Author：Jicheng Gu (GU Institute of Earthquake Prediction)
Abstract：
A large earthquake with M=6.9 occurred @ 2022-01-08 01:45:30 (Local Time) in Qinghai, China. According to Gu 's theory, we are making predictions on the sequence development trend and strong aftershocks of this earthquake, and in advance, in the evening of Jan 9th, we have officially successfully predicted the followed strong aftershock: a strong aftershock with M3.0+ would occur at 5:41AM on following morning of Jan 10th. The result was a strong aftershock with M3.1 really occurred at 6:18AM on the next day. Just after this prediction was successful, when we continued to track, we found that the large-scale stress field had abruptly changed. And it is proposed to be careful that there will be another large event in the next 3 to 5 days due to the tectonic stress unusually increased. As a result, a Tonga eruption occurred on the 14th and 15th. This did not happen in Qinghai. But it is likely to be the precursor of the impending earthquake before the volcanic eruption in the large-scale stress field of plate tectonics outside Qinghai.
Keywords: Tonga Volcano, Stress Field
1. Tonga Volcano Eruption
On January 14-15, 2022, a large-scale eruption occurred at the submarine volcano of Hunga Tonga-Hunga Ha'apai (Hunga Tonga-Hunga Ha'apai) in Tonga, a South Pacific Island country. The volcanic eruption was huge, releasing an energy equivalent to about 3981 Hiroshima atomic bombs (the energy of a magnitude 5 earthquake). That is equivalent to the energy released by a magnitude 7.4 earthquake. The eruption of volcanic dust reached nearly 20 kilometers into the stratosphere. The "epic" volcanic eruption triggered a transoceanic tsunami that affected the entire Pacific coast. Stirred nearly half the world. This is also one of the large-scale eruptions of the volcano "once in a thousand years".
Figure 1. Volcano Eruption Hunga Tonga-Hunga Ha'apai
2. VEI and geophysical causes of volcanic eruptions.
Like the magnitude M in seismology, geophysicists define a Volcanic Explosivity Index (VEI) for the intensity of volcanic eruptions. It is a scale developed in 1982 by Professor Chris Newhall of the United States Geological Survey (USGS) and Stephen Self of the University of Hawaii at Manoa to measure ejecta volume, volcanic clouds, and qualitative observations. to measure the intensity of a volcanic eruption.
Figure 2. The volcanic eruption index of Hunga Tonga-Hunga Ha'apai is VEI6.
Tonga is located on the edge of the Pacific plate - the Australian plate and the Asian continent - the Indian plate. The Pacific Plate descends from the Philippines-Tonga area to form a subduction zone. The Mariana Trench (Mariana Trench, Mariana Trench, located at 11°20′N, 142°11.5′E, is the bottom of the Pacific Ocean in the northeast of the Philippines and near the Mariana Islands), causing many deep earthquakes and volcanic lava belts from Iwo Jima in the north to Yap Island in the southwest). The eruption of the Tonga volcano was formed under the action of the compression and downward tectonic stress of the earth's plate tectonics.
Figure 3. Fig. Tonga Subduction Zone (From https://tech.ifeng.com/c/8Cu6fjbsSoE)
3. The tectonic stress field in the Qinghai earthquake zone responded to the Tonga eruption
Three days before this eruption, our research anticipated a sudden change in the continental-scale tectonic stress field in Asia.
At 1:45AM (Beijing time) on January 8, 2022, a strong earthquake of magnitude 6.9 occurred in Qinghai, China (USGS surface wave magnitude was set at 6.2). Because our institute (GU Institute of Earthquake Prediction, www.guiep.org) is focused on the prediction of destructive earthquakes that occur around the world. Therefore, after the Qinghai earthquake, we used the on-site data available on the Internet (USGS and China Earthquake Networks) and the Earthquake forecast Institute of China Earthquake Administration to follow Gu Jicheng's Theory. Tracking and predicting of the Qinghai earthquake, the identification of earthquake types and the prediction of strong aftershocks. Everything would have been normal. And according to Gu's theory, it was very successful to predict that there would be a strong aftershock of M3.0+ at 5:41 AM on the 10th (resulting in a strong aftershock of magnitude 3.1 at 6.18 AM). This is a very accurate official prediction. However, we continued to track and found that on the evening of the 11th, it was found that the large-scale in-situ stress field had undergone dramatic changes and adjustments. We did not study Tonga. But only focus on research and monitoring of the Qinghai earthquake. However, it is obvious that: the large-scale stress field specified by the prediction formula is obviously strengthened on the evening of the 11th. Therefore, I am worried that the Qinghai earthquake area will have another large quake in 3-5 days (that is, it is not a strong aftershock, but a major earthquake of magnitude 6 or above). And the sudden intensification and worry of the large-scale stress field was also officially predicted to the relevant departments. And hope to get further on-site information for the final judgment.
Figure 4. The calculation result is based on USGS data.
Figure 5. The calculation result is based on Chinese data.
The theoretical base is as follows:
Based on Gu’ prediction formula of strong aftershocks, we have
Therefore, an increase in the field tectonic stress σT results in a decrease in Δt. This is the reason that the straight line turns down dramatically in above Figures.
As a result, on the 14th, especially on the 15th 6:18:40 (local time), there was an eruption of the Tonga Century Volcano.
Of course, the source of the large-scale stress field on the Asian continental plate (the Australian plate pressing the Asian Indian plate) is related to the Tonga volcanic stress field. (The Australian plate squeezes the Asian Indian plate). Correspondingly, we believe that this should be the pre-seismic enhancement of the tectonic stress field before the eruption of magma breaking through the stratum. It can also be predicted that after the Tonga volcanic eruption, the tectonic stress field of the Asian plate will undergo adjustment and relaxation of the intrinsic time scale of rheology. Qinghai is much safer.
Conclusion:
Large earthquakes, especially earthquakes of magnitude 7 or above, have a wide range of stress fields. Just like the Tonga volcanic earthquake, the effective influence range of its stress field can reach the entire Asia-Pacific region, that is, the stress field within the range of thousands to tens of thousands of kilo-meters from the epic-enter will be affected. Our research also found that seismicity in California, USA, was also affected (introduced in a separate article).
Due to the rheological properties of the earth's medium, before this volcanic eruption (earthquake), the accelerated sudden change of in-situ stress occurred dozens of hours ago. This is a valuable anomaly of impending earthquake precursors. It is very helpful for earthquake prediction if in-situ stress observation instruments and networks are used.
Gu Jicheng's theory and formula of earthquake type discrimination and strong aftershock prediction only use the earthquake catalogue, which is a typical seismological method. The study further shows that the method can be used to predict earthquakes
Acknowledgment:
Author thanks to Prof. Xiaodong Zhang for providing the catalog, and to Mr. Wei Huang for very helpful assistance and discussions. Also thank to Dr. Yanchong Huangfu, and to Mr. Yi Gu for programming.
Reference:
(2022) https://new.qq.com/omn/20220116/20220116A07ZQU00.html
(1984) Gu, Jicheng，A Method of Distinguishing Earthquake Type and of Predicting Strong Aftershocks, EOS 1984, Vol75, No. 16
(1979) Gu, Jicheng, Characteristics of Temporal Distribution of Strong Aftershocks and its Theoretical Explanation. Acta Geophysica Sinica, Vol. 22, No.1, 1979 pp.33-45.
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