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Friday, July 27, 2018

All day
 
 
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The 2016 Mw 6.5 Pidie Jaya, Aceh, North Sumatra Earthquake
Dr. Muzli

The 2016 Mw 6.5 Pidie Jaya, Aceh, North Sumatra Earthquake

Event date: 27 July 2018 - 4:00pm to 5:00pm
Event type: Seminar
Venue: ASE 3D Viz Laboratory Room (N2-B1c-16c)
Speaker: Dr. Muzli
About the speaker:

Muzli has been a Research Fellow at EOS since 2017, working with Shengji’s group. Prior to that he was a researcher and lecturer at Badan Meteorologi, Klimatologi dan Geofisika (BMKG) in Indonesia. He completed his Masters and PhD in 2013 at the German Research Center for Geosciences (GFZ) in Potsdam, Germany; prior to that he worked as a seismic analyst at BMKG for 8 years.

 


On December 6, 2016, an Mw 6.5 earthquake occurred in Pidie Jaya, Aceh, about 30 km to the north of Sumatran Fault (SF) that killed more than 100 people and destroyed approximately 3,000 buildings. Mainshock focal mechanism inversions using regional BMKG broadband data and teleseismic waveform data all indicate a strike-slip event with a centroid depth of 11-15 km. The observed macro intensity data show that most of the damaged buildings are distributed along the coast, approximately perpendicular to the ruptured fault strike instead of parallel with it. The strong shaking/damage sites are primarily located on the coastal sedimentary soils, highlighting the importance of site conditions in determining risk. We used one-month data recorded by nine temporal broadband stations to locate aftershocks with grid search and double-difference algorithms, thereby resolving a linear trend of seismicity aligned in NE-SW direction. The refined aftershock locations indicate a left-lateral rupture that is in agreement with the preliminary finite fault slip inversion as well as geomorphic signatures of local geological structure. Using a well-located ML 4.2 aftershock for path calibration, we relocated the mainshock epicenter with regional P-wave arrivals. The refined epicenter falls within the cloud of the well-located aftershocks while locations from the global and regional catalogs are located 10–20 km away. Aftershock focal mechanisms determined by the first motion reveal similar solutions as the mainshock. This earthquake sequence ruptured a previously unidentified fault that either located at the west of the fault that produced the 1967 Mw6.1 earthquake sequence, or is actually at the same fault. The Pidie Jaya earthquake and other off Sumatran Fault events suggest strong distributed crustal deformation in Aceh, highlighting the need for better understanding of active faulting and seismic hazard in this region.

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