The 2002 GEOTER Seismic Hazard Model for the Caribbean - Lesser Antilles


The GEOTER 2002 PSHA model for the Lesser Antilles was developed under the revision of the France seismic zonation including the overseas territories. The PSHA input model for the Lesser Antilles is described in the GEOTER Report (Martin et al., 2002) . Here we present a short description of how this model was implemented in the OpenQuake-engine.

The seismic source model for the Lesser Antilles describes the major tectonic structures present in the region:

  • The mainly left-lateral-strike-slip faults along the north-eastern Caribbean plate boundary,
  • The subduction of the North American plate in the Caribbean ones in Lesser Antilles Arc,
  • The large transform right-lateral-strike-slip faults along the south-eastern Caribbean plate boundary,
  • The Lesser Antilles arc with:
    1. an extensional shear zone to the north,
    2. a transitional zone in the central part, with sinistral strike-slip deformation (between the Guadaloupe and Martinique islands), and
    3. a zone of dextral oblique compression to the south related with the accretion prism parallel to the arc,

In the original model the tectonic figures are defined as area sources. The crustal source zones were modelled with a 2D geometry at a fixed depth, while for the subduction ones a 3D geometry was used for both interface and intraslab source zones (see details in annex 3). In addition, an alternative subduction model was proposed by the authors, simplifying the geometry of several intraslab sources.

In the OpenQuake-engine implementation, the source model is implemented in a unique source model file in NRML format representing the different typology and tectonic region types defined in the original model. The shallow crustal seismicity are modeled as NRML areaSource, while the subduction interface and intraslab faults are implemented as NRML complexFaultSource objects. The alternative subduction model have not been considered in the OpenQuake-engine implementation.

The map below depicts the annual occurrence rate per source (between minimum and maximum magnitudes) for the different source models included in the hazard model. Click the show map layers icon to view different source models and base layer maps.

operating instructions

Various functions are available as part of the map.

mouse/touch operation
  • moving by grabbing the map with a mouse-click you can move the map around
  • overview map using the + button in the bottom right of the map you can expand an overview map
  • zooming in and out using the + and - buttons in the top left of the map you can obtain more or less detail in the map
  • switching themes or maps clicking on the ≡ icon on the right-hand side of the map you can view and select available maps and themes
  • retrieving information the map may contain elements that contain more information, by clicking these a popup will show this information
  • fullscreen display using the ✈ button the map can be maximized to fullscreen display, use the ✕ button to return to page display.
keyboard operation

Keyboard operation becomes available after activating the map using the tab key (the map will show a focus indicator ring).

  • moving using the arrow keys you can move the map
  • overview map using the + button in the bottom right of the map you can expand an overview map
  • zooming in and out using the + and - buttons in the top left of the map or by using the + and - keys you can obtain more or less detail in the map
  • switching themes or maps clicking on the ≡ icon on the right-hand side of the map you can view and select available maps and themes
  • retrieving information the map may contain elements that contain more information, using the i key you can activate a cursor that may be moved using the arrow keys, pressing the enter will execute an information retrieval. press the i or the escape key to return to navigation mode
  • fullscreen display using the ✈ button the map can be maximized to fullscreen display, use the ✕ button to return to page display.

It's possible that some of the functions or buttons describe above have been disabled by the page author or the administrator

 

.mbtiles

Total occurrence rate
(number of events / year)
  • < 1e-6
  • 1e-6 - 1e-5
  • 1e-5 - 1e-4
  • 1e-4 - 1e-3
  • 1e-3 - 1e-2
  • 1e-2 - 1e-1
  • 1e-1 - 1
  • 1 - 10
  • >= 10

In the original model, three GMPEs related to the main tectonic regimes present in the region were used. A logic tree combined these GMPEs.

Active Shallow Crust Weight
IPSN, 1999 0.5
Takahashi et al., 2000 0.5
Subduction Interface Weight
Youngs et al., 1997 0.5
Takahashi et al., 2000 0.5
Subduction Intraslab Weight
Youngs et al., 1997 0.5
Takahashi et al., 2000 0.5

In the OpenQuake-engine it was not possible to implement some of the GMPEs originally used by GEOTER 2002 (IPSN, 1999 and Takahashi et al., 2000). However, using well recognised GMPEs (Zhao et al., 2006 and Youngs et al., 1997) the results show an acceptable agrement with the maps published in the GEOTER 2002 report.

Active Shallow Crust Weight
Zhao et al., 2006 1.0
Subduction Interface Weight
Youngs et al., 1997 1.0
Subduction Intraslab Weight
Youngs et al., 1997 1.0

Reference site condition

A rock condition is assumed in the OpenQuake-engine implementation. The site condition is defined using a Vs30 = 760 m/s, which is equivalent to a rock condition site class in Zhao et al. (2006) and Youngs et al., (1997).

The figure below is the hazard map for peak ground acceleration, for 10% probability of exceedance in 50 years , using the OpenQuake-engine. The calculations considered Zhao et al. (2006) for active shallow crust tectonic regimes and Youngs et al. (1997) otherwise.

Comparison with GEOTER results

This is a preliminary model that does not have the same level of testing as other models implemented (i.e. USGS models) since in this specific case we did not have the original input model nor the results in an electronic format. In addition, as previously explained, we did not implement the GMPEs originally selected. However, the results show an acceptable agreement with the maps published in the GEOTER 2002 report.

The figures below show hazard maps for 10% probability of exceedance in 50 years, for the Islands of Guadeloupe and Martinique, comparing results from the GEOTER 2002 report (left) and the results computed with the OpenQuake-engine (right).



  • Feuillet N., Sismotectonique des Petites Antilles. Liaison entre activité sismique et volcanique, Thèse de doctorat de l’Université Paris 7, IPGP, 2000, 283 p.
  • IPSN (1998). Proposition de modification de la Règle Fondamentale I.2.c. relative à la détermination des mouvements sismiques à prendre en compte pour la sûreté des tranches nucléaires comportant un réacteur à eau sous pression, applicables à l’ensemble des installations nucléaires de base en surface. Rapport IPSN DES n° 348.
  • Martin C., Combes P., Secanell R., Lignon G., Carbon, D., Fioravanti A., Grellet, B. (2002). Révision du zonage sismique de la France France: Etude probabiliste. Rapport GEO-TER n°GTR/MATE/07/01-150. GEO-TER 2002 Report
  • Takahashi, T., Kobayashi, S., Fukushima, Y., Zhao, J.X., Nakamura, H., and Somerville, P.G. (2000). A spectral attenuation model for Japan using strong motion data base. In: Proceedings of the Sixth International Conference on Seismic Zonation.
  • Youngs, R.R., Chiou, S.J., Silva, W.J., and Humphrey, J.R. (1997). Strong ground motion attenuation relation-ships for subduction zone earthquakes. Seismological Research Letters, 68(1), pp.58-73. Journal website
  • Zhao, J. X., J. Zhang, A. Asano, Y. Ohno, T. Oouchi, T. Takahashi, H. Ogawa, K. Irikura, H. K. Thio, P. G. Somerville, Yasuhiro Fukushima, and Yoshimitsu Fukushima (2006). Attenuation relations of strong ground motion in Japan using site classification based on predominant period, Bull. Seismol. Soc. Am. Vol. 96, No. 3, pp.898–913. Journal website

This table summarises the main characteristics of the original implementation of this model

1 Datasets availability
1.1 Earthquake catalogue Not available. The catalogue used is a combination of local (Clement and Bernard, 2001; SRU/UWI; Rojas et al.,1993) and regional (IPGH, PDE, ISC) catalogues.
1.2 Geological database Not available. In the seismic zonation several information was used, mainly, from Feuillet (2000) and GEO-TER n° GTR/MATE/0899-108 (GEO-TER internal report). A good description is included in Martin et al. (2002)
1.3 Strong-motion database Not available
1.4 Site characterization database Not available
Notes
2 Methodology for model development
2.1 Scientific participation (SSHAC levels) and review process
2.2 Documentation describing model preparation Martin et al.(2002) provides a general description of the methodology adopted for the creation of the hazard model.
2.3 Codes used for model preparation Not available
Notes
3 PSHA input model
3.1 Seismic Source Model
3.1.1 Area sources Included
3.1.2 Grid sources Not included
3.1.3 Crustal faults Not included
3.1.4 Subduction faults The subduction sources (interface and intra-slab) are modelled as area sources with a 3D-geometry
3.1.5 Non-parametric ruptures Not included
3.1.6 Magnitude-area scaling relationships Not explicitly defined in Martin et al. (2002)
3.2 Ground Motion Model
3.2.0 Tectonic regionalisation Not included, but the seismotectonic zonation follows Feuillet (200)
3.2.1 Models for active shallow seismicity Included
3.2.2 Models for subduction interface Included
3.2.3 Models for subduction intraslab Included
3.2.4 Models for stable continental regions Not included
3.2.5 Models for deep non-subduction sources Not included
3.2.6 Models for volcanic areas Not included
3.3 Site Response Model
3.3.1 Based on GMPEs Yes, a rock site condition is considered
3.3.2 Based on site-response analysis No
3.4 Epistemic uncertainties
3.4.1 Seismic Source Model Included. A unique source model for shallow crustal sources, while for the subduction an alternative model is proposed, simplifying the geometry of several intra-slab sources.
3.4.2 Ground Motion Model Included using a logic tree (see the ground motion model section)
3.4.3 Site Response Model Not included
Notes
4 Hazard Input Description
4.1 Hazard input document Available, [add link]
4.2 Input files Not Available, but an extensive information about the parameter used is provides in Martin et al. (2002) - (annex 3)
Notes
5 Calculation
5.1 Software Available upon request (CRISISv.7)
5.2 Results
5.2.1 Hazard curves Not directly available
5.2.2 Hazard maps Not directly available
5.2.3 Uniform hazard spectra Not directly available
5.2.4 Disaggregation Not directly available
5.2.5 Stochastic event sets Not considered
5.2.6 Ground motion fields Not considered
Notes

The OpenQuake-engine input model (NRML format) can be downloaded at the link provided below - Please read the license and disclaimer attached to the model.

N.B. This is a model adapted by GEM Hazard Team to the OpenQuake-engine from the original model developed by Geoter. This explains minor differences you might encounter between the results presented in the OpenQuake platform and those disseminated by the original Organisation.

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  • geoter2002_intro.txt
  • Last modified: 2016/10/07 10:15
  • by Armando Scarpati