JP-2026074649-A - Seismic wave measurement method, program, and seismic wave measurement system

JP2026074649AJP 2026074649 AJP2026074649 AJP 2026074649AJP-2026074649-A

Abstract

[Challenge] To enable accurate correction of the internal time. [Solution] The control device 1 has a time identification unit 177 that identifies the seabed reception time, which is the absolute time when the measuring device received the first signal, based on the sea surface transmission time, which is the absolute time when a communication device located at a depth based on wave information indicating the state of waves on the sea surface detects seismic waves in response to vibration waves being emitted from the epicenter 2, and the sea surface reception time, which is the absolute time when the measuring device received the second signal, which is the response to the first signal from the measuring device, and a correction unit 179 that corrects the internal time of the measuring device associated with the measurement data based on the time difference, which is the difference between the internal time of the measuring device when the measuring device received the first signal and the identified seabed reception time. [Selection Diagram] Figure 6

Inventors

清水賢

Assignees

サイスガジェット株式会社

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (10)

A time identification step in which a communication device located at a depth based on wave information indicating the state of waves on the sea surface transmits a first signal to a measuring device installed on the seabed, which creates measurement data of the seismic waves associated with an internal time when the seismic waves were detected in response to vibration waves being emitted from the epicenter, and a time identification step in which the measuring device identifies the seabed-side reception time, which is the absolute time when the measuring device received the first signal, based on the sea surface-side transmission time, which is the absolute time when the measuring device received a second signal, which is the response to the first signal from the measuring device; A correction step of correcting the internal time of the measuring device associated with the measurement data based on a time difference which is the difference between the internal time of the measuring device when the measuring device receives the first signal and the identified seabed reception time, A seismic wave measurement method having [specific characteristics].
In the aforementioned time determination step, the time midway between the sea surface transmission time and the sea surface reception time is determined as the seabed reception time. The seismic wave measurement method according to claim 1.
In the time determination step, after determining the seabed reception time, the determined seabed reception time is corrected based on the horizontal movement distance, which is the distance the communication device moved horizontally between the sea surface transmission time and the sea surface reception time. The seismic wave measurement method according to claim 1.
The method further includes a calculation step of calculating a second distance, which is the distance from the position of the communication device to the position of the measuring device after movement, based on a first distance, which is the distance from the position of the communication device to the position of the measuring device before movement, and the horizontal movement distance. In the time determination step, the determined seabed reception time is corrected based on the ratio of the first distance to the second distance. The seismic wave measurement method according to claim 3.
The system further includes a depth determination step of determining the depth of the communication device from the sea surface based on the wave information, The seismic wave measurement method according to claim 1.
The system further includes a wave information acquisition step that acquires the wave height on the sea surface as wave information, In the depth determination step, the depth from the sea surface is determined by referring to depth management data which associates the wave height at the sea surface with the depth from the sea surface of the communication device. The seismic wave measurement method according to claim 5.
In the wave information acquisition step, the wave height on the sea surface is acquired based on the magnitude of the ship's oscillation detected by a vibration detection sensor on the ship navigating the sea, which is connected to the communication device. The seismic wave measurement method according to claim 6.
In the depth determination step, the depth of the earthquake source from the sea surface is determined based on the wave information. The seismic wave measurement method according to claim 5.
The processor in the information processing device A communication device located at a depth based on wave information indicating the state of waves on the sea surface transmits a first signal to a measuring device installed on the seabed, which creates measurement data of the seismic waves associated with an internal time when the seismic waves were detected in response to vibration waves being emitted from the epicenter. A time identification unit identifies the seabed-side reception time, which is the absolute time when the measuring device received the first signal, based on the sea surface-side transmission time, which is the absolute time when the measuring device received a second signal, which is the response to the first signal from the measuring device. A correction unit corrects the internal time of the measuring device associated with the measurement data based on a time difference which is the difference between the internal time of the measuring device when the measuring device receives the first signal and the specified seabed reception time, A program designed to function as such.
The system comprises a communication device that transmits a signal to a measuring device installed on the seabed that creates measurement data of the seismic waves associated with an internal time when the seismic waves were detected in response to the emission of seismic waves from the epicenter, and a control device installed on a ship navigating the sea that controls the depth of the communication device, The control device includes a depth control unit that controls the depth of the communication device so that the communication device is located at a depth based on wave information indicating the wave conditions on the sea surface. Either the control device or the communication device, A time determination unit that determines the seabed reception time, which is the absolute time when the measuring device received the first signal, based on the sea surface transmission time, which is the absolute time when the communication device located at the depth based on the wave information transmitted the first signal to the measuring device, and the sea surface reception time, which is the absolute time when the measuring device received the second signal, which is the response to the first signal from the measuring device. A correction unit corrects the internal time of the measuring device associated with the measurement data based on a time difference which is the difference between the internal time of the measuring device when the measuring device receives the first signal and the specified seabed reception time, Having, Seismic wave measurement system.

Description

This invention relates to a seismic wave measurement method, program, and seismic wave measurement system for measuring seismic waves. A technique for correcting the error between the clock time and absolute time in seafloor seismometers is known (see, for example, Patent Document 1). Patent No. 3037228 This is a diagram illustrating the seismic wave measurement system S.This figure shows an example of the path of an acoustic signal traveling back and forth between the communication device 5 and the measuring device 4.This flowchart shows an overview of the processing flow according to this embodiment.This is a diagram illustrating the procedure for activating multiple measuring devices 4.This figure shows an example of a management table that indicates the status of each measuring device 4.This is a diagram showing the configuration of the control device 1.This figure shows an example of depth management data.This figure shows an example of time management data.This flowchart shows the processing flow related to correcting the reception time on the seabed.This is a schematic diagram illustrating the correction of the reception time on the seabed side.This diagram shows the configuration of the communication device 5.This diagram shows the configuration of the measuring device 4. [Overview of Measurement System S] Figure 1 shows an overview of the measurement system S. The measurement system S is an ocean geophysical exploration system for analyzing the subseafloor geological structure. In the measurement system S, vibration waves are generated from a source 2 such as an air gun or sparker, and a control device 1 analyzes the subseafloor geological structure using the results of vibration wave measurements by numerous measuring devices 4 installed on the seabed. The measurement system S comprises a control device 1, a seismic source 2, an optical communication device 3, a plurality of measurement devices 4, and a communication device 5. The control device 1, seismic source 2, and optical communication device 3 are mounted on a vessel 100 capable of moving on the ocean. The control device 1 may also be mounted on a USV (Unmanned High-Performance Observation Vehicle) capable of communicating with the vessel 100. A USV is a survey vessel that navigates the sea and conducts oceanographic surveys. The plurality of measurement devices 4 are installed on the seabed at intervals of a predetermined distance or more. The communication device 5 is a device capable of communicating with the vessel 100 or the USV via cable C. The communication device 5 is located in the sea. The control device 1 is, for example, a computer. It acquires measurement data indicating the seismic state of the seabed observed by multiple measuring devices 4 at the timing of seismic wave emission, and analyzes the acquired measurement data. Specifically, the control device 1 analyzes the seismic wave measurement data detected by the measuring devices 4 in response to seismic waves emitted from the epicenter 2 towards the seabed from a ship navigating the sea during the measurement period. As shown in Figure 1(a), the control device 1 controls the multiple measuring devices 4 and receives the measurement data generated by the multiple measuring devices 4 by transmitting and receiving acoustic signals via the communication device 5. Furthermore, the control device 1 acquires information indicating absolute time from, for example, a PTP network or GPS (Global Positioning System). The control device 1 controls the depth of the communication device 5 from the sea surface. For example, the control device 1 controls the depth of the communication device 5 from the sea surface by transmitting a control signal to the communication device 5 via cable C to control the movement of the communication device 5. The seismic source 2 generates vibration waves during the measurement period. The seismic source 2 generates vibration waves based, for example, on the control of control device 1, but it may also generate vibration waves based on the control of a different control device (for example, a computer installed on a ship different from vessel 100). Furthermore, a ship different from vessel 100 may be equipped with the seismic source 2. The optical communication device 3 acquires measurement data from at least one measuring device 4 by communicating optically with it based on the control of the control device 1. The optical communication device 3 emits a first optical signal to the measuring device 4 underwater, and receives a second optical signal transmitted by the measuring device 4 that received the first optical signal. As shown in Figure 1(b), the optical communication device 3 is connected to the control device 1 by cable C. Based on the control of the control device 1, it submerges to a position where it can communicate optically with the measuring device 4, and then communicates optically with the measuring device 4. The optical communication devic