Why is it important to understand earthquakes on a global, national and local scale?
Feb 28, 2010
in
Earthquake Questions
What kinds of “earthquake measures” (precautions) are communities taking to ensure that a big earthquake will cause the least amount of damage?
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One comment
Charles K on February 28, 2010 at 1:44 pm
To understand earthquakes allows to save lives, to reduce damages,injuries,to build buildings more earthquakes resistant and find the locations that are more prone to earthquake . EARTHQUAKE SAFETY MEASURES
HAZARD HUNT- Identify potential dangers in the home using common sense, fore-sight, and your imagination to reduce risk in the event of an earthquake. Take active security measures, surveying the home for possible hazards. Take steps to correct and secure these hazards, reducing risk.
HAZARD-RISK REDUCTION
Tall heavy furniture which could fall; fix it to a wall.
Hot water heaters that can fall away from pipes and rupture need to be anchored to a wall. Use flexible gas line connectors.
Appliances that can be moved can break electrical or gas lines and must be anchored to a stable location with flexible connections.
Be sure heavy mirrors or picture frames are placed away from beds and mounted securely to the wall.
Cabinets containing breakable items should have latches and heavy objects should be placed low to the ground.
Flammable liquids must be stored securely away from flame.
Masonry chimneys need bricks checked. Firmly support the roof.
Beds should not be placed near windows.
Glass bottles should not be placed on high shelves.
FAMILY EARTHQUAKE DRILLS will help you and your family plan and react; remembering where to seek shelter and how to protect yourselves.
Identify safe spots and places in each room.
-Under a doorway, sturdy table, desk, or kitchen counter.
-Against an inside corner or wall; cover head with hands.
-Know and reinforce these locations by practice.
Beware of danger zones and stay clear of:
-Windows that may shatter, including mirrors and picture frames.
-Heating units, fireplace, stove, and area around chimneys.
-Cabinets, refrigerators, and bookcases that may topple.
Practice safe quake actions:
-Conduct drills, check reactions and choices.
Discuss what to expect following a major earthquake and be prepared:
-To treat and take care of injuries.
-To check for gas leaks and learn where and how to turn off the gas, power, and water at main switches and valves.
-For aftershocks and exiting the building.
-Remember to stay close and if separated to activate the emergency communication plan.http://sidlinger.tripod.com/esm.html ——— Measuring and locating earthquakes
Main article: Seismology
Earthquakes can be recorded by seismometers up to great distances, because seismic waves travel through the whole Earth’s interior. The absolute magnitude of a quake is conventionally reported by numbers on the Moment magnitude scale (formerly Richter scale, magnitude 7 causing serious damage over large areas), whereas the felt magnitude is reported using the modified Mercalli scale (intensity II-XII).
Every tremor produces different types of seismic waves which travel through rock with different velocities: the longitudinal P-waves (shock- or pressure waves), the transverse S-waves (both body waves) and several surface waves (Rayleigh and Love waves). The propagation velocity of the seismic waves ranges from approx. 3 km/s up to 13 km/s, depending on the density and elasticity of the medium. In the Earth’s interior the shock- or P waves travel much faster than the S waves (approx. relation 1.7 : 1). The differences in travel time from the epicentre to the observatory are a measure of the distance and can be used to image both sources of quakes and structures within the Earth. Also the depth of the hypocenter can be computed roughly.
In solid rock P-waves travel at about 6 to 7 km per second; the velocity increases within the deep mantle to ~13 km/s. The velocity of S-waves ranges from 2–3 km/s in light sediments and 4–5 km/s in the Earth’s crust up to 7 km/s in the deep mantle. As a consequence, the first waves of a distant earth quake arrive at an observatory via the Earth’s mantle.
Rule of thumb: On the average, the kilometer distance to the earthquake is the number of seconds between the P and S wave times 8. Slight deviations are caused by inhomogenities of subsurface structure. By such analyses of seismograms the Earth’s core was located in 1913 by Beno Gutenberg.
http://en.wikipedia.org/wiki/Earthquake#Measuring_and_locating_earthquakes