Tsunami Hazard Assessment Along Chinese Coast Using Scaling Relations Developed for Tsunami Prediction

Potential tsunamis in the western Pacific Ocean pose great threats to the Chinese coastal areas. Among all possible tsunami source regions, the Manila subduction zone draws the most attention and there have been many research works on the tsunami hazards in the South China Sea. In this study, we evaluate the tsunami hazard along the Chinese coast by investigating more potential sources, including the subduction zones of Manila, Ryukyu, Nankai, Izu–Bonin and Mariana. Two tsunami scenarios are considered for each subduction zone, a worst scenario of earthquake magnitude 9.0 and a scenario of largest earthquake magnitude known in history in this zone. Earthquake source parameters are calculated using scaling relations that have been shown to be suitable for tsunami generation. Our results show that for the Chinese coast, tsunami hazards from the Manila and Ryukyu subduction zones are severe in the worst scenarios, and tsunami hazards from the Nankai, Izu–Bonin and Mariana subduction zones are mild. Using the largest earthquake magnitude in history, tsunami hazards from all the investigated subduction zones are almost negligible. Through a sensitivity test on earthquake magnitude, we find that earthquakes of magnitude of 8.5 or larger in the Manila and Ryukyu subduction zones cause severe tsunami hazard along the Chinese coast with wave amplitude over 2 m.

ANALISIS KONFLIK KEPULAUAN NATUNA PASA TAHUN 2016 - 2019

Natuna merupakan sebuah Kabupaten yang terletak pada Provinsi Riau Indonesia. Perairan Natuna yang berada ditengah Laut Cina Selatan atau berada pada titik perbatasan Laut Cina dan Indonesia, kembali memanas dan mencuri perhatian pemerintah Republik Indonesia. Seperti halnya saat ini, China membuat ulah kembali sehingga menimbulkan sebuah persengketaan dengan Indonesia di Peraian Natuna. Persengketaan ini dipicu dengan berlayarnya kapal illegal Cina yaitu Kapal Coast Guard Cina di Perairan Laut Natuna Utara. Kapal tersebut memasuki perbatasan Zona Ekonomi Eksklusif Indonesia (ZEEI) tanpa izin. Penelitian ini bertujuan untuk mendeskripsikan konflik Kepulauan Natuna. Dimana, dalam konflik ini China mengklaim sepihak laut Natuna yang masih dalam wilayah perairan Indonesia. Metode penelitian ini menggunakan pendekatan kualitatif jenis kajian kepustakaan. Hasil penelitian menunjukkan bahwa perairan yang terletak di Kabupaten Natuna Provinsi Riau adalah salah satu kekayaan sumber daya alam Indonesia yang harus dijaga. Akan tetapi, konflik ini terjadi karena China mengklaim secara sepihak Perairan Natuna yang dianggap wilayah mereka. Padahal sudah ditegaskan oleh Badan Hukum Laut Internasional yang dibawah naungan PBB, UNCLOS 1982 menyatakan bahwa Natuna merupakan Zona Ekonomi Eksklusif Indonesia (ZEEI). Dengan begitu Pemerintah Indonesia tidak terima dengan tindakan China yang semena - mena. Karena, Natuna adalah salah satu wilayah teritorial Indonesia. Maka dari itu, Pemerintah Indonesia tidak hanya tinggal diam, pemerintah Indonesia bersikap tegas dengan cara langsung memanggil Duta Besar China untuk Indonesia hingga menambah mengirimkan pasukan angkatan lautnya untuk bersiaga dan meningkatkan pengawasan disekitar area Luat Natuna. Natuna is a district located in the Riau Province of Indonesia. Natuna waters are in the middle of the South China Sea or at the border point of the China Sea and Indonesia. China messed up again, causing a dispute with Indonesia at Peraian Natuna. This dispute was triggered by the sailing of an illegal Chinese ship, namely the Chinese Coast Guard Ship in the North Natuna Sea. The ship entered the Indonesian Exclusive Economic Zone (ZEEI) border without permission. This study aims to describe the Natuna Islands conflict. This research method uses a qualitative approach to the type of literature review. The results showed that the waters located in Natuna Regency, Riau Province, are one of Indonesia's natural resources that must be protected. However, the conflict occurred because China claimed unilaterally the Natuna waters which were considered their territory. Even though it has been emphasized by the International Maritime Law Agency under the auspices of the UN, UNCLOS 1982 stated that Natuna is the Indonesian Exclusive Economic Zone (ZEEI). The Indonesian government does not accept China's arbitrary actions. Because, Natuna is one of Indonesia's territorial areas. Therefore, the Indonesian Government did not remain silent, the Indonesian government took a firm stance by directly summoning the Chinese Ambassador to Indonesia to add to sending its naval forces to be on alert and increasing surveillance around the Luat Natuna area.

Genetic analysis of whole mitochondrial genome of Lateolabrax maculatus (Perciformes: Moronidae) indicates the presence of two populations along the Chinese coast

The whole mitochondrial genome of Lateolabrax maculatus (Cuvier, 1828) was used to investigate the reasons for the observed patterns of genetic differentiation among 12 populations in northern and southern China. The haplotype diversity and nucleotide diversity of L. maculatus were 0.998 and 0.00169, respectively. Pairwise FST values between populations ranged from 0.001 to 0.429, correlating positively with geographic distance. Genetic structure analysis and haplotype network analysis indicated that these populations were split into two groups, in agreement with geographic segregation and environment. Tajima’s D values, Fu’s Fs tests and Bayesian skyline plot (BSP) indicated that a demographic expansion event may have occurred in the history of L. maculatus. Through selection pressure analysis, we found evidence of significant negative selection at the ATP6, ND3, Cytb, COX3, COX2 and COX1 genes. In our hypotheses, this study implied that demographic events and selection of local environmental conditions, including temperature, are responsible for population divergence. These findings are a step forward toward the understanding of the genetic basis of differentiation and adaptation, as well as conservation of L. maculatus.