Bull. Earthq. Res. Inst. Univ. Tokyo Vol. 2.,**3 pp.,/+,00 MEMS * +, +, + +, Evaluation of MEMS Accelerometer Sensor for Earthquake Observations Fumitoshi Murakami *, Hiroshi Sato, Toru Kuroda, Susumu Abe +, +, + +, JGI Inc. Earthquake Research Institute, the University of Tokyo and Naoko Kato Abstract Technology for imaging the lithospheric structure using earthquakes, such as receiver functions and seismic interferometry, have advanced greatly in the last decade. Three component, low cost accelerometer sensors have been constructed using Micro Electro Mechanical System (MEMS) technology, and are providing new opportunities for earthquake observations. To evaluate the feasibility of MEMS sensors for earthquake observations, dense seismic array observations were carried out using MEMS sensors in Mizusawa district, northern Honshu, Japan, for three months in,**1. In comparison with observed seismograms of velocity sensors, MEMS sensors show high performance for local and regional earthquakes. However, due to high-noise levels from the sensor itself at lower frequencies, MEMS sensors are not adequate for recording teleseismic waves. Key words: MEMS sensor, earthquake observations, imaging of lithosphere + MEMS Wilson and Aster,,**/; Ruigrok et al.,,**2 -,**.;,**3 Wu et al.,,**1,**1 3,2 +,,2 3* : MEMS Abe et al.,,**1 MEMS,**3 MEMS Micro Electro Mechanical System * email: f_ mura@jgi.co.jp ++, **+, + /,+ 251
, MEMS MEMS,+ MEMS MEMS Micro Electro-Mechanical System MEMS MEMS,* Fig.,,**. MEMS MEMS MEMS MEMS MEMS MEMS MEMS Fig. + MEMS MEMS Fig. +. Schematic diagram showing the principle of capacitive MEMS accelerometer sensor after Yamada (,**0). Fig.,. Frequency and intensity range of acceleration for various objects of oscillation observation and corresponding accelerometer sensors modified after Ohtake (,**.). 252
MEMS Hz +* Hz *. + mg Fig.. SF-+/** MEMS ASIC Application Specific Integrated Circuit Digital-- ION Sercel +33* MEMS,. Fig. / Digital-- SF- +/** SF--*** AD +,2 khz Gibson et al.,,**/ Sercel MEMS Digital-- Sercel Inc.,,**1 ION MEMS Cirrus-Logic CS/-10A Colibrys Ltd.,,**0 Fig., Sercel LSI Fig. + Digital- - +0. -2. MHz TCXO ION proof mass MEMS GPS ION,, MEMS Colibrys Colibrys Fig. 0, Fig. 2 MEMS MEMS Table + SF-+/** SF--*** MEMS Colibrys Digital-- SF--*** MEMS +** mm +** mm, +.* kg +,. VG Colibrys SF--*** - G G Digital-- -** /** ngrms Fig. - Digital--, +* +*** Hz gal cms + mgal, MEMS DC Fig. -. Outlook of Digital-- MEMS accelerometer sensor and its electronics unit by Colibrys Ltd. (,**0). 253
Fig... Block diagram and electrical connections of analog-output type MEMS accelerometer sensor by Colibrys Ltd. (,**0). Fig. /. Block diagram and electrical connections of digital-output type MEMS accelerometer sensor by Colibrys Ltd. (,**0). +,. Volt DC MEMS DC Colibrys Digital-- DC DC 0/ mm 254
MEMS +1/ mm, +.. kg Table + AD : *./. G : +0. G MEMS Digital-nG - Nominal /2, khz */. Hz +** ngpeak +*.** Hz Digital-- MEMS SF-+/** SF--*** +/ +/,- MEMS *., G +,* db MEMS MEMS MEMS Colibrys SF--*** MS,*** Fig. 0 MS,*** Fig. 1 MEMS DC Fig. 0. Outlook of earthquake observation system employed MEMS Colibrys Digital-- GPS with analog-output type MEMS accelerometer sensor. Fig. 2 Table +. Main specifications of MEMS accelerometer sensors. 255
Table,. Basic specification of the recording system employed with digital-output type MEMS accelerometer sensor. Fig. 1. Configuration of earthquake observation system employed with analog-output type MEMS accelerometer sensor. Fig. 2. Outlook of earthquake observation system employed with digital-output type MEMS accelerometer sensor. MS,***,. MEMS Fig. 3 MEMS MEMS 256
MEMS, + Fig. +* MEMS X Y Z Fig. 3. Configuration of earthquake observation system employed with digital-output type MEMS accelerometer sensor. Fig. +*. Comparison of observed waveforms of impulsive seismic source by analog-output type and digital-output type MEMS accelerometer sensors. Right-hand side shows figures of spectrum comparison (top), amplitude ratio (middle), phase di# erence (bottom). 257
MEMS +* Hz 1/ Hz MS,*** + Fig. ++ +, MEMS Fig. ++. Observed waveform of vibrator sweep seismic source by analog-output type MEMS accelerometer sensor. Sweep frequency : 230 Hz, Sweep length: +* sec., Taper length: *-. sec. Fig. +,. Observed waveform of vibrator sweep seismic source by digital-output type MEMS accelerometer sensor. Sweep frequency : 230 Hz, Sweep length: +* sec., Taper length: *-. sec. 258
MEMS Fig. +-. Waveform of ground noise observed late at night by analog-output type MEMS accelerometer sensor. X Y Z 230 Hz Fig. +- +/ MEMS +* Grms Fig. +. +0 +* X Y Z RMS MEMS -. mgrms Fig. +.. Amplitude spectrum of ground noise observed late at night by analog-output type MEMS accelerometer sensor. - MEMS MEMS -+ DC MEMS +* Hz Kato et al., DC,**0 259
Fig. +/. Waveform of ground noise observed late at night by digital-output type MEMS accelerometer sensor. MEMS Fig. +1 MZ-km,**1.* -, MEMS Fig. +0. Amplitude spectrum of ground noise observed late at night by digital-output type MEMS accelerometer sensor. +/. Hz MZ-+,**1 MEMS MEMS DC MEMS 260 MEMS
MEMS Fig. +1. Location map of the dense seismic array observation in Mizusawa district, northern Honshu, Japan. Small square dots show the observation stations. A B B MEMS.*.* km *. 2 +., km, -,+ +33,2 +,,2 3* : -- +* ++,. /2 -,, A ennartz Electric LE-- D lite +*. Hz +/ B Markproducts L-.- - D +*. Hz / C Markproducts L-,, D,.* Hz +* A MEMS JGI AMS-- C +* Type-A Local Earthquake : Colibrys MEMS Si-Flex-*** L +** km B MEMS JGI DMS- -*** +* VSP : Colibrys MEMS Digital-- A JGI: MS-,***.* Type-B Regional Earthquake B JGI: DMS- -*** +* +** km,* A A, B, C.*. 261
DC Type-C Teleseismic Wave Fig.,* Type-A,/ 2* /1. Fig. +2./ km MEMS +*. Hz MEMS Type-A Fig.,+,, Type-B **+. /*. Hz MEMS Fig. +3 Fig. +2 Fig. +3 MEMS **+. 1*. Hz **+. -*. Hz Fig.,- MEMS 12. Mw MEMS */. Hz P MEMS -** MEMS /** ngrmshz MEMS MEMS / MEMS Fig. +2. Example of observed earthquake (Type-A). 262
MEMS Fig. +3. Example of observed earthquake (Type-A). After applying band-pass filter: **+. 1*. Hz. Fig.,*. Comparison of amplitude spectrum for horizontal component of Digital-MEMS and +*. Hz geophone sensor (Lennarz LE--D). Time integration was applied to the observed record of Digital MEMS. +** Hz Table - Type-A, Type-B, Type- C +* Hz +*. Hz MEMS. MEMS 263
Fig.,+. Example of observed earthquake (Type-B). After applying band-pass filter: **+. /*. Hz. Fig.,,. Example of observed earthquake (Type-B). After applying band-pass filter: **+. /*. Hz. 264
MEMS Fig.,-. Example of observed earthquake (Type-C). After applying band-pass filter : **+. -*. Hz Table -. Combination of various profiling method. Table shows profiling methods, which employ controlled seismic source and natural earthquake data, and corresponding resultant subsurface profile and related seismic sensors. MEMS MEMS + Hz 265
MEMS + Hz sensors : Some issues for consideration, The Leading Edge,,., 2, 12013*. 2..+ /0. Kato, N., Sato, H. and Umino, N.,,**0, Fault reactivation and active tectonics on the fore-arc side of the back-arc rift system, NE Japan, Journal of Structural Geology,,2,,*++,*,,.,**. MEMS No. *. 10.+.0. Ruigrok, E., D. Draganov and K. Wapenaar,,**2, Global-scale seismic interferometry : theory and numerical examples, Geophy. Prosp., /0, -3/.+1, doi: +*. ++++ /j. +-0/ -,.12.,**2. **031. Sercel Inc.,,**1, Digital sensor unit - C DSU/.,2XL, Company Brochure. Shragge, J., Artman, B. and Wilson, C.,,**0, Teleseismic shotprofile migration, Geophysics, 1+, SI,,+,,3. Wilson, D. and R. Aster,,**/, Seismic imaging of the crust and upper mantle using regularized joint receiver functions, frequency-wave number filtering, and multimode,**1 Kirchho# migration, J. Geophys. Res., ++*, B */-*/, doi: S+/, -P**/. +*. +*,3 /,**. JB **-.-*. Abe, S., Kurashimo, E., Sato, H., Hirata, N., Iwasaki, T. and Wu, F., Okaya, D., Sato, H. and Hirata, N.,,**1, Interaction Kawanaka, T.,,**1, Interferometric seismic imaging between two subducting plates under Tokyo and its of crustal structure using scattered teleseismic waves, possible e# ects on seismic hazards, Geophys. Res. Lett., Geophys. Res. Lett., -., No. +3, L +3-*/, doi: +*. +*,3 /,**1 -.,L +2-*+,doi: +*. +*,3 /,**1 GL *-*10-. GL *-*0--.,**0, Buyers Guide - Nikkei,**3 PS Electronics,,**0 +* 1+ 11. 1. -,.1,/+. (Received January +.,,*+*) Colibrys Ltd.,,**0, Product Description, Company Brochure. (Accepted March +,,*+*) Gibson, J., Burnett, R., Ronen, S. and Watt, H.,,**/, MEMS 266