# Machine Learning-Based Precursor Detection Using Seismic Multi-Parameter Data
## 3 Results
### Extrapolation Inspection
The spatial evolution of the MSER anomaly in the western section of the southern Tianshan Mountains (Figure 9) showed that the anomaly gradually increased from June 2016, reaching its maximum intensity in September 2016, and the Aktao \(M_{\rm L}7.0\) earthquake occurred near the anomaly area in November. Afterward, the anomaly gradually weakened until it disappeared. Figure 8: The MSER changes in the western section of southern Tianshan. Figure 7: Western section of southern Tianshan (within the dashed box) and \(M_{\rm L}\geq 6.3\) earthquakes from November 2016 to December 2021. The training period in the central and western sections of the Qilian Mountains (Figure 10) was from January 1991 to December 2015, during which, a total of 10 target earthquakes occurred. Among them, eight target earthquakes had high-value anomalies exceeding the threshold line before the earthquakes, and two target earthquakes were missed (Figure 11). In January 2016, as the starting time for extrapolation, the relevancy curve continued to decline after reaching the abnormal peak in July 2018, and reached its lowest point in February 2019. During this period, there was no corresponding target earthquake. Afterward, the abnormal curve rose again and reached its peak in July 2019. Two months later, on 16 September 2019, the Gansu Zhangy \(M_{\rm L}\)5.5 earthquake occurred. The relevancy curve had been continuously decreasing and remained below the threshold line after the Zhangy \(M_{\rm L}\)5.5 earthquake in Gansu. The curve began to turn and rise in March 2021, and the Aksai \(M_{\rm L}\)6.0 earthquake in Gansu occurred on 26 August 2021 during the curve ascent process, exceeding the threshold line. The curve reached its peak again in January 2022. Table 2 shows that the advantageous extrapolation time in the central and western sections of the Qilian Mountains was 170 days, so the validity period should be until 20 June 2022. From January 2022 to 20 June 2022, the study region experienced the Qinghai Menyuan \(M_{\rm L}\)7.1 earthquake on 8 January 2022, the Gansu Sunan \(M_{\rm L}\)5.5 earthquake on 17 March 2022, and the Qinghai Delingha \(M_{\rm L}\)6.3 earthquake on 26 March 2022, respectively, proving that the extrapolation effect in this study area was very good. Figure 10: Central and western sections of the Qilian Mountains (within the dashed box) and \(M_{\rm L}\geq 5.5\) earthquakes from January 2016 to December 2021. Figure 9: The spatial evolution of the MSER of the western section of southern Tianshan from January 2016 to October 2017. The extrapolation test period for the central and western sections of the Qilian Mountains began in January 2016. The spatial evolution of the MSER anomaly before the 8 January 2022 Qinghai Menyuan \(M_{\rm L}\)7.1 earthquake showed that the anomaly amplitude in the study area began to increase from August 2020, with the largest anomaly increase in November 2021 (Figure 12). The red pentagram in Figure 12 represents the epicenter position of the Qinghai Menyuan \(M_{\rm L}\)7.1 earthquake in January 2022.