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Home > Documents > Vol. pp. 2. ,**3 +,1 +-3 ˘ˇˆ˙ MeSO-net Various Types of ... · (MeSO-net), which consists of...

Vol. pp. 2. ,**3 +,1 +-3 ˘ˇˆ˙ MeSO-net Various Types of ... · (MeSO-net), which consists of...

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腅腇 臗膒臕臤膒膔臭臂 腜腈腮腝腐腯腛腉腮 臎膹臑膣膘膏膼膸自臣 腆腁 臠膅腍膼臓腐腯腖 臏腾臨膦膃膍 腏腯腭腡 臗膒臌膇臎膹膘膏膵 臗膒腫膞膚腠臠膅腱膎腦腑腖 膐腡臎膹腝腑腛腢 膲臕膗腠膻臌腟臠膅腱腪腖腭腑腖膑臌臎膹腝腉腋腣 臶腋腣腹膿膞膚臎膹 腝臫膭臗膒臎膹 臜腠臞臂腑腖臌臁膋臗臎膹 腷腳腶腴腸腂腵 腈腮腍 腞腘腭腪膓臋臔腟膉臉臬腍臀臡腐腯腮臆腡臎膹 腜腈腮腍 腏腡腬腊腟臎膹腢 臜腡膳 腜腈腮腖腩 腔腡臞臂膶膵腫臞臂臲膮腠膋腑腛腢 腥腝 膌腜臞臂腒腮腝膟腋腭腯腛腉腛 膬腠 膐腡膋臗臎 腲腞臫腭腌腠腟腙腛腉腟腉 腔腡腖腩 臚膋臗臎腻腡 膹腍臞臂腒腮腧腜腠腢 腧腗臰臱腍腈腮 腑腌腑 腏腯 膐臎膹腡臞臂膆致腱膙臄腪腮膧腠腢 膤膓腡 臜膊 腧腜腠臚膋臗臎腻腜臞臂腑腖臌臎膹腡膫膕臷腱膙腛腨腮 腠臞臂腑腖 腚腡臎膹腱至腉腛膨膴腑 膢膜 臜膊腜 膐腡臎膹腍臞臂腒腮膊腠 膐腡臎膹腍膽膄 臞臂腑腛腉腮 腔腡臞臂臢臖腢 臌臁膋臗臎膹 腼臦 臚膋臗臎腻腜臞臂腒腮 膐臎膹腠臊腑腛 臞臂臒臆腡 臜膊腡臦腍 腔腡臆腡 臜膊腠臟腤腛 臵腡臎膹臍臇腱膁臓腑 腔腯腕腯腜臠膅臈臓腱膠腙腖腝 臫腭腌腠膡腎 臃膀膌腝膈臙膌腍膝膛腠臧腯腮膂臝膾腍 腏腰 臶腋腣臗膒臸臩臣臎膹 腡臞臂腜腢 膤臌 膟腋腭腯腛腉腮 腉腓腯膈臙膌腠臛腙腛臌臎膹腍臞臂腒 腜膪膯膽臮 膖膥臔臠膅臮 臐腽臘腡膻臌腟 腮腏腝腪膟腋腭腯腮 臅臩臯膩 膱腺膷腼 腈腄腉腇 腓腗腑腖腔腐腕腘 腅腒腊腌腋腙 腆腏腍腎 ῌῌ 127 Bull. Earthq. Res. Inst. Univ. Tokyo Vol. pp. * e-mail : [email protected] M Earthquake Research Institute, the University of Tokyo The Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan Area has been ongoing ( ). Under this project, the Metropolitan Seismic Observation network (MeSO-net), which consists of about observation sites, has been constructed. The correlations of waveform from local and teleseismic events are high because observation sites are deployed at about or -km intervals. In addition, the later phase is easily identified although artificial noise is very intense. However, we are attempting to improve quality by characterizing the various types of noise. In the metropolitan area, various human activities are observed that generate noise such as trains, automobiles, aircrafts, factories, and electrical power. These adversely a ect our observa- tions. We recognize various types of noise from continuous records. A spectral graph and a spectrogram in each station are useful for characterizing signals and noise. We also discovered a form of system noise obtained from the relationship between sensor and electrical circuit. We named it Aurora Noise. The strength of Aurora Noise was reduced by improving the electrical circuit. Our study will lead to improving the quality of observed data, and contribute to a new assessment of seismic hazard in the Tokyo Metropolitan Area in Japan. : Metropolitan Seismic Observation network, noise reduction, spectrogram M . M . M M M M Fig. M M . , * Yuuko Kawakita * and Shin’ichi Sakai Abstract Key words MeSO-net Various Types of Noise in MeSO-net + + + + + + 2. ,**3 +,1 +-3 ++- **-, +++ 1* ,**. ,**/ ,**1 ,*+, .** , - # 1 +2// +23. +3,- 13 13 ,** .** 2 1 +** / -* 2 1 + 1 +3 1* +/* 1- ++ *** ++, 1 +
Transcript
Page 1: Vol. pp. 2. ,**3 +,1 +-3 ˘ˇˆ˙ MeSO-net Various Types of ... · (MeSO-net), which consists of about observation sites, has been constructed. The correlations of waveform from local

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127

Bull. Earthq. Res. Inst.

Univ. Tokyo

Vol. pp.

* e-mail : [email protected]

M

Earthquake Research Institute, the University of Tokyo

The Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan Area has

been ongoing ( ). Under this project, the Metropolitan Seismic Observation network

(MeSO-net), which consists of about observation sites, has been constructed. The correlations of

waveform from local and teleseismic events are high because observation sites are deployed at

about or -km intervals. In addition, the later phase is easily identified although artificial noise is

very intense. However, we are attempting to improve quality by characterizing the various types

of noise.

In the metropolitan area, various human activities are observed that generate noise such as

trains, automobiles, aircrafts, factories, and electrical power. These adversely a ect our observa-

tions. We recognize various types of noise from continuous records. A spectral graph and a

spectrogram in each station are useful for characterizing signals and noise. We also discovered a

form of system noise obtained from the relationship between sensor and electrical circuit. We

named it Aurora Noise. The strength of Aurora Noise was reduced by improving the electrical

circuit.

Our study will lead to improving the quality of observed data, and contribute to a new

assessment of seismic hazard in the Tokyo Metropolitan Area in Japan.

: Metropolitan Seismic Observation network, noise reduction, spectrogram

M

.

M .

M M

M M

Fig. M

M .

,

*

Yuuko Kawakita * and Shin’ichi Sakai

Abstract

Key words

MeSO-net

Various Types of Noise in MeSO-net

+

+

+ +

+ +

2. ,**3 +,1 +-3

++- **-, + + +

1* ,**.

,**/

,**1 ,*+,

.**

, -

#

1

+2// +23.

+3,- 1 3

1 3 ,** .**

2

1 +**

/ -*

2 1

+ 1 +3

1* +/*

1 -

++ *** ++,

1

+

Page 2: Vol. pp. 2. ,**3 +,1 +-3 ˘ˇˆ˙ MeSO-net Various Types of ... · (MeSO-net), which consists of about observation sites, has been constructed. The correlations of waveform from local

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Fig. . Large earthquakes (M . ) occurring in the

metropolitan area over about years.

Fig. . Map of observation points in MeSO-net.Colors indicate year of deployment. Large square indicates area

of estimated Northern Tokyo-bay earthquake. Small squares indicate the Hi-net’s station and JMA’s station.

MeSO-net

Metropolitan

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MeSO-net

Fig. . Time sequence of amplitude for each station Fig. . Time sequence of amplitude strength for each

from : to : on Oct., . station from : to : on Oct., .

(a) YYIM, W , Yayoi, Bunkyo-ku, Tokyo. (b) GSJM, (a) YYIM, W , Yayoi, Bunkyo-ku, Tokyo. (b) GSJM,

TF , Tsukuba, Ibaragi. (c) GNZM, TF , Ginza, Chuo- TF , Tsukuba, Ibaragi. (c) GNZM, TF , Ginza, Chuo-

ku, Tokyo. ku, Tokyo.

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Fig. . Waveforms observed by Tukuba-Fujisawa line are shown for Sep.,

Top is northern station and bottom is southern station. (a) Not filtered, from : to : , (b) Not filtered, from

: to : , (c) Low-pass filtered ( sec.), from : to : , (d) Low-pass filtered ( sec.), from : to : .

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MeSO-net

Fig. . Spectrums of each station for hour. Fig. . Spectrums of each station for hour.

Blue line indicates spectrum from : to : on Blue line indicates spectrum from : to : on

Oct., , and red line indicates from : to : , Oct., , and red line indicates from : to : ,

(a) YYIM, (b) GSJM, (c) GNZM. (a) YYIM, (b) GSJM, (c) GNZM.

AD Hz Hz

Hz Fig. MeSO-net

Hz

Hz

Fig.

M . km

Fig. Fig.

0 + 1 +

- ** . ** +/ - ** . ** +2

,**3 +/ ** +0 ** ,**3 +/ ** +0 **

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Fig. . Spectrogram of YYIM from : to : on Oct., .

Color indicates amplitude strength : blue is normal level and red is strong. For example, red signal at about

: indicates an earthquake (M . ) occurring in Tokyo (blue allow). Red allows and green allows indicate

weak signal and more weak signal, respectively. Pink allow indicates continuous noise around Hz.

Fig. . Spectrograms of earthquakes observed at YYIM.

(a) Earthquake (M . , km depth) occurring in eastern

Tokyo on Oct., . (b) Earthquake (M . , km

depth) occurring at Suruga Bay on Aug,, . (c)

Earthquake (M . , km depth) occurring at Samoa

Islands in southern Pacific on Sep,, .

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and red is strong.

Fig. . Spectrograms of JDJM on Oct., .

and red is strong. (a) Spectrogram from : to : .

(b) Spectrogram from : to : . (c) Spectrogram

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Fig. . Spectrograms of DSCM on Nov., .

Fig. . Relation between amplitude strength and

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Color indicates amplitude strength : blue is normal

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Ibaragi Prefecture. Solid circle and open triangle

indicate the site that observed aircraft signal and

planned site, respectively. Shaded line indicates

estimated flight course.

Fig. . Relation between time of aircrat signal and

distance from NGSM.

Fig. . Spectrograms of each station from : to

: on Oct., .

Color indicates amplitude strength : blue is normal

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Fig. . Spectrograms of each component at YYIM from Fig. . Spectrograms at YYIM.

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Fig. . Spectrograms at YYIM.

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139

MeSO-net

MeSO-net

.

MeSO-net

ACT protocol

.

. .

.

(Received November , )

MeSO- (Accepted January , )

net .

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