汤加-克马德克俯冲带的地质构造与地震火山特征

2022年1月15日西南太平洋的洪阿哈阿帕伊岛海底火山发生了爆炸式的剧烈喷发，吸引了全球的关注。洪阿哈阿帕伊岛海底火山位于汤加-克马德克俯冲带，综合前期研究结果，对汤加-克马德克俯冲带的地质构造特征、地震和火山分布进行初步分析，发现：（1）从汤加-克马德克俯冲带弧前向海方向直到俯冲的太平洋板块，构造上主要表现为大规模正断层。（2）路易斯维尔海山链的俯冲将汤加-克马德克俯冲带分为北部的汤加俯冲带和南部的克马德克俯冲带，沿汤加俯冲带板块汇聚率为67～84 mm/a，沿克马德克俯冲带板块汇聚率为41～58 mm/a，板块俯冲速度的差异造成汤加俯冲带和克马德克俯冲带目前俯冲深度的不同。（3）在路易斯维尔海山链以北，太平洋板块上覆沉积物厚度不足0.4 km，而在南侧达到1 km左右，由于俯冲板块上覆沉积物厚度的差异而造成北部的汤加俯冲带和南部的克马德克俯冲带孕育地震能力的差异。这些认识对研究该俯冲带的火山喷发机制、大地震成因机理及其灾害风险具有重要意义。

Geological structures and earthquake and volcano hazards along Tonga-Kermadec Subduction Zone

On January 15, 2022, an explosive and violent eruption occurred on the undersea volcano of Hunga Haapai Island in the southwest Pacific Ocean, attracting global attention. The Hunga Haapai Island is located in the Tonga-Kermadec subduction zone. Based on the previous research results, this paper makes a preliminary analysis of the geological structures, seismic and volcanic distribution of the Tonga-Kermadec subduction zone, and finds that (1) The forearc area of the Tonga-Kermadec subduction zone mainly develops large-scale normal faults; (2) The subduction of the Louisville Ridge Seamount Chain divides the Tonga-Kermadec subduction zone into the Tonga subduction zone in the north and the Kermadec subduction zone in the south. The plate aggregation rate along the Tonga subduction zone is 67-84 mm/a, and the plate aggregation rate along the Kermadec subduction zone is 41~58 mm/a. The difference in plate aggregation speed cause differences in the current subduction depth between the Tonga subduction zone and the Kermadec subduction zone; (3) North of the Louisville Ridge Seamount Chain, the thickness of the overburden sediment in the Pacific Plate is less than 0.4 km, and it reaches about 1 km on the south side. Differences in sediment thickness cause differences in earthquake generating capacity in the Tonga subduction zone and the Kermadec subduction zone. These understandings are of great significance for studying the volcanic eruption mechanism, the cause mechanism of major earthquakes and disaster risk in the subduction zone.