Seismic Intensity Distribution Research Articles

Development of Damage Functions on Road Infrastructures Subjected to Extreme Ground Excitations by Analyzing Damage in the 2011 off the Pacific Coast of Tohoku Earthquake

Road infrastructure damage due to extreme ground excitations during theMarch 2011 Tohoku earthquake was assessed and 161 items of damage road structure data were classified into three types of failure modes: road surface and embankment damage items, road surface crack items and road subsidence items. We then compared a damage ratio, which is defined by the number of damage points divided by total road length, to the estimated spatial distribution of JMA instrumental seismic intensity. The maximum damage ratio for the 161 damage data items is 0.0290 points/km compared to a JMA instrumental seismic intensity of 5.8. Last, we developed damage functions for road infrastructures subjected to extreme ground excitations, which describe the relationship between the damage ratios and seismic intensity.

Automatic recognition of seismic intensity based on RS and GIS: a case study in Wenchuan Ms8.0 earthquake of China.

In recent years, earthquakes have frequently occurred all over the world, which caused huge casualties and economic losses. It is very necessary and urgent to obtain the seismic intensity map timely so as to master the distribution of the disaster and provide supports for quick earthquake relief. Compared with traditional methods of drawing seismic intensity map, which require many investigations in the field of earthquake area or are too dependent on the empirical formulas, spatial information technologies such as Remote Sensing (RS) and Geographical Information System (GIS) can provide fast and economical way to automatically recognize the seismic intensity. With the integrated application of RS and GIS, this paper proposes a RS/GIS-based approach for automatic recognition of seismic intensity, in which RS is used to retrieve and extract the information on damages caused by earthquake, and GIS is applied to manage and display the data of seismic intensity. The case study in Wenchuan Ms8.0 earthquake in China shows that the information on seismic intensity can be automatically extracted from remotely sensed images as quickly as possible after earthquake occurrence, and the Digital Intensity Model (DIM) can be used to visually query and display the distribution of seismic intensity.

Examination of source fault model for the Gifu-Ichinomiya fault based on seismic intensity data

To investigate possible source fault models for the Gifu-Ichinomiya fault, we construct multiple source fault models of the 1891 Nobi earthquake, taking into account several different types of geometry for the Gifu-Ichinomiya fault, and conduct strong ground motion simulations. We choose the most plausible source model by comparing the distribution of simulated seismic intensities with the spatial distribution of a questionnaire-based intensity of 7, and with that of the damage ratio of wooden houses in the near-source region. Our results imply that the length of the source fault of the Gifu-Ichinomiya fault is relatively short and the dip angle is 75 degrees to the east. Because a seismic intensity of 7 is considered to arise from site amplification and the short distance from a source fault, we classified the points with a seismic intensity of 7 based on the H/V spectral ratio of microtremors by considering the contributing factors to the generation of a seismic intensity of 7. A linear distribution of the points, which might have relatively lower site amplification factors, in the northeastern part of the Nobi Plain implies that a part of the source fault of the 1891 Nobi earthquake existed in this area, as indicated through strong ground motion simulations.

Computational Research on Seismic Intensity Based on Ground Motion Parameters

After an earthquake event, the spatial distribution of seismic intensity of the event and extremely destructed area could be quickly evaluated by means of the empirical relationship between ground-motion parameters and seismic intensity, which has been proposed for years. This can provide a basis for the government to carry out emergency relief and reasonable distribution of relief supplies. In this paper, the computational methods of instrumental seismic intensity used at home and abroad are briefly introduced. By analyzing the advantages of the methods in the USA and Japan, a relatively simple computational method of seismic intensity is proposed. Firstly, the acceleration time history (Aall) and velocity time history (Vall) of the complete vibration are synthetized by the filtered three-direction acceleration and velocity time histories, and substituted in the empirical formulation. Then, the seismic intensity can be computed by the sorting method. After that, this method is compared with the intensity scale evaluation method and fuzzy algorithm by using the strong motion parameters of Wenchuan earthquake. The results show that the method proposed in this paper is better than the two methods and has certain practical values.

A New Ground Motion Prediction Equation for Japan Applicable up to M9 Mega-Earthquake

In this study we suggest a new ground motion prediction equation applicable up to the moment magnitude 9 using the strong motion records from the 2011 Tohoku-oki earthquake. We determined a base model with moment magnitude and the shortest distance from the source fault as parameters. In order to avoid overestimating amplitude atmagnitude larger than 8, we examined two models – a quadratic magnitude term and a linear magnitude term with a complete amplitude saturation term at someMw. We then adopt additional correction terms corresponding to amplification by deep sediments or shallow soft soils, and anomalous seismic intensity distribution in order to improve prediction.

Differences between the Ansei Nankai earthquake (1854) and the Houei earthquake (1707), the distribution of seismic intensity covering the Kawachi plain and the arrival points of Tsunami in Osaka

Differences between the Ansei Nankai earthquake (1854) and the Houei earthquake (1707), the distribution of seismic intensity covering the Kawachi plain and the arrival points of Tsunami in Osaka

Study on Ground Motion Parameters of Seismic Appraisal for Existing Structures Based on Residual Service Life

Research status of ground motion parameters of seismic appraisal for existing structures is analyzed. According to the theory of the probabilistic distribution of seismic intensity which fits Extreme Value Type Ш, the relation of multi-value seismic intensity to seismic basic intensity from different seismic hazard characteristic zone is studied in this paper. Under the principle of all the seismic actions of each fortification level have the same exceeding probability, the basic intensity for seismic assessment of buildings with different residual service lives is given to each zone. At last, after giving full consideration to the seismic hazard differences to different areas, the modification factors of seismic action of buildings at the three zones with different seismic hazard characters are given in this paper. At last, this paper provides a base for the structure designers to choose a rational seismic action during the seismic appraisal for existing structures.

Improvement in the accuracy of expected seismic intensities for earthquake early warning in Japan using empirically estimated site amplification factors

The Japan Meteorological Agency (JMA) is able to process data for its earthquake early warning (EEW) procedure very quickly by employing a seismic intensity expectation method that uses simplified strong motion characteristics. To represent one of these characteristics, the site amplification factor at the seismic intensity station, JMA uses ARV (amplitude ratio of peak ground velocity at the ground surface relative to the engineering bedrock of average S-wave velocity 700 m/s) based on topographic data. As a potential substitute for the ARV, we investigated a station correction based on empirical site amplifications obtained from recent observed seismic intensity data. When estimating this station correction, we removed an effect of the abnormal seismic intensity distribution of deep subduction-zone earthquakes and applied a correction for the earthquake source term to the attenuation relation. Station corrections were obtained for 1258 stations, representing about 30% of all current seismic intensity stations. The correlation between our station corrections at the stations and the site amplification based on topographic data is weak (correlation coefficient = 0.30). The error of the expected seismic intensity was improved by 15% by replacing ARV with the station correction.

Estimation of Seismic Intensity Distribution around Omaezaki-city from the Roof Tiles Damage by the 2009 Suruga Bay Earthquake

2009 年駿河湾の地震における御前崎市付近を対象として，瓦屋根被害（以下，瓦被害）から地震動強さ分布の推定を行った．まず，瓦被害を航空写真により判別し，瓦被害率分布を作成した．瓦被害は航空写真から明確な判別が可能であった．次に，強震観測点周りの被害調査結果から，瓦被害と相関をもつ地震動強さ指標について検討し，瓦被害は，計測震度と高い相関をもつことがわかった．そこで，計測震度を説明変数とする瓦被害の被害関数を作成し，その逆関数を用いて計測震度分布を推定した．その結果，数百m 離れるだけで計測震度が1 程度異なるところもあり，地震動強さは，地形や微地形分類から推定された一次元表層地盤特性だけでは説明できないほど局所的に大きく変化していることがわかった．以上のことから，航空写真により瓦被害を判定して，数百m メッシュという精度で計測震度分布を推定できることがわかったが，充分な数の瓦屋根建物がなければならないこと，瓦被害のない建物については，瓦屋根建物とそうでない建物の判別が航空写真では難しいなど，いくつか課題も浮き彫りになった．

Shaking Maps for Scenario Earthquakes by Applying the Upgraded Version of the Strong Ground Motion Prediction Method “Recipe”

The strong ground motion prediction method “Recipe” was published by the Headquarters for Earthquake Research Promotion (HERP) of Japan. HERP has applied this method to prepare shaking maps for scenario earthquakes in specific active faults. Recently, Recipe was updated following its verification by simulations of strong ground motions associated with the Mw = 6.6 off-shore earthquake west of Fukuoka prefecture in 2005, which occurred in the northwest part of the Kego fault zone located in northern Kyushu, Japan. One of the prominent changes in the upgraded version of Recipe is the inclusion of a procedure to evaluate seismic intensities on the ground surface from waveforms of S-wave velocity of 400 m/s on the engineering bedrock. By applying the upgraded version of Recipe, we have made shaking-maps for earthquakes in the southeast part of the Kego fault zone, which is located directly below the mega-city of Fukuoka. We assume four source models for scenario earthquakes; the locations of the asperities and the hypocenters vary between the models. The results show that in all cases, disastrous seismic intensities can strike a wide area of Fukuoka city. Differences in the distributions of seismic intensities among the four cases can be clearly observed in the area located on the extension of the source fault. Furthermore, we construct a velocity-layer structure model on the engineering bedrock for the central area of Fukuoka city. We assess not only the distribution of seismic intensities but also waveforms on the ground by using an equivalent linear method for the central area of Fukuoka city.

Role of initial stress rotations in rupture dynamics and ground motion: A case study with implications for the Wenchuan earthquake

Motivated by observations in the 2008 Mw 7.9 Wenchuan earthquake, we study effects of systematic changes in the principal stress orientation along the fault strike on rupture dynamics and ground motion using a 3‐D finite‐element method. Based on Anderson's theory of faulting, we set up the initial stress field with rotations in stress orientations along strike for a dynamic rupture model of a shallow dipping fault. We find that initial stress rotations along strike can cause dramatic changes in rupture speed and produce distinct patterns in slip distribution and peak ground motion. When a mismatch (unfavorable for faulting) between fault geometry and initial stress orientations is encountered, rupture can spontaneously stop. Some first‐order features in the Wenchuan event may be partially caused by rotations in the principal stress orientation along strike, such as the rupture arrest at the northeast end and two severe destruction zones in the observed seismic intensity distribution. These results may have important implications for assessing seismic hazards imposed by faults with changes in the initial stress field along strike worldwide.

Comparative Assessment of Civil Infrastructure Network Performance under Probabilistic and Scenario Earthquakes

The intensity of the seismic demand in a vulnerability assessment of an engineered system can be described in terms of either its annual probability of being exceeded or a scenario earthquake. A probabilistically stated hazard (e.g., one with a return period of 2,475 years) represents an aggregation of numerous earthquakes and may not represent the spatial distribution of seismic intensity from a severe earthquake over a region correctly, making its application to performance evaluation of a large-scale distributed civil infrastructure system questionable. A scenario earthquake models the spatial intensity correctly, but conveys no quantitative measure of the seismic risk. This paper examines the use of probabilistic seismic hazard analysis and corresponding scenario earthquakes as a basis for vulnerability assessment of a networked system. Following an examination of simple spatially distributed series and parallel system models, a vulnerability assessment of an electrical power network in a region of moderate seismicity in the Central United States offers additional insight into the issue.

PROPOSAL OF SIMPLE SELECTION METHOD WITH POPULATION STATISTICS

For the purpose of simplify the method on death toll, this paper proposes the simple method on population for effectively and efficiently selecting the seismic hazard maps having significant impact on Nagoya city, Japan, as an example area in this study. We select the extensive distribution of population exposure seismic intensity by use of the simple method on population, and estimate the effectiveness and the efficiency of selected it. The result shows that nearly 95% of estimated victims in Nagoya city is able to be covered by only 2 maps selected in the strategic choice approach.

Relationship between the distribution of slope failures and seismic intensity.

Relationship between the distribution of slope failures and seismic intensity.

Application of INQUA Environmental Seismic Intensity Scale to recent earthquakes in Japan and Taiwan

Abstract The INQUA Environmental Seismic intensity scale (ESI 2007 scale) is a new seismic intensity scale proposed by the Subcommission on Palaeoseismology, INQUA, based on seismically induced ground effects. This intensity scale is expected to be useful for evaluation of detailed areal distribution of seismic intensity and also for the evaluation of intensity of palaeoearthquakes. We selected four great earthquakes to map ESI 2007 scale distribution: the 1995 Kobe; the 2004 Chuetsu, Japan; the 1935 Hsinchu-Taichung; and the 1999 Chichi, Taiwan. Proposed ESI 2007 scale maps from these areas are the mesh maps with a grid of about 1 km 2 , showing more detailed intensity patterns than those previously provided by the Japan Meteorological Agency and the Central Weather Bureau for the four areas. Different responses of ground effects to the earthquakes, depending on local differences of geological materials near the surface and morphological condition of each site, are more clearly expressed by the ESI 2007 scale map, because of the large number of observed sites by the evaluation of ESI 2007 scale. Calibration exercise also reveals, however, that the classification of ESI 2007 scale needs some improvement.

STRATEGIC CHOICE APPROACH FOR SCENARIO EARTHQUAKES TO MINIMIZE THE DEATH TOLLS

For the purpose of optimizing the plan for seismic protection scenario in municipal unit, this paper proposes the strategic method for effectively and efficiently selecting the seismic hazard maps having significant impact on Nagoya city, Japan, as an example area in this study. In the first part, we make geographical database about 41 sheets of seismic intensity maps on Nagoya city and its population. In the second part, we select the extensive distribution of seismic intensity by use of the cluster analysis, and estimate the effectiveness and the efficiency of selected extensive distribution of seismic intensity. The result shows that nearly 99% of estimated victims in Nagoya city are able to be covered by only 2 maps selected in the strategic choice approach.

Historical pattern and behavior of earthquake ruptures along the eastern boundary of the Sichuan-Yunnan faulted-block, southwestern China

The eastern boundary of the Sichuan-Yunnan faulted-block in southwestern China, which contains four major fault zones named Xianshuihe, Anninghe, Zemuhe, and Xiaojiang, behaves as a huge left-lateral strike-slip active fault system, where the most frequent seismicity in continental China occurs. To uncover the history of earthquake ruptures of this fault system, we developed an empirical relation between rupture extent and seismic intensity distribution based on data of those earthquakes whose rupture extents and intensity distributions are well known. Through analyzing various types of data, including distributions of damage or intensity of historical earthquakes as well as surface ruptures and aftershock zones of modern earthquakes, we determined systematically the locations and spatial extents of ruptures for 36 main earthquakes, and built up a spatial-temporal pattern of the rupture history of the fault system for the last several hundred years. The spatial-temporal rupture pattern contains information of multi-cycle and broad-scale ruptures, from which we find that for most fault segments, scales of segment-ruptures are time- or cycle-variable and only in two or three cases do scales of segment-ruptures in successive cycles seem to be characteristic. In infrequent cases, several adjacent and connecting fault units may rupture simultaneously, resulting in cascading ruptures. Triggering of ruptures is common along the fault system but differs in various periods even on a single fault zone. Triggered ruptures may not occur on fault-segments adjacent to a preceding rupture of major earthquake but on other segments at some distance away from the preceding rupture, implying that the rupture history determines whether a segment can be triggered or not. Recurrence intervals of major segment-ruptures are longer on the Anninghe and Zemuhe fault zones and on the southernmost segment of the Xiaojiang fault zone than that on the Xianshuihe fault zone and the northern and middle segments of the Xiaojiang fault zone, probably due to the partitioning of slip along major and secondary faults and their complicated fault geometry. Four seismic gaps along the fault system are recognized, where major earthquakes have been absent for a long time.

The 1998Mw5.7 Zhangbei‐Shangyi (China) earthquake revisited: A buried thrust fault revealed with interferometric synthetic aperture radar

The 1998Mw5.7 Zhangbei‐Shangyi (China) earthquake is the largest to have occurred in northern China since the large 1976Ms7.8 Tangshan earthquake. Due to its proximity to Beijing, the capital of China, it has therefore gained a lot of attention. A great number of studies have been conducted using seismic and geodetic data, but few are able to identify conclusively the orientation of the primary fault plane for this earthquake. In this paper, two independent ERS synthetic aperture radar interferograms are used to determine precisely the location and magnitude of coseismic surface displacements (∼11 cm in the radar line of sight). Modeling the event as dislocation in an elastic half‐space suggests that the earthquake is associated with a buried shallow NNE‐SSW oriented thrust fault with a limited amount of lateral displacement, which is consistent with seismic intensity distribution and aftershock locations.

Mechanics of Seismic Emission from Solar Flares

Instances of seismic transients emitted into the solar interior in the impulsive phases of some solar flares offer a promising diagnostic tool, both for understanding the physics of solar flares and for the general development of local helioseismology. Among the prospective contributors to flare acoustic emission that have been considered are: i) chromospheric shocks propelled by pressure transients caused by impulsive thick-target heating of the upper and middle chromosphere by high-energy particles, ii) heating of the photosphere by continuum radiation from the chromosphere or possibly by high-energy protons, and iii) magnetic-force transients caused by magnetic reconnection. Hydrodynamic modeling of chromospheric shocks suggests that radiative losses deplete all but a small fraction of the energy initially deposited into them before they penetrate the photosphere. Comparisons between the spatial distribution of acoustic sources, derived from seismic holography of the surface signatures of flare acoustic emission, and the spatial distributions of sudden changes both in visible-light emission and in magnetic signatures offer a possible means of discriminating between contributions to flare acoustic emission from photospheric heating and magnetic-force transients. In this study we develop and test a means for estimating the seismic intensity and spatial distribution of flare acoustic emission from photospheric heating associated with visible-light emission and compare this with the helioseismic signatures of seismic emission. Similar techniques are applicable to transient magnetic signatures.

SOURCE CHARACTERIZATION AND GROUND MOTION EVALUATION OF THE 1938 SHIOYAZAKI-OKI EARTHQUAKES

Fault models of the 1938 Shioyazaki-oki earthquakes, event 1 (May 23) and event 2 and 3 (Nov. 5), are characterized using the slip distributions on the fault plane by waveform inversion analysis. Stress parameters of each asperity Δσa are estimated as 37MPa for event 1 and 22MPa for event 2 and 3 from empirical Green's function method (EGFM) by simulating the seismic intensity of JMA observation stations which locate in near fault region. Short-period spectral level of event 1 is higher than those of event 2 and 3 which are as high as that of the 1978 Miyagi-ken-oki earthquake. The spatial distribution of seismic intensity 5 for each event is well reproduced by EGFM using the proposed fault model in this study.