FAULT

FAULTFAULT is a break in the earths crust along which movement can take place causing an earthquake.

KINDS OF FAULTNORMAL FAULTOne block can move down and the other can move up or vise versa. Normal faults occur where forces tend to pull sections of the earths crust part.Aka: Gravity Fault

Aka: Gravity faultA dip-slip fault in which the hanging wall moves downward relatively to the footwall4THRUST FAULTOne block moves over another blocks. It occurs where forces tend to push sections of the crust together.A low angle fault (45 degrees) in which the hanging wall is moved upward in relation to the footwall.It is characterized by the horizontal compression rather by the vertical displacement.

FAULT SCARPA fault scarp is a small step on the ground surface where one side of a fault has moved vertically with respect to another.Aka: Reverse FaultThe material above the fault plane that moves up in relation to the material below.

It shows the surface area of the crust.6EARTHQUAKESEarthquake can occur along faults, Faults are cracks in the earth where sections of a plate are moving in different directions due to opposing forces at the edges of the plate. An earthquake is a shaking of the ground caused by the sudden breaking and movement of large sections (tectonic plates) of the earth's rocky outermost crust.

a sudden release of energy in the earth's crust or upper mantle, usually caused by movement along a fault plane or by volcanic activity and resulting in the generation of seismic waves which can be destructive.

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves.Seismic waves are waves of energy that travel through the Earth's layers, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations. Seismic waves are studied by geophysicists called seismologists. Seismic wave fields are recorded by a seismometer, hydrophone (in water), or accelerometer.9What is an earthquake?An earthquake is what happens when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault or fault plane. The location below the earths surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter.

Fault or fault plane = the surface where when two blocks of the earth suddenly slip past one another

Hypocenter = the location below the earths surface where the earthquake starts

Epicenter = the location on the surface of the earth directly above the hypocenter 10The fault plane is the planar (flat) surface along which there is slip during an earthquake.

Fault plane diagram11The hypocenter is the point within the earth where an earthquake rupture starts. The epicenter is the point on the earth's surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture beginsThe epicenter is the point directly above it at the surface of the Earth. Also commonly termed the focus.

The hypocenter (literally: 'below the center' from the Greek: ) refers to the site of an earthquake or a nuclear explosion. In the former, it is a synonym of the focusThe term hypocenter also refers to the point on the Earth's surface directly below an atmospheric explosion

the epicenter is directly above the point where the fault begins to rupture, and in most cases, it is the area of greatest damage12Plate Tectonics

A scientific theory of geology developed to explain the phenomenon of continental drift. large-scale motion of Earths lithosphere.These plates are constantly in motion due to the convection currents of the Earth, which are caused by heat cycles in the mantle, the fluid layer beneath the Earth's crust. At the bottom of the mantle, the fluid gets extremely hot due to its proximity to the core. The hot liquid rises to the top of the mantle. This movement creates what is known as convection currents, which causes the tectonic plates to move.Continental drift,large-scale motion or horizontal movements of continents relative to one another and to the ocean basins during one or more episodes of geologic time. 13Earthquake Waves or Seismic Waves

What Are Seismic Waves?Seismic waves are sound waves travelling through and across the earth that are produced by earthquakes. Some waves travel down through the earth and other waves travel over the surface of the ground. The surface waves travel faster than the interior waves and this is recorded on seismographs.

Seismic waves can be classified into two basic types: body waves which travel through the Earth and surface waves, which travel along the Earth's surface. Those waves that are the most destructive are the surface waves which generally have the strongest vibration.

Two basic types of seismic waves: Primary or Compression Waves (P Waves)Secondary or Shear Waves (S Waves)

P- and S- waves are called "body waves" because they can travel through the interior of a body such as the Earth's inner layers, from the focus of an earthquake to distant points on the surface.

Seismic waves can be classified into two basic types: body waves which travel through the Earth and surface waves, which travel along the Earth's surface. Those waves that are the most destructive are the surface waves which generally have the strongest vibration15P-waves travel fastest. They consist of successive contractions and expansions, just like sound waves in air. The motion of the particles in the rocks that the waves travel through is parallel to the direction of the wave.

S-waves are slower than P-waves. They are transverse waves, which means that the particle motion is at right angles to the direction of travel. S-waves cannot travel through air or liquids.

The Slinky and The Rope

The P waves move in a compressional motion similar to the motion of a slinky, while the S waves move in a shear motion perpendicular to the direction the wave is travelling.

P-waves are the fastest type of seismic wave. As P-waves travel, the surrounding rock is repeatedly compressed and then stretched.

S-waves arrive after P-waves because they travel more slowly. The rock is shifted up and down or side to side as the wave travels through it. Magnitude vs IntensityMagnitude measures the energy released at the source of the earthquake. Magnitude is determined from measurements on seismographs. The Magnitude indicates the amount of energy released at the source (or epicentre) and is measured by the open-ended Richter Scale.Intensity measures the strength of shaking produced by the earthquake at a certain location. Intensity is determined from effects on people, human structures, and the natural environment and is measured by the Modified Mercalli Scale which classifies earthquake affects into twelve grades.Magnitude and Intensity measure different characteristics of earthquakes.

Developed in 1935 by Charles Francis Richter

18Magnitude:

Magnitude is a quantitative measure of the actual size of the earthquake. Based on maximum displacement, magnitude is determined and through magnitude energy released can be computed.Intensity :

Intensity is a qualitative measure of the actual shaking at a location during an earthquake. Intensity is determined from three features of shaking -

1) perception by people and animal

2) performance of building

3) changes to natural surrounding.

Abbreviated Modified Mercalli Intensity Scale

I. Not felt except by a very few under especially favorable conditions. II. Felt only by a few persons at rest, especially on upper floors of buildings. III. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated. IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop. VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.Abbreviated Modified Mercalli Intensity Scale

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. IX. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent. XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly. XII. Damage total. Lines of sight and level are distorted. Objects thrown into the air.

Richter Magnitude ScaleMagnitude ScaleDescription2.5 or lessUsually not felt, but can be recorded by seismograph.2.5 to 5.4Often felt, but only causes minor damage.5.5 to 6.0Slight damage to buildings and other structures.6.1 to 6.9May cause a lot of damage in very populated areas.7.0 to 7.9Major earthquake. Serious damage.8.0 or greaterGreat earthquake. Can totally destroy communities near the epicenter.Magnitude / Intensity ComparisonThe following table gives intensities that are typically observed at locations near the epicenter of earthquakes of different magnitudes.

MagnitudeTypical MaximumModified Mercalli Intensity1.0 - 3.0I3.0 - 3.9II - III4.0 - 4.9IV - V5.o-5.9VI - VII6.0-6.9VII - IX7.0 and higherVIII or higherThe philippines as an earthquake countryThe Philippines lies along the Pacific Ring of Fire, which causes the country to have frequent seismic and volcanic activity. Much larger numbers of earthquakes of smaller magnitude occur very regularly due to the meeting of major tectonic plates in the region.The Philippine Archipelago lies between two major tectonic plates of the world. The northwestward- moving Pacific Plate presently pushing the Philippine Sea Plate beneath the eastern side of our archipelago. The oceanic parts of the slower-moving Eurasian Plate are being subducted along the western side of Luzon and Mindoro and the northern sections of the Zamboanga Peninsula with Western Mindanao. These plate interaction, displacements along the Philippine Fault Zone which decoupled the northwestward motion of the Pacific with the southeastward motion of the Eurasian Plate, and movements along other active faults are responsible for the present-day high seismicity of the Philippine Archipelago. There are at least 5 earthquakes per day occur in the philippines, based on the distribution of earthquake epicenters. 25Bohol EarthquakeTwenty-three years ago, on July 16, 1990, the Philippines was hit by one of the most devastating earthquakes in recent times. A 7.8-magnitude earthquake hit the northern part of Luzon,

A 7.2 magnitude earthquake struck Bohol province in central Philippines on 15 October 2013.Over 344,300 people are displaced with 80 per cent living in makeshift shelters built in open spaces near their damaged homes.

26Residents stand next to a long earthen wall which formed following the Oct. 15 earthquake in Barangay Anonang in Inabanga, Bohol. Phivolcs scientists said the wall is the face of a previously unknown fault line which caused the magnitude 7.2 quake

Friday, March 8, 2013PLANETARY TREMORS: "New" Earthquake Fault Discovered In Manila - Could Result In Monumental Geological Upheaval In The Philippines!

March 08, 2013 - PHILIPPINES - While studying movement patterns in the earth under Metro Manila, geologists have discovered a boundary or "ridge" a possible fault line between flood-prone subsiding areas and gradually rising areas in the metro