Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Finite-fault source inversion for the 1992 Flores tsunami, considering multiple data types Ignatius Ryan Pranatyo1 , Phil Cummins1,2 , Jonathan Griffin2 , Hamzah Latief3 1
Research School of Earth Sciences, the Australian National University, 2 Geoscience Australia, 3 Institute Technology of Bandung
August 22, 2017
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
The 1992 Flores Earthquake and Tsunami • 12 December 1992, 13:30
(local time). M w = 7.8 • MMI IX − X at
Maumere and Ende • More than 2000 deaths • 3-5m tsunami run-up
heights and extreme run-up at Riangkroko village (Tsuji et al. 1995)
source: Yeh et al.,1993
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Previous studies Is the Flores back-thrust a long-linear fault? 1. It’s a shallow depth earthquake (3 - 16 km) & on land epicenter 2. Its strike and aftershocks distribution crossing the thrust
Tsunami modelling
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Is it a segmented thrust fault? • Many discontinue minor
thrust faults between Flores and Alor (Silver et al. 1983, 1986) • The earthquake strike
and aftershocks distribution agree to the minor thrust structure • Semau strike-slip thrust
as the boundary of the west-end of Alor-Wetar thrust (?)
?
Summary
Objectives
Background
Imamura & Kikuchi 1995
Fixing the fault plane
Hidayat et al., 1995
Source inversion
Griffin et al., 2015
Tsunami modelling
Summary
USGS web page (access April 2017)
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Summary
Objectives
To improve the source of the Flores 1992 earthquake and tsunami that fits to the seismic, tsunami, and uplift/subsidence data. 1. Fixing the fault plane 2. Joint finite-fault source inversion 3. Forward tsunami and earthquake modelling
Objectives
Background
Fixing the fault plane
Source inversion
Fixing the fault plane 1. Forward tsunami model from many fault plane models =⇒ the most similar tsunami waveform modelled at Palopo
Strike = 60◦ − 70◦ Dip = 30◦ − 40◦
Tsunami modelling
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Summary
2 Joint inversion teleseismic and uplift data =⇒ the most fit to the surface waves and uplift/subsidence • Strike = 75◦ • Dip = 30◦ • Depth = 9
km
Objectives
Background
Fixing the fault plane
3 Earthquake modelling by EXSIM =⇒ that able to generate high intensities at Maumere and Ende
Source inversion
a
b
PGA −→ MMI a Imamura et al. (1995) b Hidayat et al. (1995) c This study
c
Tsunami modelling
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Final source inversion Joint inversion teleseismic and uplift data =⇒ Relative weight of the body and surface waves, and uplift data =⇒ Smoothing coefficient =⇒ Velocity rupture, time windows, rise time
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Forward tsunami modelling 1. Source inversion result =⇒ JAGURS code =⇒ tsunami run-up heights and waveform 2. Source inversion result + 4 landslides =⇒ JAGURS code =⇒ tsunami run-up heights and waveform 4 landslides:
Summary
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Summary
Forward tsunami modelling results
• The new source inversion result +
landslide sources improve the run-up heights estimated • The waveform at Palopo tide gauge is
still unrecovered
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Summary
Summary
1. A segmented Flores back-thrust need to be considered for earthquake and tsunami hazard study 2. A new source for the 1992 Flores earthquake and tsunami is suggested 3. A future investigation is needed to resolve the waveform at Palopo gauge
Objectives
Background
Fixing the fault plane
Source inversion
Tsunami modelling
Summary
Thank you for your attention! Any questions? e-mail:
[email protected]
Acknowledgments: • Australia Awards Scholarship • RSES-ANU student travel grant • Dr. Sebastien Allgeyer • Cipta Athanasius
