2B-P6
On-site experiment of seismic monitoring network by utilization inside sensors ofmobile terminal#Shohei Naito*1, Hiroki Azuma*1, Shigeki Senna*1, Mutsuhiro Yoshizawa*2, Hiromitsu Nakamura*1, Ken Xiansheng Hao*1,Hiroyuki Fujiwara*1, Yoshiharu Hirayama*3, Noburu Yuki, *3 and Minoru Yoshida*3*1NIED , *2Takenaka Corp. , *3Hakusan Corp.

1．INTRODUCTION
Mobile terminal devices have small, lightweight, and cheap acceleration sensors so-called MEMS(Micro Electro Mechanical Systems) with wirelesscommunication adaptors inside. By using MEMS sensors densely for monitoring earthquake, we would know detailed distribution information of shaking intensity.
By sharing those information through the cloud computing system, we could raise public awareness for disaster prevention. "i-Jishin" is one of examples, which
is an experimental earthquake observation system developed using inside sensor of iPhone/iPad/iPod touch.

2．DEVELOPMENT“i-Jishin” was released as application for iPhone/iPad/iPod touch in August 2010.
Anyone who have these terminals can install “i-Jishin” and record shakings.
Signals recorded by these terminals are sampled with frequency of 100Hz andgiven time stamp every 0.01sec synchronized with UTC by using external NTP
server.(Fig.1,Table.1) Wave data are recorded as CSV file in the memory insidethese terminals up to 30 files, and if wireless LAN connection is alive, they areuploaded to the virtual server installed in the cloud computing environment.
(Fig.2)
If we search the recorded data, to access “geonavi” web site(http://www.geonavi.com/), we can download wave data and seismic intensity.
(Fig.3) And we can also analyze data on the web browser.(Fig.4)

Fig.1 Screenshot of “i-jishin”(corresponding to multilingual)
Table.1 Specification of “i-jishin” as a seismometer

Items

Fig.2 Key map of “i-jishin” and “geonavi”

Fig.4 Wave viewer of “geonavi”

Fig.3 Screenshot of “geonavi ”

ValuesSampling frequency

100HzChannels

3Resolution

12bit (1.6gal)

Noise level

10gal(p-p)

Gauging range±2,000gal

Time Correction

NTP（10msec)

Connection

Wi-Fi / 3G

Triggering

EEW / setting value

Memory5min × 30 files

3．PERFORMANCE TESTS
・We installed “i-jishin” on the base and observed in parallelwith K-NET02, the standard seismometer used for strong
motion observation in Japan(Photo.1) , then we haveconcluded that the consistency would be perfectly for JMA
seismic intensities large than 3(Fig.5), and contaminated bynoises for less than 2(Fig.6).
・We have made a vibration test on the shaking table andexamined in parallel with other standard seismic intensity
meter (Photo.2) ,and compared them from a viewpoint of
frequency domain(Fig.7).
・We set up 12 machines of iPod-touches on the 3-D FullScale Earthquake Testing Facility ,nicknamed “E-Defense”(Photo.3) ,and observed 10 different kind of seismic waves.
The response spectrum showed nonlinear characteristics
depending on vibration levels and layers in which case they
were shook at strong motion such as JMA Kobe.
Recorded data has some differences depending on alocation setting. So, when we set ”i-jishin” we must fix on the
ﬂoor or wall tightly, so that not to conﬂict with surroundings.

Photo.1 Earthquake observation test
Fig.5 Comparison of the waveform

Fig. 7 Comparison of the spectrum recordedat vibration tests

Photo.2 Vibration tests

4．ON-SITE EXPERIMENT
(1)

(2)

Fig.6 Relationship between the Seismic Intensity
recorded at earthquake observation test

Photo.3 Performance tests on E-Defense
Table.2 Characteristics of the building(5)

Acceleration(gal)Contracted
Building
・We installed 10 terminals on two different floors in 5 low-rise RC
Building
name of Structure Floors
Standards
datebuildings, and started monitoring since January 2012(Photo.4, Table.2).
the building
ActHRC31975
oldAfter installation, we were able to get a large number of earthquake
S building
FRC
3
1981
oldH building
records corresponding up to JMA intensity 4(Fig.8). By analyzing theseSRC2
1995
new(3)(4)
K building
data, one building showed significantly high velocity response
DRC
2
1999
newK
RC
3
2003
newvalues(Fig.9). It was consistent with the fact that this building was(7)significantly damaged in the non-structural component after theTohoku-Pacific Ocean Earthquake. After that, the microtremor
F building
D building
observation using JU-310(Hakusan Corp.) also found the largest(6)amplification compared to others in this building regarding the H / V
spectral ratio.
(8)・We installed “i-Jishin” on more than 30 different buildings which havedifferent structure types and network environments around the city of
Nagaoka, Niigata Prefecture and Fujisawa, Kanagawa Prefecturesince January 2012(Fig.10). In that case, the staff of NPO installed
terminals to the houses of volunteer that well understood about thePhoto.4 (1)-(5)Appearance of buildings (6)Installation of “i-jishin”
Time(sec)
effect of sensing. However, many problems were still found such as,(7) ,(8)Damages of K building after the Tohoku-Pacific Ocean Earthquake
Fig.8 Waveforms recorded in each buildings
diversities of networking environment, uneasily understandable
benefits of installation, requirement to ensure the stability of themeasurement, and needs of human resources for maintenance.
To solve these problems, we have to develop a more reliable andaccurate systems or easily understandable systems for public. Besides
we are going to enhance the cooperation with "i-Bidou" which is thesystem of the cloud type microtremor observation (Senna et al 2012).
We are planning to keep developing of the system to visualize thehazard information of regional soil and building conditions, and keep
performing experiments of the sensor network system so thatFig.9 Velocity response spectrum calculated with
Fig.10 On-site experiment in Fujisawa and Nagaoka
waveforms recorded by “i-jishin” terminals
everyone can measure and share information of the buildings.