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Earthquakes, Tremors and Tsunamis
Earthquakes - The Tech Museum in San Jose, California, has a dynamic online exhibit on earthquakes: what they are, why they occur, and why we can't predict them (yet). It includes an interesting history of the seismograph, used to record earthquake activity. The first one may have been invented in China in A.D. 136. It involved dragon heads positioned around a copper vessel. Each dragon mouth held a ball. Below the dragons weremouthed frogs. In the event of an earthquake, a ball would fall into a frog's mouth. By noting which balls had dropped, one could tell how the ground moved in response to the quake.
Earthquakes - One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible aftereffects. An earthquake is a sudden movement of the Earth, caused by the abrupt release of strain that has accumulated over a long time. Today we are challenging the assumption that earthquakes must present an uncontrollable and unpredictable hazard to life and property. Scientists have begun to estimate the locations and likelihoods of future damaging earthquakes. Sites of greatest hazard are being identified, and definite progress is being made in designing structures that will withstand the effects of earthquakes.
Earthquakes - The Terror from Below - The ancient Babylonians believed that the "Jupiter Effect" of planetary alignment somehow caused an increase in earthquake activity on Earth. While that theory has never been scientifically proven, no one really knows how to predict earthquakes. We think we know what causes them, though: plate tectonics. This theory says that the Earth's crust is made up of jigsaw puzzle-like plates floating on a layer of liquid magma below. The plates touch and can slide against each other. The areas where they meet are called fault zones. As plates push against each other, stresses build until suddenly they are released in an event we call an earthquake. That's the simplified version--for more detail, visit this site, created by students for the ThinkQuest competition.
Earthquakes in Maryland - Earthquakes can be among the most devastating and terrifying of natural hazards. Although earthquakes have been the object of study and superstition for many centuries, the modern science of seismology really gained impetus after the famous San Francisco earthquake of 1906. Since then, geologists have learned much more about the structure and composition of the earth's interior and, more recently, have made progress in earthquake forecasting and in hazard and risk mitigation. Learn more here!
Electronic Desktop Project - Virtual Earthquake - How do scientists figure out where the starting point, or epicenter, of an earthquake was? In this cool simulation, you pick the general region for your test earthquake (California, Japan, Mexico). Use the easy-to-follow instructions to examine seismograms and pinpoint the epicenter as well as the relative strength of your quake.
Mid-America Earthquake Center - The Mid-America Earthquake Center is the first of its kind for addressing mitigation of earthquake effects in the central and eastern United States. The group of core institutions coordinates research and implementation activities with a vision towards making a difference for the better on seismic hazards evaluation and loss reduction strategies.
National Earthquake Information Center: Current Earthquake Information - How many earthquakes do you think occur in the world every day? Probably a lot more than you realize. Seismic activity is monitored day and night, and any recorded activity is posted to this site not long after the real time of each event. Check here and you'll be surprised to find there's a whole lot of shakin' goin' on.
Record of the Day - Where in the world was the biggest earthquake today? The answer is just a click away. This site will show you the most recent large earthquake recorded by the Cal Tech Seismological Laboratory in California. You can look at the actual graph that was recorded by their seismograph. Maps show you where the earthquake's epicenter was. Be sure to check often. Earthquakes are happening around the world all the time.
Seismo-Cam - Want to know what's shaking in L.A.--literally? Live shots of a seismograph as it's tracking activity in the Southern California area can be monitored here. If nothing's happening while you're watching, you can look at some archived shots from past events, including some BIG temblors. There are also lots of great links to sites with info on earthquakes, including one at the University of Nevada that explains how seismographs work.
This Dynamic Earth - Have you ever seen a bumper sticker that says "Stop Plate Tectonics!"? It's something that's an impossible task. Although continental land masses look pretty stable, they are actually moving all the time. Sometimes they just drift along very very slowly. Other times they shift or move suddenly, and that causes an earthquake. The plates don't just cruise around at random, but scientists aren't completely sure what's "driving" them, either. This nicely illustrated site will explain it all.
Tsunami Fact Sheet - A tsunami (pronounced "soo-nahm'-ee") is a series of waves generated by an undersea disturbance such as an earthquake. From the area of the disturbance, the waves will travel outward in all directions, much like ripples caused by throwing a rock into a pond. Find out what happens before, during and after a Tsunami.
Tsunami! - Tsunamis cause severe damage to coastal areas. Learn about the Tsunami Warning System and what you can do to protect yourself if one is issued for your area. But if you are ever near the ocean and feel a deep rumble in the earth, don't wait for an official warning--get moving. It could be the first sign of a tsunami, and once the wave gets to shore, you will not be able to outrun it. Another early sign of trouble is that sometimes, just before a tsunami, the water is sucked out to sea, exposing the ocean floor. This is a warning that you should move inland quickly or to a higher area, such as the top floors of a high-rise building. You'll also find detailed information about recent tsunami events as well as links to other tsunami sites.
Tsunamis & Earthquakes at the USGS - General information on how earthquakes generate tsunamis and summaries of tsunami research using animations and VRML models
USGS National Earthquake Information Center - The NEIC has three main missions. First, the NEIC determines, as rapidly and as accurately as possible, the location and size of all destructive earthquakes that occur worldwide. The NEIC disseminates this information immediately to concerned national and international agencies, scientists, and the general public. Second, the NEIC collects and provides to scientists and to the public an extensive seismic database that serves as a solid foundation for scientific research, principally through the operation of modern digital national and global seismograph networks and through cooperative international agreements. The NEIC is the national data center and archive for earthquake information. Third, the NEIC pursues an active research program to improve its ability to locate earthquakes and to understand the earthquake mechanism. These efforts are all aimed at mitigating the risks of earthquakes to mankind; and they are made possible by the fine international cooperation that has long characterized the science of seismology.
Why the Earth Shakes: Seismic Science - Throughout human history there have been many attempts to explain earthquakes, from a disturbance created by growling demons who live beneath the earth to the movements of the giant tortoise who carries the world on his back. Over time, other ideas were proffered: perhaps these shakings were the result of great subterranean explosions, or the collapse of huge underground caverns. See what else this site unveils!
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