USGS M 2.5+ Earthquakes

Thursday, September 22, 2011


Small earthquakes do not always mean the introduction of a major earthquake.
A small earthquake could be triggered by human activities such as filling the reservoir and the injection of liquid into the wells to improve oil quality and waste. Recorded several cases in several U.S. territories, Canada, Japan and India.
The biggest earthquake occurred in Chile on 22 May 1960, with the strength of 9.5 on the Richter scale. Seismic waves shaken the earth for days, this phenomenon is called with earth free Oscillation.
Seismoscope first pendulum to measure the vibrations of the earth during an earthquake is made in the year 1751.

1855, the fault was first recognized as a source of the earthquake.
Hypocenter earthquake is the location below the earth's surface where the fracture begins to crack.
The earthquake epicenter is the location right above the hypocenter on the surface of the Earth.
It is estimated that every year 500,000 detectable earthquakes in the world. As many as 100,000 of them can be felt, and 100 of them cause damage.

Magnitude quake measured based on the size of the earthquake. In the measurement of vibration is felt everywhere, magnitudenya is the same.
Earthquake intensity is measured by the vibration caused by the earthquake. The numbers vary at each location affected by the earthquake effects.
There was no earthquake due to weather.
Most earthquakes occur at depths of less than 80 km below the Earth's surface.
The earliest recorded earthquake in full is the earthquake in Shandong, China in 1831 BC. Note pickup began in 780 BC during the reign of Zhou Dynasty in China.

Aristotle in 350 BC found that the soft surface to shake harder than the hard surface during an earthquake.
In 1760 British engineer John Michell recorded earthquakes are caused by the shifting masses of rock below the surface.
Most earthquake waves have a frequency of less than 20 Hz. So a human audible roar is the sound of objects that are shaken.

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