Strong Motion Downhole Array in the Taipei Basin
In 1990, Institute of Earth Sciences (IES) in the Academia Sinica was contracted by the Central Geological Survey (CGS) in the Ministry of Economic Affairs to select suitable borehole sites to install accelerometer. In this project, an accelerometer downhole array distributing Taipei Metropolitan Area (TMA). This array is composed of eight boreholes at depths in excess of 300 meters. Data collected by this array are use to study how a local site can substantially change the characteristics of seismic waves as they pass through soft deposits below the free surface, as well as to provide basic ground motion data to measure the response of soft soil deposits at the TMA.
Broadband Seismic Array in the Taipei area
In 2004, IES was a contractor of CGS to execute a project of 「Geophysical investigation and monitoring for micro-earthquake in metropolitan Taipei」. In this project, a broadband seismic array consists of surface and borehole stations were widely deployed to observe seismic activity of in TMA. The downhole array velocity sensor composed of six boreholes at depths up to 90 meters. This is the first broadband array install to provide continuously monitor seismic activity.
Seismic Array in the Taiwan Mountain Area (MTN)
In early 1990, began to deploy the Taiwan Mountain seismic array (MTN) which was the region that lack of seismic data. Data collected from the 1999 Chi-Chi earthquake by this array was provided significant data base in the Taiwan mountain area. In 2003, the IES decided an action plan to hunt of new sites for increasing the density of seismic stations at the mountain areas. In accordance with the plans indicated of this project, the stations were deployed in the northern part of Taiwan in 2006 and 2007 and extended through northern parts of Taiwan into the central and southern parts of Taiwan in 2008 and 2011. With significant efforts, the housing and installation of 75 new seismic stations were completed in November 2011. Seismic data from MTN will be integrated to study the path effects and site effects from different seismogenic zones to the metropolitan area and provide significant information to reduce seismic hazard.
Broadband Array in Taiwan for SeismologyIn mid-1992, along with several domestic and foreign institutions, began to prepare a prospectus for establishing a broadband seismic network in the Taiwan region. The network, later named "Broadband Array in Taiwan for Seismology (BATS)," is initially designed with 15 permanent stations located on Taiwan and the surrounding islands, covering an area of approximately 350 km by 400 km. Currently the number of permanent broadband stations operated by IES is 25, including 2 located in the South China Sea with satellite transmission.
The BATS instrumentation is designed to cover a variety of research demands. All permanent stations are equipped with state-of-the-art very-broadband and strong-motion sensors and 24/26-bits digital recorders. Data streams with high sampling rates (>=80 samples per s) were recorded in triggering mode before Q330 was used. After 2002, we gradually upgrade the dataloggers to gain the ability to continuously record ground motion at high sample rates. All stations are capable of internet connection for immediate retrieval of real-time data. We fully take advantage of the Antelope software platform to operate the BATS data acquisition in the data center since 2007. Preliminary data quality control is performed at IES. Afterwards, the data are distributed to the public through the web-based data service at the official BATS website.
We have setup the IES Data Management Center (DMC-IES) which is taking care of the routine network operation, data processing, quality control, and data release, exchange, and contribution etc.
Taiwan Continuous GPS Data Analysis and a Study on Earthquake Precursor Detection
The "Taiwan Continuous GPS Array" is now composed of more than 360 stations operated by the Seismological Center, Central Weather Bureau, IES, Ministry of the Interior, Central Geological Survey and other institutions. The enormous continuous GPS data collected daily by the array need to be processed carefully. Only after the systematic and random errors or noises are removed, we may be able to detect the weak signals of crustal strain such as earthquake precursors or transient aseismic slip. GPS position time series from these continuous stations will be modeled to estimate the annual and semi-annual periodic motion, offsets due to coseismic displacement or instrument cahnge, postseismic deformation, and site velocity with more realistic uncertainties. Finally, the strain rates will be estimated directly from the precise velocity field or position time series. Then we can study the spatial and temporal variations of crustal strain and their correlation with seismic and faulting activities in and around Taiwan. The results may provide the important information for the probability evaluation of earthquake occurrence and detection of any possible earthquake precursors.
Borehole Strainmeter Network on the Plate Suture Zone, Eastern Taiwan
In cooperation with the Department of Terrestral Magnetism, Carnegie institution of Washington, have deployed 11 borehole strainmeters at a depth range of 200–270 m near Taroko, Juishi-Chimei, and Chengkung- Chihshang in eastern Taiwan. The borehole strainmeters have recorded tens of tremors between 2003 and 2007 and eleven of them are related to typhoons.
Chihshang Active Fault Observatory
We conduct a multi-disciplinary on-site measurements and experiments at Chinyuan village, east of the Chihshang Town, to monitoring the activity of the Chihshang Fault. The instrumentation includes creep meter, leveling, GPS, trilateration, Broadband Seismometer, Ground water level (including pumping and injection tests), Electric resistivity, Noble gas measurements, etc. Although we intend to first characterize surface deformation and slip rate of the fault movement at the near surface level, however, the subsurface fault activity and behaviors in the seismogenic zone at 10-30 km depth are also our scientific targets. Detailed introduction, results of studies, and data please refer to our website at Chihshang Active Fault Observatory.
Understanding the Life of the Tatun Volcanic Group:Integrated Analysis of Geophysical, Geochemical and Geodetic Observations
1. Integrated crustal deformation monitoring at Tatun volcanic Group, 2. Mass transfer and Deformation Monitoring over the Tatun Volcanic Group by Terrestrial Gravimetry, 3. Geomorphic Reanalysis of the Tatun Volcanic Group Using Airborne LiDAR Data, 4. Evaluating the activity of potential magma chamber in Tatun Volcanic Group based on the study of fluid/gas geochemistry and estimation of volcanic gas emission, 5. The most recent volcanic eruption and climate change in Tatun Volcanic Group, northern Taiwan.
Facilities
Computer: High performance computing cluster, High performance network storage, Computing node on blade server
Mineral & rock physics instruments: Raman spectrometer, Brillouin spectrometer, Polarizing microscope, Diamond anvil cells
Geochemistry instruments: α spectrometer, Gamma counting system
C-O-isotope pre-treatment system: The well-designed system can simultaneously process 20 samples both in water and carbonate phase for isotope analyses.
C-O-isotope spectrometer: SIRA10 type, double inlet – triple collector system, dedicated for CO2 isotope measurement.
Ultra High Precision δD and δ18O Analyzer: The time-based laser measurement can quantify spectral features of molecules (specifically absorption lines unique to 2H16O, 2H18O, and HD16O) in an optical cavity. The analyzer can be applied for hydrogen and oxygen isotope measurements in liquid and vapor samples.
Thermo Ionization Mass Spectrometer - MAT262, ICP Mass Spectrometer - Nu Plasma, Thermo Ionization Mass Spectrometer - Triton, ICP Mass Spectrometer - Element XR
