M 7.5 - Elbistan earthquake, Kahramanmaras earthquake sequence

  • 2023-02-06 10:24:48 (UTC)
  • 38.011°N 37.196°E
  • 7.4 km depth

Finite Fault

 Contributed by US last updated 2023-02-17 23:32:51 (UTC)
  • The data below are the most preferred data available
  • The data below have been reviewed by a scientist
Version 3

Scientific Analysis

This finite fault model includes analysis of both teleseismic and regional seismic and geodetic observations. We include observations from 38 teleseismic P-waves, 28 teleseismic SH-waves, and 48 long-period surface waves, selected based on data quality and azimuthal distribution. We also consider observations from 23 strong-motion accelerometer stations, 16 high-rate GNSS stations, and 28 static GNSS offsets. The strong-motion accelerometer and GNSS data were provided by: Prof. Dr. Tuncay Taymaz (İstanbul Technical University, Türkiye), Prof. Dr. Taylan Öcalan (Yıldız Technical University, Türkiye), Prof. Dr. Seda Yolsal-Çevikbilen (İstanbul Technical University, Türkiye), and Prof. Dr. T. Serkan Irmak (Kocaeli University, Türkiye). This solution has been update to include Synthetic Aperture Radar (SAR) range (line-of-sight) and azimuth (horizontal along-track) sub-pixel offset observations from scenes acquired on 2023-01-29 and 2023-02-10. The SAR observations are Copernicus Sentinel data 2023, processed by the European Space Agency (ESA). Sub-pixel offsets were processed with the JPL/Caltech/Stanford InSAR Scientific Computing Environment (ISCE) package. Resampled offsets, converted to meters of displacement, are available in the downloads section. Grey lines on the map view indicate preliminary fault rupture mapping (https://doi.org/10.5066/P985I7U2). These models will be updated as more information becomes available.

Data Process and Inversion

We analyzed 38 teleseismic broadband P waveforms, 28 broadband SH waveforms, and 48 long period surface waves selected based on data quality and azimuthal distribution. Waveforms are first converted to displacement by removing the instrument response and are then used to constrain the slip history using a finite fault inverse algorithm (Ji et al., 2002). We begin modeling using a hypocenter matching or adjusted slightly from the initial NEIC solution ( location = 38.0°N, 37.2°E; depth = 10.5 km ), and a fault plane defined using either the rapid W-Phase moment tensor (for near-real time solutions), or the gCMT moment tensor (for historic solutions).

Result

This result is based on the moment tensor nodal plane ( strike = 276.0°; dip = 80.0° ). The seismic moment release based upon this plane is 5.0e+20 N-m (Mw = 7.8) using a 1D crustal model interpolated from CRUST2.0 (Bassin et al., 2000).

This solution uses 3 plane segments (see Table below) designed to match a priori knowledge of the fault (e.g. 3D slab geometry).

Plane Segments
SegmentStrikeDip
1 276.0° 80.0°
2 250.0° 80.0°
3 60.0° 80.0°

Cross-section of Slip Distribution

Slip distribution map image
Cross-section of slip distribution. The strike direction is indicated above each fault plane and the hypocenter location is denoted by a star. Slip amplitude is shown in color and the motion direction of the hanging wall relative to the footwall (rake angle) is indicated with arrows. Contours show the rupture initiation time in seconds.

Surface Projection

Finite fault basemap
Surface projection of the slip distribution superimposed on GEBCO bathymetry. Thick white lines indicate major plate boundaries [Bird, 2003]. Gray circles, if present, are aftershock locations, sized by magnitude.

Moment Rate Function

Moment rate function image
Source time function, describing the rate of moment release with time after earthquake origin, relative to the peak moment rate (listed in the top right corner of the plot). The red dashed line represents the interpreted end of the event.