著者

川辺 秀憲 釜江 克宏

出版者

公益社団法人 日本地震工学会

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.13, no.2, pp.2_75-2_87, 2013 (Released:2013-03-08)

参考文献数

29

被引用文献数

3 7

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2011年東北地方太平洋沖地震(Mw9.0)に対し、経験的グリーン関数法を用いたフォワードモデリングにより工学的に重要な0.1~10秒の周期帯を対象とした震源のモデル化を行った。結果として、宮城県沖から茨城県沖にかけて、5つの強震動生成域からなる震源モデルを提案した。得られた震源モデルにおける5つの強震動生成域は、これらの地域における地震調査研究推進本部による想定震源域内にほぼ含まれていること、強震動生成域のみの地震モーメントは総地震モーメントの5%程度であり、より周期の長い地震動、巨大津波及び地殻変動を説明する震源モデル(海溝軸側に大すべり領域)とは相補的であるとの結果が得られた。

著者

釜江 克宏 入倉 孝次郎

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.62, no.500, pp.29-36, 1997

参考文献数

30

被引用文献数

24 10

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The 1995 Hyogo-ken Nanbu earthquake struck Kobe and adjacent cities, one of the most densely populated area in western Japan, and killed more than 6,400 people and destroyed more than 150,000 buildings and houses and tens of highway and railroad bridges. It is very important to examine the ground motion characteristics in the severely damaged area during the mainshock for understanding how buildings and bridges performed and why they reached collapse. Unfortunately very few strong ground motions were recorded in the severely damaged areas during the mainshock. In this study, we attempt to estimate ground motion at severely damaged sites by using the empirical Green's function method (EGF method). We derive a best source model with three asperities after several try and error with forward modeling by the EGF method. We estimate strong ground motions at sites, where the mainshock was not recorded, using aftershock records. The synthesized motions in the near-fault region in Kobe were characterized by two large long-period (1 to 3 seconds) pulses due to the forward rupture directivity. Peak horizontal acceleration and velocity of the synthesized motions at the heavily damaged sites are about 1,000 cm/sec^2 and 130 cm/sec, respectively, while those at a rock site in near-fault region show about 300 cm/sec^2 and 60 cm/sec. The reason why so strong motions hit the heavily damaged sites is that the large long-period pulses which come from two asperities in the Kobe-side segment of the fault were further amplified by the basin edge effects.

著者

入倉 孝次郎 釜江 克宏

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.52, no.1, pp.129-150, 1999-06-30 (Released:2010-03-11)

参考文献数

33

被引用文献数

9

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We simulate strong ground motions during the 1948 Fukui earthquake with the JMA magnitude 7.1 based on a heterogeneous source model and the hybrid simulation technique. So far there are no existing source models available for simulating strong ground motions from the 1948 Fukui earthquake. Most of the source models have been assumed to have uniform slip distribution on rectangular fault plane. Such models could generate ground motions only available longer than several seconds, underestimating shorter period motions (<1sec) of engineering interest. The objective of this paper is to construct a heterogeneous source model for simulating strong ground motions in a broad period band during the 1948 Fukui earthquake. We assume two source models to examine: Model 1 is a reverse fault model determined from the analysis of geodetic data by YOSHIOKA (1974) and Model 2 is a normal fault model from strong motion displacement data by KIKUCHI et al. (1999). Heterogeneous slip distribution on fault plane is estimated based on the self-similar scaling relationships of seismic moment versus asperity areas and slips by Somerville et al. (1999). Then we obtained the standardized source model consisting of two asperities to have the average characteristics of asperities for the seismic moment of the Fukui earthquake. Relative locations and rupture times of the asperities on the fault plane are determined following the source model by KIKUCHI et al. (1999). The maximum asperity corresponding to the second event in their model has an area of 12×12km2 and slip of 1.7m and is located under the most heavily damaged area along the buried fault, known as the Fukui earthquake fault. The smaller asperity corresponding to the first event is located north of the maximum asperity. Rupture was initiated at the northern edge of the smaller asperity, propagated toward south, then broke to start the maximum asperity 7 seconds after the initial rupture. Large ground motions from both models, Model 1 and 2, are spread over the Fukui basin, although peak velocity distributions are rather different between the two models. Areas over 30% collapse ratio during the Fukui earthquake correspond to those with peak velocity over 60cm/s for Model 1 and over 80cm/s for Model 2. The level of the peak velocity in the areas with more than 30% collapse ratio are estimated to be over 80cm/s connected with both results by MOROI et al. (1998) and MIYAKOSHI and HAYASHI (1998). Pseudo velocity response spectra in the center of the Fukui basin for Model 2 have almost the same level of the observed ones at Takatori (TKT) and the simulated ones at Fukuike (FKI) within the damage belt during the 1995 Hyogo-ken Nanbu earthquake. We conclude that the damage distribution during the Fukui earthquake is well explained by strong ground motions simulated for Model 2 combined with the normal fault model by KIKUCHI et al.. (1999) and a standardized heterogeneous source model developed by SOMERVILLE et al. (1999).