Optical polarization–based seismic and water wave sensing on transoceanic cables

Science ◽  
2021 ◽  
Vol 371 (6532) ◽  
pp. 931-936 ◽  
Author(s):  
Zhongwen Zhan ◽  
Mattia Cantono ◽  
Valey Kamalov ◽  
Antonio Mecozzi ◽  
Rafael Müller ◽  
...  
Keyword(s):  
Los Angeles ◽  
Water Waves ◽  
Fiber Optic ◽  
Submarine Cable ◽  
Submarine Earthquakes ◽  
Specialized Equipment ◽  
Laser Sources ◽  
Data Gap ◽  
Submarine Cables ◽  
Large Earthquakes

Seafloor geophysical instrumentation is challenging to deploy and maintain but critical for studying submarine earthquakes and Earth’s interior. Emerging fiber-optic sensing technologies that can leverage submarine telecommunication cables present an opportunity to fill the data gap. We successfully sensed seismic and water waves over a 10,000-kilometer-long submarine cable connecting Los Angeles, California, and Valparaiso, Chile, by monitoring the polarization of regular optical telecommunication channels. We detected multiple moderate-to-large earthquakes along the cable in the 10-millihertz to 5-hertz band. We also recorded pressure signals from ocean swells in the primary microseism band, implying the potential for tsunami sensing. Our method, because it does not require specialized equipment, laser sources, or dedicated fibers, is highly scalable for converting global submarine cables into continuous real-time earthquake and tsunami observatories.

Towards multi-method geophysical sensing on submarine cables 

2021 ◽  
Author(s):  
Zhongwen Zhan ◽  
Mattia Cantono ◽  
Jorge Castellanos ◽  
Miguel González Herráez ◽  
Zhensheng Jia ◽  
...  
Keyword(s):  
Laser Interferometry ◽  
Distributed Sensing ◽  
Ocean Dynamics ◽  
Submarine Cable ◽  
Geophysical Research ◽  
Acoustic Sensing ◽  
Rayleigh Backscattering ◽  
Submarine Earthquakes ◽  
Distributed Acoustic Sensing ◽  
Submarine Cables

<p>The oceans present a major gap in geophysical instrumentation, hindering fundamental research on submarine earthquakes and the Earth’s interior structure, as well as effective earthquake and tsunami warning for offshore events. Emerging fiber-optic sensing technologies that can leverage submarine telecommunication cables present an new opportunity in filling the data gap. Marra et al. (2018) turned a 96 km long submarine cable into a sensitive seismic sensor using ultra-stable laser interferometry of a round-tripped signal. Another technology, Distributed Acoustic Sensing (DAS), interrogates intrinsic Rayleigh backscattering and converts tens of kilometers of dedicated fiber into thousands of seismic strainmeters on the seafloor (e.g., Lindsey et al., 2019; Sladen et al., 2019; Williams et al., 2019; Spica et al., 2020). Zhan et al. (2021) successfully sensed seismic and water waves over a 10,000 km long submarine cable connecting Los Angeles and Valparaiso, by monitoring the polarization of regular optical telecommunication channels. However, these new technologies have substantially different levels of sensitivity, coverage, spatial resolution, and scalability. In this talk, we advocate that strategic combinations of the different sensing techniques (including conventional geophysical networks) are necessary to provide the broadest coverage of the seafloor while making high-fidelity, physically interpretable measurements. Strategic collaborations between the geophysics community and telecommunication community without burdening the telecomm operation (e.g., by multiplexing or using regular telecom signals) will be critical to the long term success.</p><p> </p><p>Marra, G., C. Clivati, R. Luckett, A. Tampellini, J. Kronjäger, L. Wright, A. Mura, F. Levi, S. Robinson, A. Xuereb, B. Baptie, D. Calonico, 2018. Ultrastable laser interferometry for earthquake detection with terrestrial and submarine cables. Science, eaat4458.</p><p>Lindsey, N.J., T. C. Dawe, J. B. Ajo-Franklin, 2019. Illuminating seafloor faults and ocean dynamics with dark fiber distributed acoustic sensing. Science. <strong>366</strong>, 1103–1107.</p><p>Sladen, A., D. Rivet, J. P. Ampuero, L. De Barros, Y. Hello, G. Calbris, P. Lamare, 2019. Distributed sensing of earthquakes and ocean-solid Earth interactions on seafloor telecom cables. Nat Commun. <strong>10</strong>, 5777.</p><p>Spica, Z.J., Nishida, K., Akuhara, T., Pétrélis, F., Shinohara, M. and Yamada, T., 2020. Marine Sediment Characterized by Ocean‐Bottom Fiber‐Optic Seismology. Geophysical Research Letters, 47(16), p.e2020GL088360.</p><p>Williams, E.F., M. R. Fernández-Ruiz, R. Magalhaes, R. Vanthillo, Z. Zhan, M. González-Herráez, H. F. Martins, 2019. Distributed sensing of microseisms and teleseisms with submarine dark fibers. Nat Commun. <strong>10</strong>, 5778.</p><p>Zhan, Z., M. Cantono, V. Kamalov, A. Mecozzi, R. Muller, S. Yin, J.C. Castellanos, 2021. Optical polarization-based seismic and water wave sensing on transoceanic cables. Science, in press.</p>

scholarly journals A revised position for the primary strand of the Pleistocene-Holocene San Andreas fault in southern California

2021 ◽  
Vol 7 (13) ◽  
pp. eaaz5691
Author(s):  
Kimberly Blisniuk ◽  
Katherine Scharer ◽  
Warren D. Sharp ◽  
Roland Burgmann ◽  
Colin Amos ◽  
...  
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
San Andreas Fault ◽  
Slip Rate ◽  
Large Magnitude ◽  
Slip Rates ◽  
San Andreas ◽  
The Pacific ◽  
Large Earthquakes ◽  
Dependent Probability

The San Andreas fault has the highest calculated time-dependent probability for large-magnitude earthquakes in southern California. However, where the fault is multistranded east of the Los Angeles metropolitan area, it has been uncertain which strand has the fastest slip rate and, therefore, which has the highest probability of a destructive earthquake. Reconstruction of offset Pleistocene-Holocene landforms dated using the uranium-thorium soil carbonate and beryllium-10 surface exposure techniques indicates slip rates of 24.1 ± 3 millimeter per year for the San Andreas fault, with 21.6 ± 2 and 2.5 ± 1 millimeters per year for the Mission Creek and Banning strands, respectively. These data establish the Mission Creek strand as the primary fault bounding the Pacific and North American plates at this latitude and imply that 6 to 9 meters of elastic strain has accumulated along the fault since the most recent surface-rupturing earthquake, highlighting the potential for large earthquakes along this strand.

Regional integration and infrastructure connectivity in Africa

2017 ◽  
Author(s):  
Maurice Mubila ◽  
Tito Yepes
Keyword(s):  
Regional Integration ◽  
Energy Supply ◽  
Fiber Optic ◽  
Initial Step ◽  
Regional Public Goods ◽  
Infrastructure Provision ◽  
Compensation Mechanisms ◽  
Small Countries ◽  
Sound Management ◽  
Submarine Cables

Regional infrastructure is one aspect of broader regional integration. In contrast to economic or political integration, however, cooperation in infrastructure provision is easier to achieve, because benefits are more clearly defined, and countries need to cede less sovereignty. Regional infrastructure cooperation is therefore an effective initial step on the path to broader integration. Some countries have more to gain from regional integration than others. Landlocked countries depend particularly on effective road and rail corridors to the sea, as well as on intra-continental fiber-optic backbones that link them to submarine cables. Coastal countries depend particularly on sound management of water resources upstream. Small countries benefit especially from regional power trade that reduces the costs of energy supply. If regional integration provides a substantial economic dividend to some of the participating countries, designing compensation mechanisms that benefit all of them should be possible. However, financing regional public goods tend to be problematic.

Nonlinear Characterization of Fiber Optic Submarine Cables

2017 ◽  
Author(s):  
Eduardo Mateo ◽  
Kohei Nakamura ◽  
Takanori Inoue ◽  
Yoshihisa Inada ◽  
Takaaki Ogata
Keyword(s):  
Fiber Optic ◽  
Nonlinear Characterization ◽  
Submarine Cables

A theoretical analysis of the use of submarine cables as electromagnetic oceanographic flowmeters

1976 ◽  
Vol 280 (1297) ◽  
pp. 355-396 ◽  
Keyword(s):  
Storm Surges ◽  
Weight Vector ◽  
Tidal Range ◽  
Submarine Cable ◽  
Vector Distribution ◽  
Simplifying Assumptions ◽  
The Mean ◽  
Residual Flows ◽  
Electro Magnetic ◽  
Submarine Cables

An examination is made of the theoretical basis and simplifying assumptions governing the use of the voltage measured across the ends of a submarine cable as a measure of the sea flow across the cable section. In part I a method of calculating the response of an electro-magnetic flowmeter by means of a weight vector is applied to the oceanographic situation. A numerical model is developed which generates the weight vector distribution for given submarine cables. In part II, weight vector distributions are obtained for various cables around the British Isles, and the cable responses to given velocity distributions in the sea are calculated. It is shown that the velocity distributions associated with different tidal frequencies, storm surges and long period residual flows will result in different responses at a given cable. The implications of this are discussed. The effect on the cable response of seasonally varying sea conductivity, and of a tidal range which is not negligible compared with the mean depth, is also modelled.

scholarly journals XXVII. On the relative speed of the electric wave through submarine cables of different lengths, and a unit of speed for comparing electric cables by bisecting the electric wave

1863 ◽  
Vol 12 ◽  
pp. 211-216
Keyword(s):  
The Other ◽  
Relative Speed ◽  
Submarine Cable ◽  
Electric Wave ◽  
Retarding Effect ◽  
The Earth ◽  
Current Flows ◽  
Electric Cables ◽  
Submarine Cables ◽  
A Current

The present paper gives the results of some experiments which were undertaken to determine, first, the relative speed of the electric wave through cables of various lengths; secondly, the retarding effect of the iron covering of the cable; and thirdly, methods for the increase of the speed of the electric wave. When a long submarine cable or subterranean wire is connected at one end through a galvanometer to the earth, and the other end is connected with a battery, a current flows through it, deflecting the galvanometer-needle.

Steerable ultrasonic source using low-power laser sources and fiber optic delivery

2001 ◽  
Author(s):  
Colin I. Swift ◽  
S. Gareth Pierce ◽  
Brian Culshaw
Keyword(s):  
Low Power ◽  
Fiber Optic ◽  
Power Laser ◽  
Laser Sources

The Analysis of Induced Voltage from AC Submarine Cable to Adjacent Communication Cable

2014 ◽  
Vol 960-961 ◽  
pp. 856-862
Author(s):  
Yang Wang ◽  
Guang Zhou Zhang ◽  
Guo Zhi Chen ◽  
Xiao Qin Zhang ◽  
Xin Long Zheng ◽  
...  
Keyword(s):  
Magnetic Induction ◽  
Normal Operation ◽  
Shielding Effect ◽  
Submarine Cable ◽  
Induced Voltage ◽  
Allowable Range ◽  
Submarine Cables ◽  
The Impact ◽  
Horizontal Arrangement

The induced voltage generated by AC submarine cables would effect the normal operation of communication cables nearby. The paper calculated the induced voltage generated by AC submarine cable according to formula and procedures related to magnetic induction. The maximum parallel length between submarine cable and communications table was calculated under horizontal arrangement, and shielding effect was taken into account to the impact of the results. The causes of various induced voltage on communication cable were analysed under normal operation and various fault conditions. The results show that the induced voltage on communication cable is proportional to the parallel length and inversely proportional to parallel spacing. When the parallel length does not exceed a certain value, the induced voltage is in the allowable range and will not affect the normal operation of the communication cable.

Axial Stresses in Armor Wires of Bent Submarine Cables

1969 ◽  
Vol 91 (3) ◽  
pp. 687-691 ◽  
Author(s):  
M. Lutchansky
Keyword(s):  
Mathematical Model ◽  
Entire Range ◽  
Free Field ◽  
Shear Stiffness ◽  
Simple Mathematical Model ◽  
Submarine Cable ◽  
Simple Description ◽  
Thin Wires ◽  
Submarine Cables ◽  
Outer Fiber

The axial stresses induced in the helically wound armor wires of a submarine cable bent over a drum are described by a simple mathematical model. The model, which represents the wire-core interaction, yields a simple description of the stress concentration at a rigid inclusion such as a clamp or apparatus housing. The “free field” expression for stresses away from an inclusion is also obtained and shows the effects of the entire range of interaction stiffness from frictionless slip to infinite interaction shear stiffness. At the latter limit beamlike outer fiber stresses are produced. Beamlike stresses are also produced in the limiting cases of infinitesimally thin wires and infinitely long lay-length where wires run parallel to the cable axis.

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