Site Amplification Characteristics at Nankai Seafloor Observation Network, DONET1, Japan, Evaluated Using Spectral Inversion

2018 ◽  
Vol 108 (3A) ◽  
pp. 1210-1218 ◽  
Author(s):  
Hisahiko Kubo ◽  
Takeshi Nakamura ◽  
Wataru Suzuki ◽  
Takeshi Kimura ◽  
Takashi Kunugi ◽  
...  
Keyword(s):  
Site Amplification ◽  
Spectral Inversion ◽  
Observation Network ◽  
Seafloor Observation

An Active Node Switching Method Based on Discrete-Voltage Intervention for Seafloor Observation Network

2017 ◽  
Vol 51 (3) ◽  
pp. 48-59 ◽  
Author(s):  
Zhifeng Zhang ◽  
Yanhu Chen ◽  
Dejun Li ◽  
Bo Jin ◽  
Canjun Yan ◽  
...  
Keyword(s):  
Base Station ◽  
Electrical Network ◽  
Test Results ◽  
Active Node ◽  
Node Failure ◽  
Emergency Situations ◽  
Observation Network ◽  
Seafloor Observation ◽  
Switching Method

AbstractThe cabled seafloor observation network, which provides abundant power and broad bandwidth to seafloor scientific packages, has become one of the most efficient ocean exploration methods because of its long-term, real-time, and sustained presence. However, node failure or maintenance may shut down the system until the situation is cleared. An active node switching method based on discrete-voltage intervention is proposed to establish a reliable and robust underwater electrical network that allows the system to operate partially amid node failure or maintenance. This method switches a specific node on/off from the network whenever necessary. The main structure and operating mechanism of this switching method are presented in this paper. A prototype was established, and several tests were performed in a laboratory to validate its feasibility and reliability. The prototype was then integrated into a pool-testing underwater network that included a 50-km electrical/optical submarine cable between the base station and the junction box. The test results demonstrated that the active node-switching method can efficiently and reliably fix node failure emergency situations for cabled ocean networks.

scholarly journals Synthetic analysis of the efficacy of the S-net system in tsunami forecasting

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Iyan E. Mulia ◽  
Kenji Satake
Keyword(s):  
Optimization Technique ◽  
Pressure Sensors ◽  
Japan Trench ◽  
Ocean Bottom ◽  
Plate Interface ◽  
Megathrust Earthquakes ◽  
Observation Network ◽  
Tsunami Forecasting ◽  
Seafloor Observation ◽  
Earthquake Size

AbstractThe Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench (S-net) is presently the world’s largest network of ocean bottom pressure sensors for real-time tsunami monitoring. This paper analyzes the efficacy of such a vast system in tsunami forecasting through exhaustive synthetic experiments. We consider 1500 hypothetical tsunami scenarios from megathrust earthquakes with magnitudes ranging from Mw 7.7–9.1. We employ a stochastic slip model to emulate heterogeneous slip patterns on specified 240 subfaults over the plate interface of the Japan Trench subduction zone and its vicinity. Subsequently, the associated tsunamis in terms of maximum coastal tsunami heights are evaluated along the 50-m isobath by means of a Green’s function summation. To produce tsunami forecasts, we utilize a tsunami inversion from virtually observed waveforms at the S-net stations. Remarkably, forecasts accuracy of approximately 99% can be achieved using tsunami data within an interval of 3 to 5 min after the earthquake (2-min length), owing to the exceedingly dense observation points. Additionally, we apply an optimization technique to determine the optimal combination of stations with respect to earthquake magnitudes. The results show that the minimum requisite number of stations to maintain the accuracy attained by the existing network configuration decreases from 130 to 90 when the earthquake size increases from Mw 7.7 to 9.1.

scholarly journals Parametric Catastrophe Bonds for Tsunamis: CAT-in-a-Box Trigger and Intensity-Based Index Trigger Methods

2019 ◽  
Vol 35 (1) ◽  
pp. 113-136 ◽  
Author(s):  
Katsuichiro Goda ◽  
Guillermo Franco ◽  
Jie Song ◽  
Alin Radu
Keyword(s):  
Wave Height ◽  
Tsunami Wave ◽  
Parametric Solutions ◽  
Catastrophe Bonds ◽  
Advantages And Disadvantages ◽  
Observation Network ◽  
Seafloor Observation ◽  
Miyagi Prefecture ◽  
Tsunami Wave Height ◽  
Trigger Mechanisms

This study presents a calibration of CAT-in-a-Box and intensity-based index trigger mechanisms for parametric tsunami catastrophe bonds. Trigger conditions for the former are based on fundamental event characteristics, such as earthquake location and magnitude, whereas those for the latter utilize tsunami wave height measurements at a series of observation stations. These solutions are illustrated for a building portfolio in Iwanuma City in Miyagi Prefecture, Japan, by considering a new seafloor observation network S-net off the Tohoku-Hokkaido coast of Japan. Performances of the two types of parametric solutions are quantitatively evaluated and compared with each other to discuss their advantages and disadvantages.

The Remote Communication Control of In Situ Laser Raman Spectroscopy System Based on Seafloor Observation Network

2013 ◽  
Vol 718-720 ◽  
pp. 1029-1032
Author(s):  
Fu Jun Qi ◽  
Xing Zhi Xiong ◽  
Jin Jia Guo
Keyword(s):  
Raman Spectroscopy ◽  
Sensor Nodes ◽  
Laser Raman Spectroscopy ◽  
Remote Communication ◽  
Laser Raman ◽  
Observation Network ◽  
Seafloor Observation ◽  
Shore Station ◽  
Spectroscopy System ◽  
Communication Control

As a powerful tool for seafloor research, the building of seafloor observation network has great value for ocean research and territory security. The seafloor observation network is consist of three parts: the shore station monitoring center, the main network system and the laser Raman spectroscopy system. As one of the sensor nodes, Raman spectroscopy system can detect multiple anions in water non-destructively. In this paper, a remote communication control subsystem for laser Raman spectroscopy system via seafloor observation network was designed. Based on the TCP/IP protocol, a suit of communication control software was developed. Communication control experiments were performed and the experiments results showed that the software was qualified.

Reliability Allocation of Seafloor Observation Network by Using Monte Carlo Method

2014 ◽  
Vol 926-930 ◽  
pp. 1997-2000
Author(s):  
Cheng Fan ◽  
Xue Jun Zhou ◽  
Xi Chen Wang
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Search Algorithm ◽  
Combinatorial Explosion ◽  
Reliability Allocation ◽  
Observation Network ◽  
Seafloor Observation ◽  
Limited Opportunity ◽  
Binary Search Algorithm ◽  
The Relationship

Seafloor observation network provides limited opportunity for repair due to the atrocious weather on the sea. As a result, reasonable reliability allocation methods are required to assure the network is sufficiently reliable during expected years. In this thesis, betweenness is used for evaluating the importance of component based on binary search algorithm, and residual connectedness reliability is calculated according to Monte Carlo method to avoid combinatorial explosion. This method is applied on meshed seafloor observation network to obtain satisfying reliability allocation for backbone nodes. Further, the relationship between nodes reliability allocation and residual connectedness reliability is discussed, on the basis of which certain suggestions for network improvement are proposed.

scholarly journals Optimal deployment of seafloor observation network for tsunami data assimilation in the South China Sea

2022 ◽  
Vol 243 ◽  
pp. 110309
Author(s):  
Zhiyuan Ren ◽  
Yuchen Wang ◽  
Peitao Wang ◽  
Xi Zhao ◽  
Gui Hu ◽  
...  
Keyword(s):  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Observation Network ◽  
Seafloor Observation ◽  
Optimal Deployment
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