What Is Seismology?

Seismology is a comprehensive science that studies topics such as the occurrence of earthquakes in solid earth media, the propagation of seismic waves, and the macroscopic consequences of earthquakes. A branch of solid geophysics.

Over the past 500 years, more than 7 million people have been killed by the earthquake, and millions more eagerly watching their sources of living and local economies destroyed. Catastrophic earthquakes have become one of the most important issues for a growing world population, driving scientists and engineers to study it. However, earthquakes have proven to be not only a source of destruction, but also a source of geological knowledge. The analysis of seismic waves is

The study of seismology originated from the need of humans to resist earthquake disasters. Early seismology mainly studied the macroscopic phenomena of earthquakes and the geographical distribution of earthquakes from the perspective of geology.

Beginning in the mid-1960s, countries around the world began to carry out planned earthquake predictions. After more than 30 years of hard work, seismic experts from various countries have accumulated a large amount of precursory earthquake case data, and have made a lot of progress in the long and medium term prediction of earthquakes. It is also increasingly recognized that earthquake prediction is far more difficult than originally expected, and that the complexity of earthquake phenomena that were not previously discovered is "discovered".

The tectonic theory of the earth plate proposed in the 1960s provided a theoretical basis for studying the causes of earthquakes. Seismologists explain that plate interactions are the basic cause of earthquakes. When rock formations

Despite the many difficulties in achieving earthquake prediction, seismologists have been working to achieve this goal. Academician Chen pointed out that a deeper understanding of the nature of earthquakes in science is the development direction of earthquake science in the next century. In this regard, new observation techniques and new theories are the focus of development.

As the seismic observation technology fully enters the digital era, new progress will be made in recording the frequency band and dynamic range of earthquakes, and the analysis and interpretation of seismic records. From

Specialize in studying the impact of earthquakes on buildings and man-made structures and their destruction laws. In order to seek the most scientific and reasonable seismic design, it will not cause serious damage when an earthquake occurs. It is a problem of structural dynamics and structural material mechanics under the conditions of earthquake action.

An extremely important goal of seismological research is to predict earthquakes as accurately as possible.

Seismic physics

a. Seismic wave theory

b. Earthquake mechanism

Study the causes of earthquakes, stress and strain in the area near the source, and the mechanical process of earthquakes.

c. Solid state physics of seismic phenomena

d. Earthquake information

(2). Application of Seismology

People's understanding of the earthquake first began in China. East Han

China's use of modern scientific methods to study earthquakes started late. Ten years after the 1920 Gansu earthquake,

A natural earthquake is a physical phenomenon that occurs underground under specific geological conditions. It causes the ground to shake and even cause damage. This phenomenon is not isolated, but a physical process

The seismic wave emitted by the seismic source can pass through any depth of the earth and return to the ground, thereby bringing information inside the earth, especially the propagation speed of the seismic wave at various depths inside the earth. And this speed is related to the density and elasticity of the medium, so

The basic principle of this technology is to use the reflection, refraction, or diffraction of seismic waves at the interfaces of different rock layers to determine the geometric relationship of these interfaces, so as to find underground geological structures, especially oil storage structures. Because the source used is artificially controlled, the time observation of seismic wave propagation can reach a high accuracy. Seismic methods are an indispensable method in petroleum exploration and have developed rapidly. They also use the effects of seismic waves and oil and gas to move directly to oil and gas fields.

Seismic waves can be used as a tool for transmitting information. During World War II, attempts were made to use seismic waves to track storms at sea. In modern times, the only effective way to monitor underground nuclear explosions is to detect and identify seismic waves generated by nuclear explosions. In this issue, the Soviet Union, the United States and other countries have done a lot of work. No matter how far away an underground nuclear explosion with an equivalent weight of over 100,000 tons can be detected by seismic methods.

Chinanews.com, October 24th. According to foreign media reports on the 23rd, Alexei Zavialov, the chairman of the European Seismic Commission, and a group of seismologists who made an incorrect prediction of the earthquake in the Italian court sentenced to six years in prison. The verdict will endanger the development of earthquake science.

"This is an extremely bad precedent that has set back earthquake predictions for decades," said Zavialov, president of the European Seismic Commission and director of the Schmidt Institute of Geophysics Laboratory.

Zavialov pointed out that since the end of the 1980s, there has been a huge controversy in the field of seismology about whether earthquakes can be predicted. In 2009, the International Association for Seismology and Internal Geophysics (IASPEI) passed a resolution on the organization's support for earthquake prediction research.

According to Zavialov, "the judgment of the Italian court has set us back two or three decades and let us start again".

Yesterday, the Italian court of L'Aquila sentenced six members of the country's Risk Prediction and Prevention Committee to six years' imprisonment, including the former director of the Italian National Center for Geophysics and Volcanology, and a head of the National Earthquake Center.

The Italian court ruled that the seven experts had issued inaccurate predictions 5 days before the L'Aquila earthquake that killed 309 people in 2009 and had committed "manslaughter."

Zavialov pointed out that individual seismic experts do not make predictions. They provide information about the development of the earthquake, and the experts do not have enough knowledge in this area.

"This verdict sets a precedent, and it will be used as an example by the judiciary of any country in the earthquake-sensitive zone in the future," he said.

China News Agency, Beijing, March 11 (Reporter Sun Zifa) The latest completed "2012 Scientific Development Report" of the Chinese Academy of Sciences states that seismology in China's earthquake mitigation faces "the rupture process of earthquake faults" and "the impact of near-surface environment on earthquake disasters" There are seven major challenges, such as the need to build a modern geophysical observation system and the implementation of two major seismological education programs.

The other five huge challenges are "the relationship between the interaction of regional tectonic blocks in China and earthquakes", "the relationship between the distribution of surface strain and stress in China and earthquakes", and "the internal structure, deformation and uplift of the Qinghai-Tibet Plateau on earthquake disasters" "The relationship between the earth's near-surface change over time and earthquakes", "the relationship between the internal structure and dynamic processes of the earth and earthquakes".

The "2012 Scientific Development Report" states that China needs to establish and implement a strong seismology education outreach plan that should include three aspects: First, establish an authoritative organization and platform to provide the public with information on earthquake occurrences and earthquake-related information when the earthquake comes. Scientific explanation of the phenomenon and the current research results of the frontiers of earthquake science; the second is to set up a special organization to formulate and implement a plan for long-term earthquake science education and publicity for the public, elementary and middle school students, college students and general scientific groups; the third is for China There are only a few inland universities that offer undergraduate majors in seismology or solid geophysics and lack the education of seismology, and strengthen the emphasis and attention of the universities on seismology.

In order to better understand China s earthquake disasters and strengthen China s future earthquake mitigation work, from 2010 to 2011, the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the China Earthquake Administration established a special working group to complete the huge challenges faced by seismology in China s earthquake mitigation Consulting research report, which was included and published in "2012 Scientific Development Report". ^[1]

Post-earthquake building