Seismic software tool Seismon WB:
Application to the 2013 West Bohemia earthquake
swarm
Jana Doubravová, Jan Michálek and Josef Horálek
Institute of Geophysics, Academy of Sciences of the Czech Republic,
Bočnı́ II/1401, 141 31, Prague, Czech Republic, [email protected]
1. Introduction
Seismon WB is a subversion of Seismon aimed to process data from local seismic network monitoring the earthquake swarm activity in West
Bohemia/Vogtland (border area between Czech Republic and Germany). To use this software for routine processing of data from local seismic network
in West Bohemia (WEBNET), some adaptations had to be done, and the modified program was called Seismon WB. We have imporoved user
friendliness, automated frequently used routine, added special tools for particular research purposes and created compiled standalone version. From
2013 it is being used routinely for all WEBNET data including swarm 2013.
4. Functions
2. WEBNET
West Bohemia/Vogtland belongs to the most active
intraplate earthquake-swarm regions in Europe. Swarm
earthquakes mostly with magnitudes ML < 4.0 occur
here quite frequently. The Nový Kostel focal zone,
which shows about eighty thousand ML > −0.5
events within the last twenty years, dominates the
recent seismicity of the whole region. Local seismic
network WEBNET is the primary source of data from
the whole region at present. It consists of 23 stations
2
which cover an area of about 900km .
12.5˚
12˚
14˚
5. Examples
18˚13˚
16˚
Germany
• reading various data formats (mSEED, SEGY, SAC, ASCII, GSE, MAT...)
• editing the database - geometry of stations, instrument specifications
• signal processing (time + frequency domain) - filtering, integration, differentiation,
frequency spectrum, rotation, particle motion, magnitude
• communication with external programs - NLLoc (location), AMT (MT solution), Google
Earth (projection to satellite map)
• visualization of results - events locations, stations position
Location using NLLoc tool with
displayed residual for each pick and MT
solution from AMT. The location
computed by NLLoc can be displayed in
simple map or in GoogleEarth. The user
can easily choose which phases to use for
location.
Poland
50˚
Czech Republic
50.4˚
Vogtland
Slovakia
Austria
West Bohemia
50.2˚
0
10
20
Frequency spectrum tool with source
parameter fitting. Waveform used for
FFT is in the left part of the window.
The criteria for corner frequency and
seismic moment determination can be
changed by user.
30
WEBNET network - map of stations
3. Seismon - General information
• original Seismon
• an open source software package under GNU General
Public License developed by Stefan Mertl (Technical
university of Vienna)
• written in Matlab
• modular, interactive, user friendly
• Seismon WB subversion
• customized for routine processing of WEBNET data
• contains new tools (i.e. frequency domain, rotation,
NLLoc tool, various types of cursors)
• user friendliness maximized (fast navigation menu,
shortcuts, automatic amplitude picking and first
motion detection)
• compiled version independent on Matlab license
Seismon WB
Seismon
S. Mertl 2003-2010
universal software, Matlab
J. Michálek, J.Doubravová 2010-...
specialized software, Matlab
for developers
pSysmon
S. Mertl 2011-...
universal, Python (obsPy)
Seismon WB
compiled
for users
6. The 2013 West Bohemia earthquake swarm
• about 1500 events detected, more than 200 events located
• present results are consistent with previous earthquake swarms in West Bohemia
considering :
• locations - the same fault plane activated (NW-SE)
• magnitudes - similar magnitude range (ML < 2.3)
• focal mechanisms - prevailing mechanism on the fault plane (oblique-thrust fault)
7. Summary
• we customized and developed Seismon WB for routine processing of WEBNET data
• since 2013 it is being routinely used without major problems
• earthquake swarm 2013 showed that Seismon WB is providing promising and reasonable
results
• future plans
• create an near real-time automatic preprocessing (i.e. event detection, classification,
picking, location...) with an output to Seismon database
Acknowledgement: the WEBNET seismic network is supported by CzechGeo/EPOS project, grant No. LM2010008.