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M5.4 - RYUKYU ISLANDS, JAPAN - 2017/05/15 07:05:36 UTC

 RYUKYU ISLANDS, JAPAN 2017/05/15 07:05:36 UTC,  Mw=5.4

 Earthquake description:
     Location (USGS) : RYUKYU ISLANDS, JAPAN
     UTC Date (USGS) : 2017/05/15 07:05:36
     Latitude (USGS) : 27.217°
     Longitude (USGS) : 130.153°
     Magnitude (SCARDEC) : 5.4 Mw
     Depth (SCARDEC) : 10 km
     Mechanism (SCARDEC) :

SCARDEC method: Analysis of the earthquake source

SCARDEC method uses the teleseismic body waves to retrieve the depth, focal mechanism, moment magnitude and source time function of earthquakes with magnitudes larger than 5.5-6. Details of the methodology are described in Vallée et al. [2011] and an application to all earthquakes with magnitude larger than 6 in the period 1992-2011 can be found in Vallée [2013]. This method has originally been developed at Geoazur laboratory, where the near-real time analysis of the earthquakes in the period 2011-2013 is available here.

In the near-real time configuration presented here, the solution is typically posted 45 minutes after earthquake occurrence. Solution includes a map summing up the SCARDEC results and a figure showing the agreement to the data. The map presents the earthquake location (together with the plate boundaries from Bird [2003] and the slab contours of SLAB 1.0 [Hayes et al., 2012]) and the main SCARDEC source parameters. Numerical values of focal mechanism parameters and seismic moment are written below the map. The data agreement figure compares the SCARDEC synthetics (red) with the FDSN data (black), in the frequency range used for focal mechanism determination. The name of GEOSCOPE stations is written in green.


See more information (about the data, the procedure, the reasons that could prevent from providing the earthquake information, the source time function determination...) in the "detailed notes".

If using some of the SCARDEC results, please refer to:

(1) Vallée, M., J. Charléty, A.M.G. Ferreira, B. Delouis, and J. Vergoz, SCARDEC : a new technique for the rapid determination of seismic moment magnitude, focal mechanism and source time functions for large earthquakes using body wave deconvolution, Geophys. J. Int., 184, 338-358, 2011.

(2) Vallée, M., Source time function properties indicate a strain drop independent of earthquake depth and magnitude, Nature Communications, doi: 10.1038/ncomms3606, 2013.



The method is running and maintained at IPGP laboratory. Apart from IPGP, past and present support to the development of the method are/were provided by the following institutes/projects :

                                                                            


We are grateful to the organisms providing, managing or federating data:

                                                                      


is used for drawing some maps of the webpage.

 
 Automatic determination of source parameters using the SCARDEC method
 Interactive map of the regional seismicity of the last ten years (Magnitude > 5; Source USGS)
Earthquake depth [km]
Magnitude
9
8
7
6
5
: GEOSCOPE stations    -    The information about the plate tectonics are provided by USGS and Bird (2003)
 Interactive map of the foreshocks and aftershocks
(2 weeks before and 2 weeks after the earthquake - Source USGS)

Earthquake depth [km]
Foreshock Aftershock Mag.
7
6
5
4
3
The information about the plate tectonics are provided by USGS and Bird (2003)

 Earthquake data of the GEOSCOPE stations in SEED format:
      Download the SEED volume (20000 seconds of data, channels: LH BH HH HN)
Show the content of the SEED volume

 Theorical arrival times at GEOSCOPE stations
     Display arrival times at available GEOSCOPE stations

 Earthquake records for all the channel stations
(BH channel : data filtered between 0.1hz and 2hz)
(LH channel : data filtered between 0.003hz and 0.02hz)

Code Location Lat. Lon. Elev. Description Records
AISNouvelle-Amsterdam - TAAF, France-37.796°77.569°0.036 kmShow station
description
Show
records
ATDArta Cave - Arta, Republic of Djibouti11.531°42.847°0.61 kmShow station
description
Show
records
CANCanberra, Australia-35.319°148.996°0.7 kmShow station
description
Show
records
CCDConcordia Base, Dome C, Antartica-75.107°123.305°3.24 kmShow station
description
Show
records
CLFChambon la Foret Observatory, France48.026°2.26°0.145 kmShow station
description
Show
records
COYCCoyhaique, Chile-45.573°-72.081°0.235 kmShow station
description
Show
records
CRZFPort Alfred - Ile de la Possession - Crozet Islands, France-46.431°51.855°0.14 kmShow station
description
Show
records
DRVDumont d'Urville - Terre Adelie, Antarctica-66.665°140.002°0.04 kmShow station
description
Show
records
DZMDzumac - New Caledonia, France-22.072°166.444°0.878 kmShow station
description
Show
records
ECHEchery - Sainte Marie aux Mines, France48.216°7.159°0.58 kmShow station
description
Show
records
FDFFort de France - Martinique island, France14.735°-61.146°0.467 kmShow station
description
Show
records
FUTUMaopo'opo, Futuna-14.308°-178.121°0.097 kmShow station
description
Show
records
HDCHeredia, Costa Rica10°-84.112°1.15 kmShow station
description
Show
records
INUInuyama, Japan35.35°137.029°0.132 kmShow station
description
Show
records
IVIIvittuut, Greenland61.206°-48.171°0.015 kmShow station
description
Show
records
KIPKipapa - Hawaii, USA21.423°-158.015°0.07 kmShow station
description
Show
records
MBOM'Bour, Senegal14.392°-16.955°0.003 kmShow station
description
Show
records
MPGMontagne des Peres - French Guiana, France5.11°-52.644°0.147 kmShow station
description
Show
records
NOUCPort Laguerre - New Caledonia, France-22.099°166.307°0.137 kmShow station
description
Show
records
PAFPort aux Francais - Kerguelen - TAAF, France-49.351°70.211°0.017 kmShow station
description
Show
records
PELPeldehue, Chile-33.144°-70.675°0.7 kmShow station
description
Show
records
PPTFPamatai - Papeete - Tahiti island - French Polynesia, France-17.59°-149.565°0.705 kmShow station
description
Show
records
RERRiviere de l'Est - Sainte Rose - La Reunion island, France-21.171°55.74°0.834 kmShow station
description
Show
records
ROCAMLeguat Reserve, Rodrigues Island, Republic of Mauritius-19.756°63.37°0.052 kmShow station
description
Show
records
SPBSao Paulo, Brazil-23.593°-47.427°0.647 kmShow station
description
Show
records
SSBTunnel de Badole - Saint Sauveur en Rue, France45.279°4.542°0.7 kmShow station
description
Show
records
TAMTamanrasset, Algeria22.791°5.528°1.41 kmShow station
description
Show
records
TAOETaiohae - Marquesas islands, France-8.855°-140.148°0.8 kmShow station
description
Show
records
TRISTristan da Cunha-37.068°-12.315°0.06 kmShow station
description
Show
records
UNMUnam - Mexico, Mexico19.33°-99.178°2.28 kmShow station
description
Show
records
WUSWushi - Xinjiang Uygur, China41.201°79.216°1.468 kmShow station
description
Show
records

 Records from LHZ channel of all GEOSCOPE stations:
    (LH channel : data filtered between 0.003hz and 0.02hz)

     Download graphic file in PDF format

This figure illustrates how the two blocks separated by the seismic fault are displaced during the earthquake. These movements are deduced from the SCARDEC focal mechanism, on the two possible fault planes. Additional information (tectonics, near-fault measurements) is required to determine which one of these two hypotheses corresponds to the real movements during the earthquake.



Note: This part has been developed for diagnostic of Geoscope data in real-time ; data shown here have not been validated, and differences between data and synthetics should be interpreted with caution, in particular for moderate earthquakes (magnitude < 6.2) and very large earthquakes (magnitude > 7.5).

The SCARDEC solution is used here to predict the waveforms at all Geoscope stations received in real time and located at distances between 30° and 150° from the earthquake. All available location codes are used, for the BH* channels. In the range [30° - ~90°], the prediction is done on P and S(H) waves and in the range [~90° - 150°], it is done on PP and SS(H) waves. See agreement for P or PP waves (vertical components) between data and synthetics in Figure 1; see agreement for S(H) or SS(H) waves (horizontal components) between data (black) and synthetics (red) in Figure 2. Tables 1 and 2 provide quantitative estimates of these agreements.

1) STATIONS-LOCATIONCODES-COMPONENTS analyzed

Figure 1: Agreement between data (black) and synthetics (red) for P or PP waves (the type of waves used is indicated in each subfigure). The comparison is shown with a time shift (noted 'Dt1' in Table 1), corresponding to the optimal fit ('Fit1' in Table 1) before the blue tick. Also indicated are the azimuth and distance of the station, and the signal to noise ratio (SNR). Note that the prediction done for PP waves is expected to be less accurate than the one for P waves.

Table 1: Quantitative estimates of the agreement between data and synthetics for P or PP waves :

  • 'Fit1' is the variance reduction allowing an optimal time shift ('Dt1')
  • 'Fit2' is the variance reduction allowing an optimal time shift ('Dt2') and an optimal amplitude normalization ('Corr_Amp'). The latter value is the factor by which data should be divided to be the closest to the synthetics.
  • 'Rad' is a measure of the amplitude of the expected radiation (normalized to 1). Low values of the radiation (<0.1-0.15) are expected to reduce the significance of the comparison between data and synthetics
  • 'Comment' column is filled when the data and/or the comparison between data and synthetics are not as expected.


Figure 2: Same as Figure 1, but for S(H) or SS(H) waves (use of the rotated horizontal component along the transverse direction). See in Table 2 the quantitative estimates ('Dt1' and 'Fit1') corresponding to this Figure.

Table 2: Same as Table 1 for S(H) or SS(H) waves.


2) STATIONS-LOCATIONCODES-COMPONENTS not analyzed

STATIONS-LOCATIONCODES-COMPONENTS received, but TOO FAR or TOO CLOSE:

STATIONS-LOCATIONCODES-COMPONENTS not present in the 2 categories above have not been received, or on a too short time window to be analyzed

1) Overview

This page gathers information on earthquake characteristics (through the SCARDEC method, see below) and on GEOSCOPE data available for these events: The “data” tab provides access to the data seed file (20000s window starting at the earthquake origin time), provides access to the theoretical arrival times, shows earthquake waveforms for each station and channel, and presents the global Earth wave propagation through the visualization of the LHZ channel. The “mechanism” tab illustrates the geometry of the movement during the earthquake, along the two possible faults planes determined by SCARDEC analysis.

Several e-mail alerts are available, as soon as a new earthquake has been analyzed: (1) for all earthquakes, (2) for earthquakes with Mw>=6.5, and (3) for earthquakes with Mw>=7. Please contact Martin Vallée (vallee@ipgp.fr) to be added in one of these mailing lists.


2) Analysis of the earthquake source (SCARDEC method)

SCARDEC method uses the teleseismic body waves to retrieve the depth, focal mechanism, moment magnitude and source time function of earthquakes with magnitudes larger than 5.5-6. Details of the methodology are described in Vallée et al. [2011] and an application to all earthquakes with magnitude larger than 6 in the period 1992-2011 can be found in Vallée [2013]. This method has originally been developed at Geoazur laboratory, where the near-real time analysis of the earthquakes in the period 2011-2013 is available here.

In the near-real time configuration presented here, the solution is typically posted 45 minutes after earthquake occurrence. Solution includes a map summing up the SCARDEC results and a figure showing the agreement to the data. The map presents the earthquake location (together with the plate boundaries from Bird [2003] and the slab contours of SLAB 1.0 [Hayes et al., 2012]) and the main SCARDEC source parameters. Numerical values of focal mechanism parameters and seismic moment are written below the map. The data agreement figure compares the SCARDEC synthetics (red) with the FDSN data (black), in the frequency range used for focal mechanism determination. The name of GEOSCOPE stations is written in green.


See more information (about the data, the procedure, the reasons that could prevent from providing the earthquake information, the source time function determination...) in the "detailed notes".

If using some of the SCARDEC results, please refer to:

(1) Vallée, M., J. Charléty, A.M.G. Ferreira, B. Delouis, and J. Vergoz, SCARDEC : a new technique for the rapid determination of seismic moment magnitude, focal mechanism and source time functions for large earthquakes using body wave deconvolution, Geophys. J. Int., 184, 338-358, 2011.

(2) Vallée, M., Source time function properties indicate a strain drop independent of earthquake depth and magnitude, Nature Communications, doi: 10.1038/ncomms3606, 2013.



The method is running and maintained at IPGP laboratory. Apart from IPGP, past and present support to the development of the method are/were provided by the following institutes/projects :

                                                                            


We are grateful to the organisms providing, managing or federating data:

                                                                      


is used for drawing some maps of the webpage.