World earthquake science knowledge 10 questions

1. What is the depth of the source?

A: The depth of the source refers to the distance from the earthquake's origin beneath the Earth's surface to the ground. Earthquakes with focal depths less than 60 km are considered shallow, while those deeper than 300 km are classified as deep. Intermediate earthquakes fall between 60 and 300 km. Shallow earthquakes tend to cause more severe damage because the energy released is closer to the surface. Most earthquakes in China occur at shallow depths.

2. What is the periodicity of seismic activity?

A: Seismic activity is not evenly distributed over time. Some periods have frequent and strong earthquakes, known as active periods, while others experience fewer and smaller quakes, called quiet periods. These cycles can last several decades or even centuries. During an active period, large earthquakes of magnitude 7 or higher may occur. Different seismic zones have different activity patterns and cycle lengths.

3. What is the intensity of earthquakes and how does it differ from magnitude?

A: Earthquake intensity measures the impact and damage caused by an earthquake, whereas magnitude reflects the total energy released. Magnitude is a single value for an earthquake, but intensity varies depending on location. For example, the Tangshan earthquake in 1976 had a magnitude of 7.8, but its intensity was highest near the epicenter (XI degrees), decreasing with distance. Intensity depends on both the earthquake’s strength and the local environment.

4. What is the technical standard for assessing earthquake intensity in China?

A: China uses the "China Earthquake Intensity Scale (1980)" which divides intensity into 12 levels. Levels I–V are based on human perception, VI–X on building damage, and XI–XII on major destruction. Generally, intensities above VI cause noticeable damage, while XI and XII result in catastrophic effects.

5. Why is the epidemic after the earthquake easily popular?

A: After a major earthquake, water sources and infrastructure are often damaged, leading to unsanitary conditions that increase the risk of disease. Historical examples, like the 1556 Huaxian earthquake, show that many deaths occurred due to disease rather than the quake itself. In modern times, effective disaster management has reduced such risks, as seen in the 1976 Tangshan earthquake where no major epidemics occurred.

6. Can the earthquake forecast?

A: Earthquake forecasting remains a scientific challenge. While some progress has been made, especially in long-term predictions, short-term forecasts are still unreliable. China has developed methods to detect precursors, but the accuracy of predictions is limited. Research continues to improve our understanding of earthquake behavior.

7. What is earthquake rumor?

A: Earthquake rumors are unverified claims about impending earthquakes, often circulating among the public. They arise from fear, lack of knowledge, or misinformation. Rumors can be mistaken for natural phenomena, normal scientific activities, or even foreign propaganda. It’s important to rely on official sources for accurate information.

The specific reasons for the occurrence of earthquake rumors include:

- Misinterpretation of natural events, such as climate changes or geological shifts.
- Confusion around scientific activities like field surveys or equipment testing.
- Influence from foreign media or individuals with hidden motives.
- Belief in superstitions or outdated traditions.

8. How is the earthquake microscopic precursor observed?

A: Scientists use specialized instruments to detect subtle signs before an earthquake. These include seismographs for small tremors, inclinometers for crustal movement, magnetometers for magnetic field changes, and devices measuring groundwater levels and temperature. These tools help monitor potential precursors to earthquakes.

9. What are the manifestations of abnormal animal behavior?

A: Animals often exhibit unusual behavior before an earthquake, acting as natural early warning systems. Common signs include sudden agitation, withdrawal, or changes in routine. Examples include dogs barking excessively, birds flying erratically, or snakes emerging from their burrows. However, these behaviors can also be caused by other factors.

10. Are animal behavior abnormalities related to earthquakes?

A: Not always. Animal behavior can be influenced by weather, illness, or environmental stress. After an earthquake, people may misinterpret normal behavior as a sign of another quake. It’s important to stay calm and consult authorities if you notice unusual activity.