A5028833232- earthquake and tectonic studies
- Seismology and Earthquake Studies
- Seismic Waves and Analysis
- Earthquake Detection and Analysis
- Seismic Imaging and Inversion Techniques
- High-pressure geophysics and materials
- Geophysics and Sensor Technology
- Botany and Geology in Latin America and Caribbean
- Geological and Geochemical Analysis
- Geological and Geophysical Studies
- Geological Studies and Exploration
- Methane Hydrates and Related Phenomena
- Geomagnetism and Paleomagnetism Studies
- Underwater Acoustics Research
- Ionosphere and magnetosphere dynamics
- Earthquake and Tsunami Effects
- Hydrocarbon exploration and reservoir analysis
- Atomic and Subatomic Physics Research
- Geochemistry and Geochronology of Asian Mineral Deposits
- Remote Sensing and Land Use
- Geology and Paleoclimatology Research
- Earthquake and Disaster Impact Studies
- Bayesian Methods and Mixture Models
- GNSS positioning and interference
- Neurological disorders and treatments
Association for the Development of Earthquake Prediction
2016-2024
The University of Tokyo
2014-2024
Earthquake Engineering Research Institute
2014-2022
Hokkaido University
2014-2015
Okayama University
2006
Research Article| June 13, 2018 Development of a Slow Earthquake Database Masayuki Kano; Kano aEarthquake Institute, The University Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, Tokyo 113‐0032, Japan, babasatoru@eri.u-tokyo.ac.jp, kano@eri.u-tokyo.ac.jp, obara@eri.u-tokyo.ac.jp, maeda@eri.u-tokyo.ac.jp, akiko-t@eri.u-tokyo.ac.jpqNow at Department Geophysics, Graduate School Science, Tohoku University, 6‐3 Aramaki Aza‐Aoba, Aoba‐ku, Sendai, Miyagi 980‐8578, Japan; masayuki.kano.a3@tohoku.ac.jp. Search for...
Abstract We have analyzed broadband surface wave data from ocean bottom seismometers deployed in the Shikoku Basin northeastern Philippine Sea to determine radially anisotropic uppermost mantle structure beneath this oceanic basin. first applied noise correlation method continuous microseismic records obtain phase velocities for fundamental‐mode and higher‐mode Rayleigh waves Love at periods of 7–29 s. At longer periods, we an array analysis teleseismic 29–117 Using these velocity...
Abstract Seismic techniques using earthquakes are powerful tools for exploring the Earth’s internal structure. However, earthquake distribution limits spatial resolution. In recent years, ambient noise surface wave tomography seismic field has resolved these limitations. A typical is microseisms excited by ocean swell activities. Ambient a technique in interferometry that extracts propagation between pairs of stations cross-correlating records. The cross-correlation function can be...
We analysed background surface waves in seismic ambient noise by cross-correlating continuous records of eight ocean bottom seismometers and nine differential pressure gauges deployed the northwestern Pacific Ocean PLATE project. After estimating clock delay instrumental phase responses using cross-correlation functions, we measured average velocities area array for fundamental-, first higher- second higher-mode Rayleigh waves, fundamental-mode Love at a period range 3–40 s waveform fitting....
Abstract Very low frequency earthquakes (VLFEs), classified as one type of slow earthquake, occur near seismogenic zones and can be a proxy for interplate slip. We investigated VLFE activity off the Hokkaido Tohoku Pacific coasts, where plate subducts under North American plate. Comprehensive detection VLFEs is performed period from January 2003 to July 2018 by matched‐filter technique utilizing synthetic waveforms calculated based on three‐dimensional velocity structure model. The...
Abstract We conducted broadband dispersion survey by deploying two arrays of ocean bottom seismometers in the northwestern Pacific Ocean at seafloor ages 130 and 140 Ma. By combining ambient noise teleseismic surface wave analyses, curves Rayleigh waves were obtained a period range 5–100 s then used to invert for one‐dimensional isotropic azimuthally anisotropic β V ( SV ) profiles beneath each array. The show ~2% difference low‐velocity zone (LVZ) depth 80–150 km spite small horizontal...
Abstract We analyzed seismic ambient noise and teleseismic waveforms of nine broadband ocean bottom seismometers deployed at a 60 Ma seafloor in the southeastward Tahiti island, South Pacific, by Tomographic Investigation ARray Experiment for Society hotspot project. first obtained one‐dimensional shear wave velocity model beneath array from average phase velocities Rayleigh waves period range 5–200 s. The shows large reduction depths between 40 80 km, where lithosphere‐asthenosphere...
Abstract The S-wave velocity ( V s) structure of sediments and the uppermost crust in landward slope a subduction zone are important for determining dynamics overriding plate. Although distributed acoustic sensing (DAS) measurements have improved horizontal resolution s marine areas, estimations been limited to sedimentary layers. In present study, we applied seismic interferometry DAS data 13 h duration image crustal offshore Sanriku, Japan with spatial 2.5 km > 3.0 depth. We grouped...
Abstract Slow earthquakes are mainly distributed in regions surrounding seismogenic zones along the plate boundaries of subduction zones. In Central American zone, large regular interplate with magnitudes 7–8 occur repeatedly around Nicoya Peninsula, Costa Rica, and a tsunami earthquake occurred off Nicaragua, just north 1992. To clarify spatial distribution various slip behaviors at boundary, we detected located very low frequency (VLFEs) Peninsula using grid‐search matched‐filter technique...
Abstract Deep low‐frequency (DLF) earthquakes occur beneath the Kirishima volcanoes in southwest Japan at depths of 10–30 km. In this study, we aim to reveal relationship between DLF and volcanic activity including eruptions by relocating hypocenters using network correlation coefficient method detecting comprehensively matched filter technique. Hypocenters are found be concentrated some separated small clusters within 10–15 20–27 Activation deeper had been observed for approximately 2 years...
We have conducted a temporal broadband seismic observation in Kii Peninsula, southwest Japan, and detected swarm of 110 very low frequency earthquakes (VLFs) deep tremors. During three days the activity, VLFs tremors occur concurrently two localized regions separated by ∼10 km. Stacking analyses are also employed to detect VLF signals period longer than 50 s, whose focal mechanisms determined for first time from data shown be consistent with subducting plate motion. Evaluation moment implies...
Abstract We analyze seismic records collected at the oldest (170–180 Ma) Pacific seafloor using broadband dispersion array analysis. Using ambient noise and teleseismic waveforms, we measure Rayleigh‐wave phase velocities in a period range of 5–200 s that are inverted for array‐average one‐dimensional isotropic azimuthally anisotropic shear‐wave velocity depth profiles from crust to 300 km. The high‐velocity Lid low‐velocity zone well‐resolved with difference ∼4%, whose transition occurs...
Abstract We investigated long‐term changes in the activity of deep very low frequency earthquakes (VLFEs) western Shikoku, southwest part Nankai subduction zone Japan for 13 years by matched‐filter technique. VLFE is expected to be a proxy interplate slips. In Bungo channel, where slow slip events (SSEs) occurred frequently, cumulative number detected VLFEs increased rapidly 2010 and 2014, which were modulated SSEs. neighboring inland region near steeply every 6 months. This stepwise change...
Abstract Strong long‐period seismic signals at periods around 25 and 18 s appear in the ambient noise cross‐correlation functions recorded by an array of ocean bottom seismometers (OBSs) western‐central Pacific. The signal amplitude varies from time to time, apparent travel times are typically smaller than those expected for Rayleigh waves propagating along great circle connecting station pairs. From functions, sources located Vanuatu Arc. Local data analysis suggests originate two different...
Abstract Deep low‐frequency tremor triggered by teleseismic surface waves is concentrated in several locations along the ambient source region Nankai subduction zone, southwest Japan. We systematically investigated northern Kii and western Shikoku, at 71 earthquakes applying a matched filter technique. detected 9 17 events of respectively. In addition, we observed migration episodes, whose directions were always along‐dip. Kii, seven episodes showed downward speed 5–20 km/hr. six migrated...
SUMMARY To obtain an internal S-wave velocity structure, we conducted a passive seismic campaign with 21 1-Hz seismometers on and around the Showa-Shinzan lava dome, which emerged during 1943–1945 eruption of Usu Volcano, Japan. Before campaign, calibrated found slight phase-response differences between less than 1–2°. After extracted wavefield by taking cross-correlations vertical-component ambient noise records sites. We developed new method to measure phase velocities Rayleigh wave...
自由落下式海底地震計を用いた海底地震観測では観測期間中の時刻を刻時する時計がレコーダに組込まれ,この時計の時刻を基準としてデータが記録される.この時計は精度が良い場合でも1年に数秒のずれが生じる.通常は観測開始・終了時にGPSなどによる正確な時刻とレコーダの時刻を比較し,観測記録の時刻を線形補間して解析に使用している.しかし何らかの原因でレコーダの時計に異常が発生し,通常の時刻補正手法が適用できなくなる場合がある.本報告では,観測記録から刻時のドリフトレートを推定する事で,異常が生じた観測記録に時刻補正を施す事が可能である事を2つの手法を用いて示した.1つは時計が正常な観測点との間のP波の相対走時残差の経時変化から推定する手法で,もう1つは相互相関関数の経時変化から推定する手法である.「ふつうの海洋マントル」プロジェクトの広帯域海底地震観測点NM02,NM20のデータに適用した結果,推定ドリフトレートはそれぞれ-10.49ms/day,...
SUMMARY Hyuga-nada, off the Pacific coast of Kyushu along Nankai Trough in southwest Japan, is one most active slow earthquake regions around Japan. We estimated energies shallow tremors and moments very low frequency earthquakes (VLFEs) Hyuga-nada using data from a permanent onshore broadband network temporary ocean–bottom seismometer observations. The these have similar along-strike variation are generally higher south subducted Kyushu–Palau Ridge than near top ridge. This spatial also...
SUMMARY In distributed acoustic sensing (DAS), optical fibre is used as sensors, which enables us to observe strain over tens of kilometres at intervals several metres. S-wave velocity (Vs) structures shallow sediments high resolution have been obtained from surface wave dispersion curves by applying seismic interferometry DAS data both onshore and offshore. However, it known that there a disadvantage interferometry. addition Rayleigh waves, Love waves are also included. Consequently, the...
Deep low-frequency (DLF) earthquakes occur beneath the Kirishima volcanoes in southwest Japan at depths of 10–30 km. In this study, we aim to reveal relationship between DLF and volcanic activity including eruptions by relocating hypocenters using network correlation coefficient method detecting comprehensively matched filter technique. Hypocenters are found be concentrated some separated small clusters within 10–15 20–27 Activation deeper had been observed for approximately two years from...