Eri Ito

ABSTRACT The main purpose of the site classification or velocity determination at a target site is to obtain or estimate the horizontal site amplification factor (HSAF) at that site during future earthquakes because HSAF would have significant effects on the strong-motion characteristics. We have been investigating various kinds of methods to delineate the S-wave velocity structures and the subsequent HSAF, as precisely as possible. After the advent of the diffuse field concept, we have derived

We first derived site amplification factors (SAFs) from the observed strong motions by the Japanese nationwide networks, namely, K-NET and KiK-net of National Institute of Earthquake Research and Disaster Resilience and Shindokei (Instrumental Seismic Intensity) Network of Japan Meteorological Agency by using the so-called generalized spectral inversion technique. We can use these SAFs for strong motion prediction at these observation sites, however, we need at least observed weak motion or micr

Abstract Tsunami evacuation simulations are often used to determine necessary countermeasures that will reduce human loss effectively after earthquakes and subsequent tsunamis. However, so far there has been no simulation for the estimated building damage using up-to-date knowledge of seismic engineering. In this study, in order to clarify the effect of building damage on a tsunami evacuation, we first predicted building damage based on the nonlinear response analysis for a realistic strong grou

Extracting the area where people have difficulty evacuating (hereafter difficult-to-evacuate areas, DEA) when tsunamis hit after an earthquake is important for effective disaster mitigation measures. The DEA was conventionally extracted by simply considering the walking speed, distance to the evacuation destination, and time needed for evacuation after considering the estimated tsunami inundation area. However, evaluating the DEA from such a simple scheme is insufficient because the behavior of

ABSTRACT Based on the diffuse field concept for a horizontal-to-vertical spectral ratio of earthquakes (eHVSR), the effectiveness of eHVSRs to invert P- and S-wave velocity structures down to the seismological bedrock (with the S-wave velocity of 3 km/s or higher) has been shown in several published works. An empirical method to correct the difference between eHVSR and a horizontal-to-vertical ratio of microtremors (mHVSR), which is called earthquake-to-microtremor ratio (EMR), has also been pro

Abstract Precisely evaluating the source, path, and site terms in a broadband frequency range is indispensable for quantitatively predicting strong motions. We conducted a generalized spectral inversion of strong motion in Japan to delineate both the spectral amplitude and phase characteristics for statistical Green’s functions. To predict ground motion from future megathrust earthquakes, we also need to model a kinematic source with a stochastic representation of the slip and rupture velocities

地震とそれに伴う津波の被害軽減のための重要な対策の一つとして、地震直後の状況のシミュレーションを行い、その影響を分析し対策立案に活用することが挙げられる。本研究においては、建物被害の津波避難への影響を明らかにするため、強震動の応答解析に基づいて建物被害を予測した上で津波避難シミュレーションを行った。結果として、研究対象地域における現状での避難対策は地区住民全員が無事に避難するには不十分であること、耐震化率を100%まで向上させれば、最大で地区の3.7％の住民をさらに助けることができ、地区の90%の住民が避難完了するまでに要する時間もおよそ1分短縮できることが分かった。このことから、家屋の耐震化は、避難場所の配置と数、収容人数とあわせて考慮していく必要があるという結論が得られた。

This paper proposes a scheme for imposing geometrical constraints in topology optimization to obtain structures considering the visibility of the product user, based on a fictitious physical model. First, a level set-based topology optimization method is concisely introduced, and geometrical requirements for the visibility are clarifid. A fictitious physical model described by a steady-state advection-dffusion equation is then constructed based on the requirements. In this model, virtual heat so

This paper proposes a method to impose geometrical constraints for ensuring the visibility of the product user on optimal structures, with less computation time. In this scheme, we incorporate a visibility evaluation method based on fictitious physical models into topology optimization. First, a level set-based topology optimization method is briefly introduced. Then, fictitious physical models represented by a steady-state advection-diffusion equation is then built based on the geometrical requ

The 1923 Kanto earthquake has not been sufficiently verified with respect to the strong ground motion generation areas with a period of less than 2 seconds, which is directly related to building damage. With the goal of determining the source rupture process by targeting the building collapse ratio, we first estimated the site amplification factors in the heavily damaged areas using the EMR method proposed by Kawase et al. (2018) and the VACF method by Ito et al. (2020). At sites with an observe