0

Full Content is available to subscribers

Subscribe/Learn More  >

The Underwater Laser Ranging for Dynamics Measurement Around Subduction Zone

[+] Author Affiliations
Hiroshi Yoshida, Shojiro Ishibashi, Hide Sakaguchi

Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan

Takashi Saito, Motoi Denou, Masatoshi Tashiro, Kiyotaka Tanaka, Minoru Suzuki

Mitsubishi Electric Tokki Systems Corp., Kamakura, Japan

Paper No. OMAE2015-41688, pp. V006T05A024; 5 pages
doi:10.1115/OMAE2015-41688
From:
  • ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering
  • Volume 6: Ocean Space Utilization
  • St. John’s, Newfoundland, Canada, May 31–June 5, 2015
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 978-0-7918-5654-3
  • Copyright © 2015 by ASME

abstract

An underwater laser ranging system to capture microscopic fluctuations in relative plate motion around subduction zone has been developed since 2010. We believe that direct detection of the fluctuations resulted from plate motion suggests the degree of interplate mechanical instability for long-term prediction of oceanic intraplate earthquake.

In April 2011, sea trial using the first prototype was carried out in shallow water zone in Okinawa. Distance measurements could be performed in the distance of 10 meters but results included large error variation of 0–10 cm. To improve measurement resolution and accuracy of the sub-millimeter fluctuations, we have developed the second prototype of laser ranging system based on the first one.

The main part of the system consists of a transmitting unit (Tx) and a receiving unit (Rx). One of the units is composed of a transparent acrylic cylindrical pressure hull (PH), a main PH, a battery pack, and sensors, which are installed on an aluminum alloy frame. The transparent PH of Tx is equipped with a 1 Watt semiconductor blue laser, a modulator and a driver which are set on a horizontal turntable with elevation adjustment. Its Rx has an avalanche photo diode as detector and a demodulator on a same type turntable. A controller and an optical communication device are installed in each main PH. The Tx is connected with the Rx via thin optical glass fiber to transmit reference signal.

We carried out a sea-trial in Okinawa by the second prototype in February 2014. We received optical signal at distance between the Tx and the Rx of up to 20 meters. The ranging was performed at 10 meters and measurement raw data errors were within a range of millimeters. On the other hand, automatic optical alignment at 20 meters was completely failed. These results show that measurement accuracy is closer to a goal but system completion is away from the goal. We need review not only the algorithm but also optical hardware of the alignment.

Copyright © 2015 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In