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Kafe 바로가기주관연구기관 | 한국지질자원연구원 Korea Institute of Geoscience and Mineral Resources |
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보고서유형 | 연차보고서 |
발행국가 | 대한민국 |
언어 | 한국어 |
발행년월 | 2014-12 |
과제시작연도 | 2014 |
주관부처 | 미래창조과학부 KA |
과제관리전문기관 | 한국지질자원연구원 Korea Institute of Geoscience and Mineral Resources |
등록번호 | TRKO201500000684 |
과제고유번호 | 1711021734 |
DB 구축일자 | 2015-04-18 |
키워드 | 수중음파,지진파,공중음파,해저면 복합지구물리 관측기지Hydro-acoustic,Seismic,Infrasound,Seafloor multidisciplinary geophysical observatory |
DOI | https://doi.org/10.23000/TRKO201500000684 |
연차목표
○ 동해 북부 해저지진 정밀 진원결정과 지진원 분류
○ 수중음파 신호 탐지기술 기반 연구
○ 공중음파 감쇠 특성 연구 및 SI 광역 관측망 확충
○ SHI 융합분석기술 정의 및 사례연구
○ 해저면 복합지구물리 관측기지 프로토타입 및 원격감시기술 설계
○ 수중 고주파수 음파 계측 모듈 프로토타입 설계 및 개발
○ 해저지각활동 위치결정 정확도 향상을 위한 수중음파 전달과정 연구
개발내용 및 결과:
○ 동해 북부 해저지진 정밀 진원결정과 지진원 분류
- 동해 북부 해역에서 발
연차목표
○ 동해 북부 해저지진 정밀 진원결정과 지진원 분류
○ 수중음파 신호 탐지기술 기반 연구
○ 공중음파 감쇠 특성 연구 및 SI 광역 관측망 확충
○ SHI 융합분석기술 정의 및 사례연구
○ 해저면 복합지구물리 관측기지 프로토타입 및 원격감시기술 설계
○ 수중 고주파수 음파 계측 모듈 프로토타입 설계 및 개발
○ 해저지각활동 위치결정 정확도 향상을 위한 수중음파 전달과정 연구
개발내용 및 결과:
○ 동해 북부 해저지진 정밀 진원결정과 지진원 분류
- 동해 북부 해역에서 발생하는 소규모의 지진이벤트들의 진앙을 이중차분 진원위치 재결정방법으로 재결정하고 진원 분포 특성 및 관측된 지진파 특징 규명
- 지진원 식별기술 개발 관련 관측소 부지효과 계산 완료, 지하 핵실험의 규모와 T-파의 진폭 간 비례관계 확인
○ 수중음파 신호 탐지기술 기반 연구
- 수중음파 분석 기술 관련 지식 기반 구축
○ 공중음파 감쇠 특성 연구 및 SI 광역 관측망 확충
- 발파자료를 통한 음원 크기 계산 및 근, 지역거리에서의 감쇠 특성 파악
- KSRS 지진관측소에 공중음파 센서 추가 및 초기분석 완료
○ SHI 융합분석기술 정의 및 사례연구
- 국외기관의 데이터/센서 퓨전 기술 조사 수행
- 융합 분석 기법 지식 기반 구축 및 기초 알고리즘 확보
- SI 신호를 통한 진주 낙하유성의 궤적 및 폭발 크기 계산
○ 해저면 복합지구물리 관측기지 프로토타입 및 원격감시기술 설계
- 동해 북부 해역에 적합한 해저면 관측기지 프로토타입 설계, 설치해역 확보 및 육상중계소 구축 완료
- SOH 원격 감시 체계 설계 및 해상 무선통신 방식 선정
- 해저정밀지형조사를 통한 3차원 해저지형도 작성 및 해저면 특성 파악
○ 수중 고주파수 음파 계측 모듈 프로토타입 설계 및 개발
- 4채널 배열 센서 구조 설계 및 음원의 입사각 탐지 알고리즘 성능 분석 및 음파 계측 모듈 프로토타입 성능 검증
- 저잡음 수중음파 신호 증폭 및 필터 회로 상세 설계 및 제작
- 저전력 데이터 수집 및 실시간 신호분석 시스템 구현
○ 해저지각활동 위치결정 정확도 향상을 위한 수중음파 전달과정 연구
- NOAA, CTBTO 수중음향 자료 확보를 통한 지진 규모와 음파 소스레벨과의 관계 분석
- 정단층과 역단층에서 수중음향전달시간의 차이 확인
기대효과
○ 해저지진 정밀관측 및 해석을 통한 육상-해양지역을 아우르는 활성 지구조 해석
○ 자연적, 인위적, 군사적, 생태학적 수중음원 DB 제공
○ 핵실험, 수중폭발, 주변국 군사활동 동향 감시
○ 해저관측소 상시 운영기술 확보
○ 해저 관측모듈 및 부이시스템 설계의 기초자료 및 해저면 관측기지 설치에 적합한 최적의 장소 도출에 적용
적용분야
○ 해저지진 위험도 평가를 포함한 종합적 지진 대책 수립
○ 대규모 탄성에너지원 탐지와 분석을 위한 지역관측망에서의 SHI 융합분석 및 탐지체계 구축에 활용
○ 북한 핵실험 등 인위적 발생 지진에 대한 신속, 정확한 탐지 기술 개발에 활용
○ 해역조건에 적합한 해저면 관측기지 구축에 활용
○ 고품질, 안정적 지구물리 관측자료 획득을 위한 운영기술 개발에 활용
○ 해상-육상 간 융복합 무선 데이터 통신
○ 해양 수중음향 환경 모니터링
Micro-earthquakes in offshore Gangneung-Sokcho-Goseong area of northeastern South Korea are reiewed and the hypocenters of these events are relocated by double-difference algorithm. Small repeating events occur predominantly in offshore area, whereas onshore event5s ar4e relatively few and unevenly
Micro-earthquakes in offshore Gangneung-Sokcho-Goseong area of northeastern South Korea are reiewed and the hypocenters of these events are relocated by double-difference algorithm. Small repeating events occur predominantly in offshore area, whereas onshore event5s ar4e relatively few and unevenly distributed. We focus on the small events occurred in the rectangular area of N37˚45'-38˚35' and E128˚30'-129˚20'. We added 5 short period Guralp CMG-40T seismometers along coastline to reinforce event detection capability and improve accuracy of event relocation. The data set consists of 137 events recorded from May to October 2014, ranging in local magnitude from 0.4 to 2.3 Total 1849 arrival times of direct P-wave phase are retrieved from 29 stations. Two major clusters in offshore Goseong(cluster 1) and Yangyang (cluster 2) provinces are found and the epicenters are relocated. The waveforms of relocated events inn cluster 1 and 2 are similar to those from explosion rather than earthquake and spectrum analysis shows eenergy concentration on low frequencies below 10 Hz.
The T-phase generated from the 2<sup>nd</sup> and 3<sup>rd</sup> unkerground nuclear test6 of North Korea was analyzed. The analysis result showed that there is a proportional scaling relationship between seismic magnitude and T-Phase amplitude. Site effect at seismic stations across Korean Peninsula and northern part of North Korea was constrained by using H/V ratio. The variations of site effect between stations are within ±0.3.
We have studied basic characteristics of underwater acoustic signals from large seismic events like submarine earthquakes and volcanic eruptions. We have collected waveforms from hydroacoustic network of CTBTO. We have tested basic waveform analysis and array processing methods. The data and the results show hydroacoustic monitoring method will definitely enhance detection capability of underwater seismic events in and around the Korean peninsula. We have investigated autonomous Lagrangian hydroacoustic monitoring technology. Technology seminaar and meeting have given us a wide-open view on Lagrangian monitoring. The Lagrangian monitoring will add synergy to our seafloor geophysical researches.
In order to establish empirical attenuation relation for infrasound signals, acoustic energy in atmosphere were quantitatively measured in local and regional distances. For the acoustic energy sources, we have acquired large number of blasts in a mine area and used them as ground truth events. The source pressure amplitudes at reference distance(1 km) were estimated by the distance and pressure ratio of blasts between two local seismo-acoustic stations deployed in vicinity of the blasting zone.
At the same time, infrasound signals of the blasts were detected at kistant array, CHNAR, that is locatin about 177 km from the blast zone. The amplitudes at CHNAR were measured and compared with the acoustic source energy at the reference distance.
Coherence analysis was performed to find a substitute of the current infrasound noise reduction system. Two brands of hoses were tested. Unfortunately the two hoses failed in passing the coherence test. A new type of hose with metal shield waas proposed by Southern Methodist University. It will be tested in a laboratory and field for the installation at the existing seismo-acoustic arrays. KSIAR, a new infrasound array, was installed on the existing four short-period seismic stations of KSRS in April 2014. A preliminary analysis detected microbarom from the two dominant directions, which needs to be eliminated fr4om the analysis in the future.
Identification of seismic events is mostly based on detection from seismic stations. Occasionally, infrasonic, hydroacoustic signals are essential in detection and location of seismic sources in both underwater and atmosphere. This shows the importance of fusion of seismic, hydroacoustic, infrasonic(SHI) data. To design model of SHI data-fusionj, we have made collaborative network with advance research roups.
On the evening of 9 March 2014, a bright fireball was observed by many people in South Korea, and the energy associated with the event was also recorded at seismic and infrasound stations at local and regional distances. Using impulsive seismic signals recorded at 19 stations, we calculated the possible extent of the sonic source of the fireball by assuming point-and line-source models, which were physically linked to a possible point-source explosion in the atmosphere or shock waves radiating from the fireball's trail, respectively. It was found that shock waves along the meteor's high-speed passage through the atmosphere were probably the dominant source of the seismic signals on the ground. The estmated parameters of the fireball's sonic trajectory, incorporating propagation dependent on the speed of the shock wave, were estimated to be an azimufh arrival angle of 313.5˚ clockwise from the north and an elevation arrival angle of 44.5˚ above the Earth's surface, with a source time of 11:04P51 UTC at which the predicted trajectory met the Earth's surface. From the infrasound measurements, the kinetic local-source energy generating the sound was estimated to be about 0.8 tons TNT, based on semi-empirical relations developed for the point-and line-source models.
A prototype of multidisciplinary geophysical observatory was designed for installation in shallow water in the eastern coast of Korea. The observatory consists of three independent stations, forming a triangular~500 meters aperture array. Each station mainly comprises of Sea Floor Module and Sea Surface Module. The modules anre connected each other with a special electro-mechanical cable for data transmission and power supply. The Sea Surface Module is based on an elastic beacon type buoy and will relay the observational data to inland station in real time, about 4.5 km apart, by 24 GHz radio frequency, cellulaar and two-way radio communications. The Sea Surface Module can autonomously produce DC power from solar power generators with batteries and supplies the power to the Sea Floor Mokulee and to its own equipment.
The seafloor observation system will be installed in the offshore area and it will be operatedby itself without human interaction. In order to keep high stability in unfavorablee ocean conditions, a remote-monitoring and disability-handling technologies are required. So we designed a remote monitoring system for the observation system. This system collects SOH(State-Of-Health) data from the seafloor observation system, anallyzes them automatically, and makes an alarm when human interaction is needed. It also sends a SMS(Short Message Service) to inform staff about the disorder quickly. This monitoring system will help to increase receiving rate of oserved data and also prevent damage and loss of equipment. In this year, web based GUI monitoring program is developed as a part of the monitoring system. We can monitor our seafloor observation system in real-time using any web-browsers. In addition, an new remote power control module is developed as a dissability-handling technology. The seafloor observation system also has its own functionality to control power by remote, but this new remote power control module has its own telecommunication system. So it will be useful when the telecommunication system of the observation system is not working. Using these two technologies. we can expect high stability of our observatiion system and also decrease of maintenance fee.
High resolution 3-D acoustic mapping and characterization of subsea area where underwater multidisciplinary geophysicaal observatories to be installed are done by multibeam echosounding survey and subsequent data processwing. A detailed 3-D bathymeetric imagee of 25 ㎢ offshore area are obtained as well as backscattering image. We found the area to be considered for underwater multidisciplinary geophysical observatories is smooth and gently dipping toward northeast. Also, the pressure level of backscattered multibeam signal does not significantly change in target area. This implies the change of sedimentary facies of bottom sediment is also small, so that sea bottom is homogeneous.
In order to gather information on acoustic signals in a higher frequency range, a prototype of a high-frequency underwater sound measurement system has been developed. The system has an array of four hydrophones with a star-shaped topology and the conventional beamforming algorithm was implemented to estimate incident angles. The real-time signal processing module of the system was assembled with commercially available e2quipment with FPGA(field-programmable gate array). A small-sized four-cchannel amplifier with band-pass-filter has been developed to fit in the processing module. The system has temperature and pressure gauges to estimate the underwater soung speed. The total power consumption is less than 20 W and the function of remote power control was also implemented in order to reach the average power consumption less than 10 W. For the performance test of the acoustic module, a temporary seafloor measurement system has been developed. It has capability of RF communication, underwater acoustic communication, electrical power supply, and real-time system monitoring. The major functions and the performance of the total system were tested and verified at a pier as well as in a water tank.
As a reference ocean environmental data around Korean peninsula such as current, wind speed, wave height etc. were collected. Underwater soundd propagation characteristics around the potential installation site was analyzed.
T-waves, acoustic waves generated from seismic sources, can travel great distances through the low velocity channel with little energy loss. Many scientists utilize the efficiency of T-wave propagation to detect small oceanic earthquakes. However, due to its complex excitation and propagation mechanism, estmation exact travel time is the problem which confronts us. The final goal of this study is examine T-wave propagation path to enhance locating accuracy for oceanic earth2quakes. We collect hydroacoustic data from NOAA (National Oceanic and Atmospheric Administration) and extract T-wave signals of the events in global CMT catalogue. We calculate acoustic source levels of the signals and compare with earthquake magnitude. We will examine effects of fault mechanism and seafloor bathymetry on the T-wave shape. Then we will develop modeling program to illustrate T-wave propagation for realistic sources and propagation medium in the next phase.
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