We use broadband seismic recordings to trace the dynamic process of the deep‐seated Akatani landslide that occurred on the Kii Peninsula, Japan, which is one of the best recorded large slope failures. Combining analyses of the seismic records with precise topographic surveys done before and after the event, we can resolve a detailed time history of the mass movement. During 50 s of the large landslide, we observe a smooth initiation, acceleration with changes in basal friction, and reversal of the momentum when the mass collides with the opposite valley wall. Of particular importance is the determination of the dynamic friction during the landslide. The coefficient of friction is estimated to be 0.56 at the beginning of the event and drops to 0.38 for most of the sliding. The change in the frictional level on the sliding surface may be due to liquefaction or breaking of rough patches and contributes to the extended propagation of the large landslide.

Large deep‐seated landslides occurred in Nara, Wakayama, and Mie prefectures of western Japan when Typhoon Talas passed through the region on September 3–4, 2011. Signals of large landslides have been recorded by seismic networks around the world, and overall force estimates have been previously determined for large landslides using long‐period waves. This study focuses on the high‐frequency waveforms and presents signals of 18 landslides caused by Typhoon Talas (2011). The location of the landslides can be determined by a seismological back‐projection technique and these locations correlate with the observed surface features. We have found that the volumes of the landslide correlated with an energy parameter derived from the seismic records.

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These results suggest that the chemical and structural changes of freshly precipitated 14 amorphous ferric hydroxide with short aging time affect their ability, such as iron 15 solubility and dissolution rate, to supply bioavailable iron for the phytoplankton growth. 16The chemical and structural conversion of solid iron phases with time is one of the most 17 important processes in changing the supply of available iron to marine phytoplankton in 18 estuarine and coastal waters and in iron fertilization experiments.

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The Barthel Index (BI) cannot be used to measure initial stroke severity or by extension, to stratify patients by severity in acute stroke trials because most patients are bedbound in the first few hours after stroke, either by their deficit or by medical directive. Our objectives were to clarify the threshold of acute BI for use in the prediction of subsequent independence in activities of daily living (ADL) and to assist in the definition of acute stroke rehabilitation goals. Subjects comprised 78 patients out of 191 inpatients admitted with acute stroke at our hospital during 2006-2007. The BI ADL score was divided into 2 ranges (BI> or =60 and < or =40), in a process similar to previous studies. During the acute period (from onset to approximately 3 weeks), all patients with a BI> or =40 could improve their ADL in 6 months. Patients with a BI< or =40 exhibited two ADL recovery outcomes (improved and no change) at 6 months. We also found that the skill level of basic activities related to standing was significant indicator of BI improvement (P<0.001). BI scores determined at approximately 3 weeks were reliable predictors of ADL disabilities at 6 months.

[1] We apply a deconvolution method to a strong motion data set recorded at the surface and in boreholes in northeast Honshu, Japan. We try to characterize the nonlinear effects of the subsurface soil during strong shaking and show the change of the subsurface velocity structure during the shaking. The deconvolved waveforms reflect the subsurface velocity structure, and their horizontal and vertical components correspond to S and P wave, respectively, traveling from the borehole to the ground surface. The strong motion records with smaller values of peak acceleration do not include significant nonlinear effects, so the deconvolved waveforms of the observed accelerations can be well simulated by the program SHAKE91. For high acceleration motions during the shaking of two separate earthquakes, large reductions of near-surface velocities are seen. In results for the 2008 Iwate-Miyagi Nairiku earthquake, the large high-frequency ground motions over 4g at one near-source station caused a nonlinear response of the soil, and the reduction of the average shear wave velocity reached 24%. This corresponds to a stiffness change of over 75%. The soil properties and the stiffness coefficient which changed during the shaking did not fully recover after the shaking, leaving a static change.Citation: Yamada, M., J. Mori, and S. Ohmi (2010), Temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry,

A precursory sequence of repeating earthquakes was recorded before the Rausu landslide in Hokkaido, Japan, on 24 April 2015. There were two seismic sequences with each consisting of very similar waveforms and leading up to significant landslide movements. The nearly identical waveform shapes indicate similar source locations and mechanisms, so repeated events originated on a particular small area. This sequence is interpreted as stick‐slip movement on a small patch leading up to the larger landslide failure. Our observations show that heterogeneous structure, such as asperities on the slip surface, can play an important role in the initiation of landslides, adding a new aspect to the conventional understanding of mechanisms controlling large mass movements.