Insights Into Tectonic Regionalisation in Seismic Hazard Analysis and Computational Methods for Delineation

Yen-Shin Chen1, Graeme Weatherill2, Marco Pagani3, GEM Working Group on Tectonic Regionalisation

1PhD Student, Understand & Managing Extremes School, Pavia, Italy2GEM Hazard Scientist, Pavia, Italy3GEM Hazard Coordinator, Pavia, Italy

26th, August, 2014 2ECEES Istanbul, Turkey

Precedents for Tectonic Regionalisation

Jordan (1981)

USGS (1997)

Douglas (2007) Kagan et al. (2010)

Precedents for Tectonic Regionalisation

Tectonic Regionalisation in Seismic Hazard Analysis

GMPEs• Active shallow crust• Subduction Interface/Intra-slab• Stable Continent Region• Volcanic• Non-subduction deep focus• Oceanic Travel Path• Q, attenuation• κappa

Magnitude Scaling Relations• Active shallow/subduction/SCR• Crustal age/structural maturity• Orogenic?• High/low stress drop

Tectonic Proxies• MMAX (e.g. EPRI, 1994) or Corner Magnitude• Recurrence (e.g. Truncated | Tapered G-R)• Seismogenic depth distribution?

Tectonic Regionalisation: Basic Objective Questions, Comments

Current Regionalisation methods are mainly performed by subjective judgements

– basis for delineation of zones remains unclear

Our goal is to design an quantitative and objective definition of a regionalisation scheme/methodology

– a global data driven and transparent, scalable, replicable approach

Possible Relevant Datasets for Seismic Hazard Regionalisation

Seismic Moment Rate

QLG Global Composite

(from Brian Mitchell, personal comm.)

Shear Wave Velocity Variation at Depth of 175 km

(Mooney, 2012)

Global Continent Crust Age Map(modified from CCGM)

Softening the Decisions: Implementation in a Fuzzy Framework

Ex: strain Rate10-9

Activenot Active

Definitely

Definitelynot

• Crisp Classification

Softening the Decisions: Implementation in a Fuzzy Framework

Ex: strain Rate10-9

Activenot Active

Definitely

Definitelynot

• Fuzzy Classification

Ex: strain Rate10-9

Softening the boundarydegree of belief

Definitely

Definitelynot

Based on knowledge …

ex:If Strain rate is high, then high chance to be Active

• Crisp Classification

Example of Fuzzy Framework

Smoothed Seismic Moment Rate

Log10(Mo)(N-m yr-1-km-2) Log10(Mo)(N-m yr-1-km-2)

Nor

mal

ized

reco

rdin

g nu

mbe

r

Stable Active Exploratory Data Analysis

Log

Mo(

N-m

yr-1

km

-2)

Stable Continent Regions by Johnson, 1994

Example of Fuzzy FrameworkSmoothed Seismic Moment Rate

Fuzzy Framework:

If moment rate is high, and S velocity var. is low Deg. of “Active” is high

Log

Mo(

N-m

yr-1

km

-2)

Shear Wave Velocity Variation

Shea

r wav

e ve

loci

ty v

ar.(%

)

(Mooney, 2012)

Stable

Shear wave velocity variation

Active

Nor

mal

ized

reco

rdin

g nu

mbe

r

Exploratory Data Analysis

Result - Degree of Being Active

SCR regions defined by Johnson, 1994

Degree of being

“Active”

Defuzzication– Active/ Stable Delineation

Stable Active

SCR regions defined by Johnson, 1994

Tectonic Regionalisation Model Drive From our Study

Stable Continent Region, Non-CratonStable Continent Region, Craton

SubductionActive Continent Shallow Region

Stable Oceanic Region Active Oceanic Region

Except where otherwise noted, this work is licensed under: creativecommons.org/licenses/by-nc-nd/4.0/

Please attribute to the GEM Foundation with a link to - www.globalearthquakemodel.org