Saturday, April 13, 2024

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The intensity of the Hualien earthquake measured in Taiwan, Japan, and the United States is very different. The Meteorological Administration revealed the reason.

At approximately 7:58 am this morning, Taiwan experienced a severe event with a scale of 7.2.EarthquakeThe whole of Taiwan was obviously shaking, butJapanThe meteorological agency’s detection scale showed a magnitude of 7.5, and the United States Geological Survey measured a magnitude of 7.4. Wu Jianfu, director of the Earthquake Prediction Center of the Central Meteorological Administration, said that the main reason is that the scale units used for earthquakes are different. Taiwan is calculated on the “rich scale”, while Japan and the United States are calculated on the “rich scale”. “Moment scale.” In addition, the wave direction received by each country is also different, so it will not be adjusted for the time being.

Wu Jianfu pointed out that the Earthquake Prediction Center of the Meteorological Administration still uses the scale 7.2 definition, because Taiwan is based on the “Rich Scale”, Japan and the United States are based on the “Moment Scale”, and Taiwan is relatively close For earthquakes, the wave direction obtained is therefore different from the wave direction obtained after it has been distributed around the world. Some waves have also been absorbed by the formation, and the scale presented will be different.

Wu Jianfu said that simply put, the measured scale in Taiwan is different from other countries, mainly because the directions of the waves are different and the units of the earthquake scale are also different. Different calculation methods will produce different results. Whether to adjust the scale in the future? He said that at present it will not be taken out to determine the scale or depth of this earthquake. For now, the focus of manpower will be on dealing with the immediate shocks.

The Center for Earthquake Prediction and Reporting explains that earthquake scales have different names and values ​​due to different observation and calculation methods. The earthquake scale referred to in earthquake reports is a scale used to describe the size of an earthquake. Our country uses the Richter magnitude scale in 1935 to study the United States, which is called local magnitude (ML). also known as.CaliforniaDeveloped based on earthquakes occurring in the area.

The Center for Earthquake Prediction and Forecasting pointed out that by the beginning of the 21st century, seismologists adopted a representation method that could more directly reflect the physical characteristics of the earthquake rupture process (such as the size of stratigraphic displacement and the energy of the earthquake). , etc.), that is, the seismic moment scale (moment magnitude scale, MW). Describe the size of the earthquake. The advantage of the seismic moment scale is that there is no saturation, that is, all earthquakes larger than a certain scale will not have the same value.

The Earthquake Prediction Center reported that the seismic moment scale has now replaced the Richter earthquake scale and has become the most commonly used scale by seismologists around the world when assessing large-scale earthquakes. For example, the U.S. Geological Survey (USGS) monitors global seismic activity, and almost all earthquakes with a magnitude greater than 3.5 use the seismic moment scale to describe the earthquake’s size.

The Center for Earthquake Prediction and Forecasting pointed out that for the same earthquake, the calculation of the RICH earthquake scale and the seismic moment scale have their own theoretical basis and applicable scope. Although the scale values ​​obtained are not the same, they can be extrapolated back to the amount of energy released by the earthquake. They are similar, like 1.78 meters and 178 centimeters. Although the values ​​are different, they are both measures of describing height.

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