eqWave 3 User Manual
Contents
1. Save As file and name formatting If you do not wish to overwrite the file you can use File gt Save As or CTRL T to save your data to a new file In the Save dialog box that pops up there are control options for naming the file The SRC filename format follows the form YYYY MM DD hhmm ss SITE If you are saving a Merged file the SITE code in the file name will be one of the channels from the recording depending on the order in which they were merged by the system If you decide to use the GA filename format the file will be named in the form SITEYYDDD_hhmmss Where YY is the last two digits of the year e g 13 for 2013 and DDD is the day number of the year i e 001 to 366 By default eqWave will save files in PC SUDS 151 format file extension dmx An alternate file export option is to save the file in a text based format whose columns are tab delimited so that it can be viewed in a text table in a text editor or spread sheet The formatting of this file is described in the following section Click on the radio button next to the file format to select it either PC SUDS or text file format Your Save As preferences are remembered by eqWave so please check before saving 22 Text Table file format When you save your seismogram as a text file it will be in a format that can be easily read by any text or data processing program It contains a header that describes the Arrivals contained in the a s2. IN S mua EN zer ge aer be ye Main Ju Ni d 16 An example of data with zero offset correction top and without zero offset correction bottom is shown at left The offset correction can be based on the zero offset of the visible data Displayed or based on the zero offset of the entire channel All Please note that the amplitude shown at the Y axis is the peak raw value and without zero offset correction enabled the motion units may lack relevance Amplitude Grouping To maximise the detail of the displayed data eqWave will scale the amplitude of each channel to fill the vertical space allowed for each channel which means each channel will have an Individual peak amplitude scale on the Y axis You can choose to group the amplitudes by Site which will scale all channels with the same site code to the largest channel amplitude based on the raw data amplitude not ground motion Alternatively you can group All channels to the single largest amplitude in the file regardless of site code The exception to the scaling rule is channels that have been converted from their natural units usually velocity or acceleration to other units they will always scale individually Acceleration Units When displaying acceleration eqWave can display amplitude in g gravity or in m s metres per second squared This user preference is stored in your user profile Pressure Units When displaying pre
3. Once you click on a channel it will be highlighted in yellow to show that channel specific display items relate to this channel e g the frequency spectrum display or channel information display When you select Channels gt Properties a window will pop up displaying extra information about this channel and the site aie FE SILA E Dis paa E ZA A ed Pere ca be d EI erem mba 1140 Tse Merge laces la as a Tee Lem Parga en APT An e Pe en P bake Rare ni ea iow ee i i i This information includes the system response information that is used to calculate the ground motion units from the raw data some instrument state of health SOH information such as battery voltage and site information such as the latitude and longitude of the site If you need to modify the system response e g if you have a specific sensitivity for that sensor channel you can modify the displayed fields and click OK to save these channel settings The editable fields have been populated by the Kelunji recorder and changing these will change the raw data so it is advisable to only fill them in if data is missing Screen Elements Once you have opened a waveform file the data will be plotted in the main eqWave window showing the full time line of available data The basic elements of the display will be described briefly below and expanded upon in later sections of the manual If a channel is recognised as having un
4. Preset and Custom filters A user will typically be interested in a particular frequency band so eqWave allows the definition of a Preset band pass filter To set the filter go to Edit gt Preset filter settings which will bring up a window defining the High Pass and Low Pass filter frequencies Signals with frequencies below the High Pass frequency will be removed as will signal with frequencies above the Low Pass frequency Once defined these values are displayed in the light blue box in the top right corner of the eqWave control panel eqWave also allows the user to set a variable frequency band filter by typing values into the dark blue Custom filter box located below the light blue box Type the High Pass frequency the lower value into the left hand box and the Low Pass higher value in the other box Setting and Clearing filters To apply a filter to a channel simply click on the light blue or dark blue tick at the top right corner of the channel display area which will apply the Preset or Custom filter respectively Once a filter has been applied to a channel the pass band is written in text to the left of the light blue filter tick so that you are aware that the data displayed has been filtered To clear the filter and return to the original channel data click on the red cross To apply the Preset filter to all channels in the eqWave window you can use the menu item Edit gt Apply Preset Filter to all channels or the
5. R IEREN LO ZE TO COOCOO rr e e dd e 16 Amplttide Grouping sica llorare subas 17 ee cion Wins tarot todos 17 PRESSURE EI vinci iii iio ege 17 SNOW and SO EE 17 STA LTA a ea aaa aan EE EE 18 Ed Men cere rer emer rer rere rrr reer ee errr errr re rr A Clip VISIDIC CG NEW WINGOW sosa 19 Fiter settings tana CONU ONS EE 19 PUES te De Ze Presetand Custom TTE Si AAA 20 SEULING anda el Tote Ee 20 Automatic filters on unit converted data ENNEN EEN EEN 21 File Meninas zz EXPONO Data o 22 Save As file and name formatting ENNEN ENNEN EEN 22 TOXE Table Metodista 23 Save En En e sc e o e eo en ia Bie e coo 24 SAVIA tE 24 History The Kelunji Seismic Recorder The Seismology Research Centre SRC was established in 1976 and incorporated into Environmental Systems amp Services ES amp S in 2002 In the 1980s the SRC began developing digital seismic recorders the Alpha the Beta the Kelunji Classic the Kelunji D series the Kelunji Echo and the current 6 generation instruments the Kelunji EchoPro Fusion twins Above the Kelunji EchoPro range of seismic recorders The SUDS data format When the Kelunji D series was introduced in the mid 1990s the SRC decided to adopt a global standard data format for our seismic recorders The SUDS Seismic Unified Data System was originally created at the U S Geological Survey and adopted for use in the IASPEI Seismological Software Library where it became known as PC SUDS It is
6. eqWave 3 SEISMIC WAVEFORM ANALYSIS environmental systems amp services mo PRODUCT USER MANUAL A E5S2S www esands com 8 River Street Richmond VIC 3121 Australia T 61 3 8420 8999 F 61 3 8420 8900 seismology esands com Table of Contents History HENO 1 The Kelunji Seismic Recorder eeeeekk ek KKK EE KEE KEE KEE EE E EE EE E EE EE EE EE e 1 the SUDS data TO Mati nio E A A AES 1 Installing eq WaVe iz Java HELENE EE 2 ADplIcation ae EE 2 CG VWWaV gel EE 2 Whats NeW m CQWaVE 3 urinaria What s New in eqWave 3 Loc ii 3 Fll HandlndO iii Ea A Opening and Closing Files aio o 4 Browsing PICS ag gebrodene eg 4 HIS lts a dd os 4 MERGING Fles a a 5 Channels Meno Merged Fe genee geseet ee die Sege dE A REPARERE AERA 6 Maximise and Minimise Channels nee e KKK KKK KEE KEE KEE EE E EE EE EE EE EEN 6 Channel Fronert fusex geess Ree a a EENS EE 7 Screen Elements BHR BRR ERR RRR RRR RRP RP RRR RR RRR RRR RRR RRR RRR RRR RRR RRR RR RRR RRR RRR RRR RRR eR eR RR eee eee eee eee RW 8 Controls Men WEE a ZOOMING EE 10 PINC ZOOM lt FMEN oia 10 SWIDE ZooM Kr En 10 uge le EE 10 REVES AA A A AN AS 10 SEFOMINO the TIMGMUNG cionado 10 USING the Syne feature nr dida 11 PICKING APPIVA S mi e TRAS PWAVG o EE A A EE 12 THE S MEET iaa 12 EXPected arriv l UMES ici 13 EStIMating Magnitlde ai iets tere teeter sea bemanree en aa EER 14 Ot er AFRIVAIS uta aoi a a aa a aE aA 15 Arrivals Menu AAA dee ENEE LD
7. 0 0000000 0 0000000 0 0000000 0 0000000 0 0000000 ROYM c03 A unnamed 20090306 0955 34 000 100 6100 0 000 00000001 H 00000005 H 00000006 H 00000002 H 00000004 0 0000000 H 00000001 0 0000000 H 00000003 H 00000002 H 00000002 ROYM c04 B unnamed 20090306 0955 34 000 100 6100 0 000 0 0006574 0 0002623 0 00049667 0 0001947 0 0003767 0 0005482 H 00014834 H 00001837 H 000075560 H 00019513 H 00042388 23 ROYM c05 B unnamed 20090306 0955 34 000 100 6100 0 000 0 0007563 0 0006263 0 0002468 0 00039259 0 00039779 0 0003976 0 00029381 0 00016904 H 00036140 H 00011705 0 0004548 ROYM c06 B unnamed 20090306 0955 34 000 100 6100 0 000 0 00000194 H 00035027 0 0010950 0 0002216 0 0002216 Q 00016311 0 0000500 0 0006219 0 0001956 0 00012152 0 00029308 fs1tename Fcomponent fauthor1ty year month day hour minute second sampLes per second number of samples SYNC i Rep ex Save Screenshot a e a emm ei ER SS fe Although most computers have a screenshot feature eqWave o conte z et a RIO tb A allows you to save a PNG format image of just the data window i aen nn l l be as excluding the control panel and window frame If you have many 4 a mm channels in the scrolling window the screenshot will be very tall pr a rat ore ere K 5 d e dia le Wh i i
8. A m A ha TA e H es d lo TZE f Dem e H AAA Mi vd t Leem i d dem e f A be ZE i Da S t on EE a ZEA H siy a e FRA m e GE E por E E A AAA ee te meet aa H PIPA Vd a paa mca FR H ATA DE ee e ze It veier Verde a A e e ES mme mmm lt Screenshot of a merged file from a laptop screen above and the same i SSS gg g merged file saved as a screenshot in eqWave right Save Fourier You can also save the data displayed in the Fourier transform window to a text file Simply right click on a channel to display the frequency spectrum for the entire channel recording or right click and drag a portion of the data you wish to analyse and its frequency spectrum will appear in the Fourier window By selecting File gt Save Fourier the data that is being displayed in the Fourier transform window will be output in three columns the first showing the frequency point in Hz followed by the real and imaginary values of the spectrum the amplitude Print If you would like to print your waveform you can use the File gt Print or CTRL P command It will print effectively the same information as the eqWave screenshot except that it will print up to 9 channels per page to the maximum scale to fill the page Close and Quit Close the eqWave window using File gt Close or CTRL W to return to an empty eqWave window Use this command again or File gt Quit or CTRL Q at any time to quit eqWav
9. amplitude Open previous file in the folder File Filter Moves timeline back text must be in filename by 25 of displayed width Blue text indicates Control key command Zooming All zoom commands are applied to all channels at the same time Point zoom Timeline Clicking and dragging your cursor over the waveform will show a red vertical marker bar Move to the area you want to zoom into and release the cursor click to leave a light grey marker line Click the 0 or use the Page Up shortcut key to zoom in to the marker time by a factor of 2 Use the Q or use the Page Down key to zoom out by a factor of 2 centred on the marker location Swipe zoom Timeline Instead of left clicking and dragging a marker line you can right click and drag to highlight an area of interest After releasing the click this area is left highlighted if you place your cursor over the highlighted section and left click or use the zoom in command you will zoom in to the highlighted area Using the zoom out command on a highlighted area will zoom out by a factor of 2 centred on the selection area Amplitude By default eqWave will set the amplitude scale for each channel separately to the peak displayed If you wish to manually scale the amplitude you can do so using the A and w icons or the Up and Down arrow keys Each tap of the icon or key will zoom the amplitude up or down by a factor of 2 Revert To return to the original wavefo
10. j xe is a very rough estimate based on a number of assumptions and should not be considered a true representation of these earthquake parameters Disclaimer eqWave uses hard coded variables to calculate event distance which may or may not fit with P and S wave travel velocities for your region Similarly eqWave uses a generic magnitude calculation formula that very roughly estimates local Richter ML earthquake magnitude which may or may not apply to ground motion attenuation factors in your region For accurate location and magnitude calculation you will need three sites to have recorded the event each with P S and MAX arrivals picked This data can be pasted into eqFocus which should be used with a localised earth model 14 Other Arrivals A drop down list is available in the Basic Controls area that shows some other common arrival types including PN PG SN and SG waves and other magnitude amplitude arrival definitions You can enter any custom arrival type you require in the drop down text field and click Other to set the arrival at the current marker position Arrivals Menu Whenever you define an arrival such as P time S time or MAX peak this data is placed in the Arrivals menu For each Phase arrival type the Time and Site code are shown the latter required because eqWave can store arrivals from many sites in the same file A RA q dr ris Avon pda P AA 4 4 Loopy Arties l es ae H s 4
11. of the STA level to LTA level is plotted in yellow on the screen The scale of this plot is related to the trigger threshold ratio which is a level at which you would expect the seismic recorder to declare than an event is underway The trigger threshold is plotted at the zero level of the channel so the Y axis range is a ratio of zero to twice the threshold level In the example below the STA setting is 2 0 the LTA is 20 0 and the threshold is 3 0 As you can see before the earthquake the STA and LTA values are similar and the ratio of the average signals sits at around 1 but as soon as the earthquake hits the signal level in the STA window is many times larger than the average signal in the previous 20 seconds and the ratio shoots through the threshold At this point the recorder would declare a trigger and store the data away STA LTA Tra Reg ratio scale 498 OE Zi S e eg Z7 d LIA A ara 5 V P i TT H 4 A 1 chen WW SS e A This feature is used to help you to understand the sensitivity of your recorder s trigger settings You can modify the STA LTA and threshold values in the STA LTA gt Setup menu item You can also define the frequency band of the signal that the STA and LTA windows are averaging to better tune your recorder to trigger on certain event types You can turn the STA LTA plot on and off toggling the STA LTA gt Show menu item 18 Edit Menu Clip visible to new window You may
12. top left of the window are used to view the recordings in detail to add arrival information to the waveforms and to help process files Zoom in and Zoom in and out Scroll time Revert Open Next Prev file out of timeline amplitude scale left and right zoom when name includes ON ERA al ii i ES 8 Y Other MAX 0 00 Sync Arrival Set P Set other types of Set selection Time trait or S Arrivals peak amplitude correction time and frequency Most of the buttons within eqWave have a corresponding keyboard shortcut which are shown in the Controls menu Commonly used shortcut keys are shown below Clear filter Display full timeline Add aP Arrival from all channels ior thesiteat and amplitude Clip displayed the time marker data to a new window amp file Zoom in to 50 of timeline or zoom selection Filter all channels using Custom filter settings Filter all channels using Preset filter settings HA a MOOG Bee 20c eoue SE KE LUT eee ooo CELL E LL ec LL Add an S Arrival for the site at the time marker Zoom out to 200 centred on click selection EP AP P ae H A B Zooms to 50 of displayed amplitude Set peak amplitude and frequency of selection Moves timeline forward Copy Arrivals aia Open next file in the by 25 of displayed width to paste folder File Filter text must be in filename Zooms to 200 into eqFocus j of displayed
13. CTRL G shortcut key Similarly to apply the Custom filter to all use the Edit gt Apply Custom Filter to all channels menu item or the CTRL H shortcut key You can use Edit gt Clear Filters on all channels menu item or CTRL J to reset all channels to their original unfiltered state 20 Automatic filters on unit converted data You may notice that when you convert from Acceleration to Velocity or Displacement and when you convert from Velocity to Displacement that the unit converted data has been filtered to drop 5 or 10 of the frequency band from either end of the spectrum This is done to make the data appear more readable as the unit conversion process in this direction introduces very low frequency and very high frequency artefacts which can be seen in the Fourier transform display demonstrated in the images below You can change or clear these filters after conversion to suit your analysis requirements fate pm eriw POT mia Am is IRE Above acceleration converted to displacement auto filtered left and unfiltered right 21 File Menu The open close and merging features of this menu have been discussed earlier The remaining items in this menu are discussed below Exporting Data Once you have merged clipped or modified your seismogram file you can save it using the File gt Save command or CTRL S This will overwrite the file whose name is displayed in the title bar or the eqWave window
14. Expected arrival times If you are using eqFocus see right sold a o Se TT TT ST separately to locate seismic events the E A AO expected P and S arrival times and PG mn and SG arrival times if appropriate for the event are superimposed on the waveforms in eqWave as light grey lines The expected arrival times are updated as eqFocus completes its calculations This can help users to see arrival times hidden in codas and background noise MOD Mura ds Mie 144 Castas igih Aris Cheri SIS AA A pS om ome i F j ext nani vn exes CERS r an Es i eet 4i 13 Estimating Magnitude Once you have a distance automatically calculated by eqWave based on the S P you can estimate the magnitude of the event using the peak vertical velocity amplitude and the dominant frequency around this peak On a vertical velocity channel either natural velocity or transformed from acceleration right click and swipe the area of peak motion which usually occurs after the S arrival for a few seconds Click the MAX control button or type m and eqWave will assign an arrival storing the peak amplitude value and the dominant frequency in the selection Note when you highlight a section the start end and length of the selection are displayed on the timeline Use the Display gt Estimate ML menu item to pop up a For event at pas window that will show the event distance and magnitude This
15. Th i 5 TT i ect E MI 4 rh Man 1 ig P e gt wuer La If you wish to remove an Arrival from the list click the red X next to the Arrival and its marker will disappear from the main window Be aware that this action cannot be undone Use Control C or select the top item in the Arrivals menu to copy the list of arrivals to the clipboard which can be pasted into eqFocus sold separately for accurate earthquake location and magnitude determination 15 Display Menu The Display menu is used to modify the way the waveform data or on screen elements are displayed and also contains the Estimate ML magnitude feature discussed in an earlier section of this manual Version information about eqWave is in the Display gt About tem Zero Correction Display Arrivals Chann Zero Correction D Amplitude Grouping Acceleration Units e Pressure Units gt Y Show 5 minus P Sort by Sitecode Sort by P arrival STA LTA Estimate ML About When a sensor is plugged into a recorder it will almost always have some level of signal offset which can be due to the sensor not being perfectly level or the sensor components having some sort of electronic adjustment required Regardless of the cause the display of offset data can be handled by eqWave in various ways The raw data is never modified only the way it is displayed Each channel is corrected individually sten dM O UT du i
16. a very flexible format which contains many fields for information relating to the raw data which has enabled our eqWave software to provide very useful information to Kelunji users For more information on SUDS visit www banfill net suds html Installing eqWave Java Runtime Environment eqWave is a Java application which means that the Java Runtime Environment needs to be running on your Windows Mac or Linux computer You can install Java for free by web browsing to www java com and following the download prompts Application Installer The installation procedure differs for each computing platform The Windows version is supplied as a self installing package the Mac version is a zipped OS X application file and the Linux version is simply the Java Archive jar file eqWave Window When eqWave starts up you will be presented with the window below which shows the basic waveform controls at top left and the filter controls at top right The main area is where the waveforms will appear and below this is a pull up drawer that reveals the frequency spectrum display window Previous versions of eqWave had a pull out drawer on the right of the screen to show Arrival times This has moved to the new Arrivals menu a a a PS z What s New in eqWave 3 eqWave 3 has changed significantly since version 2 although its basics remain familiar and easy to use The main changes include Displaying colour coded waveforms a
17. and using the NEXT command the next file that has ECHOP in the filename will open As files created by Kelunji recorders are named in a standard format that includes the date time and station code e g YYYY MM DD_HHMM_SS_ lt code gt dmx in the EchoPro you could potentially filter your file browsing by a certain month day or hour Merging Files eqWave can merge up to 24 hours of data from many stations into a single file Kelunji seismic recorders storing continuous data do so in one minute data files so it is possible that an earthquake recording will straddle two or more files To make analysis easier you can merge these files together on screen and then save the merged file to your computer The quickest way to merge files is to have all of the files you want to merge in a single folder and drag the folder into the eqWave window All waveform files in this folder and sub folders will be merged and displayed in a new eqWave window Alternatively drag a waveform file onto eqWave A N Open and then use the File gt Merge command which will take you to the folder containing the file you just opened In this file browser window select all of the files you wish to merge using your F 2009 01 06 0956 OS FRTMdma gr Friday March 6 2009 5 57 PM A e 2009 03 18 0527 59 KORUM dwx Thursday March 19 2009 9 24 AM multi select file system shortcuts usually Shift D seres dms gg Friday March 6 2009 A 57 PM Lito
18. ccording to their units The ability to convert between ground motion units at the click of a button Display Rotational sensor units A new implementation of the signal filtering interface New keyboard shortcuts Moving the Arrivals pull out window to a menu tem Simplified user interface with new icons Simplification of the frequency display window Text table output in zero offset corrected ground motion units Prompts user to save before closing if Arrivals or Channel Properties modified What s New in eqWave 3 2 In this update we have added some features and fixed some bugs including Interaction with eqFocus displays expected arrival times when location updated Timeline always visible Click selection to zoom Merge contents of a folder up to 24 hours of data Reads gains Kelunji EchoPro files correctly Reads KA1 amp KA2 Kelunji Classic format files correctly Fixed displacement velocity amp acceleration unit conversion amplitudes The vector sum feature and the ability to save in miniSEED format was removed from eqWave 3 These may return in a future update once technical issues have been resolved For further information on this and other software products email seismology esands com File Handling Opening and Closing Files You can drag a PC SUDS file from your desktop file browser onto the eqWave window and the file will open eqWave will open files from a Kelunji that are stored normally dmx file extens
19. e 24 essS SOFTWARE TO COMPLEMENT YOUR ECHOPRO eqFocus Calculate earthquake location amp magnitude from your EchoPro seismic network eqLogger Display continuous data in real time and automatically store it ina data archive eqsServer a Data acquisition archiving alerting amp network management e WEB BASED DATA MANAGEMENT SYSTEM e DATA ARCHIVE amp EARTHQUAKE DATABASE e NETWORK HEALTH amp MANAGEMENT TOOLS e EARTHQUAKE ALARM FUNCTIONS e DATA SHARING amp NETWORK INTEGRATION environmental systems amp services 8 River Street Richmond Victoria 3121 AUSTRALIA T 61 3 8420 8999 F 61 3 8420 8900 seismology esands com www esands com
20. ection that describes the time series data in the file followed by the raw data Any arrival information contained in the seismogram will be listed in the first section Each arrival will have its own column detailing the site name arrival type and time The next section describes the raw data one channel per column This includes the site name channel name the date and time of the first data point or sample and how many samples there are per second As you may have merged data of differing sample rates there may be a variable number of rows per column for a given time period The final row before the data points indicates the units of the data which could be metres m metres per second m s metres per second squared m s s etc The data is then displayed in these units one sample per row All data is saved with zero offset correction ROYM p 20090306 0955 54 400 0 100 sitename onset first motion phase year month day hour minute second uncertainty in seconds peak ampLitude frequency at P phase TIME SERIES ROYM c01 A unnamed 20090306 0955 34 000 100 6100 0 000 0 0000000 H 00000000 0 0000000 0 0000000 0 0000000 H 00000001 0 0000001 0 0000000 0 0000000 0 0000000 H 00000001 etc ROYM c02 A unnamed 20090306 0955 34 000 100 6100 0 000 0 00000006 0 0000000 0 0000000 H 00000006 0 0000000 0 0000000
21. ion or in Gzip compressed format dmx gz file extension There is no need to expand the Gzip file using a 3 party application before using it in eqWave Alternatively you can use the File gt Open menu item CTRL O to browse your computer file system for your file To close the file and go back to an empty eqWave window use the system window close button File gt Close menu item or CTRL W When you have a file open you can open another file by dragging it onto the eqWave window or using the Open command again but this will open the file in a new eqWave window If you don t want to open a new eqWave window use the File gt Close 8 Open menu item CTRL E instead of the Open command Browsing Files Once you have opened a file you can quickly scan through other waveform files in the same directory using the File gt Next CTRL N and File gt Back CTRL B menu commands These waveforms will open in the same eqWave window replacing the previous file File Filter The File Filter field in the Basic Controls area is linked to the file browsing tool If any characters have been typed into this field when you use the Next or Back commands only files that contain those characters in the filename will be opened For example if you have a folder full of triggered data from dozens of different stations but you are only interested in viewing files that have the site code ECHOP in the name by typing ECHOP in the File Filter field
22. its in velocity the trace will be drawn in green Ifa channel is defined as acceleration the trace will be drawn in red and displacement in black A key is shown at the left end of the waveform marked as D V and A with a blue mark drawn next to the original units of the channel recording Clicking on the D V or A buttons will covert the waveform to these units Other recognised units are pressure magenta and rotation orange and any unrecognised units are displayed in dark grey The boxes will disappear for these latter units as they cannot be transformed You will notice a yellow trace overlaid on your ground motion recording This is the simulated STA LTA ratio which shows you how a recorder s STA LTA trigger algorithm would see this data The settings of this simulated STA LTA ratio can be customised On the right hand end of each channel are the filter control boxes The 4 icon will filter the waveform using the Preset filter settings The amp icon will filter the waveform using the Custom filter settings which can be typed in at the top right of the screen When a filter has been applied to a channel the pass band appears next to the filter buttons The Xi icon will clear the filter from the channel There is a bar at the bottom of the screen which can be dragged up to reveal the Fourier transform window which shows the frequency spectrum of the current channel selection 8 Controls Menu The control icons in the
23. ma q Friday March 6 2009 901 PM esrees i Friday March 6 2009 6 59 pu Control or Option clicking and proceed using Fae format AS Files the Open button Cancel Open As long as all of the files are within a 24 hour time period they will be merged onto a common time line grouped by site code in alphabetical order D Mura Y Se pe PS LE wm Y ERA e LD a do lem e e i e ys ra PA eee a A t m INe e YY XA Channels Menu Channels Properties Merged Files All Vertical When you are displaying a merged file the site codes are listed in lower section of the channels menu By selecting a site from CDNM this menu you can view just this site in the eqWave window JENM MIKA If you wish to return to viewing all sites use the Channels gt All i ROYM menu command If you wish to view only the vertical channels to quickly pick arrivals from all of your sites use the Channels gt Vertical menu command This will show all vertical channels for each site typically channels 3 6 9 and or 12 Maximise and Minimise Channels To view a channel full screen use the small icon at the top of the Y axis bar for that AA rr AA rr channel and then the icon to go back When all channels are shown use the icon to hide that channel from view To restore any hidden channels use the Channels menu to show All or Vertical channels or the channels of a specific site Channel Properties
24. rm display reverting to the entire time line and the full A amplitude scale use the icon or the Home shortcut key Scrolling the Timeline The timeline can be scrolled horizontally using the and 4 icons or the Left and Right arrow keys With each tap of the icon or key the timeline will step back or forward by 25 of the displayed zoom level 10 Using the Sync feature Older instruments did not use GPS and relied on internal clocks for timing Clock errors can be compensated for by time shifting data using the sync feature Values from O to 30 seconds shift the data back in time and a sync of 30 to 60 seconds will shift data forward Picking Arrivals The main function of eqWave is to pick earthquake wave arrival times on the recordings to allow the determination of the location and magnitude of the earthquake using eqFocus The intricacies of recognising and picking wave arrivals will not be discussed here but we will cover the basics of picking P and S waves and estimating magnitudes To mark an arrival time click and drag the cursor to the point of interest and release then click on the P icon or hit the p key Similarly an S can be marked using the icon or s key 11 The P wave The first earthquake energy wave to arrive at a seismograph is the P or Primary wave As such they are generally easy to pick as there is usually a clear difference between the background noise and the earthq
25. ssure usually a recording from a microphone eqWave can display amplitude in Pa pascal or as SPL sound pressure level measured in dB This user preference is stored in your user profile Show and Sort As discussed earlier when you pick a P time and an S time eqWave displays the S P time on screen You can turn the Show S minus P feature on and off by selecting this item By default eqWave will sort the displayed channels by Sitecode in alphabetical order image below left You can also choose to re sort channels by P arrival time so that the closest sites to the earthquake appear at the top of the main window image below right Sites that have no P time picked will appear below those that do in alphabetical order If egFocus is active sites with no P picked will be sorted using the expected P arrival time GE O So PS we PS g ZE WEES pe beggen P S i LE LE d me o ZE een Ay YY K j LL 8l a a KE Zen PS Payee Y rita ca A lg o 1 a ZE PR Al arene d LEE bff K YY XK ne rege 17 STA LTA As mentioned earlier the yellow line that appears on each channel is the STA LTA ratio which is how a recorder using STA LTA triggering will see the data STA stands for Short Term Average and LTA for Long Term Average This is the average signal level over a short time period e g 2 seconds compared to the average signal level over a longer time period e g 20 seconds The ratio
26. uake arrival The P wave is usually most obvious on the vertical channel of a sensor as it is pulsating in the direction of travel up to the surface As you can see from the screenshot above the first vertical marker appears to be before the first arrival but by zooming in we can see the P much more clearly The S wave The next major earthquake energy wave to arrive at a seismograph is the S or Secondary wave It is also known as the Shear wave as it is oscillating perpendicular to its direction of travel i e it is shaking horizontally when it reaches the surface This is the wave that often does the most damage during an earthquake due to this horizontal shaking and the larger amplitude The S wave also usually has a lower frequency than the P wave Due to its motion S waves are usually more obvious on horizontal channels but as the S wave arrives in the coda of the P wave it is often difficult to determine a clear arrival time Look for a point that correlates across the horizontal channels that features a drop in frequency and increase in amplitude Once you have picked a P time and an S time eqWave will display the S minus P or S P time in seconds The time difference between these arrivals equates to the distance that the earthquake is from this site A rule of thumb to calculate the distance is to multiply the number of S P seconds by 8 to estimate the distance in kilometres e g 13 sec S P 104km
27. wish to create a new seismogram file with a subset of the data in the currently displayed eqWave data file You may wish to remove channels or restrict the time period so that you are only left with data relevant to your analysis requirements The Clip function also accessible with the CTRL L keyboard shortcut will open a new window that contains only the data that is visible in the vertically scrolling main window in eqWave This means that any channels that have been hidden using the minus button at the top of the Y axis will not be exported to the new file and only the data from the current timeline zoom level will be exported to the new file The data will appear in the new window in it s original units but filter settings will be carried across although they can be cleared so that the original raw data can be displayed Filter settings and controls The other menu items under the Edit menu relate to editing and applying frequency filtering to the waveform data This is discussed in detail in the next section Filtering 19 Filtering Signal filtering in eqWave has been improved to be more Preset 20 to 20 0 Hz user friendly and more easily controllable by channel eqWave can perform a band pass filter on the displayed Custom to Hz data to show data between two defined frequencies It is PC SUDS 151 important to note that the raw data is never modified the data is only filtered for display purposes
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