What kind of earthquake zone is Yushu in?

From the beginning of the morning sun, the first rays of sunlight on April 14 shone through the clouds on the contemporary mountains, overlooking, and a new jade tree was born.

The stone monument in front of the Yushu Earthquake Site Memorial Hall will always be fixed on April 14, 2010. Ten years later, with the deployment of the Party Central Committee and the State Council, with the assistance of the people's soldiers and all walks of life, a brand-new jade tree stands proudly on the Qinghai-Tibet Plateau.

What kind of earthquake zone is Yushu in? Is there any correlation between the Yushu earthquake and the Wenchuan earthquake? Today, ten years later, what can science do in the face of earthquakes?

In response to this series of problems, Tu Hong, an associate researcher of the Qinghai Seismological Bureau, was interviewed by a reporter from Science and Technology Daily.

Yushu is in a special seismic zone

On April 14, 2010, a strong earthquake with a magnitude of 7.1 occurred in Yushu, Qinghai. Sudden natural disasters made this small town on the plateau almost ruined, and 2,698 people lost their lives ...

Why did it happen in Yushu? Tu Hongwei said that at 7:49 on April 14, 2010, the Yushu magnitude 7.1 earthquake occurred on the Ganzi-Yushu-Feng volcanic fault zone on the southern boundary of the Bayan Hara block. The Ganzi-Yushu-Fenghuo volcanic fault zone is a large-scale left-lateral strike-slip fault zone in the central and eastern Qinghai-Tibet Plateau. It is also an important geological boundary between the Qiangtang block and the Bayankala block. The Bayan Hara block is a secondary block formed as the Indian Ocean plate advances northward. There have been multiple earthquakes of magnitude 7 or above in the boundary area of ​​this block, and the Yushu earthquake occurred in a corresponding rupture gap area.

"An earthquake of magnitude 4.7 occurred more than two hours before the Yushu earthquake of magnitude 7.1. This earthquake was considered a foreshock. Studies suggest that this earthquake saved many people's lives. Subsequently, a craze for research on foreshock recognition began. The difficulty is still very large. "Tu Hongwei said.

Looking at the data, it is not difficult to find that there have been many earthquakes of greater magnitude on the border of the Bayan Hara block. Tu Hong introduced that the regional environment where the Yushu earthquake occurred was the southern boundary of the Bayan Hara block, the northern boundary of the Bayan Hara block was the Kunlun fault zone, the southern boundary was the Ganzi-Yushu-feng volcanic fault zone, and the eastern boundary was Longmenshan fault zone. Over the past 30 years, the frequency of strong earthquakes and large earthquakes around this block has been relatively high. The most influential earthquakes were the 1997 Mani earthquake of magnitude 7.9, the 2001 Kunlun Mountain pass magnitude 8.1 earthquake, the 2008 Wenchuan magnitude 8.0 earthquake, and the 2010 Yushu magnitude 7.1 earthquake.

Yushu and Wenchuan are in the Bayan Hara block

On May 12, 2008, a strong earthquake struck Wenchuan, Sichuan. However, two years later, another strong earthquake occurred in Yushu, Qinghai. Are the two related?

"It is certain that the Wenchuan earthquake and the Yushu earthquake are indeed related, because the Wenchuan earthquake and the Yushu earthquake occurred on the boundary of the Bayan Hara block. The Wenchuan earthquake is on the east boundary of the block, and the Yushu earthquake is on the south boundary of the block. "Tu Hongwei said.

Tu Hongwei said that in the process of pushing the Indian Ocean plate to the north, many secondary blocks and fault zones were formed. Under the action of this kind of geodynamics, "mass east" was formed, and then the Bayan Hara block was formed, and a series of earthquakes occurred in the process. The occurrence of an earthquake is a process of rapid release after energy accumulation reaches a certain state. Relevant personnel's research on the Wenchuan Earthquake has shown that another earthquake of magnitude 8 or more in the same area may require 3000 to 6000 years of energy accumulation.

Tu Hongwei believes that different regions, due to different tectonic states, have different energy accumulation rates, different underground medium structures, and different rupture thresholds. The energy accumulation process in different regions shows different states, like a wooden board. When we apply force to it, it will slowly deform, and when it reaches a critical state, the wooden board will break from some vulnerable areas and break. Time is equivalent to an earthquake.

Ten years later, scientific and technological forces empower earthquake research

The reporter learned from the Qinghai Seismological Bureau that during the past ten years, the Qinghai Seismic System has done a lot of research work on the geological structures and seismic plots in some key areas, especially providing a very important reference for Yushu reconstruction.

In seismic monitoring, the density of seismic stations and geophysical field observation stations has been increased, which has further improved the monitoring capabilities and data observation capabilities. The timeliness and effectiveness of the earthquake consultation have been greatly improved. Generally, an initial judgment of the earthquake trend can be made within 30 minutes after an earthquake of magnitude 4 or higher. The first formal meeting of the chamber of commerce can be completed within 2 hours after the earthquake. And form a conclusion of consultation. This provides a very important reference basis for the government to deal with the earthquake, and also provides a scientific basis for social stability.

"Successful earthquake prediction and prediction, especially short-term prediction is still a worldwide problem, but as earthquake people, we have been doing our best to explore the mysteries of the earth and continue to summarize lessons learned in order to do better before and after the next strong earthquake. Tu Hongwei said.

Our reporter Zhang Yun