Hypocenter Magnitude Near real-time data and database Real-time systems






HYPOCENTER

A computer program to locate earthquakes both locally and globally. The original version was described by Lienert et al. (1988). Also, this program is included in the integrated software, SEISAN.

 Related URLs
    http://orfeus.knmi.nl/
    http://www.ifjf.uib.no/Seismologi/software/seisan/seisan.html.

 References
Lienert, B. R., Berg, E., and Frazer, N., 1986. HYPOCENTER: An earthquake location method using centered, scaled, and adaptively damped least squares, Bull. Seism. Soc. Am., 76, 771-783.   

Lienert, B. R. and Havskov, J., 1995. A computer program for locating earthquakes both locally and globally, Seism. Res. Lett., 66, 26-36.


HYPOELLEPSE

A program for locating regional/local earthquakes using a sparse regional network.

 Related URLs
    http://jclahr.com/science/software/hypoellipse/

 References
Lahr, J. C., 1980. HYPOELLIPSE/MULTICS: A computer program for determining local earthquake hypocentral parameters, magnitude, and first motion pattern, U.S. Geological Survey Open-File Report 80-59, 59 p.

Lahr, J. C., 1980. SQUASH/MULTICS: A computer program to be used in conjunction with HYPOELLIPSE to generate an augmented phase data archive, U.S. Geological Survey Open-File Report 80-375, 11 p.

Lahr, J. C., 1984. HYPOELLIPSE/VAX: A computer program for determining local earthquake hypocentral parameters, magnitude, and first-motion pattern, U.S. Geological Survey Open-File Report 84-519, 76 p.

Lahr, J. C., 1989. HYPOELLIPSE/Version 2.0: A computer program for determining local earthquakes hypocentral parameters, magnitude, and first-motion pattern, U.S. Geological Survey Open-File Report 89-116, 92 p.


    
HYPOINVERSE2000

Upgraded version of HYPO71. A program to determine earthquake locations and magnitudes from seismic network data like first-arrival P and S arrival times, amplitudes and coda durations. It is the standard location program supplied with the Earthworm seismic acquisition and processing system.

 Related URLs
    http://quake.wr.usgs.gov/research/software/index.html

 References
Klein, F. W., 1978. Hypocenter location program HYPOINVERSE Part 1: Users guide to versions 1,2,3 and 4, USGS Open File Report, 78-694.

Klein, F. W., 1985, User's guide to HYPOINVERSE, a program for VAX and Professional 350 computers to solve for earthquake locations, U.S. Geological Survey Open-File Report 85-515, 53 p.

Lee, W. H. K. and Lahr, J. C., 1975. HYPO71 (revised): A computer program for determining hypocenter, magnitude and first motion pattern of local earthquakes, USGS Open File Report, 1-116.

Lee, L. H. K. and Stewart, S. W., 1981. Principles and Applications of Microearthquake Networks, Academic Press.

Lee, W. H. K. and Valdes, C. M., 1989. User Manual for HYPO71PC, in IASPEI Software Library Volume 1. Toolbox for Seismic Data Acquisition, Processing and Analysis, Part III. Off-line Data Analysis, Edited by W. H. K. Lee, Published by International Association of Seismology and Physics of the Earth's Interior (IASPEI) in collaboration with Seismological Society of America, 203-236.

 









There are various types of magnitudes. Here are typical types of magnitudes.

Type Description

Duration
magnitude
Md

 The magnitude scale based on the duration of shaking. Useful to calculate magnitudes for seismograms clipped due to limited dynamic range of analog seismographs.
The applicable range is less than 4.
 The epicentral distance range where Ml is measured is 0-400 km.

Local magnitude
Ml

  The first magnitude scale developed by Richter (1935). The maximum amplitude of a seismogram recorded by a Wood-Anderson torsion instrument is used. Ml can be calculated using modern instruments after appropriate adjustments.
 The applicable range is less than 6.
 The epicentral distance range where Ml is measured is 0-400 km.

Body wave magnitude
mb

  The magnitude scale based on amplitude of P-wave.
 This scale saturates around mb=6.5, and is not reliable for larger earthquakes.

Surface wave magnitude
Ms

  The magnitude scale based on amplitude of Rayleigh waves whose period is around 20 sec.
 This scale saturates around Ms=8, and is not reliable for larger earthquakes.

Moment magnitudes
Mw

  The magnitude scale based on seismic moment (the product of rigidity in source region, displacement of an earthquake and fault area that slipped) derived by Kanamori (1977). Seismic moments can be calculated from moment tensor solutions. This scale does not saturate and represents the actual size of an earthquake.
 Tsuboi et al. (1995, 1999) derived a new magnitude scale, which they called broadband moment magnitude, Mwp.This scale is based on the far field P-wave displacement.


 References
Gutenberg, B., 1945. Amplitudes of surface waves and magnitudes of shallow earthquakes. Bull. Seismol. Soc. Am., 35, 3-12.

Kanamori, H., 1977. The energy release in great earthquakes, J. Geophy. Res., 82, 2981-2987.

Lee, W. H. K., Bennett, R. E., and Meagher, K. L., 1972. A method of estimating magnitude of local earthquakes from signal duration, Geol. Surv. Open-File Rep. (U.S.), 28.

Richter, C. F., 1935. An instrumental earthquake magnitude scale. Bull. Seismol. Soc. Am., 25, 1-32.

Tsuboi, S., Whitemore, P., and SokolowskiT., 1999. Application of Mw to Deep and Teleseismic Earthquakes, Bull. Seismol. Soc. Am., 89, 1345-1351.

Tsuboi, S., Abe, K., Takano, K., and Yamanaka, Y., (1995). Rapid Determination of Mw from broadband P waveforms, Bull. Seismol. Soc. Am., 83, 606-613.

Tsumura, K., 1967, Determination of earthquake magnitude from total duration of oscillation, Bull. Earthq. Res. Inst., Univ. Tokyo, 45, 7-18.

 









Both hypocenters and magnitudes are routinely determined and issued by various institutions. Here some web sites where you can access.
USGS sites

 Near real-time information:
      http://earthquake.usgs.gov/eqcenter/index.php

 Database:
      http://neic.usgs.gov/neis/epic/
ISC

 Bulletin of ISC
        http://www.isc.ac.uk/Bulletin/rectang.htm
 Phase data
        http://www.isc.ac.uk/Bulletin/arrivals.htm
Harvard CMT catalog

 Centriod moment tensor (CMT) consists of centroid (location and time) of moment release and moment tensor. Due to its definition, the centroid time is always behind the origin time. From moment tensor solutions, seismic moments and moment magnitudes Mw can be calculated
       http://www.seismology.harvard.edu/CMTsearch.html
Catalog of Damaging Earthquakes in the World (Through 2002)

 Compiled by late Prof. Tokuji Utsu (the IISEE is updating and maintaining this catalog since May, 2003).
       http://iisee.kenken.go.jp/utsu/index_eng







 


 JMA Earthquake Early Warning

 Realtime earthquake warning system developed by JMA and NEID.

Odaka, T., Ashiya, K., Tsukada, S., Sato, S., Ohtake, K. and Nozaka, D., 2003. A New Method of Quickly Estimating Epicentral Distance and Magnitude from a Single Seismic Record, Bull. Seismol. Soc. Am., 93, 526-532.

 Tsukada, S., Odaka, T., Ashiya, K. Ohtake, K., and Nozaka, D., 2004. Analysis of the Envelope Waveform of the Initial Part of P Waves and its Application to Quickly Estimating the Epicentral Distance and Magnitude, Zisin 2, 56, 351-361.


 SUPERME

 Super high-density real-time disaster mitigation system developed by Tokyo Gas Co. Ltd., which consists of 3,800 spectral intensity (SI) sensors. Seismic parameters such as hypocenters and magnitudes are not determined. Instead, two-dimensional distributions of SI values, PGA and liquefaction status are estimated from observations and utilized for seismic safety of city gas supply.

Shimizu, Y., Yamazaki, F., Yasuda, S., Towhata, I., Suzuki, T., Isoyama, R., Ishida, E., Suetomi, I., Koganemaru, K., and Nakayama, W., 2006. Development of Real-Time Safety Control System for Urban Gas Supply Network, J. Geotech. and Geoenvir. Engrg., 132, 237-249.

Shimizu, Y., Watanabe, A., Koganemaru, K., Nakayama, W., and Yamazaki, F. 2000. Super High-Density Realtime Disaster Mitigation System, 12th World Conference on Earthquake Engineering, CD-ROM, 7.


 UrEDAS

 Urgent Earthquake Detection and Alarm System. Early warning system for Shinkansen (bullet train). Warnings are issued based on
    earthquake parameters determined using a single station data.

Nakamura, Y., 1988. On the Urgent Earthquake Detection and Alarm System. Proceedings of 9th WCEE (7), 673-678.

Saita J. and Nakamura, Y., 2003. UrEDAS: The Early Warning System for Mitigation of Disasters Caused by Earthquakes and Tsunamis, in Early Warning Systems for Natural Disaster Reduction, pp. 453-460, eds Jochen Zschau and Andreas N.Küppers, Springer, Berlin.


 CISM (http://www.cisn.org/)

 The California Integrated Seismic Network, which is “a partnership among federal, state, and university agencies involved in California earthquake monitoring. The CISN is dedicated to serve the emergency response, engineering, and scientific communities. The CISN is a region of the Advanced National Seismic System.” (from its web site). Recent earthquake information and ShakeMaps (maps of instrumental intensities, PGAs, PGVs, and spectral responses) are available.

Kanamori, H., 1993. Locating Earthquakes with Amplitude: Application to Real-time Seismology, Bull. Seism. Soc. Am., 83, 264 - 268.

Wald, D. J., Quitoriano, V., Heaton, T. H., Kanamori, H., Scrivner C. W., and Worden, C. B., 1999. TriNet S“hakeMaps”: Rapid Generation of Peak Ground Motion and Intensity Maps for Earthquakes in Southern California, Earthquake Spectra, 15, 537 - 555.

Scrivner, C., W., Worden, C. B., and Wald, D. J., 2000. Use of TriNet Shakemap to Manage Earthquake Risk, 6th International Conference on Seismic Zonation, CD-ROM.


 TREIRS

Taiwan Rapid Earthquake Information Release System. Hypocenters and magnitudes are determined within thirty seconds after earthquakes occur, and PGAs and PGVs are estimated within two minutes.

Wu, Y.-M., Shin, T.-C., and Tsai, Y.-B., 1998. Quick and reliable Determination of Magnitude for Seismic Early Warning, Bull. Seism. Soc. Am., 88, 1254 - 1259.

Wu, Y. M., Shin, T. C., and Chang, C. H., 2001. Near realtime mapping of Peak Ground Acceleration and Peak Ground Velocity following a strong earthquake, Bull. Seism. Soc. Am., 91, 1218 - 1228.

Wu, Y. M. and T. L. Teng, 2002, A VSN approach to Earthquake Early Warning, Bull. Seism. Soc. Am., 92, 2008 - 2018.

Wu, Y.-M., Hsiao, N.-C., Teng, T.-L., and Shin, T.-C., 2002. Near Real-Time Seismic Damage Assessment of the Rapid Reporting System, TAO, 13, 313 - 324.


 SAS (http://www.cires.org.mx/sas in.php)

 Seismic Alert System in Mexico. This is an earthquake early warning system to issue alert signals when it detects strong earthquakes   in  the "Guerrero Gap".

 Espinosa Aranda, J. M., Jimenez, A., Ibarrola, G., Alcantar, F., Aguilar, A., Inostroza, M., and Maldonado, S., 1995. Mexico City Seismic Alert System, Seism. Res. Lett., 66, 42 - 53