# Presentation: 381949

## Geomagnetic measurement and data reduction of Gyeongzu(GZU) Observatory in Korea

**LIM, Mutaek*****1****,  PARK, Youngsue****1****,  RIM, Hyoungrae****1****, **
**KOO, Sungbon and KWAK, Byoungwook****1**
**limmt@rock25t.kigam.re.kr**
**1**** : Korea Institute of Geoscience and Mineral Resources (KIGAM)**
**http://www.kigam.re.kr  & **_**[http://](http://geomag.kigam.re.kr/)**__**[geomag.kigam.re.kr](http://geomag.kigam.re.kr/)**_

## Contents 

**    ***** main processing **

**    ***** p****roblems on abs. meas. data**

**2. GZU Data : 3-comp. meas. data & abs. meas. data**

**4. Conclusive remarks  **

**1. Present status of geomag. meas. in Korea**

**3. Processing results**

**1. Present status of geomag. meas. in Korea : overview**

**Notes:**
목 차

##  
~ 1995
  Radio Res. Lab. under Min. of Inform. & Comm. 
  Nat’l Geogr. Inform. Inst. under Min. of Constr & Transp. tried to do continuous geomag. Meas. on Korea.
  data not remaining

1995 ~ present
  Radio Res. Lab. installed 3 sys. in 1996 ~ 1997
    at present stopped operating : because there not being personnel

  Kor. Inst. of Geosc. & Min. Res. installed 3 sys. in 1998, 2000, & 2002 respectively as seen in overview, but mag. environ. so bad as sites were selected for seismometers’ instal. in borehole
    at present : operating, but only one person caring for them, always vulnerable to be stopped

  Kor. Meteor. Agency is planning to install an observatory in a mag. clean site to become a central obs., 
    as not considering seriously continuation in future by permanent personnel, abs. meas., additional facilities ; strongly advised to consider such things.

  Most important : site selection, install., permanent personnel, abs. meas., additional facilities

**~ 1995**
**  ****Radio Res. Lab.**** under Min. of Inform. & Comm. **
**  ****Nat’l Geogr. Inform. Inst.**** under Min. of Constr & Transp. tried to do continuous geomag. Meas. on Korea.**
**  ****data not remaining**
**1995 ~ present**
**  ****Radio Res. Lab.**** installed 3 sys. in 1996 ~ 1997**
**    ****at present stopped operating : because ****there not being personnel**
**  **
**  ****Kor. Inst. of Geosc. & Min. Res. ****installed 3 sys. in 1998, 2000, & 2002 respectively as seen in overview, but ****mag. environ. so bad**** as sites were selected for seismometers’ instal. in borehole**
**    ****at present : operating, but ****only one person caring for them****, always vulnerable to be stopped**
**  **
**  ****Kor. Meteor. Agency**** is planning to install an observatory in a mag. clean site to become a central obs., **
**    ****as ****not considering seriously continuation in future**** by permanent personnel, abs. meas., additional facilities ; ****strongly advised to consider such things****.**
**  ****Most important : ****site selection****, install., ****permanent personnel****, ****abs. meas.****, additional facilities**

**Notes:**
목 차

## DZN Obs. : 

**DZN Obs. : **
**  ****installed Flare+ of BGS in KIGAM in 1998  **
**  ****at around 70 m distance from the sensor huts, a new building**
**    ****was constructed 2004 ~ 2006**

- 1998. **. **.

## GZU Obs.

**GZU Obs.**
**  ****in a site of composite earthquake obs. center (geophones **
**    ****(borehole), GPS receiver)**
**  ****Flare+ installed in 2000 in a corner as far as possible from road **
**  ****from 2006, a house **** ****& vinyl tunnels were constructed nearby ;**
**    ****mag. environ. getting worse**
**  **

**~ 50 m**

- house

- vinyl tunnels

## HOS Obs.

**  ****in a site of composite earthquake obs. center (geophones **
**    ****(borehole), GPS receiver)**
**  ****Flare+ installed in 2002 in a corner of this site **
**  ****from the very beginning small agricultural machines passing by,**
**    ****agricultural activities done, mag. environ. being always bad**

## 2. GZU Obs. Data

**   ****3-comp. meas. data logged on Flare+ **
**      ****1 min averaged data to mid 2004**
**      ****5 sec data from mid 2004**
**   ****abs. meas. data by Mag-01H, Bartington Co.**
**       ****so rare meas., **
**       ****baseline fluctuating too much. **

## * main processing 

| 0501 000000   -71.5   -39.0   -19.1    18.0 No Data   |
| --- |
| 0501 000005   -71.8   -39.5   -19.8    17.8 No Data   |
| 0501 000010   -71.5   -39.3   -19.6    18.0 49361.4 a |
| 0501 000015   -71.4   -39.4   -19.5    18.0 49361.4 a |
| 0501 000020   -71.8   -39.7   -19.6    17.9 49361.4 a |
| 0501 000025   -71.9   -39.6   -19.4    17.9 49361.4 a |
| 0501 000030   -71.9   -39.5   -19.5    17.9 49361.4 a |
| 0501 000035   -71.9   -39.5   -19.5    18.0 49361.4 a |
| 0501 000040   -71.2   -39.2   -19.4    18.0 49361.4 a |
| 0501 000045   -71.7   -39.5   -19.2    18.0 49361.4 a |
| 0501 000050   -71.7   -39.6   -19.2    18.0 49361.4 a |
| 0501 000055   -71.9   -39.8   -19.2    18.0 49361.4 a |
| 0501 000100   -71.9   -39.6   -19.3    18.0 No Data   |
| 0501 000105   -72.1   -39.7   -19.6    17.9 No Data  
...... Continued ...... |

**GZU20080501.5sc**

**abs. meas. data**

**averaging**

| Baselines: H:30988.1nT D:  -6.7945deg Z:38444.9nT I:  51.1297deg F:49378.9 |
| --- |
|              H(nT)    D(dg)    Z(nT)    I(dg)    F(nT)    PPMF(nT)  T(dgC) |
| 0501 0000  30916.5   -6.8675  38425.4   51.1803  49318.8  49361.4     18.0 |
| 0501 0001  30916.3   -6.8679  38425.5   51.1806  49318.8  49361.4     18.0 |
| 0501 0002  30915.9   -6.8692  38425.6   51.1810  49318.6  49361.5     18.0 |
| 0501 0003  30915.7   -6.8698  38425.7   51.1813  49318.6  49361.4     18.1 |
| 0501 0004  30915.6   -6.8706  38426.1   51.1816  49318.7  49361.5     18.2 |
| 0501 0005  30915.1   -6.8711  38426.0   51.1821  49318.4  49361.0     18.2 |
| 0501 0006  30914.8   -6.8716  38426.0   51.1823  49318.1  49360.9     18.4 |
| 0501 0007  30914.6   -6.8723  38426.0   51.1825  49318.0  49360.7     18.4 |
| 0501 0008  30914.7   -6.8729  38426.2   51.1826  49318.3  49361.2     18.5 |
| 0501 0009  30915.0   -6.8731  38426.3   51.1824  49318.5  49361.3     18.6 |
| 0501 0010  30915.5   -6.8729  38426.7   51.1822  49319.2  49361.9     18.6 |
| 0501 0011  30915.3   -6.8729  38426.4   51.1821  49318.8  49361.3     18.6 |
| 0501 0012  30915.1   -6.8722  38426.2   51.1822  49318.5  49361.3     18.8 |
| 0501 0013  30914.8   -6.8713  38425.5   51.1820  49317.8  49360.6     18.9
...... continued ...... |

**GZU20080501.1mnHDZ**

## * problems on abs. meas. data  GZU 2000 ~ 2008

**horiz. baseline**

## decl. baseline

## vert. baseline

## 3. Processing results

**3 comp. meas. data : example of 20-05-2008, GZU**

**3. Processing results**

## 1 day average data : example of 01-2008, GZU

**1 day average data : example of 01-2008, GZU**

## 1 month average data (ppmf) : 2005 ~ 2008

**1 month average data (ppmf) : 2005 ~ 2008**

- -22.53 nT/yr

- -10.35 nT/yr

## In summary, 

**   ****thinking that the ppmf data could be useful**
**      ****for some specific purposes,**
**   ****but, as abs. meas. data being so rare, **
**       ****and baseline fluctuating too much,**
**      **
**   ****3 comp. meas. data would be less useful **
**      ****than ppmf data if not applying much efforts &**
**      ****not applying good processing methods, **
**   ****nevertheless, should be well archived for potential **
**      ****use in the future.**

## Conclusive remarks : 

**KIGAM should ;**
**1. maintain the obs. systems alive to get and save**
**    ****as much data as possible for the potential use in the future.**
**2. process the existing data**** with the help of IAGA **
**    ****society, by getting good softwares especially,**
**    ****to remove spikes, to make proper averaging etc. **
**3. do abs. meas. correctly and as often as possible.  **
**4. install a new observatory on as clean site as possible ; KMA(Kor. Meteor. Agency) planning.**
**5. the most important : persuade decisive institution to assign permanent personnel to geomagnetism so that measurement be continued effectively.**

**Notes:**
목 차