Working models for spatial distribution and level of Mars' seismicity

Abstract

[1] We present synthetic catalogs of Mars quakes, intended to be used for performance assessments of future seismic networks on the planet. We have compiled a new inventory of compressional and extensional tectonic faults for the planet Mars, comprising 8500 faults with a total length of 680,000 km. The faults were mapped on the basis of Mars Orbiting Laser Altimeter (MOLA) shaded relief. Hence we expect to have assembled a homogeneous data set, not biased by illumination and viewing conditions of image data. Updated models of Martian crater statistics and geological maps were used to assign new maximum ages to all faults. On the basis of the fault catalog, spatial distributions of seismicity were simulated, using assumptions on the available annual seismic moment budget, the moment-frequency relationship, and a relation between rupture length and released moment. We have constructed five different models of Martian seismicity, predicting an annual moment release between 3.42 Â 10 16 Nm and 4.78 Â 10 18 Nm and up to 572 events with magnitudes greater than 4 per year as upper limit end-member case. Most events are expected on the Tharsis shield, but minor seismic centers are expected south of Hellas and north of Utopia Planitia.Citation: Knapmeyer, M., J. Oberst, E. Hauber, M. Wählisch, C. Deuchler, and R. Wagner (2006), Working models for spatial distribution and level of Mars' seismicity,

Interpretation and analysis of planetary structures

“…11) displays a characteristic tri-segment shape (Mansfield and Cartwright, 2001). Similarly shaped plots were shown for Martian faults on global (Knapmeyer et al, 2006) and local scales (Schultz, 2000b;Hauber et al, 2007). The fault population shown here (Fig.…”

Impact airblast triggers dust avalanches on Mars

“…Although the seismic properties of the martian crust are not well understood (Knapmeyer et al, 2006), short-wavelength seismic waves produced by the impact must attenuate as either 1/r surface waves on an approximately homogeneous layered target (Davis, 1993;Collins et al, 2005) or, if the near-surface of Mars is as chaotically fractured as that of the Moon, as an exponential due to intense scattering (Oberst and Nakamura, 1987). In either case, seismic wave propagation is basically the same in all directions radiating away from the impact site, except as modified by local structure beneath the surface.…”

Planetary structural mapping

“…The most common types of structures on Mars -grabens, thrust faults, and wrinkle ridges -demonstrate the predominance of extensional and contractional deformation, respectively, of the planet'S crust or lithosphere (Plate 24; see Tanaka et ai., 1991;Scott and Dohm, 1997;Dohm and Tanaka, 1999;Schultz, 2000a;Dohm et ai., 200 I a,b;Knapmeyer et at., 2006;Schultz et ai., 2007;Golombek and Phillips, Chapter 5). However, Mars also displays clear evidence of strike-slip faulting (Forsythe and Zimbelman, 1988;Schultz, 1989;Okubo and Schultz, 2006).…”

“…As in the previous lunar work, stratigraphic mapping of regionally extensive terrains on Mars provides the context for defining the relative ages of major deformational events (e.g ., Scott and Tanaka, 1986;Greeley and Guest, 1987;Tanaka, 1986Tanaka, , 1990Tanaka et ai., 1991Tanaka et ai., , 1992Dohm, 1990, 1997;Dohm and Tanaka, 1999;Dohm et ai., 2001 a,b;Anderson et ai., 2001;Knapmeyer et al, 2006). In contrast to the Moon, however, internal processes have largely dominated the production of surface-breaking structures on Mars, with impact-basin tectonics playing a subsidiary role (e.g., Phillips et ai., 2001) .…”