| PaperNO | Paper / Abstract |
|
SS1-007
10:50
|
11:10
|
The 1960 Chile Earthquake -- Implication for Slip Partitationing at a Convergent Boundary
The 1960 Chile Earthquake -- Implication for Slip Partitationing at a Convergent Boundary
Hiroo Kanamori
1960 Chile Earthquake
|
|
SS1-001
11:10
|
11:30
|
What have we learned from the 1999 Ms7.6 Chi-Chi, Taiwan, Earthquake for Resolving the basic Problems in Earthquake Physics?
There have been long three debatable basic problems in earthquake physics (Sornette, 1999): (1) the strain problem (localized versus non-localized); (2) the stress problem (high versus low); and (3) the heat flux problem (high versus low). Based on the Reid’s elastic rebound model (see Turcotte and Schubert, 2002), the width, 2w, in which the shear strain develops progressively across the fault prior to the earthquake, is 2w=mD/Ds where m, D, and Ds are the rigidity of fault-zone material, final slip, and static stress drop (see Turcotte and Schubert, 2002). For the 1999 Chi-Chi earthquake, the estimated value of D=3.1–6.0 m (Wang, TAO 2005), Ds=4.2–10.0 MPa (Wang, GRL 2005), and m=19 GPa (Wang et al., JAES 2009) lead to 2w=5.9–27.1 km, with an average of 18 km. This suggests strain localization. From near-field seismograms, Wang (JGR, 2006) obtained the initial stress on the fault, so, is 52% and 70% less than average crustal stress, sL, respectively, on the southern and northern segments. This implies that the Chelungpu fault was weaker prior to faulting, and the southern segment was weaker than the northern one. From the borehole data, Wang (JGR, 2009) assumed that the heating time span was short and heat flux during the earthquake was low.
Jeen-Hwa Wang
strain, stress, heat flux
|
|
SS1-012
11:30
|
11:50
|
Probing fault friction and crustal rheology from co-seismic and postseismic observations
Thanks to the abundance and the quality of local and global field data (accelerometric seismological and geodetic data in particular) as well as remote sensing observations (from optical and radar imaging), the Mw7.6 Chi-Chi earthquake stands out as one of the best-constrained earthquake ever documented. I’ll discuss some of the key observations that were made on this earthquake, and similar observations from other case-examples, and what we have learned regarding fault frictional properties, the bulk rheology of the crust.
Jean-Philippe Avouac
co-seismic, fault friction, postseismic
|
|
SS1-002
11:50
|
12:10
|
WHAT WE LEARN FROM THE TAIWAN CHELUNPGU FAULT DRILLING PROJECT
Scientific questions are commonly raising after big earthquakes, e.g., what are the fault-zone materials and how the material properties of the active fault and associated processes affect its propensity to catastrophically slide rather than creep? what was the absolute stress levels on the fault during the earthquake? and how the stresses recover afterward to prepare for the next event? The Taiwan Chelungpu fault Drilling Project (TCDP) provided the opportunity to collect key physical and chemical data for answering the questions raised by the 1999 Mw7.6 Chi-Chi earthquake. Almost 100% recovery fault-zone rocks indicate the seismic slip occurred along an exceptionally narrow zone (1- to 3-millimeter wide), showing the physical, chemical, microstructural, magnetic, mineralogical anomalies. The obtained anomalies were utilized for the estimate of earthquake source parameters. In addition, the results on the core samples from two boreholes of TCDP document that slipping-zone fault gouges were experiencing high temperature and fluid-rich conditions, suggesting the processes of thermal pressurization (up to 300?C) and frictional melting (up to 1000?C). Integrated with the recent established concept, the efficiency of thermal pressurization relevant to the hydraulic properties of damage zone, our results suggest that multi-fault zone processes occurred simultaneously during the earthquake likely due to the heterogeneous hydraulic properties of damage zone and/or fault geometry. Recently, we obtain an additional critical scientific information, stress states, estimated from clay fabrics reoriented by thermal pressurization, which may explain the presence of aseismic deformation in the area or changed focal mechanisms after main shocks.
Li-Wei Kuo, Sheng-Rong Song, Kuo-Fong Ma, Chien-Ying Wang, En-Chao Yeh, Hiroki Sone
1999 Chi-Chi Earthquake, fault gouge, frictional melting, TCDP, thermal pressurization
|
|
SS1-013
12:10
|
12:25
|
STATUS OF THE ISC BULLETIN AND ASSOCIATED DATASETS IN THE AREA OF 1999 CHI-CHI EARTHQUAKE
The International Seismological Centre (ISC) continues with its long-term mission of producing the most complete, comprehensive and homogeneous summary of instrumentally recorded seismicity on a global scale, based on seismic bulletin reports from ~150 seismic networks, observatories and data centres worldwide, including the Central Weather Bureau (CWB) and the Institute of Earth Sciences of Academia Sinica. Several associated datasets such as the ISC-GEM, ISC-EHB, GT and the Event Bibliography further expand the ISC Bulletin data for use both in education and in various research fields, such as general earthquake studies and forecasting, earthquake source, tectonics, seismic hazard studies and nuclear test monitoring. In this presentation we describe the status of these datasets in the area of Chi-Chi earthquake. We show what parametric earthquake data are openly available to researchers and how these data have been improved over the years since this notable earthquake has occurred.
Dmitry A. Storchak, James Harris
1999 Chi-Chi Earthquake, ISC, Seismology
|