GPS World

Tag: Nankai Trough

  • Advancing earthquake prediction with a UAV

    Advancing earthquake prediction with a UAV

    Researchers demonstrate a seaplane-type UAV using GNSS-A can precisely measure seafloor deformation

    Megathrust earthquakes are large earthquakes that occur on faults found along the boundaries between tectonic plates. The Nankai Trough is a megathrust earthquake zone lying off the southwestern coast of Japan, and experts estimate that this zone could generate a potentially devastating (magnitude 8 or 9) large earthquake sometime in the next 30 years. A seismic event of this magnitude could trigger cascading hazards such as destructive tsunamis.

    Developing the technologies for efficient and reliable seafloor monitoring is paramount when considering the potential for socioeconomic harm represented by megathrust earthquakes. Traditionally, seafloor measurements have been obtained using transponder stations on the seafloor that communicate with satellites via buoys or ocean-going vessels to produce accurate positional information. However, data collection using such systems has problems such as low efficiency and speed.

    In a study published in Earth and Space Science, researchers at Institute of Industrial Science, the University of Tokyo, addressed the challenge of acquiring reliable, high-precision, real-time seafloor measurements by constructing a seaplane-type unmanned aerial vehicle (UAV) that can withstand ocean currents and wind. This vehicle is intended for use with the GNSS–Acoustic (GNSS-A) ― a system that uses satellites to determine locations on Earth ― to provide a communication link with seafloor transponder stations.

    “We conducted initial experiments in a water tank,” explains lead author of the study Yuto Yoshizumi, “and found that the proposed system can detect distances to an accuracy within 2.1 cm.”

    To further evaluate the system, at-sea trial tests were performed by landing the UAV on the sea surface off the coast of Japan under optimal sea conditions. “The results were hugely encouraging,” said senior author Yusuke Yokota. “These seafloor positioning measurements are the first ever achieved using a UAV, and we attained a horizontal root mean square error of approximately 1–2 cm, which is easily comparable to that of existing vessel-based systems.”

    The rapid real-time acquisition of seafloor information using the UAV system developed by the research team at Institute of Industrial Science, the University of Tokyo, is expected to provide the foundation for advanced research into earthquake disaster prevention. Such data are urgently needed given the speed and frequency of occurrence of megathrust earthquakes on the Nankai Trough.

    Full paper, DOI: 10.1029/2025EA004237.

  • Seen & Heard: Hitchhiking marine life heads to Antarctica

    Seen & Heard: Hitchhiking marine life heads to Antarctica

    “Seen & Heard” is a monthly feature of GPS World magazine, traveling the world to capture interesting and unusual news stories involving the GNSS/PNT industry.

    Photo: Anton Rodionov/iStock/Getty Images Plus
    Photo: Anton Rodionov/iStock/Getty Images Plus

    UNWANTED HITCHHIKERS

    Antarctica’s pristine marine ecosystem, isolated for 15–30 million years, could be threatened by species such as mussels, barnacles, crabs and algae arriving on ships from 1,500 ports worldwide. A research team from the British Antarctic Survey and the University of Cambridge used automatic identification system (AIS) data, which relies on GNSS navigation data, and shipping databases to determine traffic to the Antarctic. The study is published in the Proceedings of the National Academy of Sciences, January 2022.

    Photo: FrankRamspott/iStock/Getty Images Plus
    Photo: FrankRamspott/iStock/Getty Images Plus

    QUAKE PREDICTION

    Within the next 30 years, a highly destructive Nankai Trough megathrust earthquake is predicted to hit southwest Japan. Understanding long-term slow slip events under the Bungo Channel is essential for pinpointing when such an earthquake will happen. Kobe University’s Yoshioka Shoichi and Seshimo Yukinari analyzed the 2018–2019 Bungo Channel slow-slip event using longitudinal GNSS data provided by the Geospatial Information Authority of Japan. The data revealed that even though the 2018–2019 event was shorter than others, it was bigger in terms of slippage and slip velocity, as well as magnitude. Results appear in Scientific Reports, Jan. 10, 2022.

    Photo: Bluesky
    Photo: Bluesky

    SUPPORTING SOLAR 

    British aerial mapping company Bluesky is helping Derby Homes roll out integrated solar photovoltaic systems across its housing stock. A project to identify suitable roof coverings assessed more than 8,000 addresses for size, pitch, aspect, existing structures and infringing vegetation. Using its ultra-high-resolution imagery, Bluesky determined the solar suitability of each property, the number of panels needed, and their potential output. Derby Homes recently installed its first integrated solar array on an initial batch of trial properties identified by Bluesky.

    Photo: JohnCarnemolla/iStock/Getty Images Plus
    Photo: JohnCarnemolla/iStock/Getty Images Plus

    TAKING MOM TIME 

    CQUniversity’s precision livestock management research team is using GNSS to detect calving events in extensive grazing herds. The discovery could provide beef producers in Australia with a way to remotely monitor their cattle and improve calf survival rates, one of their biggest challenges. The research project used GNSS collars with motion-detecting accelerometers on 30 cows in a 28-hectare paddock over an eight-week period at Belmont Research Station. The collars captured the animals’ location information every 10 minutes. Because the distance between mother and herd increases during calving, the data helped predict calving events, which were then visually confirmed by the research team.