This document discusses evaluating the seismic risk to geodetic survey markers in western Riverside County from a large earthquake. Data on earthquake shaking potential, landslides, liquefaction, faults and roads were analyzed in GIS to assess risk to each survey marker. A table was created showing the nearest low-risk road to each marker and whether it is at risk from hazards. A graph shows the number of markers at risk from landslides, liquefaction or being near a fault. The analysis will help plan access to the markers after a major quake.

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David Guenaga
12/10/15
Western Riverside County Roads and UCR Measured Survey Marker Seismic Risk Evaluation
1.0 Introduction
If a large earthquake occurs in Riverside County what would be the best routes to reach the
University of California, Riverside (UCR) measured survey markers from UCR campus? Will it even be
possible to reach all sites? Will the markers remain intact and accessible to be measured after such an
incident? To answer these question, a map consisting of roads and UCR measured geodetic survey
markers with an earthquake (related) risk evaluation was constructed. A graph outlining the number of
survey markers that are at risk from these hazards and a chart that includes the nearest road and distance
from that road for each marker was made. The approximate spatial extent of my analysis is the western
part of Riverside County. The seismic hazards associated with any major active faults that were
considered in this project are a landslide, liquefaction, (seismic produced) shake, and fault proximity.
2.0 Background Information
Geodetic survey markers are objects placed to mark key survey points on the Earth's surface.
Using GPS surveying equipment, data can be obtained from these markers to create velocity models and
constraints on fault slip rates. This research is especially important in Southern California where there is
various large active fault including the San Andreas Fault which is capable of large (> 6 Mw)
earthquakes. Thus, it is important that we can get to these markers to continue gathering data -- even in
the aftermath of a large earthquake. During the summer of 2015, I had the great pleasure of conducting
such a GPS survey campaign with Dr. Funning and Nader Shakibay-Senobari here at the UCR. The
experience gave me an appreciation for the surveying geodetic survey markers. For this reason, my
project focuses on determining the best routes to take to reach various geodetic survey markers measured
by UCR in the aftermath of a large earthquake.
3.0 Data
3.1 Inset Map Data
To create the inset map, the US States and US Counties shapefiles were used.
The US States map layer portrays the State boundaries of the United States, and the boundaries of
Puerto Rico and the U.S. Virgin Islands. It uses North American Datum of 1983 geodetic datum and was
created at 1:2,000,000 scale by the U.S. Geological Survey last updated in June 2005. To acquire this data
go to National Maps-Small Scale Collection site (http://nationalmap.gov/small_scale), click
Governmental Units/Boundaries. Scroll down to State Boundaries, Two Million-Scale, and find
shapefile: statesp020.tar.gz. The shapefile will be named statesp020.
The US Counties map layer portrays the County boundaries of the United States. It uses North
American Datum of 1983 geodetic datum. To acquire this data go to Census-TIGER site
(http://www.census.gov/geo/www/tiger), click TIGER/Line Shapefiles – New 2015 Shapefiles. Open the
2015 tab and choose Download > Web interface. Under Select, a Layer Type, click Counties (and
equivalent). The shapefile will be named tl_2014_us _county.
3.2 Main Maps Data
To create the main (or final) map, the following layer in addition to the county shapefiles were used.

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The Shake CA (a.k.a. Earthquake Shaking Potential for California) map shapefile portrays the
probabilistic seismic hazard caused by potential earthquakes in California. It uses the North American
Datum of 1927 geodetic datum. The data is from Department of Conservation California Geological
Survey site (http://www.quake.ca.gov/). To acquire the shapefile go to (ftp://ftp.consrv.ca.gov), click pub/
> dmg/ > rgmp/ > MS48. The shapefile will be named ms48r_1hz_2pc50. Only data in western Riverside
County was considered for this project, see Fig 1.
Figure 1
Map of Shake Potential in western Riverside County.
Note: Map does not show all the data included in the original shapefile, but only the data relevant to
this project.
The Landslide SoCA raster file shows the relative likelihood of deep-seated land sliding based on
regional estimates of rock strength and steepness of slopes. It uses the North American Datum of 1983
geodetic datum and was created using United States Geological Survey (USGS) 2009 National Elevation
Dataset (NED) with 10-m grid size as the base map. Data is from Department of Conservation California
Geological Survey site (http://www.quake.ca.gov/). To acquire the shapefile go, to
(ftp://ftp.consrv.ca.gov), click pub/ > dmg/ > rgmp/ > MS58, then download Susdata.zip. The raster file
will be called sus2re_socal. Only data relevant to western Riverside County was used in this project, see
Fig 2.

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Figure 2
Map of landslide susceptibility and active faults in western Riverside County.
Note: Map does not show all the data included in the original shapefiles, but only the data relevant to
this project.
The Faults shapefile contains information on faults in the United States that are believed to be
sources of > 6 Mw earthquakes during the Quaternary (past 1,600,000 years). It uses a geographic
coordinate system specifically the World Geodetic System of 1984. The shapefile was mapped at various
scales, however, it is accurate on a 1:250,000 scale. To acquire shapefile, go to the USGS Earthquake
Hazards site (http://earthquakes.usgs.gov/hazards/qfaults), click GIS Shapefiles. The shapefile will be
named qfaults. Faults located western Riverside County were the only faults considered for this project,
see Fig. 2.
The Liquefaction shapefile contains information about areas in Riverside County identified to be
susceptible to liquefaction. The shapefile is part of CWStatic geodatabase file. It uses a projected
coordinate system, (North American Datum of 1983 based) State Plane California VI coordinate system.
Due to a lack of metadata the scale at which this shapefile was created/digitized is not known. To acquire
the file, go to Riverside County Information Technology: GIS Data site
(http://gis.rivcoit.org/GISData.aspx), click on Countywide Static. Liquefaction data in western Riverside
County was the only data used in the consideration of this project, see Fig. 3.

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Figure 3
Map of liquefaction susceptibility western Riverside County.
Note: Map does not show all the data included in the original shapefile, but only the data relevant to
this project.
The Roads shapefile contains Riverside County roads infrastructure. The shapefile is part of
CWActive geodatabase file. It uses a projected coordinate system, (North American Datum of 1983
based) State Plane California VI coordinate system. Due to a lack of proper metadata, the scale at which
this shapefile was created/digitized is not known. To acquire file go to Riverside County Information
Technology: GIS Data site (http://gis.rivcoit.org/GISData.aspx), click on Countywide Active. Only roads
and highways in western Riverside County were considered for this project, see Fig. 4.

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Figure 4
Map of roads and highways in western Riverside County.
Note: Map does not show all the data included in the original shapefile, but only the data relevant to
this project.
The UC, Riverside shapefile shows the general campus location of University of California,
Riverside (UCR), see Fig. 5. I created this shapefile using coordinate obtained from Google Earth. Also,
the symbol (UCR logo) used in this shapefile was obtained from UCR’s Creative Design Services site
(http://creativedesign.ucr.edu/standards.html).
The Survey Marker shapefile contains various information on UCR measured geodetic survey
markers, see Fig. 5. Coordinates for sites where obtained from various sources which have been added to
a KMZ file. UNAVCO: Data Archive site (http://www.unavco.org/data/gps-gnss/data-access-
methods/dai2/app/dai2.html#) should also contain the coordinate to these survey markers.

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Figure 5
Map with the Cities in Western Riverside County, the locations of UCR and relevant geodetic survey
markers. Note: Cities data was not used in this project.
4.0 Method
4.1 Methods used for Inset Map
The CA Counties layer was made from the US Counties shapefile. In US Counties layer,
California Counties were selected and extracted into a new shapefile. To do this the Select by Attribute
option from the attribute table was used to select relevant counties and then exported as a new layer.
A new shapefile, Riverside County, was made from the CA Counties layer. In CA Counties layer,
Riverside County was selected and extracted into a new shapefile. To do this the Select by Attribute
option was used to select Riverside County and then exported into a new layer. Note that this file was
later used as the base (cookie-cutter) layer for the main map.
4.2 Methods used for Main Maps
The Survey Marker KMZ file was converted into a GIS layer using the Conversion Tools > From
KML > KML to Layer tool. Note that to convert this layer into an editable shapefile the layer was
exported/saved as a shapefile.

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Due to the map being on a county scale, a projected coordinate system (NAD 1983 State Plane
California VI). Thus, Earthquake Shaking Potential, Faults, Riverside County, Geodetic Survey Markers
and Land Slide layers were projected to this coordinate system. For the shapefiles, Data Management
Tools > Projections and Transformations > Project can be used to achieve this. In the Input Class, use the
shapefile (i.e. Earthquake Shaking Potential, Faults, and Riverside County) and NAD 1983 State Plane
California VI as the Output Coordinate System. For the Land Slide layer use Tools > Projections and
Transformations > Raster > Project Raster. Set Land Slide as the Input Raster and NAD 1983 State Plane
California VI as the Output Coordinate System.
The Earthquake Shaking Potential, Faults, and Roads are clipped using “Riverside County”
shapefile. To achieve this the Analysis Tools > Extract > Clip tool was used. For each previously
mentioned shapefile put it as the Input Features and Riverside County as the Clip Features. To do this for
the Landslide raster file, the Spatial Analyst Tools > Extraction > Extract by Mask tool was used. For the
Input raster use Landslides layers and Riverside County as the Input Mask.
The Faults layer was then used to make a buffer show areas that may be damaged by the fault
itself. To do this the Analysis Tools > Proximity > Buffer tool was used. The Faults layer was set as the
input, the dissolve type was set to all and the buffer distance parameter was set to 50 ft. This distance was
used because it is the distance at which the California Code of Regulations CCR 3603 generally states
that buildings should not be built within 50 ft. from a fault. Thus, it was assumed that this legal limit
suggests that any structure located 50 ft. from a fault would be damaged by the fault itself.
The Landslides raster layer was converted into a shapefile with Conversion Tools > From Raster
> Raster to Polygon tool. The Land Slides raster was put as the input.
To create a Hazards layer a union of the Land Slide, Faults Buffer, Liquefaction, and Shake
Potential shapefiles was made. To do this the Analysis Tools > Overlay > Union tool was used. The Land
Slide, Faults Buffer, Liquefaction, and Shake Potential shapefiles were all used as input features.
To create a (new) Survey Markers Layer with hazards information the Analysis Tools > Overlay
> Intersect tool was used. Both the Survey Markers and Hazards layer were used as input features.
Afterward, any irrelevant information in the attributes table in the new Survey Markers Layer was
removed (i.e. hazards FID, and data not associated with measured risk).
The Analysis Tools > Overlay > Erase tool is then used to create a Safe (assessed as low risk)
Roads shapefile. You will need to make a new (temporary) Hazards shapefile that only has polygons
which have a risk value as high as or higher than the one determined to affect the roads. For the purposes
of this project, it was assumed that any road segment that were located in an area with within the fault
buffer, at least a moderately high (GRIDCODE ≥ 8) landslide susceptibility, at least a moderate risk
(SUSCEPTIBI = Moderate, High) of liquefaction, or at least moderately high (g ≥ 1.0) shake potential
was considered at risk. Note that these value found in the hazards related layers are dimensionless. Thus,
the aforementioned threshold for roads hazard was determined using the most rational value.
Nevertheless, the Select By Attribute option can be used to select these areas from the Hazard layer and
exported into a temporary layer. Then the new/temporary Hazards layer is set as the Erase Feature and the
Roads layer as the input feature.
The Analysis Tools > Proximity > Near tool can be used determine the closest safe low-risk road
and added to every survey marker’s attribute. Set the Survey Marker layer as the input feature and the
Safe Roads layer as the near feature. The new Survey Marker shape file thus now contain various
information about the markers local seismic hazard (i.e. Liquefaction, Land Slide, Near Fault, High

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Shake), distance from nearest safe low-risk road and that road’s name. This data was exported from the
attributes table option into a text file. Then this text file was imported into excel to create a graph and a
table.
Figure 6
Flow map of the general analysis/steps taken throughout the project to create the final map, chart, and
table.
5.0 Results
In the clipping process, four new layers were made. These new layers included a shake potential,
faults, landslide susceptibility, and roads layer which only display/contain data in Riverside County.
These new layers are all shapefiles with the exception of the landslide which remains as a raster layer. A
Faults Buffer layer was created with the buffer tool. This layer contains polygons that encompass the fault
line features with a buffer distance of 50 ft. The raster to polygon conversion created a polygon version of
the Riverside Land Slide Susceptibility raster file. The intersection involved with the hazards and the
survey markers shapefiles created another point shapefile. This also combined any information that was
located at those points from the input shapefiles. This includes data about the survey marker, landslide
susceptibility, fault buffer, and liquefaction susceptibility. By exporting the survey markers file’s
attributes table, a text file with comma separated values was created. With this file a table containing the
marker’s names, local landslide susceptibility, liquefaction susceptibility, fault buffer information
(located on it or not), and the nearest safe road and its distance from it, see Table 1. This data was then
furthered used to create a graph that contains the seismic hazards (landslide susceptibility, liquefaction
susceptibility, near a fault) and shows the number of survey markers at affected, see Fig. 7.

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Table 1: Geodetic Survey Marker Assessment
Marker
Name
Nearest Low-Risk Road Distance
(m)
Marker
Risk
N410 MISSION CREEK RD 8206.466 T
N409 MISSION CREEK RD 7359.357 T
INDO FOREST ROUTE 4S21 90.28578 F
822 FALLS CREEK RD 6661.258 T
MCFN ROUSE HILL RD 1210.183 T
Z311 BRIGGS RD 8.554382 F
APPL LAMBS CANYON RD 3722.463 T
RNGR POPPET FLAT DIVIDE TRUCK
TRL
478.8331 F
G077 FOREST ROUTE 6S18 1507.564 T
BERN DALE ST 255.6651 F
BEFT HOMESTEAD HILLS RD 12.48998 F
G078 ROUSE HILL RD 1567.813 T
ANZA HWY-371 178.4815 T
821 HWY-74 236.8038 T
SONY HALLS GRADE RD 3448.804 T
BONO HALLS GRADE RD 2444.84 T
G076 ROUSE HILL RD 1891.554 T
YUNG I-15 273.563 F
RIT2 APEX WAY 64.34989 T
BOWN CAJALCO RD 1574.213 T
51 INTERNATIONAL TRUCK TRL 622.737 T
SHAW LAMBS CANYON RD 4809.987 T
LACY MANZANITA TRUCK TRL 2495.048 T
G068 KEISSEL RD 401.5395 F
G069 MORENO BEACH DR 3655.421 T
DRVE RECHE CANYON RD 2248.855 T
FATL SMILEY BLVD 2521.513 T
FRMT HOUGHTON AVE 51.34457 T
CLSA MARKET ST 772.463 T
LAST CAJALCO RD 12.88025 F
TBLR REGULUS ST 356.1878 T
CAJB EL SOBRANTE RD 136.4955 F
WALN WALNUT AVE 134.3959 T
METZ I-215 51.21245 F
SDA1 CENTRAL AVE 66.4268 T
WDA2 BELLINO WAY 372.5101 T
VERS COLLEGE PL 116.3565 T

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Figure 7
Survey markers risk assessment graph.
A map showing roads, the location of UCR and geodetic survey markers was constructed, see
Fig. 8. The map also distinguishes between roads and survey markers that are located in either an area that
has a moderately high or higher of landslide susceptibility, a moderate or higher risk of liquefaction, a
moderately high or higher shake potential, or is located within 50 ft. from fault.
6.0 Error Analysis
6.1 Error: Original Data
The county boundaries shapefile was digitized at a relatively small scale (1:1,000,000); thus, is highly
generalized. However, since in this project this layer was only used to limit the study area it should not
have a negative effect on the results produced in this project. The Faults shapefile likely suffers from
some errors. There is a ± 500 m accuracy mentioned in the metadata. The metadata also states that there is
some detection problem in regards to fault location, but this is mostly found in eastern parts of the U.S
(not necessarily in California, where the analysis takes place). More relevantly it states, the data is
appropriate at a 1:250,000 scale and that the California database is incomplete; not all faults are included.
Survey markers were measured consistently with survey grade equipment and the methods used produce
measurements with a ≤ 1 cm level of accuracy. However, there may be some digitizing (rounding) errors
present in the data. The shake potential shapefile is generalized and assumes shaking at a frequency of 1
Hz. No metadata could be found for this file; thus, it must be assumed that there likely are other errors
that have not accounted for as well. The landslide raster file states that its data is intended to provide a
general overview of where landslides are more likely to occur. Hence, it is not appropriate for evaluation
1
13
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27
36
24
21
17
10
0
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4
6
8
10
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14
16
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38
Near Fault (50 ft) Liquefaction Risk Land Slide Risk High Shake Risk Any Risk
NumberofSurveyMarkers
Risk Assessment
UCR Measured Survey Marker Damage Risk
Markers at Risk Markers Not at Risk

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of landslide potential at any specific site. The liquefaction shapefile description states that the coverage is
intended for reference only in cartographic products and analysis. Also, no proper metadata could be
found for this file. Roads layer has some inaccuracies, especially near UCR, where roads network are
displaced by ≤ 100 m. The metadata states that the horizontal spatial accuracy is appropriate for statistical
analysis and may not be appropriate for high precision measurement.
6.2 Error: Main Map Data
The main map produced is a highly generalized modeled that should only be used to obtained a general
evaluation of damage that may affect a GPS survey campaign. The use of some thresholds for
determining whether roads or survey markers would be at risk is also somewhat arbitrary. It should also
be noted that a change of these threshold values (to include or omit different values) would produce a
vastly different map, table, and graph.
7.0 Discussion
Visually interpreting the final map produced, it seems that the majority of relevant survey
markers cannot be reached from UCR without crossing a road or road segment marked at risk of
earthquake-related damage. Furthermore, the graph created shows that about 76% of survey markers are
also at risk of being negatively affected by a large seismic event. These risks include those caused by
landslides, liquefaction, proximity fault, or high amounts of shaking. Specifically, landslides risks include
the burial or roads/survey markers by relatively large amounts of sediments or the collapse of the
sediment which these structures are built on. Liquefaction would damage these structures by damaging
the integrity of the ground which it is placed on. Being near or on a fault has the risk of ground
displacement which can warp or divide (break) the features being considered. The high shake could cause
shear stress damage on buildings, boulders and other large features that could damage or cover
roads/markers.
8.0 Future Work
Due to the data used, there are very few survey markers that can be reached from UCR effectively
making the results of this project somewhat impractical. For this reason considering specific seismic
events from specific faults (e.g. San Andreas, San Jacinto, etc.) can be assessed individually. This may
provide more practical maps where only roads affected by single events will be marked at risk. This
would allow for some flexibility as in the case of any particular large event the map relating to it; thus, it
would omit irrelevant information from other seismic events. For a complete evaluation, all of the
geodetic survey markers ever measured by UCR could be included. In this project only geodetic survey
markers measured during UCR’s 2015 summer GPS campaign where considered. Additionally, there are
various other data that could consider for a more comprehensive evaluation. Hence, more research,
evaluations and models should be done.

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Figure 8
Final map showing (seismic related) damage potential to roads and geodetic survey markers.