How I spent my summer vacation. By: Matthew Ludwig

How I spent my summer vacation.

By: Matthew Ludwig

GEM-2 and Geomagnetic Surveying at a Coalition Period

Archeological Site

Looking for “hidden treasures” in the GEM-2 and GM data sets collected at the LANL Archaeological Site #LA-135290

SAGE 2002Matthew Ludwig

Santa Fe, NM

Presentation OutlineGEM-2

The Raw DataThe Data & ProcessingThe Interpretation

GMThe Raw DataThe Data & ProcessingThe Interpretation

Comparisons & Conclusions

The GEM-2





Step 1 Unprocessed GEM Data

Low Frequency

Real Component

GEM-2 Data Processing





Step 2 Linear Trend

Removal


Step 3 5 Pass

Smoothing


Step 4 Expanding the Scale






Low Frequency ~1000HzIn-Phase Quadrature

GEM-2 Interpretation

Middle Frequency-5000HzIn-Phase Quadrature


In-Phase Quadrature


High Frequency-15000Hz





Geomagnetics





Survey #1 6/28/02 N-S

Northing

(m)

Easting (m)

Field Strength

(nT)

STAKE

8 15

Survey #2 6/30/02 W-E

Northing

(m)

Easting (m)

Field Strength

(nT)

STAKE

2

40

W-E vs. N-S





Step 0 – Raw Data (SD)

Data Point (distance)

Field Strength (nT) x 10,000

Step 0 – Raw Data (SD)

Y=mx+b



Step 1 Removal of Trend (SD)



Step 2 – FFT to Frequency Domain Log Plot (FD)

FrequenciesLog Field Strength (nT) x 10,000

Nyquist Frequency

+LOW-

+High-

Step 3 – Log plot of the Results of Bandpass Filter in Frequency Domain

Frequencies

Log Field Strength (nT) x 10,000

Finally – Bandpass filtered data



Comparing Filtered ResultsLine 8-1 Line 40-2


The BasicsThe Data & ProcessingThe Interpretation

GMThe BasicsThe Data & ProcessingThe Interpretation


GEM-2 (LF) vs Magnetics (NS)

STAKE

MN

Conclusions

• Both data sets turned out to appear more meaningful after filtering

• Low Frequency GEM-2 and Magnetics Plots show obvious similarities

• Surface structure correlations are more apparent in the GM data

• It will be interesting to see the results of the excavation study

Documents

How I spent my summer vacation. By: Matthew Ludwig