoes.

intensity perceived and magnitude based

Ways of describing the strength of an earthquake

ground shaking, ground rupture, liquefaction, earthquakes-induced landslide

earthquake hazards:

Ground shaking

 It refers to what we feel when energy built up by the application of stress to the lithosphere is released by faulting during an earthquake.

ground shaking

Technically, it refers to the disruptive up and down and sideways motion experienced during an earthquake.

fault

is a fracture on which one body of rock slides past another.

primary waves, secondary waves, surface waves,

types of seismic waves

Primary Waves

The fastest seismic waves are called

primary waves

These waves are the first to reach any particular location after an earthquake occurs

primary waves

can travel through solids, liquids, and gases.

5km per sec

Primary waves travel through Earth’s crust at an average speed of about

primary waves

Buildings also experience this push and pull as primary waves pass through the ground they are built on.

secondary waves

These are the second seismic waves to arrive at any particular location after an earthquake, though they start at the same time as primary waves.

secondary waves

travel through Earth’s interior at about half the speed of primary waves

secondary waves

As they pass through a material, the material’s particles are shaken up and down or from side to side, shaking small buildings back and forth as they pass.

primary waves

As they pass through a material, the particles of the material are slightly pushed together and pulled apart.

secondary waves

can travel through rock, but unlike primary waves, they cannot travel through liquids or gases.

surface waves

These are seismic waves that move along Earth’s surface, not through its interior.

surface waves

They make the ground roll up and down or shake from side to side.

surface waves

cause the largest ground movements and the most damage.

surface waves

travel more slowly than the other types of seismic waves.

ground rupture

The creation of new or the renewed movement of old fractures, oftentimes with two blocks on both sides moving in opposite directions.

Liquefaction

takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking.

flow failure, lateral spread, ground oscillation, loss of bearing strength

Types of Liquefaction Features

flow failure

Considered the most dangerous type of ground failure due to liquefaction, this occurs on liquefiable slope material with steepness greater than 3 degrees.

lateral spread

blocks or broken pieces of the flat or very gentle grounds above the liquefied zone move laterally.

ground oscillation

Due to the flat or nearly flat slope, the ground is unable to spread and instead oscillates like a wave.

loss of bearing strength

loss of strength of sediments resulting in tilting of houses and floating of buoyant structures that are anchored on the liquefied zone.

removal of support, ground water pressure, volcanic eruption, intense rainfall, snowmelt, human intervention, earthquakes

 Why Landslide Occur

topples, rock falls, slides, lateral spread, flows

types of landslide

tsunamis

Travel 20-30 miles per hour with waves 10-100 feet high.

tsunamis

Causes flooding and disrupts transportation, power, communications, and the water supply.

tsunami generation

  A tsunami may occur when ocean water is displaced suddenly, causing the formation of waves that reach the shore in large heights. The movement of an offshore fault during an earthquake may trigger displacement of ocean water if accompanied by an uplift of the seabed

tsunami generation

This causes a piece of seabed to be pushed up onto the overlying ocean. The water above is displaced or pushed up, triggering waves to be formed.

drawback

when the ocean recedes drastically or the water level falls unusually along the shoreline.

lahar

move rapidly down valleys like rivers of concrete. \can occur with or without a volcanic eruption.

lahar

pick up material as they travel, which can cause damage to structures in their path

lahar

cause serious economic and environmental damage to river valleys and flood plains.

ashfalls

consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions

ashfalls

Also refer to all explosive eruption products

ashfalls

Can pose significant disruption and damage to water, buildings, transportation, power supply, communications equipment and agriculture

ballistic projectile

Volcanic explosions can propel rock fragments on ballistic trajectories that may differ from the wind direction.

steam blast eruptions

no warning

magmatic eruptions

involve rise of magma toward the surface

topples

Occur suddenly when a massive part of every steep slope breaks loose and rotates forward.

rock falls

Involve chunks of detached rock that fall freely from some distance or bounce and roll down the steep slope

slides

Involve large blocks of bedrock that break free and slide down along a planar or curved surface

lateral spread

Are triggered by earthquakes and affect gentle slopes with less than 10 degrees of inclination. Slope material loses cohesion through liquefaction caused by the shaking during earthquakes.

flows

involve downslope motion of fine-grained clay, silt, and fine sand made mobile by water saturation. These flows include mudflows and earthflows and are common during the rainy season.