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Pelatihan : Techniques in Active Tectonic Study Juni 20-Juli 2, 2013

Pelatihan : Techniques in Active Tectonic Study Juni 20-Juli 2, 2013 Instruktur: Prof. J Ramon Arrowsmith (JRA) Dari Arizona State University (ASU) - US. Tempat Pelaksanaan:

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Pelatihan : Techniques in Active Tectonic Study Juni 20-Juli 2, 2013

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  1. Pelatihan : Techniques in Active Tectonic Study Juni 20-Juli 2, 2013 Instruktur: Prof. J Ramon Arrowsmith (JRA) Dari Arizona State University (ASU) - US Tempat Pelaksanaan: Ruang Pangea, Laboratorium Gempabumi (LabEarth) – Puslit Geoteknologi LIPI dan Kuliah lapangan akan dilakukan disekitar Sesar Lembang, Jawa Barat. * Lebih jelas baca TOR/KAK dan daftar acara

  2. Earthquake RecurrenceOutline of this lecture • Simple models of earthquake recurrence • Segmentation • Earthquake rate models: Gutenberg-Richter and Characteristic • Earthquake recurrence simulation

  3. Simple Earthquake Machine

  4. Subduction earthquake cycle

  5. A. Periodic earthquake model in which stress levels at the time of rupture and after it are known. These yield a predictable time and slip for each earthquake. B. Time-predictable model based on a consistent stress level at which failure occurs. Stress drop and slip magnitude are unpredictable, but given previous slip, time until the next earthquake (with unknown slip) is predictable. C. Slip-predictable model based on a consistent stress level at the end of an earthquake. Given time since the last rupture, magnitude of slip is predictable. Modified after Shimaki and Nakata (1980) Burbank and Anderson

  6. Burbank and Anderson, 2011, Tectonic Geomorphology, Chapter 4

  7. Burbank and Anderson, 2011, Tectonic Geomorphology, Chapter 4

  8. Basic fault segmentation Burbank and Anderson

  9. Fault zone is comprised of heterogeneous non coplanar fault surfaces bounding oblate blocks whose geometry and activity varies in time and space 3D mixed mode stepover Cross-section view mode III step (bend) Map view mode II step (bend) Questions: Geometric—Fault surface and block shapes and sizes Time—How long are they active? What is slip history? Block motion history? Development—Linkage and evolution of roughness • Strong influences on • Stress and displacement fields around the fault surfaces • Further development and linkage • Fluid flow • Rupture dynamics • Fault zone strength

  10. Predicting the endpoints of earthquake ruptures (I) Wesnousky, 2006

  11. Predicting the endpoints of earthquake ruptures (II) Step size “stop light color scheme” About 2/3 rupture terminations are associated with discontinuities or fault ends Wesnousky, 2006

  12. Megathrust earthquake segmentation model for Indonesia region (Irsyam et.al., 2010)

  13. Estimated maximum magnitude and slip rate of faults in Indonesia (Irsyam et.al, 2010)

  14. Earthquake magnitude and frequency: Earthquake rate model

  15. 1984 “…individual faults and fault segments tend to generate essentially the same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum” given fault geometry Full Rupture of seismogenic width of fault Zielke and Arrowsmith, 2008

  16. High resolution satellite imagery based offset reconstruction along Fuyun Fault, China

  17. Approximately 2kyr recurrence interval

  18. If we know slip rate du/dt And we assume u(x) per event We can get recurrence time uave or umax per event should also imply length and M Burbank and Anderson

  19. Synoptic view of continental shear zone (Scholz, 1988)

  20. Burbank and Anderson, 2011, Tectonic Geomorphology, Chapter 4 Modified from Zielke and Arrowsmith, 2008

  21. Burbank and Anderson, 2011, Tectonic Geomorphology, Chapter 4 Modified from Zielke and Arrowsmith, 2008

  22. Thatcher, 1990 So what do these earthquakes look like along the fault over time? Quasi-static earthquake simulator using elastic dislocations with stress boundary conditions and simple friction produces synthetic earthquake catalogue (900,000 events > 5km2 over 540kyr; cumulative stress history) Zielke and Arrowsmith, 2008; Zielke, 2009

  23. RW vs. Freq. Bimodal Seismicity Distribution • Down-dip rupture width RW of small EQs is limited by zp • Rupture of strength barrier zp causes activation of full seismic zone • Abrupt increase in RW and RA at transition from small to large EQs • Abrupt increase in Magnitude Small vs. Large EQ Mag. vs. Freq.

  24. Implies bimodal M, RA, and slip at surface->controlling influence of event on landscape Moderate M, partial rupture, Gutenberg-Richter Large M, full rupture, Characteristic Zielke and Arrowsmith, 2008

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