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Hypocenter and magnitude analysis of aftershocks of the 2018 lombok, indonesia, earthquakes using local seismographic networks
Sasmi A.T.a, Nugraha A.D.a, Muzli M.c, Widiyantoro S.a,d, Zulfakriza Z.a, Wei S., Sahara D.P.a, Riyanto A.e, Puspito N.T.a, Priyono A.a, Greenfield T., Afif H.g, Supendi P.a,h, Daryono D.c, Ardianto A.a, Syahbana D.K.g, Husni Y.M.a, Prabowo B.S.a, Sarjan A.F.N.a
a Geophysical Engineering, Institut Teknologi Bandung, Bandung, Indonesia
b Earth Observatory of Singapore, Asian School of the Environment, Nanyang Technological University, Singapore
c Meteorology, Climatology, and Geophysics Agency (BMKG), Jakarta, Indonesia
d Universitas Kristen Maranatha, Maranatha Christian University, Bandung, Indonesia
e Meteorology, Climatology, and Geophysics Agency (BMKG), Mataram, Indonesia
f Bullard Laboratories, University of Cambridge, Cambridge, United Kingdom
g Center for Volcanology and Geological Hazard Mitigation (PVMBG), Bandung, Indonesia
h Meteorology, Climatology, and Geophysics Agency (BMKG), Bandung, Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]© 2020 Seismological Society of America.The island of Lombok in Indonesia is located between the Indo-Australian and Eurasian subduction trenches and the Flores back-arc thrust, making it vulnerable to earthquakes. On 29 July 2018, a significant earthquake Mw 6.4 shook this region and was followed by series of major earthquakes (Mw > 5:8) on 5, 9, and 19 August, which led to severe damage in the northern Lombok area. In this study, we attempt to reveal the possible cause of the sequences of the 2018 Lombok earthquakes based on aftershock monitoring data. Twenty stations were deployed to record earthquake waveform data from 4 August to 9 September 2018. In total, 3259 events were identified using 28,728 P- and 20,713 S-wave arrival times during the monitoring. The aftershock hypocenters were determined using a nonlinear approach and relocated using double-difference method. The moment magnitude (Mw) of each event was determined by fitting the displacement spectrum amplitude using a Brune-type model. The magnitudes of the aftershocks range from Mw 1.7 to 6.7. The seismicity pattern reveals three clusters located in the Flores oceanic crust, which fit well with the occurrences of the four events with Mw > 6. We interpret these events as the main rupture area of the 2018 Lombok earthquake sequence. Furthermore, an aseismic zone in the vicinity of Rinjani extending toward the northwestern part of Lombok was observed. We propose that the crust in this area has elevated temperatures and is highly fractured thus inhibiting the generation of large earthquakes. The aseismic nature is therefore an artifact of the detection threshold of our network (Mw 4.6).[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Detection threshold,Double differences,Earthquake sequences,Earthquake waveforms,Elevated temperature,Magnitude analysis,Nonlinear approach,Seismicity pattern[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]The authors would like to thank their colleagues at Institut Teknologi Bandung (ITB), the Earth Observatory Singapore (EOS), the Agency for Meteorology, Climatology, and Geophysics of Indonesia (Badan Meteorologi Klimatologi dan Geofisika [BMKG]), and the Center for Volcanology and Geological Hazard Mitigation of Indonesia (PVMBG) for their collaboration. They also express their gratitude for the Pendidikan Magister Menuju Doktor Untuk Sarjana Unggul (PMDSU) Batch IV scholarship program (2018) established by the Indonesian Ministry of Research, Technology, and Higher Education and for the support and research opportunities given to A. T. Sasmi, Kementrian Riset dan Teknologi / Badan Riset dan Inovasi Nasional (KEMRISTEK/BRIN) Indonesia research funding 2019 awarded to A. D. Nugraha and N. T. Puspito, and the World Class Research funding to S. Widiyantoro. Our thanks to R. Ryannugraha, A. D. Sasongko, F. T. Dasahruddyn, G. S. Fatih, and A. W. Baskara for their help during the data preparation process.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1785/0220190348[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]