Tinjauan Seismologi dan Tomografi di Sekitar Zona Sumber Gempa Lombok 2018
Andri Dian Nugraha1,2, Sri Widiyantoro1, Ridwan Kusnandar 3, Shindy Rosalia4, Zulfakriza1, Muzli3, Pepen Supendi3, Daryono3, Samsul Wiyono 3, Nanang T Puspito3, Awali Priyono1, Billy S Prabowo 5, Yayan S M 5
1 Global
Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung 2 Presiden Himpunan Ahli Geofisika Indonesia (HAGI) 3Meteorological, Meteorological, Climatological, Cli matological, and Geophysical Agency (BMKG), Indonesia 4 Graduate Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung 5 Volcanology and Geothermal Laboratory, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung
OUTLINE
•
INTRODUCTION
•
HYPOCENTER RELOCATION
•
REGIONAL TOMOGRAPHY
•
LOCAL EARTHQUAKE TOMOGRAPHY
•
SEISMIC MONITORING IN LOMBOK (LOM-ITB SEISMOGRAPH STATION)
OUTLINE
•
INTRODUCTION
•
HYPOCENTER RELOCATION
•
REGIONAL TOMOGRAPHY
•
LOCAL EARTHQUAKE TOMOGRAPHY
•
SEISMIC MONITORING IN LOMBOK (LOM-ITB SEISMOGRAPH STATION)
Hypocenter Relocation
Hypocenter Relocation BMKG CATALOG DATA
SELECTION PHASE ≥ 8
SELECTION MAGNITUDE ≥3
52,155 Events
SELECTION AZIMUTHAL GAP ≤ 210 ~40,000 Events
Resulting ~35,000 events
as input for hypocenter relocation using teletomoDD
Periods: April 2009 up to June 2018
3D Velocity Model •
•
3D seismic velocity model beneath Indonesia region was taken from Widiyantoro & van der Hilst (1996) with grid size of 10x10 1D seismic velocity model from ak135 (Kennet et al., 1995) was used for regions outside Indonesia
(Pesicek, 2008)
Regional 3D Velocity Model (Widiyantoro & van der Hilst, 1996)
1D Global Velocity Model ak135 (Kennet et al., 1995)
Relocation Result
TeletomoDD successfully relocated ~35,000 events in Indonesia
Relocated Hypocenter Period of April 2009-June 2018 M≥3
M3 M4 M5 M6 M7
(Nugraha et al., 2018)
Historical Seismicity 1976-07-14
1963-05-18
1979-12-17
1979-10-20
(Nugraha et al., 2018) 1966-02-09 Historical Seismicity based on Newcomb & McCann (1987). Relocated hypocenter using teletomoDD period April 2009-June 2018
Seismicity in Lombok Area
A’
B’
A
B
(Relocated event for periods of April 2009 to June 2018) Lombok M 6.9 LOM1 (USGS)
LOM7
M 6.4 (BMKG) LOM6
M 6.9(BMKG) LOM5 LOM2
LOM3
Lombok Earthquake M 6.4 BMKG Time: 29-Jul-2018 05:47:39 WIB Location: 8.26 LS - 116.55 BT
Lombok Earthquake M 6.9 -BMKG Time 2018-08-05 T 11:46:34 Loc 116.48 -8.33 Depth 13 km -USGS Time 2018-08-05 11:46:37 (UTC) Loc 116.451 -8.287 Depth 31 km Mt. Rinjani B B’ S
A
A’
BMKG GFZ
B
B’ A’
B’
C’
D’
E’
A
B
C
D
E
USGS
Bali
C
C’
D
D’
E
E’
Lombok
Seismicity in Lombok Area M 6.4 29 July 2018 Long 116.508 lat -8.3239 Depth 14 km
(Relocated event for periods of April 2009 to June 2018) M7 05 August 2018 Long 116.47 lat -8.35 Depth 32 km
BMKG Catalog
M 6.4 29 July 2018 Long 116.5 lat -8.35 Depth 13 km
M 6.9 05 August 2018 Long 116.436 lat -8.26 Depth 31 km
USGS Catalog M 6.9 19 August 2018 Long 116.626 lat -8.324 Depth 25 km
M 5.6 19 August 2018 Long 116.53 lat -8.35 Depth 10 km
M 5.9 09 August 2018 Long 116.208 lat -8.394 Depth 10 km M 6.9 19 August 2018 Long 116.68 lat -8.44 Depth 10 km M 5.9 09 August 2018 Long 116.21 lat -8.44 Depth 14 km
M 6.3 19 August 2018 Long 116.59 lat -8.44
M 6.3 19 August 2018 Long 116.576 lat -
M 5.9 19 August 2018 Long 116.607 lat -
Focal Mechanism
Focal mechanism data are taken from USGS website for magnitude > 5
(Nugraha et al., 2018)
Regional Tomography Rinjani (Lombok)
(Widiyantoro et al., 2011)
Local Earthquake Tomography
RELOCATED EVENTS IN SUNDA-BANDA TRANSITION ZONE (April 2009 to December 2015, Waveform & Data Catalog from BMKG)
Wilis (A-A'), Kelud (B-B'), Semeru (C-C'), Raung (D-D'), Agung (E-E'), Rinjani (F-F), Tambora (G-G), Sangeang (H-H), Sumba (I-I), Kelimutu (J-J)
Mt Wilis
Mt Kelud
Mt Semeru
Mt Raung
Mt Agung
Mt Rinjani
Mt Tambora
Sumba
Mt Sangeang
Mt Kelimutu
Wilis (A-A'), Kelud (B-B'), Semeru (C-C'), Raung (D-D'), Agung (E-E'), Rinjani (F-F), Tambora (G-G), Sangeang (H-H), Sumba (I-I), Kelimutu (J-J)
Model Parameterization
West Region
East Region
Number of Grid Nodes 21 x 19 x 15 Horizontal Grid Nodes Spacing: 30 - 80 km Vertikal Grid Nodes Spacing: 10 – 50 km
Number of Grid Nodes 21 x 19 x 15 Horizontal Grid Nodes Spacing: 30 - 80 km Vertikal Grid Nodes Spacing: 10 – 50 km
(Kusnandar et al., 2018, in prep)
Vp Structure beneath Mt. Rinjani (Lombok)
(Kusnandar et al., 2018, in prep)
Vs Structure beneath Mt. Rinjani (Lombok)
(Kusnandar et al., 2018, in prep)
Vp/Vs Structure beneath Mt. Rinjani (Lombok)
(Kusnandar et al., 2018, in prep)
Vp Structure beneath Mt. Agung (Bali)
(Kusnandar et al., 2018, in prep)
Vs Structure beneath Mt. Agung (Bali)
(Kusnandar et al., 2018, in prep)
Vp/Vs Structure beneath Mt. Agung (Bali)
(Kusnandar et al., 2018, in prep)
Vp Structure beneath Mt. Tambora
(Kusnandar et al., 2018, in prep)
Vs Structure beneath Mt. Tambora
(Kusnandar et al., 2018, in prep)
Vp/Vs Structure beneath Mt. Tambora
(Kusnandar et al., 2018, in prep)
Seismograph Deployment in Lombok: Aftershock Monitoring (LOM-ITB Seismograph Network) S
6 Unit (KK GG - ITB): 2 BB (Guralph), 1 SP (Leinartz), 3 BB Borehole (Geobit)
20180805-11.46.38 (5 Agustus 2018) M6.9 – 0km SW of Loloan, Indonesia S V LOM03 SP
N-S
E-W
V LOM02 BB N-S
E-W
50 seconds
180809 05:25:31 (9 Agustus 2018) M5.9 – 3km SE of Todo, Indonesia 10 seconds S V LOM03 SP
N-S
E-W
LOM02 BB
V
N-S
E-W E-W
2018-08-19 04:10:21 (19 Agustus 2018) M6.3 – 6km NE of Sembalunlawang, Indonesia 20 seconds V
LOM03 SP
N-S
E-W
V LOM02 BB
N-S
E-W
S
2018-08-19 14:56:28 (19 Agustus 2018) M6.9 – 2km S of Belanting, Indonesia 20 seconds S V
LOM03 SP
N-S
E-W
V LOM02 BB N-S
E-W
2018-08-19 15:16:35 (19 Agustus 2018) M5.8 – 2km ENE of Sembalunlawang, Indonesia 10 seconds V
LOM03 SP
V V
N-S
E-W
V LOM02 BB
N-S
E-W
S
Earthquake Triggering Volcanism ?
Oct. 28, 1707 Nankai EQ M8.3 Dec. 16, 1707 Eruption of Fuji volcano July 16, 1990 Luzon EQ M7.7 June 15, 1991 Eruption of Pinatubo volcano
Denali EQ, Alaska, 2002
