Naturel disasters Exercise.. please more details will be great. thanks 1. a. Exp
ID: 113458 • Letter: N
Question
Naturel disasters Exercise.. please more details will be great. thanks
1. a. Explain what an earthquake is and what causes it
b. Explain the process of how an earthquake’s epicenter is located)
c. Describe each of the 4 kinds of seismic waves produced by an earthquake, how they behave, how fast they travel, and what impact they have.
2. a. Explain what a tsunami is and how the one associated with the Japan March 11, 2011
Earthquake was initiated, what event set it in motion
b. What other events can cause a tsunami?
c. How does the shape of the coastline determine the impact that an incoming tsunami can have?
d.. What do we know about how many waves will be produced, which is the largest wave, how far apart they will be from each other time-wise or distance-wise)?
e. How does a tsunami travel in the open ocean with respect to its speed and size as a wave?
f. How does a tsunami behave as a mass as it approaches shore along a linear coast line, with
gently sloping upward ocean bottom and beach towards that shoreline?
3. Go to the U.S. Geological Survey website (http://www.usgs.gov) and search their site on the search engine provided there for the following: Japan Earthquake, March 11, 2011. Write a brief half page summary of what happened that set off the earthquake and tsunami event of this date.
4. a. How can we know that tsunami have happened in our coastal areas prior to written records and
European settlement ?
b. How does an early warning system for tsunami events work ?
c. All three coasts of the US lower 48, Alaska and Hawaii can have tsumani events impact their
coasts from stick-slip subduction action, underwater landslides, mountains and volcanoes mass
wasting and land sliding into the sea, or an asteroid impact to the ocean. For the following explain
why they have a risk of tsunami in each case and where the risk is located:
The Pacific Northwest States of the US
The entire West Coast in relationship to Hawaii
The Atlantic Coast of the US with respect to the Canary Islands
5. a. How can a community at risk like our Pacific Northwest (Northern California, Oregon, Washington State, British Columbia prepare for an earthquake and tsunami event that it knows is highly likely to happen at some time in the future?
b. If you are traveling in these areas impacted by earthquake and tsunami, what should you do if there is a warning sounded after a major seismic event and a tsunami may be on the way?
Explanation / Answer
(a) In simple words an earthquake (or quakes, tremors) is defined as shaking, rolling or rumblings of the surface of earth. It generally caused by the movement of the earth crust or sudden breakage of the rocks under the earth surface along with releasing of pent of energy which produces the seismic waves causes the shaking of the earth surface, in other words the earthquake.
(b) For locating an earth quake epicenter you need seismograph of particular earth quake along with scale ruler and compass. Generally seismologists need at least 3 seismographs for plotting the exact location of the epicenter of an earthquake .The point where at least three circles intersect on a map is the epicenter of the earthquake.
You can refer the following pages with complete brief notes how to come about finding the epicenter along with pictures of seismograph and map’s ‘http://www.geo.mtu.edu/UPSeis/locating.html’ or’’ http://www.instructables.com/id/The-Steps-to-Locating-the-Epicenter-of-an-Earthqua/’’
(c) Seismic waves are basically of four types, They are:
(i) P-waves are the first waves to arrive on a complete record of ground shaking because they travel the fastest. It’s name’ P also taken from the primary means first. P waves travels at a speeds between 1 to 14 km/sec. The slower speeds refers to P-wave traveling in water, the higher speeds refers to waves travelling near the base of Earth's mantle.
(ii) Secondary waves or S waves generally travels slower if compared with the speed of P waves. It also can be called as "shear" waves due to the reason of shearing of the material to which it propagate rather the changing the volume of the material. These are transverse waves, it vibrates the ground in a direction or perpendicular or transvers to the direction in which it was traveling.
(iii) Lovewaves also vibrates the ground horizontally perpendicular to direction it travels. These are also transverse waves. Love waves created due to the interaction of s waves with shallow structures or earth surface. The speed of love waves depends on the wave's period. Mostly earthquakes produce Love waves over a range of periods from 1000 to a fraction of a second. The velocity are ranging between 2 to 6 km/second due to the reason of each period travels with different velocity
(iv) Rayleigh waves: these travels at low speed among all the seismic waves and are complicated in nature. Similar to Love waves these are also dispersive in nature due to that its speed depends on the wave period and the near-surface geologic structure, more over these are also decrease in amplitude with depth. Typical speeds ranging between from 1 to 5 km/s.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.