UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY User's Guide to HYPOINVERSE-2000, a Fortran Program to Solve for Earthquake Locations and Magnitudes 4/2002 version by Fred W. Klein U. S. Geological Survey 345 Middlefield Rd., MS #977 Menlo Park CA 94025 [email protected] Open File Report 02-171 Version 1.0 This report is preliminary and has not been reviewed for conformity with U. S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 4/2002 program version 1 TABLE OF CONTENTS TABLE OF FIGURES AND TABLES .......................................................................................4 INTRODUCTION ......................................................................................................................5 Initializing with your defaults and input files...........................................................................7 Remark codes for earthquakes and station data........................................................................7 CRUSTAL VELOCITY MODELS.............................................................................................8 Multiple models ......................................................................................................................8 Alternate models ...................................................................................................................12 Model types: homogeneous layer and linear gradient.............................................................13 Homogeneous layer models...................................................................................................13 Linear gradient models using a travel time table....................................................................13 THE STATION LIST AND USE OF STATION DELAYS, GAIN HISTORY AND MAGNITUDE CORRECTIONS ..............................................................................................14 Station location file ...............................................................................................................14 Station name codes and file formats ......................................................................................15 Specifying instrument types and calibration factors ...............................................................16 Station delay file ...................................................................................................................19 Station attenuation and calibration factor files .......................................................................21 Station magnitude correction files .........................................................................................24 Other station comments.........................................................................................................27 PHASE DATA INPUT FORMATS ..........................................................................................27 Archive output format ...........................................................................................................29 Weight codes, name codes, and other parameters common to all phase input formats............29 Archive files read as phase input ...........................................................................................30 The terminator line and trial locations (all ASCII formats) ....................................................31 Reading earthquakes directly from CUSP “MEM” files.........................................................33 Input of new phase data from the keyboard ...........................................................................34 EARTHQUAKE LOCATION METHODS...............................................................................35 Interactive earthquake processing..........................................................................................35 How to change weights in the print file..............................................................................37 Flow of steps in interactive processing ..............................................................................37 Fixing depth or hypocenter....................................................................................................38 Keeping or eliminating poor earthquakes...............................................................................39 CODA MAGNITUDES ............................................................................................................40 Types of coda magnitudes and how the coda is measured......................................................40 Coda magnitude options........................................................................................................41 Selecting coda magnitude types.............................................................................................41 Coda magnitude examples.....................................................................................................42 Gain corrections to coda magnitudes .....................................................................................44 Duration magnitude expressions............................................................................................45 Lapse time (tau) magnitude expressions ................................................................................46 AMPLITUDE (LOCAL) MAGNITUDES ................................................................................46 Local magnitudes from Wood-Anderson seismometers .........................................................46 Amplitude magnitude distance corrections ............................................................................47 Magnitudes (XMAGs) from electromagnetic (velocity) seismometers...................................48 Analog data transmission and recording ............................................................................48 2 Amplitude magnitude relation for velocity seismometers...................................................49 Relating MX to ML.............................................................................................................51 Digital data recording and units of amplitude measurement...............................................52 Full digital systems with velocity seismometers.................................................................52 Seismometer instrument types ...........................................................................................54 CAL factors for various digitizing systems........................................................................55 Amplitude magnitude comments .......................................................................................55 Computing two amplitude magnitudes ..................................................................................56 P-amplitude magnitudes ........................................................................................................56 Amplitude magnitude command example..............................................................................56 The weighting of duration and amplitude magnitudes............................................................57 PREFERRED EARTHQUAKE MAGNITUDES......................................................................57 WEIGHTING OF P & S TIMES...............................................................................................58 Distance Weighting...............................................................................................................59 Residual weighting................................................................................................................60 SOME SIMPLE COMMAND SEQUENCES ...........................................................................61 COMMANDS RECOGNIZED BY HYPOINVERSE ...............................................................63 INPUT FILES.......................................................................................................................63 BINARY FILES....................................................................................................................64 READING ADDITIONAL STATION DATA ......................................................................65 FILE FORMATS AND RELATED CONTROLS .................................................................67 OUTPUT FILES ...................................................................................................................70 MULTIPLE CRUSTAL MODELS .......................................................................................71 PROCESS EVENTS IN A PHASE FILE ..............................................................................73 PRINTED OUTPUT FORMAT ............................................................................................74 TRIAL DEPTH, VELOCITY RATIO & ERRORS ...............................................................75 CONVENIENCE AND CONTROL COMMANDS ..............................................................76 MAGNITUDES ....................................................................................................................77 CODA DURATION MAGNITUDES ...................................................................................78 AMPLITUDE MAGNITUDES.............................................................................................81 MISCELLANEOUS COMMANDS......................................................................................84