*%_double_couple The percentage of the focal mechanism which can be modeled as a double couple mechanism. In the prinaxes data set. The percentage of the moment tensor determined by Sipkin which can be ascribed to a double couple mechanism. *percent_double_couple The percentage of the focal mechanism which can be modeled as a double couple mechanism. In the prinaxes data set. The percentage of the moment tensor determined by Sipkin which can be ascribed to a double couple mechanism. *ad1_polarity_station Data collection variable definition is not available. *ad2_polarity_station Data collection variable definition is not available. *ad3_polarity_station Data collection variable definition is not available. *ad4_polarity_station Data collection variable definition is not available. *ad5_polarity_station Data collection variable definition is not available. *ad6_polarity_station Data collection variable definition is not available. *ad7_polarity_station Data collection variable definition is not available. *ad8_polarity_station Data collection variable definition is not available. *adk_polarity_station Data collection variable definition is not available. *ak1_polarity_station Data collection variable definition is not available. *ak2_polarity_station Data collection variable definition is not available. *ak3_polarity_station Data collection variable definition is not available. *ak4_polarity_station Data collection variable definition is not available. *ak5_polarity_station Data collection variable definition is not available. *authority_for_location In the DNAG catalog, this is the source from which the epicenter was taken. *azimuth_dip_direction When the orientation of the geologic fault slip is taken from the orientation of the fault attitude and the primary sense of offset in the world stress data, this is the dip azimuth of the fault plane when only the primary sense of offset is known. *azimuth_maximum_horizontal_stress The available evidence from the orientation of fault planes observed in the field as well as inferred from earthquake focal mechanisms, attitude of dikes and deep in situ stress measurements suggests that the principal stress field in the lithosphere lies in approximately horizontal and vertical planes. The orientation of the in site stress tensor is thus approximated from the maximum horizontal stress (SHmax) azimuth. This is given in degrees clockwise, 0 to 180 deg from north. Also see stress_regime. *azimuth_of_b_axis Azimuth(deg clockwise from N) of B or S2 axis or N axis. *azimuth_of_null_axis The azimuth (strike) of the associated eigenvector of the moment tensor in the principal axis system associated with the null (N) axis. This is equivalent to the moment_tensor_2nd_strike in the Harvard moment tensor catalog. *azimuth_of_p_axis The azimuth (strike) of the associated eigenvector of the moment tensor in the principal axis system associated with the compression (P) axis. This is equivalent to the moment_tensor_3rd_strike in the Harvard moment tensor catalog. *azimuth_of_sigma1 Azimuth(deg clockwise from N) of S1 or P axis. *azimuth_of_sigma2 Azimuth(deg clockwise from N) of S2, or B axis or N axis. *azimuth_of_sigma3 Azimuth(deg clockwise from N) of S3 or T axis. *azimuth_of_t_axis The azimuth (strike) of the associated eigenvector of the moment tensor in the principal axis system associated with the tension (T) axis. This is equivalent to the moment_tensor_strike in the Harvard moment tensor catalog. *azimuthal_gap_maximum The largest azimuthal gap between azimuthally adjacent stations (in degrees). *azimuthal_gap_deg The largest azimuthal gap between azimuthally adjacent stations (in degrees). *azimuthal_gap_maximum_deg The largest azimuthal gap between azimuthally adjacent stations (in degrees). *blank Refers to an empty space in a data record - no information is recorded in this space. *blank1 Refers to an empty space in a data record - no information is recorded in this space. *blanks Refers to empty spaces in a data record - no information is recorded in this space. *bottom_of_measurement_interval_m When stress is determined by borehole breakouts or by hydraulic fracturing in world stress data, this is the bottom of the interval of measurements (in meters). *centroid_depth Unlike the epicentral coordinates, the focal depth determinations are generally reliable. All surface reflections are automatically included in the analysis and the match between the synthetic and observed seismograms depends quite critically on focal depth. The solution for the moment tensor becomes unstable when the source approaches the surface and therefore, the focal depth is not allowed to becomes less than 15 km. If, in the iterative inversion, the depth crosses that limit, it is set at the value of the previous iteration and is held fixed. Under certain circumstances waveforms may be relatively insensitive to the focal depth. In such cases, the depth (given in Km) is determined by comparing observed and predicted broad band data. A letter B follows the focal depth when it is determined using broad band data analysis. *centroid_latitude The determined latitude of the centroid in the Harvard moment Tensor catalog. Lateral heterogeneity can introduce substantial bias in the geographical coordinates of the centroid. The change in the source coordinates from the epicenter, though not necessarily reflecting the true position of the source, leads to a better estimate of the moment tensor. Introduction of corrections for lateral heterogeneity reduces the overall size of these changes. For earthquakes at the lower limit of the moment method for which little data can be used, the PDE coordinates may be assumed, no standard deviation is given in these cases. *centroid_longitude The determined longitude of the centroid in the Harvard moment Tensor catalog. Lateral heterogeneity can introduce substantial bias in the geographical coordinates of the centroid. The change in the source coordinates from the epicenter, though not necessarily reflecting the true position of the source, leads to a better estimate of the moment tensor. Introduction of corrections for lateral heterogeneity reduces the overall size of these changes. For earthquakes at the lower limit of the moment method for which little data can be used, the PDE coordinates may be assumed, no standard deviation is given in these cases. *centroid_time_difference_sec The shift in time between the time determined for the centroid and the time reported by NEIS in their Preliminary Determination of Epicenters (PDE), given in seconds. This time difference closely approximates, in a statistical sense, the half-duration of the event. *century_and_year In most catalogs this is the term for the combined Gregorian year. Since "year" was defined as a two-digit number, the century_and_year is needed to include zero's in the given year. The first three characters are the century, the last two the year within the century. For example -1395 is the year 1395 B.C. where the negative defines the B.C. the year 1675 A.D. is given as " 1685". *century First three digits of the year of the Gregorian calendar (e.g. 2600 B. C. = -26; 1992 A. D. = 19) *column_19_instruction There are numbers in this column. Contact the author for explanation of these codes. Found in the SCALASKA catalog. *comments In the world stress data, this is a comment about the data record, these comments are used for noting possible errors with data or conflicting results with some indication of why the particular result was used. The comments can also be used to indicate the number or name of this solution or result in a particular reference, e. g. BELLPO85#41W-371 would indicate well number #41W-371 in a Bell and Podrouzky (1985) paper. NC: the Characters NC are used if there are no additional comments. In the ALEVENT or ALRUNUP tsunami files, comments include effects at the location including damage and deaths and comments on the accuracy of the report. *comment A statement regarding the particular data record. *comment_location A statement regarding the location of a particular earthquake *comments_location A statement regarding the location of a particular earthquake *comment_time A statement regarding the timing of a particular earthquake *common_FMAG_data_source A alphanumeric code (generally 3 characters long) belonging to the station or network supplying parameters for the listed duration or coda magnitude. *common_XMAG_data_source A alphanumeric code (generally 3 characters long) belonging to the station or network supplying parameters for the listed amplitude of local magnitude. *common_coda_magnitude_code The code representing the specific duration or coda magnitude scale. Duration magnitude scales normally are adjusted to agree with ML or Mn estimates. The MD formulas vary for different geographic regions and for different seismographic instruments. For the specifics of the duration magnitude in the catalog of interest, contact the catalog source. *common_p_s_data_source A alphanumeric code (generally 3 characters long) belonging to the station or network supplying parameters for the listed difference in the arrival time of p- and s- phases. *crust_and_delay_code Two delay models may be specified, and one, the other or a combination of both can be used in computing station delays. When both are used the choice of which delay model to use depends only on epicentral position relative to a dividing line drawn through the array. A transition zone of variable width along the dividing line smooths the discontinuity between delay models and epicenters near the dividing line. The code given identifies the model used. Station Delays: P delays are always taken from the station cards. Of course, leaving the P delay field blank will use a delay of 0.0 or no delay. S delays can be specified in one of two ways: 1) If the parameter NOSDLY equals 1 in the file HYPINST, S delays are assumed equal to Vp_Vs_ratio times the P delays for all stations. 2) if NOSDLY equals 0, S delays are specified independently of the P delays. Two different delay models can be specified (two each for both P and S). The delay model can be made to depend on which side of a line drawn through the array origin the epicenter lies on. P delay in seconds for delay model 1, similarly for S delay. *crust_model_code The identification of the velocity model used in determining travel time residuals. Layered models are used with constant velocity between the layers. Crustal model used in calculating all travel times to a particular station. These are usually numbers representing the model. The crustal model must consist of flat homogeneous layers and velocity must increase with depth. Up to 12 layers (including the halfspace are allowed in each model, and a maximum of 3 models is allowed. Which of the 3 crustal models to use in travel time calculation is specified on the station card, and that model is always used for that station. Thus, different sub-arrays within a large network may use different models, or a vertical discontinuity may be crudely modeled. If only one model is needed, the space for the remaining models may be left blank on the input lines. Each model may have a different number of layers. The crustal models described here are P velocity models. Travel times for S waves are calculated using the same model and multiplied by the P over S velocity ration. A crustal model specified the velocity and depth of the top layer(s) of the model(s). The last velocity entry for each model is that of the halfspace. An alternative crustal model uses a travel time table. The program reads the table generated independently of the location process, and calculates travel time, travel time derivatives, and emergence angles at the source by interpolation from the table. Three point interpolation is used within the table, and linear extrapolation is used beyond the table. The table itself is a condensed grid of travel times as a function of distance and depth. Travel time curve ASCII data is located in the directory : supplmnt/travtime contained on the North American CD-ROM. *data_source This is a code referring to the source of the data, a reference or seismological observation, network or data collection agency. In the Boyd catalog these are the catalogs from which the original catalog was obtained BCIS, ISC or ISS. The reference from which the data were obtained. In the PACHSYKES and the significant earthquake catalogs this is a number referring to a reference in the document files. In the Significant Earthquake catalog, This is a code referring to the source of the data, a reference or seismological observation, network or data collection agency. References are given in Significant earthquake help files. *data_source_1 The first of four sources of data listed in the Zoback World Stress data base. *data_source_2 The second of four sources of data listed in the Zoback World Stress data base. *data_source_3 The third of four sources of data listed in the Zoback World Stress data base. *data_source_4 The fourth of four sources of data listed in the Zoback World Stress data base. *day Day of the month. Values range from 1 to 31. *death_description When only a describer was found in the historical literature, a code for the number dead was used as follows in the significant earthquake catalog: S = Some F = Few M = Many symbols are used. *deaths When only a describer was found in the historical literature, a code for the number dead was used as follows in the significant earthquake catalog: S = Some F = Few M = Many symbols are used. *depth Hypocentral Depth (positive downward) in kilometers from the surface. In the tsunami data, the depth of the earthquake causing the tsunami. SH = shallow (depth 70 km or less). In the Canadian Geological Survey of Canada catalog the depth is given only if the Free Depth solution (code=Z) is used. *depth_negate In order to plot the depths correctly (from the surface downward) in catalogs containing positive values for depth, this variable multiples the given depth in km by (-1). *error_dip_intermediate_axis_deg The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principal axes and their azimuths and dips in degrees. the error_dip_of_smallest_axis is the standard error in degrees of the dip of the major axis with neither the largest nor the smallest length. *dip_of_plane_one The angle of dip of the first nodal plane according to the convention of Aki and Richards (1980, p 106). This is calculated from the directions of the P, T and N axes. Equivalent to the scalar_dip in the Harvard Moment Tensor catalog. *dip_of_plane_two The angle of dip of the second nodal plane according to the convention of Aki and Richards (1980, p 106). This is calculated from the directions of the P, T and N axes. Equivalent to the scalar_plunge in the Harvard Moment Tensor catalog. *error_dip_smallest_deg The standard error of the dip of the smallest axis in the fault parameter ellipsoid in degrees. *dip_smallest_error_deg The standard error of the dip of the smallest axis in the fault parameter ellipsoid in degrees. *distance_radial In the USGS catalogs there is a position for radial distance. This position refers to the distance of the given event from a central point. While this remains in the format, it is a variable that is not used in the given USGS catalog. *md_dr_magn_duration The duration magnitude is calculated on the basis of duration or coda or F-P time as read on a short period seismogram. The general practice is to read the end of the coda or F phase when the signal decays to 10 mm peak-to-peak on the develocorder viewer. Amplitude and duration magnitudes are calculated independently, and both may appear. Choosing between or averaging the two must be done by the user. Magnitude corrections (FCOR) may specified for each station. If FMP is the duration dime in seconds, D the epicentral distance to the station and Z the depth, the duration magnitude is: Md(f-p) = FMA +FMB*log(f-p) +FMF*(f-p) +FMD*D + FMZ*Z + STACOR +FMGN*g where: f-p is the end of coda minus P-time or duration, D is the epicentral distance Z is the (positive) depth STACOR is the duration magnitude correction from the station card G is the gain correction The lapse time (tau) magnitude expression is: Mt(tau) = DMAO + DAM1*log(tau) +DMA2*log2(tau) + DMLIN*tau + DMZ*Z + DMGN*G + STACOR where: tau is the lapse time (P travel time + coda duration) (f-p) Z is the (positive) depth STACOR is the duration mag correction from the station card G is the gain correction *magn_coda_average The duration magnitude is calculated on the basis of duration or coda or F-P time as read on a short period seismogram. The general practice is to read the end of the coda or F phase when the signal decays to 10 mm peak-to-peak on the develocorder viewer. Amplitude and duration magnitudes are calculated independently, and both may appear. Choosing between or averaging the two must be done by the user. Magnitude corrections (FCOR) may specified for each station. If FMP is the duration dime in seconds, D the epicentral distance to the station and Z the depth, the duration magnitude is: Md(f-p) = FMA +FMB*log(f-p) +FMF*(f-p) +FMD*D + FMZ*Z + STACOR +FMGN*g where: f-p is the end of coda minus P-time or duration, D is the epicentral distance Z is the (positive) depth STACOR is the duration magnitude correction from the station card G is the gain correction The lapse time (tau) magnitude expression is: Mt(tau) = DMAO + DAM1*log(tau) +DMA2*log2(tau) + DMLIN*tau + DMZ*Z + DMGN*G + STACOR where: tau is the lapse time (P travel time + coda duration) (f-p) Z is the (positive) depth STACOR is the duration mag correction from the station card G is the gain correction *magn_duration The duration magnitude is calculated on the basis of duration or coda or F-P time as read on a short period seismogram. The general practice is to read the end of the coda or F phase when the signal decays to 10 mm peak-to-peak on the develocorder viewer. Amplitude and duration magnitudes are calculated independently, and both may appear. Choosing between or averaging the two must be done by the user. Magnitude corrections (FCOR) may specified for each station. If FMP is the duration dime in seconds, D the epicentral distance to the station and Z the depth, the duration magnitude is: Md(f-p) = FMA +FMB*log(f-p) +FMF*(f-p) +FMD*D + FMZ*Z + STACOR +FMGN*g where: f-p is the end of coda minus P-time or duration, D is the epicentral distance Z is the (positive) depth STACOR is the duration magnitude correction from the station card G is the gain correction The lapse time (tau) magnitude expression is: Mt(tau) = DMAO + DAM1*log(tau) +DMA2*log2(tau) + DMLIN*tau + DMZ*Z + DMGN*G + STACOR where: tau is the lapse time (P travel time + coda duration) (f-p) Z is the (positive) depth STACOR is the duration mag correction from the station card G is the gain correction *dr_magn_duration The duration magnitude is calculated on the basis of duration or coda or F-P time as read on a short period seismogram. The general practice is to read the end of the coda or F phase when the signal decays to 10 mm peak-to-peak on the develocorder viewer. Amplitude and duration magnitudes are calculated independently, and both may appear. Choosing between or averaging the two must be done by the user. Magnitude corrections (FCOR) may specified for each station. If FMP is the duration dime in seconds, D the epicentral distance to the station and Z the depth, the duration magnitude is: Md(f-p) = FMA +FMB*log(f-p) +FMF*(f-p) +FMD*D + FMZ*Z + STACOR +FMGN*g where: f-p is the end of coda minus P-time or duration, D is the epicentral distance Z is the (positive) depth STACOR is the duration magnitude correction from the station card G is the gain correction The lapse time (tau) magnitude expression is: Mt(tau) = DMAO + DAM1*log(tau) +DMA2*log2(tau) + DMLIN*tau + DMZ*Z + DMGN*G + STACOR where: tau is the lapse time (P travel time + coda duration) (f-p) Z is the (positive) depth STACOR is the duration mag correction from the station card G is the gain correction *duration_magnitude_weights The weighting factors given for duration magnitudes. Magnitude corrections may be specified for each station. An average duration magnitude includes station magnitude corrections. *duration_magnitude_weight The weighting factors given for duration magnitudes. Magnitude corrections may be specified for each station. An average duration magnitude includes station magnitude corrections. *duration_magn_weights The weighting factors given for duration magnitudes. Magnitude corrections may be specified for each station. An average duration magnitude includes station magnitude corrections. *earthquake_catalog This is a constant BOYD in the Boyd catalog, denoting the fact that this event is in the Boyd catalog. *earthquake_second_err The standard error calculated by computer program for the timing error in seconds. *earthquake_second_err_std The standard deviation on the standard error calculated by computer program for the timing error in seconds. The square root of the average value of the square of the individual deviations. The square of this quantity is called the variance. For n independent measurements with equal weighting, the standard deviation is: sqrt(SUM(xi -xm)(xi-xm)/n) where xi is each individual measurement, xm is the mean of the individual measurements, and n is the number of individual measurements. *error_azimuth_of_axis_with_intermediate_dip The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principle axes and their azimuths and dips in degrees. The error_azimuth_of_axis_with_intermediate_dip is the standard error in degrees of the azimuth of the major axis with the dip which is neither the smallest nor largest of the three. *error_azimuth_of_axis_with_intermediate_dip The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principle axes and their azimuths and dips in degrees. The error_azimuth_of_axis_with_intermediate_dip is the standard error in degrees of the azimuth of the major axis with the dip which is neither the smallest nor largest of the three. *error_azimuth_of_axis_with_smallest_dip The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principle axes and their azimuths and dips in degrees. the error_azimuth_of_axis_with_smallest_dip is the standard error in degrees of the azimuth of the major axis with the smallest dip. *azimuth_smallest_error_deg The azimuth of the principal axis with the smallest trix error in degrees from north. *error_azimuth_of_intermediate_axis The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principle axes and their azimuths and dips in degrees. the error_azimuth_of_smallest_axis is the standard error in degrees of the azimuth of the major axis with neither the largest nor smallest length. *error_azimuth_of_intermediate_axis The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principle axes and their azimuths and dips in degrees. The error_azimuth_of_smallest_axis is the standard error in degrees of the azimuth of the major axis with neither the largest nor smallest length. *error_azimuth_of_smallest_axis The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principle axes and their azimuths and dips in degrees. The error_azimuth_of_smallest_axis is the standard error in degrees of the azimuth of the major axis with the smallest length. *error_depth The estimated error in the determination of the depth of an earthquake is given in km of depth. *error_depth_std_100s_of_meters The standard deviation on the error in the determination of the depth of an earthquake is given in 100s of meters of depth. The square root of the average value of the square of the individual deviations. The square of this quantity is called the variance. For n independent measurements with equal weighting, the standard deviation is: sqrt(SUM(xi -xm)(xi-xm)/n) where xi is each individual measurement, xm is the mean of the individual measurements, and n is the number of individual measurements. *error_magn_std_EPB The standard deviation on the magnitude estimate as given by the Canadian Earth Physics Branch (EPB). This is used in the Canadian Geological Survey (GSC) catalogs. *error_depth In the USSR catalog, the estimated error in the determination of the depth of an earthquake is given in km of depth. *error_dip_of_axis_with_intermediate_dip The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principal axes and their azimuths and dips in degrees. The error_dip_of_axis_with_intermediate_dip is the standard error in degrees of the dip of the major axis which has neither the largest nor smallest dip angle. *error_dip_smallest_deg The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principal axes and their azimuths and dips in degrees. The error_dip_of_axis_with_smallest_dip is the standard error in degrees of the dip of the major axis with the smallest dip. *error_dip_of_axis_with_smallest_dip The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principal axes and their azimuths and dips in degrees. The error_dip_of_axis_with_smallest_dip is the standard error in degrees of the dip of the major axis with the smallest dip. *error_dip_of_intermediate_axis The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principal axes and their azimuths and dips in degrees. The error_dip_of_intermediate_axis is the standard error in degrees of the dip of the major axis with neither the largest nor the smallest length. *error_dip_of_smallest_axis The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The error ellipsoid consists of the lengths of the principal axes and their azimuths and dips in degrees. the error_dip_of_smallest_axis is the standard error in degrees of the dip of the major axis with the smallest length. *error_epicenter_km The estimated error in the determination of an earthquake epicenter is given in kilometers. *flag_quality A diagnostic in the USSR catalog as follows: (russian letters used: ' ',' ','','','', '','',' ',' ','',' '; letter '' in 37 signifies non capital letters in data source for pos. 36; letters similar to latin have the same EBCDIC code, other ones have following EBCDIC codes: - 10110001, - 10110011, - 10110111, - 11000011; *error_latitude_std_deg The standard deviation on the error in latitude given in geocentric degrees and derived from various hypocenter determinations. The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The latitude error is a simplified error derived from the lengths and directions of the principal axes of the error ellipsoid. Each of the three principal axes (whose lengths are the standard errors) are projected onto a vertical line through the hypocenter. The latitude error is simply the length of the longest of the principal axes projected onto a north-south plane. *error_longitude_std_deg The standard deviation on the error in latitude given in geocentric degrees and derived from various hypocenter determinations. The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The longitude error is a simplified error derived from the lengths and directions of the principal axes of the error ellipsoid. Each of the three principal axes (whose lengths are the standard errors) are projected onto a vertical line through the hypocenter. The horizontal error is simply the length of the longest of the principal axes projected onto the east-west plane. *error_horizontal_km The error ellipsoid is specified by the 3 X 3 sub-matrix derived by removing the origin time from the covariance matrix. The 3 X 3 covariance matrix must be rotated into the principal coordinates of the solution whose axes are the major axes of the error ellipsoid. The three principal standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3 X 3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors. An error ellipsoid whose major axes are 2.4 times the standard errors calculated has a 95% chance of containing the true hypocenter. The horizontal error is a simplified error derived from the lengths and directions of the principal axes of the error ellipsoid. Each of the three principal axes (whose lengths are the standard errors) are projected onto a vertical line through the hypocenter. The horizontal error is simply the length of the longest of the principal axes when viewed from above (projected onto a horizontal plane). The error_horizontal_km is equivalent to the error_standard_horizontal_km. *error_standard_small_location In the Adak catalog this is a quality flag according to the following notation: 1 = high accuracy in epicentral location , SE<=0.30 2 = intermediate accuracy in epicentral location, 0.300.30 seconds (2events) z: depth above the surface or depth > 300 km (5 events) r: Undefined *flag_waves_generated Indicates the generation of waves by an earthquake according to the following codes: T: T-wave observed A: Acoustic wave observed G: Gravity wave generated B: Both Acoustic and Gravity waves were generated *fe_region The numerical value of the geographical region in which an earthquake occurred. These regions are described in: Flinn, Edward A., E. R. Engdahl and Alan R. Hill, 1974. Seismic and Geographical Regionalization, Bulletin of the Seismological Society of America. v64, No 3, Part II, pp771- 993. A number of changes in the geographic region names have been recently introduced by the U. S. Geological Survey to reflect either recent political changes or usages more common than the names used in the past. The boundaries of these regions are defined at one degree intervals and differ slightly from irregular political boundaries. *Flinn_Engdahl_region The numerical value of the geographical region in which an earthquake occurred. These regions are described in: Flinn, Edward A., E. R. Engdahl and Alan R. Hill, 1974. Seismic and Geographical Regionalization, Bulletin of the Seismological Society of America. v64, No 3, Part II, pp771- 993. A number of changes in the geographic region names have been recently introduced by the U. S. Geological Survey to reflect either recent political changes or usages more common than the names used in the past. The boundaries of these regions are defined at one degree intervals and differ slightly from irregular political boundaries. *geologic_age A description of the geologic age of the strata in which a stress measurement was obtained for the world stress data. Used only for geologic data. *half_duration The half duration of an earthquake is either calculated from the formula: dto = 1.7 X 10-8 Mo1/3 where dto is in seconds and Mo is in dyne-cm or for large earthquakes, it is established by requiring that the seismic moments determined from the analysis of body waves (dominant period 50-60s) and mantle waves (dominant period 150-180 s) are approximately equal. The source time is modeled by a box-car. *horizontal_component_maximum The maximum component of stress in the horizontal direction - in the Estabrook catalog. *time_hour Origin time of an earthquake in Hours of the day (0-23) in Greenwich Mean time (GMT). (Used in the Geological Survey of Canada catalogs). *hour Hour of the day (0-23) in Greenwich Mean time (GMT). *infrasonic This flag indicates the type of waves generated in the sonic range as follows: T T-wave A Acoustic Wave G Gravity Wave B Both A and G *flag_infrasonic This flag indicates the type of waves generated in the sonic range as follows: T T-wave A Acoustic Wave G Gravity Wave B Both A and G *instruction_record While 4 spaces are allowed for this instruction in the SCALASKA catalog no instructions are found in this field. *intensity_number_of_observations In the USSR catalog the number of points with macroseismic intensity known. *intensity_code In the USSR catalog a code indicating availablity of macroseismic data. ('I' makroseismic data are available in bulletin) *intensity Modified Mercalli Scale intensity or converted to the Modified Mercalli scale. 1-9 = I-IX, X =X, E = XI, T = XII in BEQ.afm, in signif.afm I-XII are values. In the USSR catalog these are arabic numbers. Macroseismic information is compiled from various sources including newspaper articles, Foreign broadcasts, U.S. Geological Survey Earthquake reports and seismological station reports. *intensity_tsunami In the ALEVENT tsunami file Tsunami intensity is defined as by Soloviev and Go (1974) as I=log2(21/2xh) , where "h" is the maximum runup height of the wave. The height above sea level of a tsunami in meters at a specific time after the event recording begins. The amplitude may be given rather than the runup. Amplitude may be half the range. *error_magnitude_of_intermediate_axis_km The error computed by computer program on the horizontal location of the intermediate axis on the earthquake epicenter, given in km. The standard error computed by computer program on the horizontal location of the earthquake epicenter, given in km. The error ellipsoid is specified by the 3X3 matrix derived by removing origin time form the covariance matrix. The 3X3 covariance matrix must be rotated into the principal coordinates of the solution. Standard errors are calculated by taking square roots of the eigenvalues (diagonal elements in diagonal form) of the 3X3 covariance matrix. The earthquake then has a statistical probability of 32% of lying inside an ellipsoid of error whose major axes are given by the three principal standard errors calculated by this program and has a 95% chance of containing the "true" hypocenter. The program also calculates the azimuths and dips of the principal axes of the error ellipsoid. The vertical error ERZ and the horizontal error ERH are simplified errors derived from the lengths and directions of the principal axes of the error ellipsoid. Each of the three principal axes (whose lengths are the standard errors) are projected onto a vertical line through the hypocenter, and the largest value is ERZ. The magnitude of the intermediate error is simply the length of the intermediate of the principal axes when viewed from above. (projected onto a horizontal plane). *ide In the PDE catalog some large events are designated as events for which international data exchanges are encouraged. These are flagged with the letter "X". *international_data_exchange_event In the PDE catalog some large events are designated as events for which international data exchanges are encouraged. These are flagged with the letter "X". *Iteration_factor A diagnostic in the Kanto Japan Catalog. This factor indicates the quality of the solution as follows: Smaller IT is, better the obtained hypocenter is. Smaller IT is, less the result depends on the initial guess. *magn_f-p In the Kanto Catalog, a magnitude determined by the total duration time (F-P). *MF-p A magnitude determined by the total duration time (F-P). *isoseismal Three-letter abbreviation indicating the publication of an flag_isoseismal (intensity) map. USE: United States Earthquakes PDE: Preliminary Determination of Epicenters WEL: New Zealand Seismology Report BSS: Bulletin of the Seismological Society of America ZUR: Zurich, Switzerland NTR: Nature Magazine FPS indicates a fault-plane solution was computed. BOT means that both a fault plane solution and an flag_isoseismal *flag_isoseismal Three-letter abbreviation indicating the publication of an flag_isoseismal (intensity) map. USE: United States Earthquakes PDE: Preliminary Determination of Epicenters WEL: New Zealand Seismology Report BSS: Bulletin of the Seismological Society of America ZUR: Zurich, Switzerland NTR: Nature Magazine FPS indicates a fault-plane solution was computed. BOT means that both a fault plane solution and an flag_isoseismal map were produced by the U.S. Geological Survey. *flag_isoseismal_map Three-letter abbreviation indicating the publication of an flag_isoseismal (intensity) map. USE: United States Earthquakes PDE: Preliminary Determination of Epicenters WEL: New Zealand Seismology Report BSS: Bulletin of the Seismological Society of America ZUR: Zurich, Switzerland NTR: Nature Magazine FPS indicates a fault-plane solution was computed. BOT means that both a fault plane solution and an flag_isoseismal map were produced by the U.S. Geological Survey. *latitude This is the geographic latitude expressed as a decimal number. The units are degrees. The range is -90.0 to +90.0. North is Positive, South is Negative. For earthquakes it is the epicentral latitude, for volcanoes, the location of an individual volcano or the center of a volcanic field. In the tsunami files the latitude of the earthquake epicenters. Blanks indicate data are unknown, dashes(-) indicate the parameters do not exist (i.e. earthquake magnitude for tsunamis caused by volcanos). Where cause = "v" or "L", coordinates (latitude and longitude ) are for volcano or landslide. *latitude_abs The absolute (unsigned), latitude. *latitude_deg The degree portion of the latitude when the latitude is given in degrees, minutes, and seconds. The range is -90 to +90. North is positive, south is negative. *latitude_deg_abs The absolute (unsigned), latitude. *latitude_min The minute portion of the latitude when the latitude is given in degrees, minutes, and seconds or degrees and decimal minutes. The range is 0 to less than 60. *latitude_ns North (N) or South (S) designator of latitude. *location_description In the Significant Earthquake catalog, the country is listed first, then the province or state, and finally the city or cities where damage was reported. If there are different spellings of a city name, the current spelling is listed first followed by the alternate spelling in parentheses. This is only an approximate location. Events prior to 1900 were not instrumentally located, therefore, the location given is based on the latitude and longitude of the city where the damage occurred. In the geographic location column, the country is listed first, then the province or state, and finally the city or cities where damage was reported. If there are different spellings of a city name, the current spelling is listed first followed by the alternate spelling in parentheses. A geographic and tectonic description of the location of stress measurements in the world stress data. Usually a place name or a well name. *location_description_state Usually a country name; except for U.S. , Canada, Mexico where state or province are included with country name, e.g. Connecticut, U.S.A.; in the world stress data. *location_number This is a coded number indicating the location of an earthquake in the Pachsyke catalog. *longitude This is the geographic longitude expressed as a decimal number. The units are degrees. The range is -180.0 to +180.0, where plus designates East longitude and minus designates West longitude. For earthquakes it is the epicentral longitude, for volcanoes, the location of an individual volcano or the center of a volcanic field. In the tsunami data, the longitude of the earthquake or volcanic event which caused the tsunami. The epicenter in this case is not critical information since it represents a single point where the rupture began while the actual rupture that generated the tsunami may cover thousands of square kilometers. *longitude_abs The absolute (unsigned) longitude. *longitude_deg The degree portion of the longitude when the longitude is given in degrees, minutes, and seconds. *longitude_deg_abs The absolute (unsigned) value of the degree portion of longitude. *longitude_east The longitude of the event given in degrees east of Greenwich. These can range from 0 to 360 degrees east of Greenwich. *longitude_ew East (E) or West (W) designator of longitude. *longitude_min The minutes portion of the longitude when the longitude is given in degrees, minutes, and seconds or degrees and decimal minutes. Values range from 0 to less than 60. *number_ms_observations The number of observations used by a network or station in determining the local ms magnitude. *ml_magn_local These local magnitudes are computed according to the formula: ML = LogA - Log Ao defined in Richter (1935) where A is the maximum trace amplitude in micrometers recorded on a standard short-period torsion seismometer and Log Ao is a standard value as a function of distance where distance >600 km. This definition may vary slightly from catalog to catalog. Other local magnitude scales are found under the name ml_magn_local_scale. Richter, C. F, 1935, An instrumental earthquake scale, Bulletin of the Seismological Society of America, V 25, p 1- 32 CL: Coda-Length Magnitude MS: Surface-wave Magnitude DR: Duration Magnitude NU: Nuttli Magnitude MW: Moment Magnitude (Abe, 1983, 1984) Abe, Katsuyuki, 1983, Revision of Magnitudes of Large Shallow Earthquakes, 1897-1912, Physics of the Earth and Planetary Interiors, V33, pp1-11. Abe, Katsuyuki, 1984, Complements to Magnitudes of Large Shallow Earthquakes from 1904 to 1980, Physics of the Earth and Planetary Interiors, V 34, p 17-23. MR: Magnitude determined from energy class by Rautian for earthquakes listed in Russian catalog (Kondorskaya and Shebalin, 1982) Kondorskaya, N.V., and N.V. Shebalin, Editors, 1982 (Russian Edition, 1975): New Catalog of Strong Earthquakes in the U.S.S.R. from Ancient times through 1977, Report SE-31, World Data Center-A for Solid Earth Geophysics, Boulder, CO, 608 pp. LH: Magnitude MLH determined using USSR calibration curve for earthquakes in Russian catalog (Kondorskaya and Shebalin, 1982) LG: MBLG body-wave magnitude (Nuttli, 1983) These Lg body wave magnitudes are computed according to the formula: mbLg = 3.75 + 0.90 Log D + Log(A/T) for 0.5 deg