Report of Hydrographic And Oceanographic Researches

No.50 (March, 2013)
Japanese

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Contents

Article

  1. abstract pdf Developed tectonic relief and frequency of great earthquakes caused by normal faults in the outer slope of the Japan Trench(in Japanese)
    Yo IWABUCHIp.1

Short article

  1. abstract pdf Topographic evolution of volcanic islands(in Japanese)
    KazukiWATANABEp.25
  2. abstract pdf Computation of geodesics and rhumb lines on spheroid(in Japanese)
    Naohiko NAGASAKAp.37
  3. abstract pdf(in English) Estimation of total vertical uncertainty for the bathymetry acquired by autonomous underwater vehicle in deep water
    Hiroki MINAMIp.58

Technical report

  1. abstract pdf Analysis with airborne LIDAR data(in Japanese)
    Shinjiro TOMIZAWA and Tomozou ONOp.65
  2. abstract pdf Preliminary report on the bathymetric surveys along the northwestern coast of Okinawa Island(in Japanese)
    ToruYASUHARAp.80
  3. abstract pdf New analysis method for maintaining the observation continuity after replacement of seafloor stations(in Japanese)
    Naoto UJIHARA, Mariko SATO, Tadashi ISHIKAWA, and Shun-ichi WATANABEp.84
  4. abstract pdf Installation of seafloor geodetic observation system on the S/V "Kaiyo"(in Japanese)
    Yuhei AKIYAMA, Naoto UJIHARA, and Hajime DAIMONp.91
  5. abstract pdf Hardware replacement and analysis engine update on the automatic data acquisition and baseline analysis system for continuous GPS observations of Japan Coast Guard(in Japanese)
    Kazuyoshi OICHI, Fusako OHASHI, Masayuki OKUMURA, Hajime DAIMON, and Nobuhiro IKEDAp.97
  6. abstract pdf Examination of observation method for strong tidal current in heavy marine traffic area(in Japanese)
    Yasunori FURUKAWA, Toru NANBA, Kazuhide TANAKA, and Kouichiro NAKAYAMAp.104
  7. abstract pdf Tidal current observation in the Kurushima Strait in future(in Japanese)
    Takeshi KUMAGAI,Yasushi NABAE, andYasuhiro KOSOp.115
  8. abstract pdf Study on the method to prioritize hydrographic surveys using information on marine traffic and quality of bathymetric data encoded in electronic navigational charts(in Japanese)
    Yoshihiro OBANA and Hisashi MASAOKAp.119
  9. abstract pdf pdf(Fig. 6 left), pdf(Fig. 6 right)
    3D bathymetric image along the Sagami Trough and the Boso Triple Junction area deduced from 150meter grid DEM(in Japanese)
    Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Takashi NAKATA, Hideaki GOTO, Mitsuhisa WATANABE, and Yasuhiro SUZUKIp.126

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Abstracts (Article)

Developed tectonic relief and frequency of great earthquakes caused by normal faults in the outer slope of the Japan Trench

Yo IWABUCHI

Iwabuchi(2012) analyzed 23 topographic profiles on the outer slope of the Japan Trench derived from swath multi-beam bathymetries. According to the study, strain rates close to the axis of the Japan Trench were estimated as 7x10 - 8/yr (at the southern Japan Trench) to 11x10 - 8/yr (at the northern most of Izu-Ogasawara Trench).

Iwabuchi(2012) indicated the measurements of relative heights of horsts and grabens on only two profiles because of the limits of pages of the journal. Thus, I will show all the measurements of the relative heights of horsts and grabens in this paper. In addition to this, I will infer the frequency of great tensional earthquakes in the outer slope of the Japan Trench.

It is well known that 1933 Sanriku earthquake(Mw 8.4) is the example of tensional events in the outer slope of the trench. Topographic analyses resulted in the displacement rates of whole of the outer slope of the northern and southern Japan Trench are estimated as 3.5mm/yr and 3.6mm/yr, respectively. On the assumption that the great earthquake equal to 1933 Sanriku earthquake in magnitude will occur in repeatedly as the characteristic earthquake, a frequency of the great earthquake is estimated about one thousand years to one thousand and several hundred years per one earthquake.

No earthquakes in large scale with M > 8 are known in the outer slope of the southern Japan Trench. However, the displacement rate in the outer slope of the southern Japan Trench is almost same as the northern Japan Trench. If normal-faulting earthquake equal to the magnitude of 1933 Sanriku earthquake will occur, a frequency of the earthquake is estimated as same as the northern Japan Trench.

At the northern most of Izu-Ogasawara Trench, off Boso peninsula, an average displacement rate is almost two times higher than the Japan Trench. If the great earthquake which is equal to the magnitude of 1933 Sanriku earthquake will occur in the area, a frequency of the earthquake is estimated lower than one thousand year per one earthquake.


Abstracts (Short article)

Topographic evolution of volcanic islands

KazukiWATANABE

The topography of volcanic islands evolves, as follows. Initially, volcanic islands grow up to be cone-shaped body after repeated eruptions. Then, waning of volcanic eruptions allows gradual erosion around the islands by waves,making the islands trapezoid body surrounded by steep cliffs. Finally, volcanic islands become rock pillar-like body after intensive erosions. Because of this temporal evolution of volcanic islands, in addition to the state of vegetation that covers the islands, the rough age and history of volcanic islands can be presumed.

Computation of geodesics and rhumb lines on spheroid

Naohiko NAGASAKA

In Japan, domestic laws for surveying and hydrographic services define the shape of the Earth as an oblate spheroid (ellipsoid). Therefore, in order to determine precise positions and distances in accordance with those laws, the geometry on spheroid is required. The geometry is also essential to precise maritime delimitation such as computing equidistant lines between Japan and adjacent countries as the limit of exclusive economic zone of Japan. This report introduces some basic concepts of geometry on the spheroid, especially, geodesics and rhumb lines. It also describes a full detail of a method to compute geodesics proposed by T. Vincenty in 1975.

Estimation of total vertical uncertainty for the bathymetry acquired by autonomous underwater vehicle in deep water

Hiroki MINAMI

Total vertical uncertainty (TVU) for the bathymetry acquired by multibeam echo sounder deployed on Autonomous Underwater Vehicle (AUV) in deep water was estimated. The existing uncertainty model for hydrographic survey using survey vessel was applied to AUV for estimation. Estimated TVU are between 0.27m and 0.35m

With the estimation method described in this paper, the uncertainty can be estimated for any AUV depth and altitude, regardless of vehicle' s platform.


Abstracts (Technical report)

Analysis with airborne LIDAR data

Shinjiro TOMIZAWA and Tomozou ONO

Japan Coast Guard has been working about how to incorporate airborne LIDAR (light detection and ranging) data to nautical charts while operating the airborne LIDAR system SHOALS1000. In order to use airborne LIDAR data to nautical charts, not only knowledge and experience of the hydrographic survey but also understanding the characteristics of the airborne LIDAR data are necessary. We describe the analysis methods for airborne LIDAR data in the Japan Coast Guard.

Preliminary report on the bathymetric surveys along the northwestern coast of Okinawa Island

ToruYASUHARA

The 11th Regional Coast Guard Headquarters has carried out the detailed bathymetric surveys using a multi-beam echo sounder in the area along the shore of the northwestern part of the Okinawa Island for five years from fiscal year 2008 to 2012. These surveys revealed prominent topographic features indicating global sea level fluctuations and presence of faults in some areas.

New analysis method for maintaining the observation continuity after replacement of seafloor stations

Naoto UJIHARA, Mariko SATO, Tadashi ISHIKAWA, and Shun-ichi WATANABE

Japan Hydrographic and Oceanographic Department (JHOD) has been carrying out GPS/acoustic seafloor geodetic observation for monitoring crustal movements. Since 2009, we have replaced seafloor transponders, starting from the oldest sites, before runout of the battery to ensure the continuity of observation. In this report, we propose a new method applying array constraint analysis (Ishikawa and Sato, 2012) for maintaining the continuity of observation results between from new and old transponders, and consider the possibility that the number of parallel observations or the number of the ranging data obtained in parallel observations can be reduced.

Installation of seafloor geodetic observation system on the S/V "Kaiyo"

Yuhei AKIYAMA, Naoto UJIHARA, and Hajime DAIMON

Japan Hydrographic and Oceanographic Department (JHOD) installed an acoustic transducer on the bottom of the S/V "Meiyo"(550tons) in 2008 and the S/V "Takuyo"(2,400tons) in 2010, and started sailing measurements for more efficient and precise seafloor positioning. JHOD also have installed a new seafloor geodetic observation system on the S/V "Kaiyo"(550tons) in 2012.

This report presents the new system mounted on the S/V "Kaiyo" and the results of test observation.

Hardware replacement and analysis engine update on the automatic data acquisition and baseline analysis system for continuous GPS observations of Japan Coast Guard

Kazuyoshi OICHI, Fusako OHASHI, Masayuki OKUMURA, Hajime DAIMON, and Nobuhiro IKEDA

Japan Coast Guard has been carrying out continuous GPS observations at 35 stations in the coastal area of Japan.

An integrated system for automatic data acquisition and baseline analysis is applied to continuous service on the crustal movement monitoring with GPS. In January 2011, major hardware components of the system were replaced and also the baseline analysis program was updated. This report presents outline of the updated system and evaluation of the new analysis engine.

Examination of observation method for strong tidal current in heavy marine traffic area

Yasunori FURUKAWA, Toru NANBA, Kazuhide TANAKA, and Kouichiro NAKAYAMA

In the 5th Regional Coast Guard Headquarters, we examined a tidal current observation technique in the strong tidal current area with heavy marine traffic. We report the test results of real time and long term observation by using floating light with the supersonic wave current meter in Akashi Strait.

Tidal current observation in the Kurushima Strait in future

Takeshi KUMAGAI,Yasushi NABAE, andYasuhiro KOSO

The methods of tidal current observation in the Kurushima Strait and providing in future are introduced.

Study on the method to prioritize hydrographic surveys using information on marine traffic and quality of bathymetric data encoded in electronic navigational charts

Yoshihiro OBANA and Hisashi MASAOKA

In order to effectively determine the areas where hydrographic surveys are preferentially required within limited resources, priorities in hydrographic survey are evaluated using information on marine traffic and quality of bathymetric data collected by previous surveys. Ships' traffic flows in each 1min * 1min grid-cell are acquired in coastal areas by analyzing AIS (Automatic Identification System) data. CATZOC values, which are encoded in Electronic Navigational Charts, are used as the information of quality of bathymetric data.

Using the evaluation method developed in this study, survey priorities can be derived simply by processing objective information in a normalized way. The derived priorities are not biased from region to region and can be compared on the same criterion.

3D bathymetric image along the Sagami Trough and the Boso Triple Junction area deduced from 150meter grid DEM

Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Takashi NAKATA, Hideaki GOTO, Mitsuhisa WATANABE, and Yasuhiro SUZUKI

We have made detailed anaglyph images based on 150m DEMprocessed from the original data obtained by Japan Coast Guard and JAMSTEC, in order to analyze submarine topography for more precise interpretation of submarine active faults than that mapped by previous workers along the Sagami Trough and the Boso Triple Junction area.

Younger fault escarpments on the both sides of northern part of the Sagami Trough in the Sagami Bay suggest their historical activities. In the vicinity of the Boso Triple Junction, trench-parallel west-dipping thrusts form extensive fault scarps in the aseismic gaps during historical period. One of the scarps is longer than 200km associated with evidence of repeated activity, and is probably a candidate of M8 earthquake in not far future.


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