Earthquake Damage Can Be Reduced 2.3 Notes Earthquake Damage Can Be Reduced

Earthquakes can cause severe damage and loss of life Each year, there is about one earthquake with a magnitude of 8 or higher-this is an extremely powerful earthquake. https://www.youtube.com/watch?v=EAc3epDW8 UM Earthquakes can cause severe damage and loss of life

Earthquakes can cause severe damage and loss of life 8.0 earthquakes (or bigger) can destroy all buildings near their epicenters and cause huge loss of life. 9.0 Earthquake in Japan in 2011 lasted 6 minutes and killed 18,000 people. Earthquakes can cause severe damage and loss of life

Earthquakes can cause severe damage and loss of life Most deaths from earthquakes are caused by collapsing buildings and fires, not by the shaking of the ground. Earthquakes can cause severe damage and loss of life

The most powerful earthquakes can release more energy than 1 million weak earthquakes combined! Earthquake magnitude is described using a number scale from 0-10 (no real maximum possible value). Earthquake magnitude

The first number scale was developed in the 1930’s by Charles Richter and Beno Gutenberg. Describes an earthquake’s magnitude based on how fast the ground moves at a seismic station. Earthquake magnitude

Most scientists today prefer the moment magnitude scale (MMS), which measures the total amount of energy released by an earthquake. Earthquake magnitude

Both the Richter Scale and the MMS increase by 32 times with each whole number increase. A magnitude 5 earthquake is 32 times stronger than a magnitude 4 earthquake. A magnitude 6 earthquake is 1000 times stronger than a magnitude 4 earthquake! Earthquake magnitude

The MMS is more accurate and also allows scientists to measure the strength of earthquakes that occurred before seismographs were invented by measuring the strengths of rocks and length they moved along a fault. Earthquake magnitude

Damage from earthquakes Earthquakes can crack roads, buildings, damns, and any other structures that exist on top of a fault. Damage from earthquakes

Damage from earthquakes Earthquakes can also raise, lower, or tilt the ground surface. Damage from earthquakes

Damage from earthquakes An aftershock is a smaller earthquake that follows a more powerful earthquake in the same area. Sometimes aftershocks cause buildings that were weakened by an initial earthquake to collapse. Damage from earthquakes

Damage from earthquakes Fire caused by earthquakes can cause significant damage. In the 1906 San Francisco Earthquake, fire caused more than 90% of the damage. Damage from earthquakes

Damage from earthquakes Landslides are a common side effect of earthquakes as soil is shaken loose. Liquefaction is a process in which shaking of the ground causes soil to temporarily act like a liquid. Damage from earthquakes

Damage from earthquakes Liquefaction can cause structures to sink down into the soil or flow away with it. Damage from earthquakes

A tsunami is a water wave triggered by an earthquake, volcanic eruption, or landslide. Tsunamis can be taller than a 20-story building! Damage from tsunamis

A tsunami may be a single wave but can also be several waves that have different heights and arrive hours apart. https://www.youtube.com/watch?v=FCW fRs1frYE Damage from tsunamis

In deep water, tsunamis can travel at 700 km/hr (430 mi/hr)! As tsunamis approach coastlines, they slow down and grow in height. Damage from tsunamis

In 2004, an earthquake off the coast of Sumatra caused a tsunami. 280,000 people died. Damage from tsunamis

Scientists work to monitor and predict earthquakes We cannot predict the day or even year that an earthquake will occur. Sometimes there are signs and sometimes there are none at all. Scientists work to monitor and predict earthquakes

Scientists work to monitor and predict earthquakes Long term predictions can be generated. Example: An area might have a 60% chance of being hit by an earthquake with magnitude 7 or higher in the next 25 years. Scientists work to monitor and predict earthquakes

Scientists work to monitor and predict earthquakes Scientists around the world work constantly to try to better predict earthquakes, by observing the following things: Tilts or changes in the elevation of the ground Slow movements or stretching in rock The development of small cracks in the ground Scientists work to monitor and predict earthquakes

Structures can be designed to resist earthquake damage For safety during an earthquake, the best place to be is outside and away form any buildings. Structures can be built to withstand strong ground shaking. https://www.youtube.com/watch?v=NisWbAXfyW I Structures can be designed to resist earthquake damage

Structures can be designed to resist earthquake damage Scientists make maps of areas that have many earthquakes. Planners use these maps to develop rules for building in these areas. Structures can be designed to resist earthquake damage

Structures can be designed to resist earthquake damage For small buildings (like houses): Should be firmly fastened to the foundation Should have strong walls Structures can be designed to resist earthquake damage

Structures can be designed to resist earthquake damage For large buildings (like skyscrapers): Base isolators: flexible material between building and foundation Cross braces: X shaped braces added to a building to help a building keep its shape. Structures can be designed to resist earthquake damage

review The moment magnitude scale is based on the Amount of ground movement at a seismic station Amount of building damage caused by an earthquake Number of human deaths caused by an earthquake Amount of energy released by an earthquake review

review 2. One method of making a building earthquake resistant is to Add sand under the foundation Reduce the use of steel Make the walls of brick Use cross braces review