A year ago, I began to write natural disasters, blog, hoping to do the popularization of natural disasters, but the personal ability and influence are very limited. The Sichuan earthquake disaster in China makes me feel popular science work long way to go. Will be very pleased to join the squirrel, squirrels would be a good platform for science. In order to popularize knowledge of earthquakes by Beijing Normal University to allow publishers and authors agreed to the network serial "natural disasters" a book chapter on earthquake disaster. I will be reproduced in the graphic here, the main content is divided into four parts: the earthquake, the characteristics of the earthquake, seismic hazards and earthquake disaster mitigation. We want to understand some of the science knowledge of the earthquake help.
The author is engaged in natural disasters for many years, Chen Yong academicians and Professor Shi Peijun, the book soon to conduct its 2nd printing, the authors also hope you can point out the lack of content and errors can be corrected in good time in the pre-press to say thank you to you first .
Natural disasters, sometimes near us, please pay attention to around natural disasters.
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Source: Chen Yong, SHI Pei-Jun. Of natural disasters [M]. Beijing: Beijing Normal University Press, 2007.
Serious statement: Copyright the author and the Beijing Normal University Press for all. Reprinted sure to keep the source.
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0 Introduction
As human beings facing a major natural disaster, natural seismic (earthquake) a long history. China's earliest reports on the earthquake in 1831 BC that the 18th century BC. Earlier written records, including hieroglyphs recorded an earthquake in the Middle East and Arab, in these areas, we recorded an earthquake can be traced back to 40th century BC. Give people the impression that the earthquake disaster. A large earthquake caused some of the most important history of disasters, there is no other natural phenomena can be as big as the size, so a short period of time, causing so much damage. Such as the 1923 Great Kanto earthquake in Japan, away from the epicenter 60 kilometers outside of Tokyo and Yokohama in ruins, some 140,000 people were killed; 1556 Hua county, Shaanxi earthquake death toll estimated at nearly 830,000, the "easy to move mountains and rivers, roads improved, Yi Ran into the sky by Fu, Hom, however, those into the next gully, Yau Chung persons into the spring, however, suddenly, while the split those into a stream Yan. China Cottage official Xie, Shen-yu cities, blink of an eye and carry on the dumping of Qi "(Ming-Lung Yu Qing "Delaware Chi"). Even the earthquake can completely change landforms such as mountains and roads, its power is evident.
Figure 1 Seven Wonders of the ancient world were destroyed by the earthquake disaster: Egypt's Great Pyramid (The Great Pyramid of Giza), Hanging Gardens of Babylon (Hanging Gardens of Babylon), Lighthouse of Alexandria (The lighthouse of Alexandria), Artemis (Moon Goddess) Temple (The Temple of Artemis at Ephesus), Zakaria Tomb (The Mausoleum at Halicamassus), Apollo Bronze Colossus (The Colossus of Rhodes), Olympia Statue of Zeus ((The Status of Zeus at Olympia).
Figure 2 Western engraving recorded in 1805 in Naples, Italy, earthquake.
Photo Source Jan T. Kozak Collection, Na. 'L Information Service for Earthquake Engineering
Figure 3 Ancient Japanese people imagine that the earthquake was due to turn over a huge catfish caused to stop the emancipation of the catfish, you can avoid the earthquake.
Photo Source University of Tokyo Earthquake Research Institute
But the earthquake in the end how the case? This is the people have been thinking about and explore issues. Ancient Japanese considered to be a catfish (Catfish) to turn over caused by the earthquake, the Indians considered to be the ground floor of an earthquake triggered angry elephants, ancient Chinese people put the quake due to the abstract of "yin and yang imbalance" Of course, these are just but for the earthquake imagination. Truly scientific understanding of earthquakes began in the Eastern Han Dynasty 132 years of Zhang Heng's Seismoscope appear. Seismoscope is based on the nature of such a nature of earthquake science and the understanding that the earthquake is a distant pass over the ground vibration. And this concept of earthquakes and seismic waves set up a direct link, the concept was only until the 18th century, Western scientists are reaffirmed. Seismoscope, and it is based on the emergence of such a scientific thinking actually represented the beginning of earthquake science. And modern seismology, has begun in the 19th century, the emergence of sophisticated seismograph.
From the date of the birth of earthquake science, it has been along two directions, the first one is to recognize the direction of the earthquake, the second direction is to use the earthquake. Let's start with the first talk in one direction.
Figure 4, the Eastern Han Zhang Heng in AD Yisanernian create the world's first earthquake observation instruments - Hou wind seismograph. "Later Han. Heng Chuan," Reporter: "Yang Jia first year of the re-created the earth, Hou wind instrument, made with refined copper, round diameter bachi, closing lid uplift, the shape of bottles, decorated with Zhuanwen, mountain turtle animal's shape. There are columns, next to the line 8, Shi Guan hair dryer; outside the eight dragons, the first title of copper balls, mouth opening commitments under the toad's. his teeth ingenious system, are hidden in the bottle, the coverage of well-sight. If the earth, bottles then the vibration, Long machine hair, spit balls and the title of the toad, Zhen-Sheng boosting, and it will be thus awareness. Although a Long machine made, while seven did not move, look for the direction, Nai Zhi Zhen lie, ... ... the "Year Yisanbanian, Longxi earthquake thousands of miles away there is no sense of Luoyang, but the seismograph was detected, and many people do not believe that after a few days, horses sent the message, so internal and external foes in convincing the court. Unfortunately, the fourth century, this instrument were lost in the war has been lost.
An earthquake
1.1 What is an earthquake
People think the role of the earliest volcanic primary cause of the earthquake, but many large earthquakes occur far away from the volcanic areas. Now, most people believe that earthquakes are sudden underground rock fracture caused by the continuous movement of the Earth's interior caused by large-scale crustal deformation of the root causes of the earthquake along the seismic fault slip surface of a sudden seismic wave energy radiation is the direct cause.
Figure 5 a fence across the San Andreas fault in the San Francisco earthquake of 1906 occurred after the 3-meter dislocation.
Photo Source a: Robert E. Wallace, USGS b: GKGilbert, USGS
1906 San Francisco earthquake occurred, in order to understand what an earthquake provided direct observational facts. San Francisco earthquake occurred in the San Andreas fault, California, earthquake, the fault occurred in two right-lateral dislocation of 3-4 meters (standing on a fault observed on the movement of another plate, right is called dextral movement, the left is called the L-motion), perpendicular to the fault of the farm fence had obviously been staggered by 3-4 meters.
Figure 6 Cross-fence when the San Andreas fault rupture caused by elastic snap-back results. (a) the fence vertically through the fault, deformation before the earthquake did not occur. (b) under the action of tectonic forces across the fault bend fence, A point and B point move in the opposite direction; (c) in the C point of rupture, in the fracture strain on both sides of the rock bounced back to C1 and C2.
As a result, the U.S. engineers Reid (Reid) the basis of these observational results, the proposed seismic elastic rebound hypothesis: Earth the force of deep seismic activity area so that the rock deformation, deformation gradually increases over time, larger. This deformation to a large extent, at least about the millennium scale, is the elastic deformation. The so-called elastic deformation refers to the augmentation of rock produced when the size and shape of changes, when the force removed when the shells back to their original state. San Francisco before the earthquake, including the San Andreas Fault, including the vast region of elastic deformation occurs, the accumulation of elastic energy, earthquake, San Andreas fault dislocation occurs, the release of accumulated energy, the whole region back to the original state.
Figure 6 vividly expressed the earthquake elastic rebound hypothesis. There is a vertical through the fault, extending many meters on both sides of the fence. With arrows indicate the role of the construction of power so that the rock elastic strain. When they are slowly making power, the line (fence) bending, and left the right side of the relative dislocation. The role of this strain can not be sustained indefinitely, sooner or later those weak rock, or those in the maximum strain point of the rock to destroy. The ensuing rebound after rupture, or rupture of both sides of the snap-back. So that the figure on both sides of the rock breaking C-back jump C1 and C2.
Figure 7 earthquake along the fault displacement of dislocation, not only appears in the San Andreas fault, in many parts of the world can be seen. Such as: 1739-Ping Luo earthquake fault clockwise movement of the dislocation caused by the Great Wall in Ningxia Section (Lan-Min Wang provided)
Since the elastic rebound hypothesis proposed by Reid after the earthquake scholars generally agreed that the upper part of the Earth's natural earthquake occurred along a geological fault slip suddenly arising. This slip along the cross-section expansion, this slip rupture is less than the speed of spread around the rocks in the earthquake shear wave velocity. The stored elastic strain can jump back to breaking rocks on both sides generally not strain position. Like the more tightly on the clock, like clockwork, the greater the elastic strain of rock, the greater the energy is stored as a regional seismic deformation of the longer, the more wide, slip away from the larger, the more seismic energy released, we use the seismic moment to indicate the size of the earthquake energy release:
Figure 8 pull small pieces of wood worm sliding along the ground. Wood adhesive per unit area with the ground force μ (also called a shear strength) the larger pieces of wood with the ground contact area A larger, sliding the greater the distance D, the small insects made the greater the power μ AD . In accordance with this principle, when the fault occurred two when the relative sliding, μ is the shear strength of faults, A part of the fault plane slide that occurred the area, D is the fault of the two sliding distance, while the μ AD is released by fault slip energy.
Figure 9 earthquake occurred deep underground, where an earthquake is called the source, focal distance from the ground is called the focal depth, the ground opposite the local source is called the epicenter.
Source curriculum standard textbooks for high school geography elective ⑤
In accordance with the different focal depth of earthquakes usually divided into three categories:
Shallow earthquake: focal depth of less than 70 km;
The source of the earthquake: focal depth of 70-300 km in between;
Deep earthquakes: focal depth greater than 300 km.
90% of the world's earthquakes focal depth of less than 100 kilometers, only 3% of the earthquakes are deep-source earthquakes. Because of shallow earthquakes can generate a greater shock the Earth's surface, therefore, shallow earthquakes are most destructive.
Focal depth of earthquakes and plate boundaries are closely related, in the divergent plate boundaries and conversion-type boundaries, earthquakes are mostly shallow source or the source, while in the aggregation boundary, earthquakes are mostly deep-source, with the the ocean plate subduction from the trench to the mainland, the depth of source is also constantly rising.
1.2 Seismic wave
1.2.1 Body wave
Earthquakes in the earth's interior will produce two kinds of body waves: P waves (Primary waves) and S waves (Secondary waves).
P waves are the fastest running wave, which can be in solid, liquid and gas transmission. P waves and sound waves in air is very similar to the direction of wave propagation along the particles to do compression and stretching movements.
Figure 2-10 earthquake in the Earth's interior will produce two kinds of body waves: P waves (primary waves) and S waves (secondary waves). (Added a diagram is to explain the speed differences by strata because of the impact (if there is no low-velocity body, seismic wave propagation velocity is usually more down faster), the P-wave seismic waves in the ray propagation path is not linear, but the curve, when close to the ground the greater the vertical component of P waves, of course, if it is not perpendicular to a shoot, there is also a horizontal component of the movement; while some careful readers find The figure shows the P-wave seems to be horizontal movement, it is because this map is diagram.)
S-wave running slower than P waves, which only can be spread in the solid. In the S wave propagation, the particle motion direction and S-wave propagation direction perpendicular to each other, medium shear stress generated. Can not afford due to fluid shear stress, so S-wave can not spread in the liquid and gas.
P wave and S wave velocity from the medium's density and elastic constant.
Tangshan earthquake, Beijing felt the two kinds of seismic waves
Tangshan earthquake occurred at 3:00 on July 28, 1976 over a minute. At that time I (Chen Yong) living in Beijing, near the front door of a dilapidated two-story wooden structure of buildings, the buildings at least fifty years old, and in addition is a brick wall, floor and frame are wood, and a walking the floor on the issue "Lozhiluozhi" and groans. At that time exactly in the summer, the weather was unusually hot and makes it difficult to fall asleep. I just lay a moment, drowsily on that bed jumping up and down some large, floors and even entire buildings, have issued a "crunch" sound. I immediately realized that "a big earthquake took place." Engaged in seismic work for many years I was Huang did not immediately get out of bed after waking, but lying in bed and began to count, "One, two, three, ... ...", counting the number of implantation shaking smaller. When the number of the 20th, when suddenly came a shaking, more terrible than the first time, the entire floor all to endure pain like "splashed 啦" chaos ring. This is a short 20-second interval is the longitudinal wave and S-wave arrival time difference (earthquakes often generate longitudinal and transverse wave, longitudinal wave in the Earth's media to spread quickly, first to reach our feet, causing the Earth's surface up and down movement; transverse wave Paode Man, We feel a strong vibration is the second S-wave caused by the ground to demonstrate the level of direction. As the S-wave carrying most of the energy generated by the earthquake, so it is even more serious damage to the building surface), reflecting the observation and source distance, difference 1 second, indicating a distance of about eight kilometers an earthquake, 20 seconds is illustrated in the quake occurred about 160 kilometers. So, I had a preliminary conclusion: the earthquake is not in Beijing - Beijing 160 kilometers away from the places where the earthquake occurred.
This thunderstorm lightning principle is the same: two thunder clouds to meet the sky, the issue of lightning and thunder, lightning (electromagnetic waves) run fast, thunder (in the air may sound) Paode Man, let's see the flash, After the hearing thunder, flash and thunder was the time difference between, it indicates that a lightning flash and the cloud away from our distance.
1.2.2 Surface Wave
Surface waves along the Earth's surface in the vicinity of a spread of elastic waves. Surface wave propagation speed slower than the body wave. The most important are two kinds of surface waves: Rayleigh wave (R wave) and Love wave (L wave), which are named to commemorate the discoverer of these waves, the British scientist Lord Rayleigh and AEH Love.
Figure 11 Rayleigh wave propagation, the particle in the direction of wave propagation along the vertical plane to do the elliptical motion counter-clockwise, wave comes, the ground movement and water wave motion on the same (see "Tsunami" a chapter, "Wave Movement" section).
Figure 12 Love wave (L wave) propagation, the particle horizontal movement, but also the direction of motion and wave propagation direction of the vertical, the largest particle motion on the ground, the more the depths of the movement Wang Dexia magnitude smaller.
Figure 13 December 26, 2003 earthquake in Bam, Iran, produced by seismic waves spread around the world, the theory of time (unit: min)
Source USGS
Figure 14 July 19, 2006 10:57:36.8 Indonesia's Sunda Strait Ms6.0 earthquake (S6.5 °, E105.4 °), which is Kunming seismic station (KIM, epicentral distance 31.6 °, azimuth 355.0 °) of the actual record. The vertical axis is the ground motion displacement (unit: microns), the horizontal axis is time.
The earthquake as the Earth's interior as a shock occurs when the fluctuations that will produce a series of seismic waves, seismic waves are present we know only a way to penetrate the Earth's interior wave. Today we are all on the Earth's interior knowledge of how he come from? This is largely due to seismic waves. The nineteenth century, people had to know, the earthquake is a illuminate the underground light.
1.3 earthquake is a illuminate the Earth's interior light
Figure 15 people to have a selection of watermelon experience, hand tapping listen to the voices of watermelon watermelon maturity can be judged, it is because the vibration of different watermelon sent a different tone and timbre. Geophysical workers, business and film is very similar to watermelon, but sometimes through artificial means to make the earth quake vibration, sometimes it is the Earth's own earthquake vibrations, the scientists through the records and "listen" to those from the vibration of the earth's interior symphony - seismic waves to determine the Earth's internal structure and status. To date, the seismic wave is the only running through the Earth's fluctuations.
Given source of seismic waves through the Earth's media to spread in all directions, and we are in the world can be recorded by a seismograph. The early 20th century, seismologists found that the earthquake occurred, away from the earthquake epicenter 103 o -143 o failing to record an earthquake within the P wave. So they suspect that the Earth has a layered structure, and the Earth's Interior of the Earth's core there is a low seismic P-wave due to refraction, can not reach 103 o -143 o range. Understanding of the people on the Earth's interior derived from seismic waves come.
Figure 16 (a) recorded the earthquake in Indonesia, the world's seismic station locations and their distance from the earthquake epicenter (degrees); (b) within 6 hours after the earthquake stations recorded Rayleigh wave vertical ground motion (peak - peak, with cm indicated), R 1 along the epicenter - the shortest distance transmission station great circle wave, R 2 along with a great circle of the most long-distance spread of the wave, R 3 and R 1 the same as more than just turning around the earth circle, R 4 and R 2 the same, and very often turn full circle around the Earth.
Source J. PARK, K. ANDERSON, R. ASTER, et al (2005)
Figure 17 the early 20th century, seismologists found that the earthquake occurred, away from the earthquake epicenter is about 103 o -143 o failing to record an earthquake within the P wave. So they suspect that the Earth has a layered structure, and the Earth's Interior of the Earth's core there is a low seismic P-wave due to refraction, can not reach 103 o -143 o range.
Figure 18 Now we already know that the Earth can be divided into crust, mantle and core, the core also includes a liquid outer core and a solid core. The figure shows the layers of the seismic wave velocity. Understanding of the Earth's interior, are derived from natural seismic information and data.
This hierarchical structure to obtain the Earth's chronology of events can be briefly listed below:
1906 Oldham first attempt from the seismic waves through the Earth's time to infer the internal structure of the entire planet.
1909 mohorovicic recent findings from the early shock wave travel time, calculated at 56 kilometers underground there is a discontinuity, between the cross-section of material with an average of more than 5.6 kilometers / second, the following material speed of 7.8 km / sec. Was later discovered, whether it is ocean or the continent, the vast majority of region exists between the cross-section, usually call the Moho, the average depth of about 30 km above the Moho part is called the crust, the following part is called mantle.
1914 Gutenberg (Gutenburg) based on seismic body waves of the "shadow zone" confirmed the existence of the Earth's core and mantle and the Earth's core was measured between the inter-section, its depth of 2900 kilometers. This value is fairly accurate and has so far not much improvement. Nuclear can not be transmitted S-wave base (a kind of seismic waves can not be in liquid communication) feature, seismologists also infer that the Earth's core is liquid.
Lyman 1936 by body-wave "shadow zone" further study and found that in the liquid in the Earth's core there is a solid inner core.
1996 US-based Chinese scholar Xiao-Dong Song by studying seismic waves through the Earth's core, to infer inner core is rotating faster than the outer core, fast, this discovery and further deepened the understanding of human beings on the Earth, was named the year the United States one of the top ten science stories .
Figure 19 US-based scholar Song Xiaodong China in 1996 through the Earth's core by studying the seismic waves to infer inner core is rotating faster than the outer core, fast, this discovery and further deepened the understanding of human beings on Earth, and his research published in NATURE on, and was named the 1996 U.S. top ten science news stories.
1.4 Seismic wave a variety of applications
The use of seismic waves Another important aspect is seismic exploration. Seismic exploration history dating back to the mid-19th century. As early as 1845, Mallett once artificial excitation of seismic waves to measure the Earth's crust elastic wave propagation velocity, while in the First World War, the warring sides have used heavy artillery recoil generated by seismic waves to determine each other's artillery, which can be said that the seeds of seismic exploration. As with other geophysical seismic exploration methods can not achieve the accuracy and resolution, so oil and other mineral resources exploration, space exploration is the main shock and the most effective methods. Construction on a variety of mineral resources will have some features, such as oil, natural gas only in a certain structure in order to form a closed and saved. Seismic waves passing through these structures will produce reflection and refraction, by analyzing the received signal on the surface, you can of underground rock structures, depth, and shape make presumption, allowing for future drilling to provide accurate positioning.
Figure 20 using seismic exploration
Figure 21 Comprehensive Nuclear-Test-Ban Treaty (CTBT) in the distribution of seismic stations
Seismic can also defense construction. As of November 2000, 160 countries have signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Are facing a common problem is how to effectively monitor global underground nuclear explosions. Which is useless seismology, underground nuclear explosions and natural earthquakes also produce the same seismic waves will be recorded in various places on the seismic trace. The underground nuclear explosions and natural earthquakes recorded there are certain differences between waveforms, and therefore not only based on their waveform it can be distinguished with the natural earthquake, but also given moment of its occurrence, location, yield and so on.
Figure 22 figure is the red color of seismic waves generated by underground explosion, its record is characterized by a "big small tail", and blue colors are natural seismic waves generated by earthquakes, which is characterized by a "small top-heavy tail." The use of recorded seismic waves of the characteristics that can distinguish underground nuclear explosions and natural earthquakes.
Figure 23 Russia's Kursk submarine sinking into the Barents Sea, no one thought of going to tell a seismologist. However, in January 2001, it was seismologists makes the final debate the causes of this catastrophe to an end. The Baltic Sea seismic station recorded the Kursk exploded to illustrate the problem arising from vibration. This is evidence that this tragedy is that when a submarine on the surface of the water when the boat accident caused by a torpedo, and then in the deep explosion took place several torpedoes. The Russian authorities blamed earlier this incident an unidentified foreign submarine collision.
Source a: AP Associated Press (http://www.aeronautics.ru/img003/kursk-017.jpg) b: EOS (2001)
Figure 24 from the U.S. World Trade Center 34 kilometers of seismic station to record the events of the 911 full-time process.
Source Kim, WY (2001)
In fact, the application of seismology is also far more than of these. For example, current methods of seismic forecasting volcanic eruptions have made great progress; pairs of reservoir-induced earthquake study can provide security for large reservoirs, such as China's Three Gorges reservoir area earthquake engineering feasibility study is an important argument one of the elements; of mine seismic monitoring is an important means of protecting one of mine safety; seismology can be used for planetary exploration, through the study of planetary free oscillations can reveal large-scale structure of planetary interiors. Therefore, seismology this ancient discipline, constant access to energy, rapidly developing into one of the leading edge disciplines.
Figure 25 seismic events recorded worldwide each year the number in 1900 was about 100 times, the late 20th century more than 10,000 times, in 2006 more than 100,000 times. This is due to the increase in seismic stations, reflecting the rapid development of earthquake science.
That's great you have an empty mistake!
[...] "Natural disaster" of the earthquake disaster -1 earthquake [...]
I believe that part of the Japanese catfish to see, think of a few days ago to see the paper, who in 2004 also by looking for abnormal behavior of catfish try to predict earthquakes, it is interesting; Also, the phrase "away from the earthquake epicenter 103o-143o within the framework of "the same paragraph, the rear has become a" 105-143 "Is it all wrong.
The first time that the usefulness of an earthquake there are so many remember a word all the advanced science and magic is no different at first glance
Earthquake can be done just found so many things ah suddenly remembered the words of advanced science and magic is no different at first glance
"20 seconds is illustrated in the quake occurred about 160 kilometers,"
Is it really this simple linear relations?
Thank you Orange corrected, I go home and look of the original book. I am now using a pre-publication of the book, may also be somewhat different.
General P-wave and S wave away the time difference × 8 is about equal to the epicentral distance. This recent earthquake can be roughly calculated, as we heard the thunder knew that the clouds play the same physical distance.
【P-wave in earth media to spread quickly, first to reach our feet, causing the Earth's surface up and down movement; transverse Paode Man, we feel a strong vibration is the second S-wave caused by the ground to show direction. 】
The original direction of movement seems to engage in anti-a!
Should be:
P wave (longitudinal wave) (primary wave \ pressure wave) caused by the level of surface movement.
S wave (shear wave) (secondary wave) caused by the surface of the upper and lower vibration.
Thank you for reminding. Modern three-component seismograph generally, P-wave normally distributed in the vertical component. Of course, not all P-wave vertical out of shooting, so the horizontal component will also appear. At that time I paste a picture to illustrate.
[...] Serial】 【important "natural disasters" of the earthquake disaster -1 Earthquake (uploaded by empty right or wrong, the network starts) aftershocks】 【matter of trust you can have more aftershocks forecast? (Orange to help small Bangzhu; biology doctoral student in the United States) earthquake prediction】 【Seismoscope really able to record an earthquake do? (Kansas and plants, a doctoral student, popular science writer) 【】 earthquake earthquake and epidemic prevention should focus on those diseases? (Green party, in the United States, MD) 【】 Communications earthquake and the power of communication - Wenchuan after the earthquake (babymouse, computer Master)】 【earthquake prediction before the earthquake, 10 seconds (By DNA, User manuscripts) 【】 earthquake earthquakes and epidemics Anti-big epidemic after the disaster (BoBo, Medical Doctor) 【】 What is the basic knowledge of earthquake seismic intensity (Mammoth; popular authors) the Professional Analysis】 reposted elsewhere: Earthquake Administration have done what (blank wrong; Ph.D., artificial earthquake Research) 【Description】 search tool for life detectors: to capture every aspect of hope (an elderly woman in the United States and brain science doctoral student)】 【Journalist's notes of a non-professional science and technology Notes from journalists covering the earthquake peripheral (fish, science and technology journalists) the Professional Analysis】 7.8 earthquake in Sichuan About (empty fault; Ph.D., artificial seismic studies) 【】 psychological intervention after the earthquake disaster out of a nightmare (melodious; psychology students) 【】 crustal earthquake basics, what you Akira Akira (orange to help small Bangzhu; biology doctoral student in the United States) 【】 animals, animals and earthquake prediction earthquake prediction, Kaopu do? (Lean camel; college biology teacher) [...]
[...] "Natural disaster" of the earthquake disaster -1 earthquakes Chen Yong, SHI Pei-jun [...]
1.2.1 Body-wave icon in the P-wave caused by the ground shaking around, and in the Tangshan earthquake was felt in Beijing, P-wave caused by the ground bounce up and down, and some do not understand
I added a diagram, add some text, do not know if this explanation is that can not be made clear.