The use of waveform cross correlation for creation of an accurate catalogue of mining explosions within the Russian platform using joint capabilities of seismic array Mikhnevo and IMS arrays
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In the current study of mining activity within the Russian platform, we use the advantages of location and historical bulletins/catalogues of mining explosions recorded by small-aperture seismic array Mikhnevo (MHVAR). The Institute of Geospheres Dynamics (IDG) of the Russian Academy of Sciences runs seismic array MHVAR (54.950N; 37.767E) since 2004.
Small-aperture seismic array “Mikhnevo” includes ten vertical stations (solid triangles), with one station in the geometrical centre of the array (C00) and other nine stations distributed over three circles with radii of 130 m, 320 m, and 600 m. The array aperture in approximately 1.1 km. Two 3C stations (solid triangles in circles) were added to the outer circle in order to improve the overall stations sensitivity (detection threshold) and resolution. All stations are equipped with short-period seismometers SM3-KV, which are characterized by flat response between 0.8 Hz and 30 Hz and gain of 180,000 [Vs/m]. Later, a 3C broad band station (BB) was installed in the centre of the array for surface wave measurements. The array response function (only for 12 vertical channels) is similar to that for many small-aperture arrays. Such arrays are designed to measure high-frequency signals from regional and near-regional sources with magnitudes above 1.5-2.0.
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MHVAR detects regional seismic phases (Pn, Sn, Lg, Rg) from various sources. Figure shows some selected waveforms with source-station distance decreasing up-down. Correspondingly the length of records decreases – for the closest mines it’s harder to distinguish between P and S phases.
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More than 50 areas at regional and near regional distances with different levels of mining activity have been identified by MHVAR. Since 2004, thousands of events have been reported in the IDG seismic catalogue as mining explosions. The IDG publishes this mining event catalogue as a part of the annual issues of “Earthquakes in Russia”, which is available for the broader geophysical community. The map shows several selected mines at near-regional distances where MHVAR successfully detects events with magnitudes 1.0 and lower. We also show a few selected mines at regional distances with the largest events of magnitude (ML) 2.0 and above. Such events should be also detected by IMS arrays. Joint interpretation of signals detected by MHVAR and IMS arrays allows significant improvements in signal detection, location, characterization and identification of events in the IDG catalogue when the historical data are revisited. The work on joint analysis of the IDG and IMS data is possible under the “Contract for limited access to IMS data and IDC products” between the CTBTO and IDG, which allows obtaining data through 2011.
To begin with, we have chosen blasts with larger magnitudes from well-known ironstone mine Mikhailovskiy (red circle), which is situated at regional distances somewhere between MHVAR (~330 km) and IMS array AKASG
Historical IBM quarterly dividend rates and payable and records dates.
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The use of waveform cross correlation for creation of an accurate catalogue of mining explosions within the Russian platform using joint capabilities of seismic array Mikhnevo and IMS arrays
1. Page 1
The use of waveform cross-correlation for creation of
an accurate catalogue of mining explosions within
the Russian platform using joint capabilities of
seismic array Mikhnevo and IMS arrays
Ivan Kitov1, Mikhail Rozhkov2, Irina Sanina1
1Institute of Dynamics of Geospheres, RAS, Moscow
2Comprehensive Nuclear Test Ban Treaty Organization, Vienna, Austria
Mikhail.Rozhkov@ctbto.org
06.01.2015Institute of Geospheres Dynamics and International Data Centre
2. Page 2
Outline
• Seismic array “Mikhnevo” - MHVAR
• Catalogue of regional seismic events since 2007
• Main task – to improve location and identification of quarry blasts by
joint use of waveform cross correlation at MHVAR and IMS array
stations
• Example: MHVAR and AKASG for Mikhailovskiy Mine
• Station Detections – Master Events and Waveform Templates
• Station Cross Correlation
• Association of Cross Correlation Detections
• Dimensionality Reduction and Detectability Enhancement with
Principal Component Analysis
• Other Mines
• Introduction of the Independent Component Analysis for quarry
discrimination
06.01.2015Institute of Geospheres Dynamics and International Data Centre
3. Seismic Array MHVAR
IDG runs MHVAR array since 2004
SМ3-КV RESPONSE FUNCTION
ARRAY RESPONSE FUNCTION
Vertical channel
3-C station
Ten vertical channels
Two 3C stations
New - one 3C broadband
Central station- 54.950N; 37.767E
BB
Page 306.01.2015Institute of Geospheres Dynamics and International Data Centre
4. MHVAR - typical waveforms
Page 406.01.2015Institute of Geospheres Dynamics and International Data Centre
5. Page 5
Mining blasts measured at MHVAR
IDG catalogue includes thousands of mining events
AKASG
29.0 34.0 39.0
L
M
Mikhailovskiy
06.01.2015Institute of Geospheres Dynamics and International Data Centre
6. Mikhailovskiy mine
20
15
18 19
22 21
23
0
5
10
15
20
25
2007 2008 2009 2010 2011 2012 2013
#
Annual statistics at MHVAR
Magnitude distribution
Coordinates:
52.25 N -52.35 N
35.30 E – 35.61 E
Blast times
between 08:00 and 09:00 UTC
Page 606.01.2015Institute of Geospheres Dynamics and International Data Centre
1
4
2
4
8 8
12
9
13
17
27
7 6
1
3
5
10
2 1 1
0
5
10
15
20
25
30
1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9
#
ML
All
2011
7. MHVAR – typical waveforms from Mikhailovskiy
P-waves for templates S-waves
8. Waveforms from Mikhailovskiy: AKASG
50.50
50.55
50.60
50.65
50.70
50.75
50.80
29.0 29.1 29.2 29.3
Lat,deg
Long, deg
AKASG
P-waves
Page 806.01.2015Institute of Geospheres Dynamics and International Data Centre
S23 vertical channels
~25 km aperture
12. Principal Component Analysis MHVAR
P-wave
13 waveforms
S-wave
8 + 7 waveforms
Rg-wave
12 waveforms
Best waveforms were selected from 20 available
Page 1206.01.2015Institute of Geospheres Dynamics and International Data Centre
13. Institute of Geospheres Dynamics and International Data Centre 06.01.2015 Page 13
PCA_P1 PCA_S1
Quality of CC detections:
FK-analysis of CC-traces
Actual P Actual S
07/01
07/20
08/03
16. Institute of Geospheres Dynamics and International Data Centre 06.01.2015 Page 16
Two detection/association procedures
MHVAR
Data
Beam, FK,
Azimuth and
Slowness
STA/LTA,
Arrival time
Beam, FK,
Azimuth and
Slowness
STA/LTA,
Arrival time
AKASG
Data
Association:
Time,
Azimuth,
Slowness
Bulletin
Standard detection and association procedure
Cross correlation detection and association for repeated events
MHVAR
Data
AKASG
Data
Multichannel
matched filters
Multichannel
matched filters
STA/LTA,
Arrival time
STA/LTA,
Arrival time
Association
by
Arrival
Time
Bulletin
Beam, FK,
Azimuth and
Slowness
17. Institute of Geospheres Dynamics and International Data Centre 06.01.2015 Page 17
Cross correlation procedure for unknown signals
Data Beam, FK,
Azimuth and
Slowness
STA/LTA,
Arrival time
Association:
Time,
Azimuth,
Slowness
Bulletin
Extended procedure for signals detected by
standard detector
Available
matched filters
yes
no
noTentative
matched filter
STA/LTA,
Arrival time
Association
Historical
data,
repeated signals
yes New matched
filter
Unassociated
detections
Cross correlation detection
and association
18. Next step
cross correlation with waveforms from
neighbouring mines
Page 1806.01.2015Institute of Geospheres Dynamics and International Data Centre
MHVAR
AKASG
50.0
51.0
52.0
53.0
54.0
55.0
56.0
29.0 31.0 33.0 35.0 37.0 39.0
Lat,deg
Long, deg
Lebedinskiy GOK
Mikhailovskiy GOK
Stoilenskiy GOK
MHVAR
AKASG
Lebedinskiy
Stoylenskiy
Lebedinskiy 51.27 N 37.67E; MHVAR distance ~410 km
Stoylenskiy 51.25 N 37.74 E; AKASG distance ~600 km
Discrimination between Lebedinskiy
and Stoylenskiy mines is
a challenge
19. Waveforms from
Lebedinskiy and Stoylenskiy
Page 1906.01.2015Institute of Geospheres Dynamics and International Data Centre
20. Quarry #1 Quarry #1Quarry #2Quarry #2
Quarry #1+ Quarry#2 signals mixture Quarry #1+ Quarry#1 signals mixture
Separation results. Original
signals, separated (ICA) and
PCs of original signals
Separation results. Original
signals, separated (ICA) and
PCs of original signals
Solid lines indicate input waveforms for the actual example (mixture, and decomposition on the right). Dash line indicates typical waveform
used to produce similar signal separation result. In first case primary phase of Q#1 event fall onto the secondary phase of Q#2 event making
them visually inseparable. In second case all arrivals of both events fall on the same time producing visually a new event. A figure with
separation results consists of: (1) a pair of input signals (from same channels) composing the mixture, (2) separated signals, and (3) first
principle components of the array seismograms corresponding to each signal. We present the PCs to emphasize that the restored signals
inherit the property of the whole array, not just some single component, since the best similarity is provided between the first PCs of the input
array and the best Independent Component. The black vertical rounded lines indicate corresponding signals (omitted on right figure).
Correlation coefficients between the original and restored signals are in a range (0.84, 0.92).
Separation and recovery of signals from different
quarries arrived simultaneously enhance a CC-detector
(an excerpt from our poster presentation, current session)
21. Institute of Geospheres Dynamics and International Data Centre 06.01.2015 Page 21
Discussion
• IMS array stations can be helpful in improvement of the IDG catalogue of
mining events
• Additional stations provide higher accuracy of location and origin times
estimates
• Waveform cross correlation improves detection capability and effectively
rejects wrong detections
•The analysis of mining activity within the Russian platform justifies the use
of waveform cross correlation for automatic detection/association of repeated
events
• Joint use of standard and cross correlation detection/association provide a
prototype procedure for automatic recovery of aftershock sequence at the IDC