Earthquakes! Earthquakes!

What are Earthquake’s??? Earthquake = a sudden and violent shaking of the ground as a result of movements within the earth's crust or volcanic action

Stress = the total force acting on crustal rocks per unit of area -when stress overcomes the strength of the rocks involved, movement occurs along fractures in the rock (earthquakes) Strain = the deformation of materials in response to stress Epicenter = point on the earth's surface vertically above the focus of an earthquake Earthquake epicenter offshore or underwater, it can cause a massive tidal wave (tsunami). -Earthquakes can also cause/trigger landslides and/or volcanic activity

Three kind of stress: Compression = the maximum compressive stress that can be applied to a material before failure occurs Tension = a stress which stretches rocks in two opposite directions Shear = where the stress is parallel to the surface of the material

Hanging Wall = The block positioned over the fault Footwall = the block positioned below the fault

Types of Faults Compression causes horizontal and vertical movement Tension causes horizontal and vertical movement Shear causes horizontal movement

Types of Seismic Waves Squeeze and push rocks in the Seismic wave animation Squeeze and push rocks in the direction along which the waves are traveling. BODY WAVE Slower than P-waves. Similar to the movement of a jump rope that is jerked up and down at one end. BODY WAVE Slowest. Only travel along Earth’s surface. Cause the most destruction

Richter Scale -Numerical rating system that measures the energy of the largest seismic waves Developed in 1935 by Charles Richter in partnership with Beno Gutenberg, both of the California Institute of Technology. Charles Richter The Richter magnitude scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. It is a base-10 logarithmic scale obtained by calculating the logarithm of the combined horizontal amplitude of the largest displacement from zero on a Wood–Anderson torsion seismometer output. So, for example, an earthquake that measures 5.0 on the Richter scale has a shaking amplitude 10 times larger than one that measures 4.0. The effective limit of measurement for local magnitude is about ML = 6.8.

Other scales used Moment magnitude scale – a rating scale that measures the energy released by an earthquake. Takes into account the size of the fault rupture, amount of movement along the fault, and the rocks’ stiffness Modified Mercalli scale – rates the types of damage and other effects of an earthquake. Uses Roman numerals, goes from I - XII

10 Most Destructive Earthquakes Location Date Magnitude Chile May 22, 1960 9.5 Prince William Sound, Alaska March 28, 1964 9.2 Andréa of Islands, Aleutian Islands March 9, 1957 9.1 Kamchatka Nov. 4, 1952 9.0 Off western coast of Sumatra, Indonesia Dec. 26, 2004 Off the coast of Ecuador Jan. 31, 1906 8.8 Rat Islands, Aleutian Islands Feb. 4, 1965 8.7 Northern Sumatra, Indonesia March 28, 2005 India-China border Aug. 15, 1950 8.6 Feb. 3, 1923 8.5

1960 Valdivia earthquake Tsunami Animation News Coverage The 1960 Valdivia earthquake or Great Chilean Earthquake of May 22 1960 is the most powerful earthquake ever recorded, rating 9.5 on the moment magnitude scale. It occurred in the afternoon around 2:11 pm local time and its resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, south east Australia and the Aleutian Islands in Alaska. The epicenter was near Canete about 435 miles south of Santiago although Valdivia, Chile was the most affected city. It caused tsunamis that severely battered the Chilean coast, with waves up to 82 feet. The main tsunami raced across the Pacific Ocean and devastated Hilo, Hawaii. Waves as high as 35 feet were recorded 6,000 miles from the epicenter, and as far away as Japan and the Philippines. The death toll and monetary losses arising from such a widespread disaster can never be precisely known. Various estimates of the total number of fatalities from the earthquake and tsunamis have been published, with the USGS citing studies with figures of 3000-5700 killed, and another source uses an estimate of 6000 dead. Different sources have estimated the monetary cost ranged from 400 million to 800 million US dollars. In 2005 terms adjusted for inflation about 2.6 to 5.2 billion Tsunami Animation News Coverage

Map Showing the Areas Affected by the Tsunami

Video Footage During an Earthquake https://www.youtube.com/watch?v=4Y-62Ti5_6s