Fs2014 3018. Seismic History: The Deadly 1985 Mexico City Earthquake. On this day in 1985, a magnitude 8.0 earthquake rocked Mexico City and its surrounding environs at 9:17 a.m.
EDT (7:17 a.m. local time). The quake was felt as far away as Guatemala City, Guatemala and Houston, Texas, over an area of about 319,000 square miles (825,000 square kilometers), but the most intense shaking occurred in Mexico City, Ciudad Guzman and the Pacific Coast towns of Lazaro Cardenas, Ixtapa and La Union, according to the U.S. Geological Survey (USGS). Error loading player: No playable sources found The earthquake caused landslides, rockslides, and sandblows, opened cracks in the ground and damaged or destroyed buildings. The damage killed at least 9,500 people according to USGS figures, with another 30,000 people injured and more than 100,000 left homeless. Building Resonance: The resonant frequency of different seismic waves- Incorporated Research Institutions for Seismology. Why do some buildings fall in earthquakes?
All buildings have a natural, period, or resonance, which is the number of seconds it takes for the building to naturally vibrate back and forth. The ground also has a specific resonant frequency. Hard bedrock has higher frequencies softer sediments. Earthquake Testing movie. Movie courtesy of NSF.
Scientists are using the world's largest "shake table" to test new construction methods for buildings in areas prone to earthquakes. They believe they have devised a system to build taller, wood-frame buildings that can still safely withstand even very powerful tremors. Right-click (Windows) or Option-click (Mac) here to download a copy of this video in QuickTime format. Shop Windows to the Universe Science Store! Animations for Earthquake Terms and Concepts. Earthquake Intensity- Incorporated Research Institutions for Seismology. What controls the shaking you feel during an earthquake?
We compare a light bulb to an earthquake to clarify the difference between magnitude and intensity, two concepts that are often used interchangably, but in error. Though both are related to a measured earthquake, intensity reflects what is felt during an earthquake at many locations, and the magnitude is a single measured value. Intensity was originally calculated by gathering personal, anecdotal reports during an earthquake. intensity can be estimated by instrumentally, but the definitive intensity is assigned either via Did You Feel It ( or via expert judgement, as was done historically. (An IRIS/USGS collaboration)
Geophysics Unit of Menlo Park-GUMP. For additional information see the following publications: Watt, J.T., Graymer, R.W., Simpson, R.W., Ponce, D.A., Jachens, R.C., Phelps, G.A., and Wentworth, C.M., 2007, A Three-dimensional geologic model of the Hayward-Calaveras Fault junction: Eos Trans.
AGU, v. 88, no. 52, Fall Meet. Water cycle - animated diagram. Images - Multimedia Gallery Page 2. 2014 South Napa CA M6 Earthquake - August 24. 2014 Napa earthquake continued to creep, weeks after main shock: Continuing seismic activity could pose additional hazards to infrastructure. Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016.
Animations for Earthquake Terms and Concepts. AmplificationShaking levels at a site may be increased, or amplified, by focusing of seismic energy caused by the geometry of the sediment velocity structure, such as basin subsurface topography, or by surface topography.
AsperityAn asperity is an area on a fault that is stuck. The earthquake rupture usually begins at an asperity. AttenuationWhen you throw a pebble in a pond, it makes waves on the surface that move out from the place where the pebble entered the water. The waves are largest where they are formed and gradually get smaller as they move away. Earthquakes for Kids.
Virtual Earthquake - An Introduction. What's an earthquake?
Earthquakes occur because of a sudden release of stored energy. This energy has built up over long periods of time as a result of tectonic forces within the earth. Most earthquakes take place along faults in the upper 25 miles of the earth's surface when one side rapidly moves relative to the other side of the fault. This sudden motion causes shock waves (seismic waves) to radiate from their point of origin called the focus and travel through the earth.
Fault Motion Animations : IRIS. Explaining Earthquakes - KQED QUEST. The Science Behind the 1906 Earthquake. A New Earthquake-Proof Calaveras Dam - KQED QUEST. The Hayward Fault: Overdue for Disaster - KQED QUEST. Shaking Things Up: 10 Resources for Exploring Earthquakes. Does the anniversary of the 1906 San Francisco earthquake trigger a landslide of questions from your students about why earthquakes happen, what faults are, or if scientists can predict quakes?
Seismic Waves - 2004 Sumatra Quake & Tsunami. Jumbo Seismic Monitor. IRIS Earthquake Browser. IRIS: MB5.1 North Korea. Quake or Bomb? Seismic Waves Speak Truth, Even If Nations Don't. Last week, North Korea tested what it claimed to be a hydrogen bomb, or as the North Korean government declared in its official statement, an “H-Bomb of justice.”
However, it’s not likely that North Korea has actually developed a hydrogen bomb and successfully tested it on 6 January local time (the evening of 5 January on the U.S. East Coast), as announced. The U.S. Geological Survey recorded the subsequent seismic event as having a 5.1 magnitude, which is much lower than would be expected from such a powerful weapon. But even if North Korea or anyone else conducting a clandestine nuclear test makes no announcement, seismologists can still figure out if an underground bomb test or an earthquake took place by analyzing how energy propagates from the seismic event in question.
Explosions Send Compression Waves in All Directions P waves are the fastest-moving type of seismic waves. Bigger Interior Waves Suggest an Explosion. A Tested, Inexpensive Way to Protect Buildings from Earthquakes — NOVA Next. In 1985, construction workers in the southern California city of Rancho Cucamonga put the finishing touches on an unremarkable looking yet revolutionary building.
Foothill Communities Law and Justice Center is a four-story courthouse located just 12 miles from the San Andreas fault, the crack in the Earth’s crust responsible for the devastating 7.9 magnitude quake that struck southern California in 1857 and the infamous 1906 earthquake in San Francisco. Geologists think the fault is due for a “big one” with a magnitude that could top 8.0. If and when that comes, the Foothill Communities Law and Justice Center will be prepared, not because it’s anchored in stone, but because sits atop its foundations on pads of rubber.
The Foothill Communities Law and Justice Center in Rancho Cucamonga, California. Cloaking Buildings from Earthquakes and Tsunamis — NOVA Next. In August 2012, civil engineers from the French firm Menard drilled three rows of shallow holes into the soft clay soil at the base of the Alps near Grenoble. How an Earthquake, Tsunami, and Firestorm All Hit Lisbon at Once.
StructureDesign. IRIS - Incorporated Research Institutions for Seismology. How does a seismograph record the incoming P and S waves? Generalized P and S-wave behavior are shown on this simplified model of a vertical-component seismograph station. Animation of the principles of a drum-style vertical seismograph station that records up-and-down movement. Seismographs are designed so that slight earth vibrations move the instrument. Incorporated Research Institutions for Seismology. How do seismometers measure vertical ground motion? Animation of the principles of a drum-style vertical seismograph station that records up-and-down movement. Seismographs are designed so that slight earth vibrations move the instrument. IRIS - Incorporated Research Institutions for Seismology. How does a seismometer measure horizontal ground motion? IRIS - Incorporated Research Institutions for Seismology.
IRIS - Incorporated Research Institutions for Seismology.