Terdapat dua cara yang digunakan secara meluas di seluruh dunia untuk mengukur kekuatan gempa bumi iaitu skala Modifikasi Intensiti Mercalli dan Skala Richter.
Richter Scale
The Richter scale measures the energy released by an earthquake. To give you a rough idea here are some examples:
The first, those who are below 3 are virtually undetectable from the seismological point of view. In this scale, the earthquake generates an intensity equivalent to that of a conventional bomb or gas explosion. Sounds very appealing, but in reality, apart from hardly noticeable, the effect is minimal.
4 to 5 would be talking about an energy equivalent to the explosion of 200 tons of TNT. The damage would be minimal and the earthquake can be detected by humans.
5 to 6 hard start to feel the effects on building structures. On this scale we might get, for example, the earthquake in El Calvario (Colombia), 2008.
From 6 to 7. On this scale it gets more serious. The effects of an earthquake of this level could cause the destruction of an area of 100 km from the epicenter. The earthquake in Haiti in 2010, is on this scale. The energy released would equate to four times the power of “the Tsar Bomba, the most powerful bomb ever exploded. In total about 200 kilotons.
7 to 8. The energy released in this range would amount to approximately 450 joint blast bombs like Hiroshima. The devastation in the area is full if not have adequate facilities. An earthquake of this type could be the one that devastated Pisco (Peru) in 2007.
8 to 9. Are earthquakes that can destroy areas hundreds of miles. An example would be the recent earthquake in Mexico City 1985. It is clear that a greater extent it depends on what country you are prepared to endure.
From 9 to 10. On this scale we have from the strongest earthquakes which data are available (Valdivia Earthquake, 1960, and Chile 2010) to the impact of a meteorite than 2 km in diameter that impacts to 90000 km / h. In the case of earthquake, if the country is ready, could be arranged, in the case of the meteorite that God we caught confessed.
12 to 13. The energy released in these scales would mean the end of life on earth. Come to mean the planet’s internal breakdown or, for instance, the impact of a meteorite like the one that collided with the Yucatan Peninsula. The energy released would be something like the equivalent of the simultaneous explosion of two million artifacts as “the Tsar Bomba.”
Over 13. At this level the energy released is unknown. It would be similar to the one generated the collision of Earth and Mars
Skala Richter di cipta oleh Charles F. Richter. Charles F. Richter merupakan seorang pakar seismologi yang terkenal. Charles F. Richter dilahirkan di sebuah ladang ternak di Ohio, Amerika Syarikat pada 26 April 1900.
Charles F. Richter telah mempelajari bidang seismologi di "University of Southern California" dan Universiti Stanford. Pada tahun 1927, Charles F. Richter mula bekerja di makmal seismologi di Pasadena California dan setahun kemudian Charles F. Richter telah berjaya mendapat ijazah doktor dalam bidang theori fizik di Universiti CalTech pada tahun 1928.
Pada tahun 1935, Charles F. Richter telah mengembangkan satu sistem untuk mengukur kekuatan gempa bumi yang dikenali sebagai skala Richter sempena namanya dan pada mulanya hanyalah digunakan di California. Skala Richter yang dikembangkannya merupakan gandaan methematik untuk membezakan sesuatu kekuatan gempa bumi dan diterima pakai secara meluas setelah diubah suai. Kekuatan gempa bumi ditetapkan dengan penggunaan logaritma gandaan (amplitude) gelombang yang dirakamkan oleh mesin seismograf.
Each year our planet is rocked by more than 50,000 earthquakes, of which approximately 99% are earthquakes too small to pose a real danger. In contrast, the remaining 1% consists of demonstrations that can be a source of serious harm if they occur in populated places. Did you know that many of the worst earthquakes in history have happened in the last century?, What we will be saying the Earth?. Nothing good, surely.
Most earthquakes do not come to light, or even out of the archives of the seismological center. They are events that go to swell the statistics to shape theories of forecasts of seismic events. However, despite all this information, you can not determine exactly how and when earthquakes will occur. It is one of the great unfinished business of science.
What we can know, more or less certain, is the energy released (Richter scale) and the destructive effects (Mercalli scale) of different possible earthquakes. Come on, we can assess what can be catastrophic but we can not avoid them. Anyway. Let’s see.
Mercalli Scale
Using this index we can determine the potential effects of earthquakes. Low levels of the scale are associated with how people feel the tremor, while higher grades are associated with structural damage.
Level I – Very weak. It is unlikely that a person can detect
Level II – Weak. Perceived by those people who are at rest and / or concentrates, especially on the upper floors of buildings. Hanging objects may swing.
Level III – Slight. It may be noted on the upper floors. At street level would be similar to the vibration that produces a small truck tonnage.
Level IV – Moderate. Would equate to the vibration generated by the passage of heavy trucks. It is noticeable to most. Some objects such as doors or walls may crack slightly. Those who have a very mild sleep may be awakened.
Level V – Somewhat stronger. At this point it really gets ugly. The vibrations are now considering, walking is difficult, falling objects and walls may crack.
Level VI – Strong. This is where you usually start to panic people, where many go into the street and it is difficult sustain standing. There may be structural damage to buildings which are suited to seismic tremors.
Level VII – Very strong. Those poorly designed structures fall to the ground, while good buildings, although damaged, can still stand.
Level VIII – Destructive. The buildings built specifically to withstand earthquakes damaged remarkable. By vibration furniture out of their holes, possible collapse of cities due to the inability to walk and move.
Level IX – ruined. Widespread panic. Buildings designed to withstand severe earthquakes damaged. Some buildings are out of their bases.
Level X – Disastrous. Rails bent, thousands dead. Few buildings remain standing.
Level XI – Very disastrous. Probably no building would be on foot, the area would be devastated. Few survivors.
Level XII – Catastrophic. Total destruction. Probably no survivors. The terrain would change its appearance.
Tahap pecahan skala Richter meliputi variasi jarak antara seismograf yang pelbagai dengan pusat gempa (epicenter). Menurut skala Richter, kekuatan gempa bumi digambarkan dengan pecahan desimal. Sebagai contoh, gempa dengan kekuatan 2.0atau lebih kecil dianggap gempa mikro, biasanya tidak dapat dikesan oleh manusia dan hanya dirakamkan di mesin seismograf tempatan. Gempa bumi dengan kekuatan 4.5 mampu dirakam di mesin seismograf di seluruh dunia dan berlaku beribu kali setahun. Kekuatan 5.3 dikelaskan sebagai gempa bumi serdahana dan kekuatan 6.3 dikelaskan sebagai gempa bumi yang kuat. Oleh kerana skala Richter menggunakan pengiraan gandaan logaritma, setiap angka mewakili kekuatan yang 10 kali lebih kuat berbanding angka sebelumnya.
Gempa bumi besar seperti yang terjadi di Alaska tahun 1964, memiliki magnitude 8,0 atau lebih. Rata-rata satu gempa bumi yang berukuran seperti itu terjadi setiap tahun.
sos:Understanding the Richter Scale
Post time 30-3-2012 11:45 AM
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