About Us. B2B Publishing. Business Visionaries. Hot Property. Times Events. Times Store. Facebook Twitter Show more sharing options Share Close extra sharing options. But what exactly is magnitude? Magnitude 6. How a seismogram worked. USGS Originally, the definition of magnitude related to seismograms, in which machines used an ink stylus to record rapid motions on a rolling drum of paper that would measure shaking. The freeway collapsed in the massive Loma Prieta earthquake.
This week's magnitude 7. The Sept. Magnitude 8: The aftermath of the earthquake in Mexico City. Intensity 9, or "violent," shaking, only struck a small section of Southern California in the magnitude 6. Vast swaths of the region was hit by less severe shaking. USGS That earthquake was a magnitude 6. Magnitude 9: A street in Ofunato, in Japan's Iwate prefecture, after an earthquake struck off the coast in , triggering a tsunami. What intensity shaking would Southern California feel?
Meanwhile, one hypothetical magnitude 7. Can you describe it more? Intensity 2: Weak — Felt only by a few persons at rest, especially on upper floors of buildings. Intensity 1: Not felt — Not felt except by a very few under especially favorable conditions. Magnitude 9. Geological Survey, Seward Highway near Anchorage is badly damaged after the massive quake off Alaska.
What happened to the Richter scale? Look up your address on these databases Why some buildings crumbled and others survived the Mexico City quake: A sober lesson for California Fearing a big earthquake like the one in Mexico isn't enough. Here's how to turn anxiety into action Mexico City residents whose buildings survived the quake thought they'd be safe in the next big one.
Rong-Gong Lin II. Follow Us twitter instagram email facebook. More From the Los Angeles Times. An earthquake's intensity is determined by collecting felt reports or by measuring the actual shaking of the ground. Intensity values are assigned using the Modified Mercalli Intensity Scale. Unlike magnitude, intensity may vary greatly from one place to another for a given earthquake.
Intensity values are usually, but not always, highest near an epicenter and decrease with distance from the source. Public domain. CIIM show average intensity values for each zip code region from which a report is received. The more felt reports received for your ZIP code, the more reliable will be the average intensity assigned to that ZIP code. Information in CIIMs is particularly useful to fill in geographic gaps where there are few seismic stations. Learn more about DYFI.
These maps show a combined ground motion and shaking intensity for earthquakes with magnitudes of 3. They incorporate measurements of ground acceleration and velocity recorded by seismic instruments and felt reports submitted through DYFI. ShakeMaps, therefore, offer more complete pictures of the shaking produced by earthquakes. However, there are other reasons than tectonics for the occurrence of earthquakes.
Very strong earthquakes with magnitudes of 8 and higher occur once a year on a global average. On average, 15 quakes ranging in magnitude between 7 and 8 strike on an annual basis. Quakes with magnitudes greater than 7 can have devastating effects on people and the environment. Up to 1, moderate quakes on a scale of 5 to 6 take place worldwide every year, smaller quakes with magnitudes of 3 to 4 occur, roughly speaking, , times a year.
Magnitude 3 earthquakes are usually still noticed by people if they are in the vicinity of the epicentre, but in most cases they do not cause any damage. Earthquakes are usually measured by seismometers. Seismometers are installed on the Earth's surface around the globe in particularly "quiet places", generally in seismological observatories.
These may be old tunnels, basements in remote buildings or specifically dedicated buildings on their own piece of land. All observatories record their data on a standardised time basis Coordinated Universal Time, UTC , so that the data of a recorded earthquake can be collected in one place and jointly analysed. In addition to the traditional observatories, seismometers are now being operated on the sea floor, at active volcanoes, on ice floes, in glaciers, and even temporarily on the moon.
The uppermost layers of the earth are made up of many rigid plates tectonic plates that either slide towards or away from each other or over and under each other. The strongest earthquakes usually occur along the plate boundaries. Severely affected regions include, for example, the west coast of North and South America, Indonesia, Japan, Central Asia and parts of China and Turkey, and in Europe, Italy, Greece and Iceland in particular, where strong quakes are recurrent. No, the precise date, place and magnitude of an earthquake cannot be predicted.
However, seismologists nowadays develop seismic hazard maps in which the probability of the occurrence of strong ground tremors due to tectonic quakes can be indicated for a specific period. One reason may be that different "strength scales" are being cited. For example, there are several different magnitude scales for earthquakes that are based on different types of data and analyses.
Other reasons could be that just after an earthquake has struck, the various services and observatories can initially only access different monitoring stations and are not yet able to share or analyse all the data completely.
This may be one of the reasons for slightly different results for one and the same magnitude scale. The first early statements about the strength of an earthquake are associated with greater uncertainties due to the still small amount of data. Over the course of time, more and more data is analysed by an increasing number of monitoring stations, so that the statements about the strength of an earthquake become more accurate. The GFZ in Potsdam operates a global network of stations consisting of over stations in which seismometers detect ground tremors.
All in all, there are only a few of these global networks, but they all work closely together. The denser the monitoring network, the faster the location of the epicentre and the magnitude of the earthquake can be determined.
You can find current global earthquake reports at www. There is no specific protection against earthquakes as they cannot yet be predicted. However, the GFZ has published a list of rules of conduct: Stay calm!
Do not panic! Do not jump out of the window or from the balcony! Seek immediate protection beneath a heavy, sturdy piece of furniture for example a table and hold on tight to something as long as the tremors persist, even if the furniture moves. If this is not possible, take refuge under a sturdy door frame or lie down on the floor near to a load-bearing interior wall away from windows and protect your head and face with crossed arms.
Stay in the building as long as the earthquake tremors persist! The most dangerous thing you can do is to try and leave the building during the quake.
You can be injured by falling objects or broken glass. Exception: When the earthquake begins, you are on the ground floor and near to an exit door that leads directly to the outside garden or open square, not a narrow street. Do not use the stairs!
Do not use the elevator! Go as quickly as possible to an open area, far away from buildings, street lamps and utility lines. Stay there until the tremors have stopped. If you are in a car, drive immediately to the side of the road, away from buildings, trees, flyovers and utility lines. Stay in the car as long as the earthquake tremors persist! Turn on the radio. Do not drive over bridges, cross-roads or below flyovers!
When the quake has subsided, continue to drive with the utmost caution avoid bridges and ramps that could have been damaged by the event or leave the car parked where it is. If you are at the foot of a steep slope when the tremors begin, move immediately away from it risk of landslides or falling rocks! An earthquake can trigger extreme up to 30 m high ocean waves tsunami. These waves sometimes hit the shoreline long after the quake tremors have subsided.
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