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S-net is a large-scale seafloor network in the Japan Trench area, consisting of inline-type 150 observatories with seismometers and pressure gauges. We analyzed the strong-motion data recorded at the S-net sites from earthquakes with magnitudes between about 4 and 7 with focal depths lower than 70 km. To minimize the effects of nonlinear site response and weak-couplings between the seabed and sensor houses, recordings with vector peak accelerations lower than 50 gals were selected. More than 6,000 recordings with high S/N ratios from about 600 earthquakes were used. Using the spectral inversion technique, we obtained some fundamental properties of the earthquake source spectra, path attenuation, and site factors from the horizontal-component S-wave portions of the recordings. The source spectra followed the source model generally well, and the estimated magnitudes were similar to the catalog magnitudes. The stress drops increased systematically with the focal depths, and the stress-drop values differed between the earthquake types. The path-averaged quality factors were somewhat larger than those in the past studies. The peak site frequencies ranged between about 0.2 and 10 Hz, while the peak amplification factors were between about 10 and 50. A moderate regionality was also observed in the distribution of site amplification factors. At some stations which were not buried, spurious site spectra were recognized. We discuss the above results and their implication in the presentation., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The deformation level of the surface soil layerdue to strong ground motion has a considerable effect in soil-structureinteraction problems. The shear strain values of the near surface soil depositswhich are calculated by one dimensional (1D) seismic site response analyses canalso be estimated by incorporating the results obtained fromHorizontal-to-Vertical Spectral Ratio (HVSR) analysis of microtremor data and peakhorizontal acceleration value of design ground motion. In this study, theseismic behaviour of soil layers at a site located in the vicinity of NorthAnatolian Fault were estimated by both 1D equivalent linear seismic site responseanalyses under 14 different rock outcrop motion records and analyses of groundambient noise-microtremor measurement data. A correlation is proposed forelastic and elasto-plastic deformation levels of surface soil layers in orderto estimate the value of shear strain due to strong ground motion, Depremler sırasında zemin tabakalarında oluşan deformasyonseviyeleri, yapı-zemin etkileşiminde önemli rol oynamaktadır. Kuvvetli yer hareketi kayıtları kullanılarakyapılan bir boyutlu (1D) dinamik analizlerle yüzeye yakın zemin tabakaları içinhesaplanan kayma şekil değiştirmeleri, küçük genlikli titreşimler-mikrotremor verisianaliz sonuçlarının tasarım yer hareketine ait en büyük yatay ivme değeriyle birliktedeğerlendirilmesiyle de tahmin edilebilmektedir. Buçalışmada, Kuzey Anadolu Fay Hattına yakın bir bölgede zemin tabakalarının depremhareketi karşısındaki davranışı hem 14 farklı anakaya ivme kaydı kullanılarak yapılan 1D eşdeğer lineer dinamik analizlerle hem de mikrotremor ölçümlerininanalizi yardımıyla elde edilmiştir. Verilerin değerlendirilmesi sonucunda;kuvvetli yer hareketi sırasında yüzeye yakın zemin tabakalarında oluşacak kaymabirim şekil değiştirmesinin belirlenebilmesi amacıyla, elastik ve elasto-plastikdeformasyon seviyelerini kapsayan bir bağıntı önerilmiştir.

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本研究では，表面波の位相速度からS波速度分布を推定するために遺伝的アルゴリズムと焼きなまし法を組み合わせたハイブリッド逆解析手法を提案している。この方法の計算フローは遺伝的アルゴリズムを基本としているが，交叉における親モデルと子モデルの選択の際に更新世代数に応じた受理確率を導入した。この受理確率を焼きなまし法と同様に世代数に依存した温度の関数として定義した。これにより，世代更新数が少ない場合には，誤差の大きいモデルも次世代に残り，大局的探索が可能となり，一方，世代更新により温度が低下すると，誤差の小さいモデルが多く次世代に残ることになり，局所的探索が主体となる。さらに，モデルパラメータのコード化では，実数を用いることにした。このアルゴリズムの適用性を深部地盤構造モデルに対するレイリー波の理論位相速度を擬似的な観測データとして用いた数値実験で検討した。その結果，ハイブリッド手法では収束性と安定性が高く，遺伝的アルゴリズムや焼きなまし法に比べてより少ない計算量で最適解近傍のモデルを探索することが可能であることがわかった。さらに，関東平野での既往の微動探査により得られたレイリー波の位相速度にも適用し，数値実験と同様の結果を確認することができた。

S-wave velocity profiles of sedimentary layers in Tacna, southern Peru, based on analysis of microtremor array data and earthquake records, have been determined for estimation of site amplification. We investigated vertical component of microtremors in temporary arrays at two sites in the city for Rayleigh wave phase velocity. A receiver function was also estimated from existing earthquake data at a strong motion station near one of the microtremor exploration sites. The phase velocity and the receiver function were jointly inverted to S-wave velocity profiles. The depths to the basement with an S-wave velocity of 2.8 km/s at the two sites are similar as about 1 km. The top soil at the site in a severely damaged area in the city had a lower S-wave velocity than that in a slightly damaged area during the 2001 southern Peru earthquake. We subsequently estimate site amplifications from the velocity profiles and find that amplification is large at periods from 0.2 to 0.8 s at the damaged area indicating possible reasons for the differences in the damage observed during the 2001 southern Peru earthquake.

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PubMed: 18067585, Cleavage of the extracellular matrix (ECM) by proteolysis unmasks cryptic sites and generates novel fragments with biological activities functionally distinct from those of the intact ECM molecule. The laminin G-like (LG)4-5 fragment has been shown to be excised from the laminin ?4 chain in various tissues. However, the functional role of this fragment has remained unknown to date. To investigate this, we prepared ?4 LG1-3 and ?4 LG4-5 fragments by elastase digestion of recombinant ?4 LG1-5, and examined their effects on de novo adipogenesis in mice at the site of injection of basement membrane extract (Matrigel) and fibroblast growth factor (FGF)-2. Although the addition of whole ?4 LG1-5 suppressed adipogenesis to some extent, the ?4 LG4-5 fragment could strongly suppress adipogenesis at a concentration of less than 20 nm. Addition of the ?4 LG4 module, which contains a heparin-binding region, had a suppressive effect, but this was lost in mutants with reduced heparin-binding activity. In addition, antibodies against the extracellular domain of syndecan-2 and -4, which are known receptors for the ?4 LG4 module, suppressed adipogenesis. Thus, these results suggest that the cryptic ?4 LG4-5 fragment derived from the laminin ?4 chain inhibits de novo adipogenesis by modulating the effect of FGF-2 through syndecans