Indonesia (IDN)

Authors:

M. Irsyam., L. Faizal, D. Natawidjaja, I. Meilano, S. Widiyantoro, W. Triyoso, A. Rudiyanto, S. Hidayati, M. Asrurifak, M. Ridwan, P. Cummins

Summary

The 2017 seismic hazard model for Indonesia was developed by the Team for Updating Seismic Hazard Maps of Indonesia of the National Center for Earthquake Studies, Indonesia. (Irsyam et al., 2017). The model builds on the experience collected throughout the last 15 years and on international collaborations notably with the United States Geological Survey (USGS) and Geoscience Australia. The model was originally produced partly using the NSHMP software of the USGS and partly in the OpenQuake (OQ) engine. To achieve an entirely OQ implementation, part of the model has been translated from its original format into OQ.

Information about the OQ model versions and input files can be found on the Results and Dissemination page.

Interactive Viewer

The viewer below depicts the seismic sources and hazard results in terms of PGA for a return period of 475 years. Click on the menu in the upper right corner to select the layer.

viewer_legend

Tectonic overview

Indonesia is one of the most tectonically complex nations on Earth. The majority of the country is on continental and transitional crust of Indochina, and many oceanic plates and microplates subduct under this more buoyant crust. A continuous subduction zone from offshore Myanmar to Papua forms the south and west border of the country, where crust of the Indian and Australian plate dives beneath Indonesia, creating great megathrust earthquakes as well as smaller, shallower faults and volcanoes in the upper plate that can be very hazardous. To the east, very complicate and poorly understood subduction systems also create the potential for damaging earthquakes throughout Sulawesi, the Moluccas, Papua, Timor and eastern Borneo, and the many smaller intervening isles.

Basic Datasets

See Irsyam et al. (2017) for a description of the datasets used for developing the hazard model.

Hazard Model

Seismic Source Characterisation

The seismic source characterisation (SSC) consists of various seismic source typologies to describe earthquake occurrence in different tectonic settings. Distributed seismicity is used to model both active shallow and deep intraslab seismicity, while fault sources are used to model seismicity occurring on shallow crustal faults and large subduction interface events.

The OQ implementation uses three OQ source typologies. The background (gridded) seismicity models are implemented as collections of Point Sources. Crustal faults are modelled using Simple Fault Sources, and and subduction faults are modeled using Complex Fault Sources. The OQ sources are depicted in the interactive viewer.

Ground Motion Characterisation

The table below shows the ground motion characterisation (GMC), which is comprised of a set of ground motion prediction equations (GMPEs). The GMM for the 2017 Indonesia model distinguishes between three main tectonic regions: Active Shallow Crust, Subduction Interface, and Subduction Inslab.

Epistemic Uncertainties

For every tectonic region, epistemic uncertainty is considered by using multiple GMPEs, each with an associated logic tree weight.

Active Shallow Crust Weight
BooreAtkinson2008 0.2
CampbellBozorgnia2008 0.2
ChiouYoungs2008 0.2
BooreEtAl2014 0.133
CampbellBozorgnia2014 0.133
ChiouYoungs2014 0.134
Subduction Interface Weight
YoungsEtAl1997SInter 0.15
AtkinsonBoore2003SInter 0.15
ZhaoEtAl2006SInter 0.3
AbrahamsonEtAl2015SInter 0.4
Subduction Inslab Weight
Geomatrix1993SSlabNSHMP2008 0.333
AtkinsonBoore2003SSlabNSHMP2008 0.333
AtkinsonBoore2003SSlabCascadiaNSHMP2008 0.334

Results

Hazard curves were computed with the OQ engine for peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2s, 0.5s, 1.0s, and 2s. The computation was performed on a grid of 51725 sites (spaced at approximately 10 km) with reference soil conditions with shear wave velocity in the upper 30 meters (Vs30) of 760-800 m/s.

The hazard map for PGA corresponding to a 10% probability of exceedance in 50 years (475 year return period), can be seen using the interactive viewer. For a more comprehensive set of hazard and risk results, please see the GEM Visualization Tools.

References

M. Irsyam, S. Widiyantoro, D. Natawidjaja, I. Meilano, A. Rudiyanto, S. Hidayati, W. Triyoso, N. R. Hanifa, D. Djarwadi, L. Faizal, Sunarjito (editor), Team for Updating of Seismic Hazard Maps of Indonesia 2017. 2017. Earthquake Source and Hazard Maps of Indonesia 2017. National Center for Earthquake Studies (PusGen), Research Center for Housing and Human Settlement, Directorate General for Research and Development, Ministry oof Public Works and People Housing, ISBN 978-602-5489-01-3. (in Indonesian)

Irsyam, M., Natawijaya D. H., Daryono M.R., Widiyantoro S., Asrurifak M., Meilano I., Triyoso W., Hidayati S., Rudiyanto A., Sabaruddin A., Faisal L. (2017). Development of new seismic hazard maps of Indonesia 2017. In Proceedings of the19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul 2017.