Introduction: Seismicity estimates play an important role in creating regional geological characterizations, which are useful for understanding a planet's formation and evolution, and of key importance to site selection for landed missions. Here we investigate the regional effects of lunar seismicity with the goal of determining whether surface features such as landslides and boulder trails on the Moon are triggered by fault motion

Nahm, A. L.

Schmerr, N.

Weber, R. C.

Yanites, B.

NASA Technical Reports Server

MASS WASTING ON THE MOON: IMPLICATIONS FOR SEISMICITY.  R. C. Weber,1 A. L. Nahm2,3, B. 
Yanites3, and N. Schmerr4, 1NASA Marshall Space Flight Center (renee.c.weber@nasa.gov), 2DLR Institute for 
Planetary Research, 3University of Idaho, 4University of Maryland. 
 
 
Introduction: Seismicity estimates play an im-
portant role in creating regional geological characteri-
zations, which are useful for understanding a planet’s 
formation and evolution, and of key importance to site 
selection for landed missions. Here we investigate the 
regional effects of lunar seismicity with the goal of 
determining whether surface features such as land-
slides and boulder trails on the Moon are triggered by 
fault motion (Fig. 1).  
Lobate scarps: Lobate scarps, the typical surface 
expressions of thrust faults resulting from tectonic 
compression, are widely observed on the Moon [1]. 
Compared to other types of tectonic faults, surface-
cutting thrust faults require the largest amount of stress 
to form and/or slip, and thus are expected to result in 
large quakes. While normal faults, graben, and wrinkle 
ridges are also abundant on the Moon, these structures 
would generate smaller theoretical maximum quakes 
than lobate scarp thrust faults. Thus, we optimize our 
chances of finding mass wasting associated with faults 
by studying lobate scarps. 
Methodology:  We first calculate the theoretical 
maximum quake that could occur as a result of slip on 
a fault and then determine the effects on the surround-
ing surface morphology. The expected damage area 
indicated by seismic wavefield modeling is compared 
to mapped imagery to determine the likelihood of a 
quake having triggered mass wasting.  
Theoretical maximum quake.  Following the meth-
od outlined in [2], the theoretical maximum quake 
magnitude is derived from basic fault properties. These 
are either estimated from imagery or derived from la-
boratory rock experiments or elastic dislocation mod-
els, and include the fault length, width, dip angle, and 
depth of faulting. Fault displacement is calculated us-
ing displacement-length scaling such that D=γL, where 
γ is determined by rock type and tectonic setting [3].  
The best measure of the size of a quake is the seis-
mic moment, which is calculated by multiplying the 
shear modulus of the ruptured rock by the area of the 
ruptured portion of the fault and the average displace-
ment produced during the quake [2]. The seismic mo-
ment represents the total energy consumed in produc-
ing displacement on a fault, regardless of the local 
strain rate or fault formation mechanism. 
Seismic wavefield modeling. In order to determine 
the dimensions of an area affected by seismic shaking, 
we model the ground motion resulting from the theo-
retical maximum quake along a given fault. We use the 
Serpentine Wave Propagation Program (WPP), a nu-
merical code for simulating seismic wave propagation 
in 3D [4, 5]. The initial model of a given fault includes 
regional topography derived from digital elevation 
models, and the Moon’s background 1D velocity. 
Geomorphological analysis: Peak vertical ground 
motion occurs within a few kilometers of the main 
shock and drops off rapidly away from the source. 
Thus we should expect most of the mass wasting phe-
nomena to occur in the immediate vicinity of the fault. 
However, this result may depend on regional effects 
such as surface slope and megaregolith thickness; a 
thicker megaregolith (as might be expected in the vi-
cinity of large craters) would tend to focus shaking in 
some of the crater basins.  
We will compare the observed extent of mass wast-
ing in the vicinity of a fault to the modeled event mag-
nitude and peak ground motion in order to establish a 
method to translate quake parameters into mass wast-
ing estimates. This has been performed for terrestrial 
examples focused on determining landslide area and 
density over time in seismically active regions [6]. We 
expect to find systematic variations in fit parameter 
estimates for each body, reflecting different gravita-
tional strengths, regolith cohesion properties, and other 
geomorphic settings local to each study region. 
 References: [1] Watters, T. R. et al. (2015) Geol-
ogy 43/10, 851–854. [2] Nahm, A. L. and Velasco, A. 
A. (2013) LPSC 44th, Abstract #1422. [3] Cowie, P. A. 
and Scholz, C. H. (1992) J. Struct. Geol. 14, 1149–
1156. [4] Schmerr, N. et al. (2013) LPSC 44th, Abstract 
#2438. [5] Sjogreen, B. and Petersson, N. A. (2012) J. 
Sci. Comp. 52, 17–48. [6] Meunier, P. et al. (2007) 
GRL 23, doi:10.1029/2007GL031337. 
 
Fig. 1: (left) Landslide deposits in Marius crater (11.9°N,    
-50.8°E). (right) Evershed S1 lobate scarp (33°N, 197.1°E). 
https://ntrs.nasa.gov/search.jsp?R=20160006720 2019-08-31T02:42:47+00:00Z


Mass Wasting on the Moon: Implications for Seismicity

Seismicity estimates play an important role in creating regional geological characterizations, which are useful for understanding a planet's formation and evolution, and are of key importance to site selection for landed missions. Here we investigate the regional effects of seismicity in planetary environments with the goal of determining whether such surface features on the Moon, could be triggered by fault motion

Weber, Renee

Yanites, Brian

Nahm, Amanda

Schmerr, Nick

Mass wasting on the Moon: Implications for seismicity
RENEE WEBER - NASA MARSHALL SPACE FLIGHT CENTER             AMANDA NAHM - DLR INSTITUTE FOR PLANETARY RESEARCH
                        NICK SCHMERR - UNIV. OF MARYLAND                                                          BRIAN YANITES - UNIV. OF IDAHO
Overview
Seismicity estimates play an important role in creating 
regional geological characterizations, which are useful for 
understanding a planet’s formation and evolution, and 
are of key importance to site selection for landed 
missions. Here we investigate the regional eects of 
seismicity in planetary environments with the goal of 
determining whether such surface features on the Moon, 
could be triggered by fault motion (Fig. 1).
Fig. 1: (left) Landslide 
deposits (granular ow) 
on an interior slope of 
Marius crater  
(11.9° N, -50.8° E). 
(right) Boulder track 
emanating from the 
central peak complex of 
Schiller crater 
(-51.8° N, -40.0° E). 
Lobate scarps, the typical surface expressions of thrust 
faults resulting from tectonic compression, are widely 
observed on the Moon (Figs. 2&3). Compared to other 
types of faults, surface-cutting thrust faults require the 
largest amount of stress to form and/or slip, so they could 
possibly generate large quakes. While normal faults, 
graben, and wrinkle ridges may be more abundant on 
Mars, the Moon, and Mercury respectively, these struc-
tures would create smaller theoretical maximum quakes 
than lobate scarp thrust faults. Thus, we optimize our 
chances of nding mass wasting associated with faults by 
studying lobate scarps.
Lobate scarps
Fig. 2: Examples of lobate scarps
Evershed S1
center lat/lon 
33°N/197.1°E
Utopia Planitia #s 1801, 1802, 1804
 center lat/lon
52.9°N/119.2°E
Beagle Rupes
center lat/lon
 -3.5°N/100.7°E
Fig. 3: Map of digitized locations of lobate scarps on the Moon. Over 3200 lunar scarps 
(red) have been mapped. Mare basalt units are shown in tan. From Watters et al., 2015. 
(Geology Vol. 43 No. 10)
Waveeld modeling
0
50
100
0 50 100
0
1
2
3
4
5
6
0
50
100
0 50 100
0
1
2
LO
G
10 [A
m
plitude] (cm
/s)
E
levation (km
)D
is
ta
nc
e 
(k
m
)
Distance (km) Distance (km)
Topography Maximum Vertical Velocity
Fig. 5: (left) LOLA surface topography input into the wave propagation simulation. The 
Evershed scarp is centered in the image (see Fig. 2). (right) Predicted maximum vertical ground 
motion for a MW=7.8 quake on a subjacent reverse fault, with a 2.25 km depth of faulting. The 
surface trace of the scarp is marked with a red line. A random distribution of heterogeneity of 
25% in S- and P-wave velocity with 100 km scale length scatterers is placed in the megaregolith 
to simulate the scattering observed on Apollo seismograms.  The expected damage area indi-
cated by seismic waveeld modeling is compared to mapped imagery to determine the likeli-
hood of a quake having triggered mass wasting. 
Future work
Map instances of mass
wasting around faults 
Rule out
impact-
generated
shaking
100m
Methodology
Following the method outlined in Nahm & Velasco, 2013 
(LPSC 44th Abstract #1422), we derive a theoretical quake 
magnitude from basic fault properties. These are esti-
mated either from imagery, laboratory rock experiments, 
or elastic dislocation models, and include the length (L), 
dip angle (δ), depth of faulting (T), displacement (D), and 
fault width (w). Fault displacement is calculated using 
displacement-length scaling such that D=γL, where γ is 
determined by rock type and tectonic setting. 
To determine the dimensions of an area aected by 
seismic shaking, we model the ground motion resulting 
from the theoretical maximum quake along a given fault 
(Figs. 4&5). We use a numerical code for simulating 
seismic wave propagation through a 3-D structure model 
including topography. Peak vertical ground motion typi-
cally occurs within a few kilometers of the main shock 
and drops o rapidly from there. This implies that we 
should expect most of the mass wasting phenomena to 
occur in the immediate vicinity of the fault. However, this 
result may depend on regional eects like surface slope 
and megaregolith thickness. A thicker megaregolith (as 
might be expected in the vicinity of craters) would tend 
to focus shaking in some of the crater basins. 
Fig. 4: Seismic structure of the lunar crust and megaregolith. (left) The crustal velocity model 
after Weber et al., 2011 (Science Vol. 331), showing the geology of the subsurface. The 
megaregolith extends from the surface to just above the structurally disturbed crust. (right) 
Wave propagation for a model with a 1 km thick layer of low-velocity megaregolith showing 
the development of surface waves and reverberations trapped in the layer. From Weber et al., 
2015 (Extraterrestrial Seismology, Cambridge Univ. Press).
75
150
225
300
450
600
750
900
1000
Ep
ice
nt
ra
l D
ist
an
ce
 (k
m
)
Time(s)
0 500 1000 1500 2000 2500 3000 3500
REGOLITH
EJECTA
FRACTURED CRUST
STRUCTURALLY 
DISTURBED CRUST
LUNAR CRUST
LUNAR MANTLE
Vp (km/s)
0
2
15
38
1 3 5 7
De
pt
h 
(k
m
)
Vs (km/s)
Geomorphological analysis:
Establish a method to translate 
quake parameters into mass 
wasting estimates 
e.g. 
quake magnitude
~
area of damage 
zone?
e.g.
fault length
~
boulder trail 
density?
https://ntrs.nasa.gov/search.jsp?R=20160006721 2019-08-31T02:42:48+00:00Z


Nahm, Amanda L.

Institute of Transport Research:Publications

MASS WASTING ON THE MOON: IMPLICATIONS FOR SEISMICITY.  R. C. Weber,1 A. L. Nahm2,3, B. Yanites3, and N. Schmerr4, 1NASA Marshall Space Flight Center (renee.c.weber@nasa.gov), 2DLR Institute for Planetary Research, 3University of Idaho, 4University of Maryland.   Introduction: Seismicity estimates play an im-portant role in creating regional geological characteri-zations, which are useful for understanding a planet’s formation and evolution, and are of key importance to site selection for landed missions. Here we investigate the regional effects of lunar seismicity with the goal of determining whether surface features such as land-slides and boulder trails on the Moon are triggered by fault motion (Fig. 1).  Lobate scarps: Lobate scarps, the typical surface expressions of thrust faults resulting from tectonic compression, are widely observed on the Moon [1]. Compared to other types of tectonic faults, surface-cutting thrust faults require the largest amount of stress to form and/or slip, and thus are expected to result in large quakes. While normal faults, graben, and wrinkle ridges are also abundant on the Moon, these structures would generate smaller theoretical maximum quakes than lobate scarp thrust faults. Thus, we optimize our chances of finding mass wasting associated with faults by studying lobate scarps. Methodology: We first calculate the theoretical maximum quake that could occur as a result of slip on a fault and then determine the effects on the surround-ing surface morphology. The expected damage area indicated by seismic wavefield modeling is compared to mapped imagery to determine the likelihood of a quake having triggered mass wasting.  Theoretical maximum quake.  Following the meth-od outlined in [2], the theoretical maximum quake magnitude is derived from basic fault properties. These are either estimated from imagery or derived from la-boratory rock experiments or elastic dislocation mod-els, and include the fault length, width, dip angle, and depth of faulting. Fault displacement is calculated us-ing displacement-length scaling such that D=γL, where γ is determined by rock type and tectonic setting [3].  The best measure of the size of a quake is the seis-mic moment, which is calculated by multiplying the shear modulus of the ruptured rock by the area of the ruptured portion of the fault and the average displace-ment produced during the quake [2]. The seismic mo-ment represents the total energy consumed in produc-ing displacement on a fault, regardless of the local strain rate or fault formation mechanism. Seismic wavefield modeling. In order to determine the dimensions of an area affected by seismic shaking, we model the ground motion resulting from the theo-retical maximum quake along a given fault. We use the Serpentine Wave Propagation Program (WPP), a nu-merical code for simulating seismic wave propagation in 3D [4, 5]. The initial model of a given fault includes regional topography derived from digital elevation models, and the Moon’s background 1D velocity. Geomorphological analysis: Peak vertical ground motion occurs within a few kilometers of the main shock and drops off rapidly away from the source. Thus we should expect most of the mass wasting phe-nomena to occur in the immediate vicinity of the fault. However, this result may depend on regional effects such as surface slope and megaregolith thickness; a thicker megaregolith (as might be expected in the vi-cinity of large craters) would tend to focus shaking in some of the crater basins.  We will compare the observed extent of mass wast-ing in the vicinity of a fault to the modeled event mag-nitude and peak ground motion in order to establish a method to translate quake parameters into mass wast-ing estimates. This has been performed for terrestrial examples focused on determining landslide area and density over time in seismically active regions [6]. We expect to find systematic variations in fit parameter estimates for each body, reflecting different gravita-tional strengths, regolith cohesion properties, and other geomorphic settings local to each study region.  References: [1] Watters, T. R. et al. (2015) Geol-ogy 43/10, 851–854. [2] Nahm, A. L. and Velasco, A. A. (2013) LPSC 44th, Abstract #1422. [3] Cowie, P. A. and Scholz, C. H. (1992) J. Struct. Geol. 14, 1149–1156. [4] Schmerr, N. et al. (2013) LPSC 44th, Abstract #2438. [5] Sjogreen, B. and Petersson, N. A. (2012) J. Sci. Comp. 52, 17–48. [6] Meunier, P. et al. (2007) GRL 23, doi:10.1029/2007GL031337.  Fig. 1: (left) Landslide deposits in Marius crater (11.9°N,    -50.8°E). (right) Evershed S1 lobate scarp (33°N, 197.1°E). 6009.pdfNew Views of the Moon 2 (2016)

Mass Wasting on the Moon: Implications for Seismicity

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