U.S. Geological Survey

U.S. Department of the Interior

Prepared in cooperation with the Mojave Water Agency

U.S. Geological Survey

Water-Resources Investigations

Report 03-4015

Detection and Measurement of Land Subsidence Using

Interferometric Synthetic Aperture Radar and Global

Positioning System, San Bernardino County,

Mojave Desert, California
Detection and Measurement of Land Subsidence 

Using Interferometric Synthetic Aperture Radar 

and Global Positioning System, San Bernardino 

County, Mojave Desert, California

By Michelle Sneed1, Marti E. Ikehara2, Sylvia V. Stork1, Falk Amelung3, and Devin L. 

Galloway4

Prepared in cooperation with the

MOJAVE WATER AGENCY

Sacramento, California

2003

Water-Resources Investigations Report 03-4015

U.S. GEOLOGICAL SURVEY

1U.S. Geological Survey, Placer Hall, 6000 J Street, Sacramento, CA 95819-6129

2National Geodetic Survey, 1727 30th Street, MS35, Sacramento, CA 95816

3Division of Marine Geology and Geophysics—RSMAS, University of Miami, 4600 Rickenbacker

Causeway, Miami, FL 33149

4U.S. Geological Survey, 7801 Folsom Boulevard, Suite 325, Sacramento, CA 95826 7002-04
For additional information write to:

District Chief

U.S. Geological Survey

Water Resources Division

Placer Hall, Suite 2012

6000 J Street

Sacramento, California 95819-6129

http://ca.water.usgs.gov/ 

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does 

not imply endorsement by the U.S. Government.

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director
Contents iii

CONTENTS

Abstract ................................................................................................................................................................. 1

Introduction ........................................................................................................................................................... 2

Description of Study Area..................................................................................................................................... 2

Geohydrology........................................................................................................................................................ 4

Mojave River Ground-Water Basin ............................................................................................................. 4

Morongo Ground-Water Basin .................................................................................................................... 7

Mechanics of Land Subsidence............................................................................................................................. 7

Global Positioning System (GPS) Survey of Lucerne Valley Area...................................................................... 8

Land-Subsidence Monitoring Network........................................................................................................ 8

Determination of Ellipsoid Heights and Orthometric Heights (Elevations) ................................................ 11

GPS Results and Ground-Water Levels in Nearby Wells............................................................................ 12

Interferometric Synthetic Aperture Radar (InSAR) .............................................................................................. 15

InSAR Methods............................................................................................................................................ 15

InSAR Results.............................................................................................................................................. 16

Mojave River Ground-Water Basin .................................................................................................... 16

El Mirage Area........................................................................................................................... 16

Lockhart–Harper Lake (Dry) Area ............................................................................................ 24

Newberry Springs Area.............................................................................................................. 39

Morongo Ground-Water Basin—Lucerne Valley Area...................................................................... 47

Future Monitoring ................................................................................................................................................. 57

Conclusions ........................................................................................................................................................... 58

References Cited ................................................................................................................................................... 58
iv Figures

FIGURES

Figure 1. Map showing locations of the Mojave River and Morongo ground-water basins, San Bernardino County, 

California, and of three High Precision Geodetic Network (HPGN) stations ................................... 3

Figure 2. Geophysical and lithologic logs and construction diagrams of piezometers 9N/3E-22R4–7 in the 

Newberry Springs area of the Mojave River ground-water basin, San Bernardino County, 

California ........................................................................................................................................... 5

Figure 3. Geophysical and lithologic logs and construction diagrams of piezometers 4N/1W-1R4–9 in Lucerne 

Valley in the Morongo ground-water basin, San Bernardino County, California ............................. 6

Figure 4. Map showing location of Global Positioning System (GPS) stations and wells used to monitor 

vertical changes in land surface and ground-water levels, respectively, in Lucerne Valley, San 

Bernardino County, California........................................................................................................... 9

Figure 5. Hydrographs showing depth to water for selected wells near Global Positioning System (GPS) 

stations in Lucerne Valley, San Bernardino County, California, where vertical changes were 

largest................................................................................................................................................. 10

Figure 6. Photographs showing fissures near Lucerne Lake (dry) in San Bernardino County, Mojave 

Desert, California............................................................................................................................... 13

Figure 7. Amplitude image showing land-surface features and locations of wells used to evaluate 

subsurface geology or to monitor ground-water levels, and phase images and graphs showing 

vertical land-surface changes in the El Mirage area, San Bernardino County, California ................ 17

Figure 8. Hydrographs showing depth to water for selected wells and relative land-surface change in the 

El Mirage area, San Bernardino County, California.......................................................................... 23

Figure 9. Amplitude image showing land-surface features and locations of wells used to evaluate 

subsurface geology or to monitor ground-water levels, and phase images and graphs showing 

vertical land-surface changes in the Lockhart–Harper Lake (dry) area, San Bernardino 

County, California.............................................................................................................................. 25

Figure 10. Hydrographs showing depth to water for selected wells and relative land-surface change in the

Lockhart–Harper Lake (dry) area, San Bernardino County, California ............................................ 38

Figure 11. Amplitude image showing land-surface features and locations of wells and piezometers used 

to evaluate subsurface geology or to monitor ground-water levels, and phase images and graphs

showing vertical land-surface changes in the Newberry Springs area, San Bernardino 

County, California.............................................................................................................................. 40

Figure 12. Hydrographs showing depth to water for selected wells and piezometers, and relative 

land-surface change in the Newberry Springs area, San Bernardino County, California.................. 46

Figure 13. Amplitude image showing land-surface features and locations of wells and piezometers used 

to evaluate subsurface geology or to monitor ground-water levels, and phase images and 

graphs showing vertical land-surface changes in the Lucerne Valley area, San Bernardino 

County, California.............................................................................................................................. 48

Figure 14. Hydrographs showing depth to water for selected wells and piezometers and relative land-surface

change in the Lucerne Valley area, San Bernardino County, California........................................... 56
Tables v

TABLES

Table 1. Horizontal position, current (1998) ellipsoid and orthometric heights (elevations), historical 

elevations, and elevation change at geodetic monuments in the land-subsidence monitoring 

network in Lucerne Valley, San Bernardino County, California....................................................... 11
vi Conversion Factors, Vertical Datum, Abbreviations, and Well-Numbering System

CONVERSION FACTORS, VERTICAL DATUM, ABBREVIATIONS, AND WELLNUMBERING SYSTEM

CONVERSION FACTORS

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 × °C) + 32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C = (°F - 32) / 1.8

VERTICAL DATUM

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of

1929)—a geodetic datum derived from a general adjustment of the first-order level nets of both the

United States and Canada, formerly called Sea Level Datum of 1929.

ABBREVIATIONS

ERS European Earth Remote Sensing satellites

GPS Global Positioning System

HPGN High Precision Geodetic Network

InSAR interferometric synthetic aperture radar

MWA Mojave Water Agency

NAD83 North American Datum of 1983

NGS National Geodetic Survey

NGVD29 National Geodetic Vertical Datum of 1929

SAR Synthetic aperture radar

USGS U.S. Geological Survey

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

kilometer (km) 0.6214 mile (mi)

millimeter (mm) 0.03937 inch

millimeter (mm) 0.003281 foot (ft)

meter (m) 3.281 foot (ft)

square kilometer (km2) 0.3861 square mile (mi2)
Conversion Factors, Vertical Datum, Abbreviations, and Well-Numbering System vii

Well-Numbering System

Wells are identified and numbered according to their location in the rectangular system for the subdivision of 

public lands. Identification consists of the township number, north or south; the range number, east or west; and the 

section number. Each section is divided into sixteen 40-acre tracts lettered consecutively (except I and O), 

beginning with “A” in the northeast corner of the section and progressing in a sinusoidal manner to “R” in the 

southeast corner. Within the 40-acre tract, wells are sequentially numbered in the order they are inventoried. The 

final letter refers to the base line and meridian. In California, there are three base lines and meridians; Humbolt (H), 

Mount Diablo (M), and San Bernardino (S). All wells in the study area are referred to the San Bernardino base line 

and meridian (S). Well numbers consist of 15 characters and follow the format 004N001W01M001S. In this report, 

well numbers are abbreviated and written 4N/1W-1M1. The following diagram shows how the number for well 

4N/1W-1M1 is derived.

R4W R3W R2W

Meridian

San Bernardino

 T5N

 T4N

 T3N

RANGE

TOWNSHIP

 R1W R1E

27

R1W

T4N

Well-numbering diagram

6 5 4 3 2 1

7

18 13

8 9 10 11 12

17 16 15 14

19 24

30 25

31 36

20 21 22 23

29 28 26

32 33 34 35

4N/1W-1M1

SECTION 1

D C B A

EFGH

M L K J

N P Q R
Abstract 1

Detection and Measurement of Land Subsidence Using 

Interferometric Synthetic Aperture Radar and Global 

Positioning System, San Bernardino County, Mojave 

Desert, California

By Michelle Sneed, Marti E. Ikehara, Sylvia V. Stork, Falk Amelung, and Devin L. Galloway

ABSTRACT

Land subsidence associated with groundwater-level declines has been recognized as a 

potential problem in parts of the Mojave Desert, 

California. Ground water has been the primary 

source of domestic, agricultural, and municipal 

water supplies in the desert since the early 1900s. 

Pumping of ground water from the Mojave River 

and Morongo ground-water basins in the 

southwestern Mojave Desert resulted in waterlevel declines of more than 30 meters (100 feet) 

between the 1950s and the 1990s.

A Global Positioning System (GPS) survey 

of a geodetic network was used to determine the 

location, extent, and magnitude of vertical landsurface changes in Lucerne Valley in the Morongo 

ground-water basin. The GPS survey was 

conducted in 1998 to estimate historical elevation 

changes by comparing GPS-derived elevations 

with historical elevations (which were available 

for some of the monuments in the network as early 

as 1944) and to establish baseline values that can 

be used for comparisons with future GPS surveys. 

The GPS measurements indicated that about 

600 millimeters (2 feet) [plus or minus 1,500 

millimeters (5 feet)] of subsidence occurred at 

three of the monuments between 1969 and 1998 

but that very little to no vertical change in position 

occurred at seven other monuments in the 

network. Water levels in the area of subsidence in 

Lucerne Valley declined about 15 meters (50 feet) 

during 1970–98.

Interferometric synthetic aperture radar 

(InSAR) methods were used to characterize 

vertical land-surface changes in the Mojave River 

and Morongo ground-water basins during various 

intervals of time between 1992 and 1999. 

Interferograms, InSAR-generated displacement 

maps, show that subsidence ranging from 45 to 90 

mm (0.15 to 0.3 ft) occurred in four areas of these 

two ground-water basins—the El Mirage, 

Lockhart–Harper Lake (dry), Newberry Springs, 

and Lucerne Valley areas. Some of the InSAR 

measurements were affected by the earthquakes at 

Landers and Hector Mine, California, and by 

atmospheric artifacts.

Water-level data were examined for areas 

undergoing vertical land-surface changes to 

determine whether the vertical land-surface 

changes may be related to aquifer-system 

compaction caused by ground-water-level 

changes. Temporally relevant water-level data 

were sparse for some areas, particularly the El 

Mirage and Lockhart–Harper Lake (dry) areas. 

Water levels in wells proximate to the subsiding 

areas generally declined between 1992 and 1999; 

water levels in some wells proximate to the 

subsiding areas experienced seasonal periods of 

declines and recoveries.
2 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

INTRODUCTION

The Mojave River and Morongo ground-water 

basins are in the southwestern part of the Mojave 

Desert in southern California, approximately 130 and 

200 km (80 and 120 mi) northeast of Los Angeles (fig. 

1), respectively. Surface water in these basins is 

minimal and normally is limited to ephemeral flow 

during winter and spring storms and to continuous flow 

from springs. Because of the lack of significant 

surface-water resources in these basins, ground water 

has been the primary source of water supply for 

domestic, agricultural, and municipal water 

consumption since the early 1900s. Increased demand 

on local water supplies owing to increasing 

urbanization has resulted in overdraft conditions in 

some areas of the Mojave River and Morongo groundwater basins and caused water levels in some wells to 

decline more than 30 m (100 ft) between the 1950s and 

the 1990s. Ground-water levels in some areas were 

lower in the 1990s than were the previously recorded 

low levels (Trayler and Koczot, 1995; Smith and 

Pimentel, 2000). These low water levels have the 

potential to induce or renew land subsidence (the 

lowering of land-surface elevations) in the Mojave 

River and Morongo ground-water basins. Land 

subsidence can result in disruption of surface drainage, 

reduction of aquifer-system storage capacity, formation 

of earth fissures, and damage to wells, buildings, roads, 

and utility infrastructure.

Because of concerns related to the potential for 

new or renewed land subsidence in the Mojave River 

and Morongo ground-water basins, the Mojave Water 

Agency (MWA) entered into a cooperative agreement 

with the U.S. Geological Survey (USGS) to assess land 

subsidence. The agreement included establishing a 

geodetic network of monuments to monitor land 

subsidence in the Lucerne Valley using GPS. In 

addition, spatially detailed maps were developed using 

interferometric synthetic aperture radar (InSAR) to 

determine changes in vertical land-surface elevation for 

the parts of the Mojave River and Morongo groundwater basin that are managed by the MWA.

This report presents the results of a comparison 

between elevation data for the monuments in the GPS 

network, determined from the GPS survey made in 

1998, and historical elevation data for these 

monuments to determine whether land subsidence has 

occurred. Historical ground-water-level data were 

compiled and reviewed and then compared with the 

GPS measurements of the monuments for which 

elevation changes were significant. This report also 

presents spatially detailed maps developed using 

InSAR; the maps show vertical land-surface changes, 

or displacements, between 1992 and 1999 for intervals 

ranging from about 3 to 41 months. For areas where 

InSAR showed vertical land-surface displacements, 

ground-water-level data were examined to determine 

whether land-surface displacements were related to 

water-level changes.

The geodetic network used for the 1998 GPS 

survey is located only in the Lucerne Valley part of the 

study area. The InSAR-generated spatially detailed 

maps cover much of the southwestern Mojave Desert, 

but only the areas that showed land-surface 

displacements are discussed in this report. These areas 

are El Mirage, Lockhart–Harper Lake (dry), Newberry 

Springs, and Lucerne Valley (fig. 1).

DESCRIPTION OF STUDY AREA

The climate of the Mojave Desert region of 

southern California is characterized by low 

precipitation and humidity, and temperatures that range 

from above 38°C (100°F) in the summer to below 0°C 

(32°F) in the winter. Average annual precipitation 

ranges from 100 to 150 mm (4 to 6 in.) in the study 

area to more than 1,000 mm (40 in.) in the San 

Bernardino and the San Gabriel Mountain Ranges to 

the south of the study area (Lines, 1996). Recharge to 

the ground-water system from direct infiltration is 

minimal (Smith and Pimentel, 2000).

The Mojave River and Morongo ground-water 

basins have a combined area of about 6,200 km2 (2,400 

mi2) (fig. 1). Although these basins are largely 

undeveloped, many of the desert communities in these 

basins are expanding. Agriculture is concentrated in 

and near the El Mirage, Lockhart–Harper Lake (dry), 

and Newberry Springs areas; along the Mojave River in 

the Mojave River ground-water basin; and in the 

Lucerne Valley area in the Morongo ground-water 

basin (Smith and Pimentel, 2000).
Description of Study Area 3

Figure 1. Locations of the Mojave River and Morongo ground-water basins, San Bernardino County, California, and of three High Precision Geodetic 

Network (HPGN) stations. Figure modified from Smith and Pimentel (2000).

Emerson Fault Calico- Newberry Fault

San Andreas 

Fault Zone

Pipes W

San Bernardino Mts

ash

Mojave

River

Copper Mountain Fa

PintoMoun ult

tain Fault

SAN BERNARDINO MERIDIAN

Camp Rock-Harper Lake Fault Zon

Upper

Narrows

0

0

100 Kilometers

100 Miles

Mojave Water Agency

management area

Mojave River

drainage basin

boundary

0

0

10 Kilometers

10 Miles

Faults modified from Schaefer, 1978; Bortugno, 1986; Londquist and Martin, 1991;

 and J.C. Matti and G.I. Dixon,U.S. Geological Survey, written commun., 1994

Perched water—Approximate area

Boundaries—

HPGN station and identifier

Fault—Dashed where approximately located, dotted where concealed

Mojave River drainage

Mojave Water Agency management area

 

Mojave River ground-water basin (approximate)

Morongo ground-water basin (approximate) 

Four 

Corners

Adelanto 

Lockhart 

Hesperia

 San 

 Bernardino

Landers

Daggett Newberry

 Springs

Barstow

Joshua

Yucca Tree

Valley

Victorville

Apple

Valley

Harper

Lake (dry)

El Mirage

Lake (dry)

Coyote

 Lake 

(dry)

Troy

Lake 

(dry)

Gravel Hills

395

Newberry Mts

Cady 

 Mts

Iron Mtn

Ord

Granite

San Gabriel

Mts

Mts

Mts

247

18

43

247

15

10

15

15

40

U.S. Marine Corps

Fort Irwin National Training Center

Air/Ground Combat Center

(USMCAGCC)

 Edwards Air Force Base

(USMCAGCC)

(USMCAGCC)

Helendale Fault

Lenwood 

 Fault

George

AFB

LOS ANGELES COUNTY

SAN BERNARDINO COUNTY

SAN BERNARDINO COUNTY

 RIVERSIDE COUNTY

KERN COUNTY

KERN COUNTY

Camp

Cady

Alton Canyon

Mojave Desert

Mojave River ground-

 water basin

Morongo ground-

 water basin

 San

Diego

 Los

Angeles

 Los

Angeles

INYO CO

RIVERSIDE CO

SAN BERNARDINO 

 CO

SAN BERNARDINO

COUNTY

KERN CO

37°

33°

120°

116°

 LOS

ANGELES

 CO

Johnson Valley Fault

Transverse Arch Elkins Fault

Surprise Spring Fault

ANTELOPE

 VALLEY

EXPLANATION

Base from U.S. Geological Survey digital elevation data, 1:250,000, 1987, and digital data, 1:100,000, 1981–89;

Universal Transverse Mercator Projection, Zone 11. Shaded relief base from 1:250,000-scale Digital Elevation 

Model; simulated sun illumination from northwest at 30 degrees above horizon 

Mojave

River

34°30'

 34°45'

 35°00'

117°45' 117°30' 117°15' 117°00' 116°45' 116°30' 116°15'

 34°15'

 34°00'

T. 

4 

N.

T. 

2

N.

T. 

 1

 N.

T. 

1 

S.

T. 

6 

N.

T.

 8

 N.

 T. 

10 

 N.

 T. 

12 

 N.

 T.

 32

 S.

R. 8 W. R. 6 W. R. 4 W. R. 2 W. R. 1 E. R. 2 E. R. 4 E. R. 6 E. R. 1 W. R. 8 E.

Pinto Mts

Bullion Mts

Little San Bernardino Mts

18

247

58

58

MAP

AREA

0804

HECT

LAZY







LAZY

Lucerne

 Valley

 El Mirage area

 (figure 7)

 Lucerne Valley area

 (figure 13)

 Lockhart-Harper Lake (dry) area

 (figure 9)

 Newberry Springs area

 (figure 11) 

 Lucerne

 Lake (dry)
4 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

The Mojave River ground-water basin has an 

area of about 3,600 km2 (1,400 mi2) and extends from 

the San Bernardino and the San Gabriel Mountains 

north, then northeastward to Afton Canyon (fig. 1). The 

basin is bounded by Antelope Valley to the west and 

shares its southeastern boundary with the Morongo 

ground-water basin near the town of Lucerne Valley. 

The Mojave River ground-water basin consists of 

several alluvial-filled valleys that are hydraulically 

connected. Streamflow in the Mojave River is the 

principal source of ground-water recharge to the 

Mojave River ground-water basin. Since July 1994, 

imported water has been released to the Mojave River 

southeast of Hesperia, which has resulted in additional 

recharge in the basin (Mojave Water Agency, 1996).

The Morongo ground-water basin has an area of 

about 2,600 km2 (1,000 mi2) and is bounded by the San 

Bernardino Mountains to the southwest, the Granite 

and the Ord Mountains to the northwest, the Bullion 

Mountains to the northeast, and the Little San 

Bernardino and the Pinto Mountains to the south (fig. 

1). The ground-water basin is recharged by infiltration 

of streamflow from ephemeral stream channels, and 

more recently (1995), it has been recharged by 

artificial-recharge ponds constructed in the Yucca 

Valley area in 1995 (Smith and Pimentel, 2000).

GEOHYDROLOGY

Non-water-bearing consolidated igneous and 

metamorphic rocks underlie and surround the waterbearing unconsolidated deposits that compose the 

Mojave River and Morongo ground-water basins. Only 

the joints and fractures of the consolidated rocks 

contain water. The non-water-bearing rocks are not 

exposed in many areas of these basins but may form 

barriers to ground-water movement if they are present 

at altitudes higher than the water table (Mendez and 

Christensen, 1997).

The Mojave River and the Morongo groundwater basins are traversed by northwest to southeast 

right-lateral strike-slip faults (fig. 1) that, in many 

places, displace the aquifers (Smith and Pimentel, 

2000). The fault planes generally are of low 

permeability and produce barriers or partial barriers to 

ground-water flow that result in abrupt changes in the 

water table across the fault (Londquist and Martin, 

1991). The water table between the fault barriers is 

fairly flat in undeveloped areas; but in the developed 

areas, depressions have formed in the areas of 

substantial ground-water pumping and ground-water 

mounds have formed in areas of artificial recharge 

(Smith and Pimentel, 2000).

Mojave River Ground-Water Basin

The water-bearing deposits in the Mojave River 

ground-water basin are unconsolidated and partly 

consolidated alluvial material (Smith and Pimentel, 

2000). The aquifer system in the Mojave River groundwater basin consists of two interconnected aquifers: a 

shallow alluvial flood-plain aquifer (Lines, 1996) and a 

regional aquifer (Hardt, 1971) underlying and 

surrounding the flood-plain aquifer. The flood-plain 

aquifer, which consists mainly of sand and gravel 

deposited by the Mojave River, is as much as 75 m 

(250 ft) thick. It generally increases in width from less 

than 35 m (120 ft) at the Upper Narrows to more than 8 

km (5 mi) near Newberry Springs and is the most 

productive aquifer in the ground-water basin. The 

regional aquifer consists of unconsolidated older 

alluvium, fan deposits, and partly consolidated to 

unconsolidated sedimentary deposits as much as 1,220 

m (4,000 ft) thick (Subsurface Surveys, 1990; Stamos 

and others, 2001). These deposits generally are fine 

grained, and their permeability decreases with depth 

(Stamos and Predmore, 1995; Smith and Pimentel, 

2000). Perched ground-water conditions exist near El 

Mirage and Adelanto (Smith and Pimentel, 2000) 

(fig. 1). Perched ground water is unconfined ground 

water that is separated from an underlying aquifer by 

an unsaturated zone (Lohman, 1972).
Geohydrology 5

Figure 2. Geophysical and lithologic logs and construction diagrams of piezometers 9N/3E-22R4–7 in the Newberry Springs area of the Mojave River 

ground-water basin, San Bernardino County, California. Figure modified from Huff and others (2002). (See figure 11A for locations of piezometers and figure 

12 for hydrographs.)

DEPTH, IN FEET BELOW LAND SURFACE

DEPTH, IN METERS BELOW LAND SURFACE

0 0

0 20 0 200 -80 185 0 100 0 100

100

200

300

400

500

600

700

800

30.5

61.0

122.0

244.0

183.0

152.5

213.5

91.5

 Caliper, 

in inches

Lithology Description

 Gamma-ray,

 in counts

 per second

 Spontaneous

 potential,

 in millivolts

 16-inch

 resistivity, 

in ohm-meters

 64-inch

 resistivity, 

in ohm-meters

Piezometer

 diagram 9N/3E-22R4 9N/3E-22R5 9N/3E-22R6 9N/3E-22R7

no sample

sand

sand

silty sand

silty sand

silty sand

silty sand

silty sand

silty clay

silty sand

sandy clay

sandy

 clay

weathered 

 bedrock

slightly

gravelly

 silty

 sand

slightly

gravelly

 sand

slightly

gravelly

 sand

water

 level

clay

clay

clay

clay

perforated

interval
6 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 3. Geophysical and lithologic logs and construction diagrams of piezometers 4N/1W-1R4–9 in Lucerne Valley in the Morongo ground-water basin, 

San Bernardino County, California. Figure modified from Huff and others (2002). (See figure 13A for locations of piezometers and figure 14 for hydrographs.) DEPTH, IN FEET BELOW LAND SURFACE DEPTH, IN METERS BELOW LAND SURFACE

0 0

0 20 0 200 -50 15 0 100 0 100

100

200

300

400

500

600

700

800

30.5

61.0

122.0

244.0

183.0

152.5

213.5

91.5

 Caliper, 

in inches

Lithology Description

 Gamma-ray,

 in counts

 per second

 Spontaneous

 potential,

 in millivolts

 16-inch

 resistivity, 

in ohm-meters

 64-inch

 resistivity, 

in ohm-meters

 Piezometer

 diagram 4N/1W-1R4 4N/1W-1R5 4N/1W-1R6 4N/1W-1R7 4N/1W-1R8

4N/1W-1R9

sand

sand

sand

sand

sand

sand

silty 

sand

silty 

sand

sandy

 silt

sandy

 silt

 clayey

 sand

 silty

 sand

 clayey

 sand

perforated

interval

gravelly

 sand

gravelly

 sand

gravelly

 sand

gravelly

 sand

water

 level
Mechanics of Land Subsidence 7

Three of the four areas discussed in this report—

the El Mirage, Lockhart–Harper Lake (dry), and 

Newberry Springs areas—are in the Mojave River 

ground-water basin. The lithologic (driller) logs of four 

wells near El Mirage (wells 6N/6W-18L2, -18P4, 

-30M3, and 6N/7W-23J1) indicate an assemblage of 

alternating sand and clay with minor gravel, and claydominated sequences that range from about 30 m 

(100 ft) to nearly 60 m (200 ft) in thickness (see figure 

7A in the section “El Mirage Area” for locations of 

wells). The maximum depth of these wells is 91 m (300 

ft). The lithologic logs of five wells near Lockhart–

Harper Lake (wells 11N/3W-8Z1, -28L4, -28L5, 

-28M1, and -28R5) indicate an assemblage of 

alternating sand and clay with minor gravel, and 

clay-dominated sequences that range from about 1.5 to 

18 m (5 to 60 ft) in thickness [see figure 9A in the 

section “Lockhart–Harper Lake (dry) Area” for 

locations of wells]. The maximum depth of these wells 

is 340 m (1,117 ft). The lithologic log of well 

11N/3W-8Z1 indicates nearly 76 m (250 ft) of clay, 

most of which is at depths greater than 260 m (850 ft). 

The lithologic and geophysical logs of the piezometers 

9N/3E-22R4–7 at the multiple-completion monitoring 

site near Newberry Springs indicate a complex 

assemblage of clay, silt, and sand with minor gravel in 

the upper 143 m (470 ft) (see figure 11A in the 

“Newberry Springs Area” for location of monitoring 

site). The maximum depth of the piezometers is 186 m 

(610 ft). This assemblage includes a clay-dominated 

sequence at depths between about 113 and 143 m (370 

and 470 ft) below land surface (fig. 2) (Julia Huff and 

others, 2002).

Morongo Ground-Water Basin

The water-bearing deposits in the Morongo 

ground-water basin consist of continental deposits of 

Quaternary and Tertiary ages that extend to a maximum 

depth of 3,050 m (10,000 ft) near the eastern edge of 

the basin (Moyle, 1984). In general, the continental 

deposits are unconsolidated at land surface and become 

partly consolidated with depth. The unconsolidated 

deposits form the most productive aquifer in the 

ground-water basin. Perched ground-water conditions 

exist in the Lucerne Valley area (Smith and Pimentel, 

2000) (fig. 1).

Lucerne Valley, the fourth area discussed in this 

report, is in the Morongo ground-water basin. The 

geophysical and lithologic logs of the piezometers 

4N/1W-1R4–9 at the multiple-completion monitoring 

site in Lucerne Valley, which has a maximum depth of 

244 m (800 ft), indicate a complex assemblage of sand 

and silt with minor clay and gravel (see figure 13A in 

the section “Lucerne Valley Area” for location of 

monitoring site). The resistivity logs of this site 

indicate that permeability decreases with depth (fig. 3)

(Huff and others, 2002).

MECHANICS OF LAND SUBSIDENCE

Land subsidence can occur in valleys containing 

aquifer systems that are, in part, made up of finegrained sediments and that have undergone extensive 

ground-water development. The pore structure of a 

sedimentary aquifer system is supported by a 

combination of the granular skeleton of the aquifer 

system and the fluid pressure of the ground water that 

fills the intergranular pore space (Meinzer, 1928). 

When ground water is withdrawn in quantities that 

result in reduced pore-fluid pressures and water-level 

declines, more of the weight of the overlying 

sedimentary material must be supported by the 

skeleton. A loss of fluid-pressure support increases the 

intergranular load, or effective stress, on the skeleton. 

With a change in effective stress, the skeleton is subject 

to deformation—an increase in effective stress causes 

some degree of skeletal compression and a decrease 

causes expansion. The vertical component of this 

deformation sometimes results in irreversible 

compaction of the aquifer system and land subsidence. 

An aquifer-system skeleton that consists of primarily 

fine-grained sediments, such as silt and clay, is much 

more compressible than one that consists of primarily 

coarse-grained sediments, such as sand and gravel.
8 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Aquifer-system deformation is elastic 

(recoverable) if the stress imposed on the skeleton is 

smaller than the previous maximum effective stress. 

The largest historical effective stress imposed on the 

aquifer system, sometimes the result of the lowest 

ground-water level, is called the “preconsolidation 

stress.” When stresses are greater than the 

preconsolidation stress, the pore structure (granular 

framework) of the fine-grained sediments undergoes 

rearrangement toward a configuration that is more 

stable at higher stresses. This rearrangement results in 

an irreversible reduction of pore volume and, thus, in 

inelastic compaction of the aquifer system. 

Deformation under stresses in excess of the 

preconsolidation stress is 20 to more than 100 times 

greater than deformation under stresses less than the 

preconsolidation stress (Riley, 1998).

For an aquifer-system skeleton that has an 

appreciable thickness of fine-grained sediments, a 

significant part of the total compaction may be residual 

compaction (compaction that occurs in confining layers 

while heads in the confining layers equilibrate with 

heads in the adjacent aquifers). Depending on the 

thickness and the vertical hydraulic diffusivity of a 

confining layer, fluid-pressure equilibration—and thus 

compaction—lags behind pressure, or hydraulic head, 

declines in the adjacent aquifers; concomitant 

compaction may require decades or centuries to 

approach completion. The time required to attain about 

93 percent of the total compaction after water levels 

have stabilized is referred to as the time constant 

(Riley, 1969). Ireland and others (1984) estimated that 

the time constants for aquifer systems at 15 sites in the 

San Joaquin Valley ranged from 5 to 1,350 years. 

Terzaghi (1925) described this delay in his theory of 

hydrodynamic consolidation. Numerical modeling 

based on Terzaghi’s theory has successfully simulated 

complex histories of compaction caused by known 

water-level fluctuations (Helm, 1978; Hanson, 1989; 

Sneed and Galloway, 2000). For a more complete 

description of aquifer-system compaction, see Poland 

(1984), and for a review and selected case studies of 

land subsidence caused by aquifer-system compaction 

in the United States, see Galloway and others (1999). 

GLOBAL POSITIONING SYSTEM (GPS) 

SURVEY OF LUCERNE VALLEY AREA

GPS is a U.S. Department of Defense satellitebased navigation system designed to provide 

continuous worldwide positioning and navigation 

capability. GPS surveying uses the satellite-based 

system with Earth-based reference stations to 

accurately determine the position (latitude and 

longitude) and the ellipsoid height (vertical coordinate) 

of geodetic monuments. In 1998, the USGS established 

a geodetic network in the Lucerne Valley to determine 

changes in land-surface elevations (land subsidence) at 

selected geodetic monuments by comparing GPS 

measurements made in 1998 with historical leveling 

measurements and to establish baseline values that can 

be used for comparisons with future monitoring 

measurements.

Land-Subsidence Monitoring Network

The land-subsidence monitoring network for this 

study consists of geodetic monuments used as GPS 

stations (fig. 4) at which horizontal and vertical 

positions can be measured accurately and repeatedly to 

determine changes in positions. Geodetic monuments 

are markers that are anchored in the ground or to a 

structure. For this study, historical data for the 

monuments in the Lucerne Valley were compiled and 

reviewed to determine the geographic extent and the 

quality of this data for use as vertical-control data. 

Because no monuments could be found in the area just 

southeast of Lucerne Lake (dry), an area where groundwater levels have declined about 30 m (100 ft) since 

about 1950 (fig. 5), four new monuments were 

installed—GOBAR, HOLMES, CAMBRIA, and 

RAINBOW (GPS stations GOBR, HOLM, CMBR, 

and RAIN, respectively). Historical land-surface 

elevations for these monuments were determined from 

spot elevations or interpolated from topographic 

contours on 7.5-minute topographic maps determined 

from aerial photography. The elevation for GOBAR is 

from the White Horse Mountain, California, 

7.5-minute quadrangle developed from aerial 

photographs taken in 1975. The elevations for 

HOLMES, CAMBRIA, and RAINBOW are from the 

Lucerne Valley, California, 7.5-minute quadrangle 

developed from aerial photographs taken in 1969.
Global Positioning System (GPS) Survey of Lucerne Valley Area 9

Figure 4. Location of Global Positioning System (GPS) stations and wells used to monitor vertical changes in land surface and ground-water levels, 

respectively, in Lucerne Valley, San Bernardino County, California. (See figure 5 for hydrographs of wells).

13LC

49WB

46WB

GOBR

CMBR

W710

Z710

D720 R710

W115

W115

RAIN

HOLM

T115

W325

Lucerne

Lake (dry)

Lucerne 

Valley

R. 1 W.

T. 5 N.

T. 5 N.

T. 5 N.

T. 6 N.

T. 4 N.

R. 1 E.

247

18

18

L U C E R N E V A L LEY

EXPLANATION

Global Positioning System (GPS) station and identifier

Well and identifier

(powerline)

116°59' 116 116°57' 116°55' 116°53' °51'

5N/1E-17D1

4N/1W-1H1

4N/1W-1R1

4N/1W-1R1

4N/1W-1M1

Approximate location 

 and orientation of

 fissures in figure 6

faults

NORTH SIDE ROAD

SAN BERNARDINO MERIDIAN

247

34°34'

34°32'

34°30'

34°28'

34°26'

34°24'

0

0

5 Miles

5 Kilometers

GRANITE 

MOUNTAIN

5N/1W-25G1
10 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 5. Depth to water for selected wells near Global Positioning System (GPS) stations in Lucerne Valley, San Bernardino County, California, where 

vertical changes were largest. (See figure 4 for locations of wells).

5N/1W-25G1

20

40

60

80

100

120

140

160

5N/1E-17D1

20

40

60

80

100

120

140

160

4N/1W-1H1

20

40

60

80

20

10

30

40

100

120

140

160

4N/1W-1M1

4N/1W-1R1

DEPTH TO WATER, IN FEET BELOW LAND SURFACE

DEPTH TO WATER, IN METERS BELOW LAND SURFACE

1950

20

10

30

40

20

10

30

40

1955196019651970197519801985199019952000

YEAR
Global Positioning System (GPS) Survey of Lucerne Valley Area 11

The land-subsidence monitoring network in the 

Lucerne Valley consists of 17 geodetic monuments 

(fig. 4; three of the monuments are located outside the 

area of figure 4; they are shown in figure 1). The 

spacing between the monuments met the generalized 

network design criterion established by Zilkoski and 

others (1997), which requires that the distance between 

local network points does not exceed 10 km (6 mi).

Determination of Ellipsoid Heights and 

Orthometric Heights (Elevations)

GPS measurements were made using five dualfrequency, full-wavelength P-code GPS receivers 

(Ashtech Z-XII) and choke-ring antennas (DorneMargolin) and three dual-frequency, full-wavelength 

GPS receivers (Trimble 4000SSi or 4000SSe) and 

compact L1/L2 antennas with ground planes. GPS 

measurements were made at the 17 GPS stations 

between June 17 and 19, 1998, to obtain ellipsoid 

heights and elevations (orthometric heights) (table 1). 

Ellipsoid height is the vertical coordinate relative to a 

geodetic reference system. The ellipsoid that closely 

approximates the Earth’s shape in the study area is the 

North American Datum of 1983 (NAD83). Elevation is 

the vertical coordinate relative to a geodetic datum; the 

datum used in this report is the National Geodetic 

Vertical Datum of 1929 (NGVD29).

Table 1. Horizontal position, current (1998) ellipsoid and orthometric heights (elevations), historical elevations, and elevation change at geodetic 

monuments in the land-subsidence monitoring network in Lucerne Valley, San Bernardino County, California

[Location of Global Positioning System (GPS) stations shown in figures 1 and 4. Latitude and longitude are referenced to the North American Datum of 1983. 

Elevation is referenced to the National Geodetic Vertical Datum of 1929. Negative values for elevation change indicate subsidence. m, meter; ft, foot; mm, 

millimeter. —, no data]

1Network control station. 2High Precision Geodetic Network (HPGN) station. 3Determined from historical leveling measurements. 4Values are within measurement error. 5Estimated by interpolating elevation values from 3-m (10-ft) topographic contours. Elevation changes computed using these estimated elevations have 

a 1,500 mm (5-ft) uncertainty.

GPS code 

name

Monument 

name

Latitude 

(1998)

Longitude 

(1998)

1998 

ellipsoid 

height

(m)

1998

orthometric height 

(elevation)

Historical elevation Elevation change

Time 

period

of 

elevation

change

(m) (ft) (m) (ft) (mm) (ft)

0804 1,2 HPGN 08-4 GPSSOAP 1990 34°54′14′′ 116°58′51′′ 662.050 — — — — — — —

HECT 1,2 HECTOR 2 1966 34°47′06′′ 116°25′15′′ 598.370 — — — — — — —

13LC 13 LC 1953 34°35′12′′ 116°58′28′′ 901.778 932.89 3,060.66 3932.86 33,060.57 430 40.1 1976–98

49WB 49 WBC 1976 34°31′52′′ 116°56′42′′ 836.935 868.05 2,847.93 3868.16 32,848.31 4–120 4–.4 1976–98

46WB 46 WBC 1976 34°31′52′′ 116°53′34′′ 855.291 886.36 2,908.02 3886.36 32,908.01 fixed fixed 1976–98

Z710 Z 710 1944 34°31′35′′ 116°49′40′′ 907.638 938.66 3,079.59 3938.70 33,079.72 4–30 4–.1 1944–98

GOBR GOBAR 34°30′08′′ 116°54′38′′ 839.442 870.52 2,856.04 5871.1 52,858 4–600 4–2 1976–98

CMBR CAMBRIA 34°29′13′′ 116°53′51′′ 843.659 874.71 2,869.78 5874.8 52,870 40 40 1976–98

W710 W 710 1944 34°28′56′′ 116°51′28′′ 856.756 887.78 2,912.66 3887.84 32,912.86 4–60 4–.2 1944–98

RAIN RAINBOW 34°27′44′′ 116°57′01′′ 841.976 873.03 2,864.27 5873.6 52,866 4–600 4–2 1976–98

HOLM HOLMES 34°27′38′′ 116°55′42′′ 845.095 876.12 2,874.41 5876.6 52,876 4–600 4–2 1976–98

W325 1 W 325 RESET 1958 34°26′57′′ 117°00′08′′ 870.932 902.02 2,959.37 3902.02 32,959.37 fixed fixed 1993–98

R710 R 710 1944 34°26′38′′ 116°53′56′′ 870.922 901.87 2,958.89 3901.91 32,959.01 4–30 4–.1 1993–98

D720 D 720 1944 34°26′23′′ 116°50′28′′ 879.640 910.56 2,987.39 3910.56 32,987.39 fixed fixed 1993–98

T115 T 1152 1961 34°26′02′′ 116°56′14′′ 892.822 923.76 3,030.71 3923.76 33,030.71 40 40 1961–98

W115 W 1152 1961 34°24′04′′ 116°53′25′′ 974.110 1,004.80 3,296.60 31,004.80 33,296.60 fixed fixed 1961–98

LAZY 1,2 LAZY 1980 34°20′38′′ 116°30′50′′ 1,028.220 — — — — — — —
12 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

GPS surveying was done in accordance with 

version 4.3 of “Guidelines for Establishing GPSDerived Ellipsoid Height” by Zilkoski and others 

(1997). GPS measurements were made at 13 of the 17 

GPS stations on at least 2 days, and data were recorded 

during 50-minute observation periods. GPS 

measurements were made at the other four GPS 

stations—the network control stations—on all 3 days 

of the GPS survey, and data were recorded during 5.5-

hour observation periods. Three of the four network 

control stations—HPGN 08-4 GPS-SOAP 1990, 

HECTOR 2 1966, and LAZY 1980 [0804, HECT, and 

LAZY, respectively (fig. 1)]—are part of the statewide 

High Precision Geodetic Network (HPGN); the fourth 

network control station, W325 RESET 1958 (W325) 

(fig. 4) is not. The network control stations were 

selected on the basis of their vertical stability and 

geographic distribution; these stations are located at the 

perimeter of the land-subsidence monitoring network 

(fig. 1) and in areas where little ground-water pumping 

occurs and vertical land-surface changes were assumed 

small. The only variation in the way the GPS surveys 

were conducted for this study from that in the 

guidelines of Zilkoski and others (1997) was that 

single-baseline, rather than multi-baseline, processing 

software was used for postprocessing. There are no 

known conclusive tests that permit an objective 

evaluation of the effect of using single-baseline, rather 

than multi-baseline, processing software (Craymer and 

Beck, 1992) and, therefore, the single-baseline 

software was used because it was readily available. 

GPSurvey version 2.30 (Trimble) was used for the 

baseline and relative-positioning computations.

The orthometric heights (elevations) of 14 of the 

GPS stations in the network were determined during 

two phases of relative positioning. During the first 

phase, the horizontal coordinates and ellipsoid heights 

of three of the network control stations (the three 

HPGN stations) were held fixed to calculate the 

horizontal coordinates and ellipsoid heights of the 

fourth network control station, W325, and network 

station GOBR. GOBR was selected for determination 

of ellipsoid heights during the first phase of relative 

positioning because several surveying measurements 

had been made at this station and because it was not 

adjacent to W325 (fig. 4). During the second phase, the 

elevations of GPS stations 46WB, D720, W115, and 

W325 were obtained from National Geodetic Survey 

(NGS) data sheets. The elevations of these four stations 

and the horizontal coordinates for W325 and GOBR, 

determined during the first phase, were held fixed, and 

the horizontal positions and elevations (derived from 

ellipsoid heights determined using modeled geoid 

separations of GEOID96) were calculated for the other 

10 GPS stations (table 1).

GPS Results and Ground-Water Levels in Nearby 

Wells

The elevations of the GPS stations determined 

from the 1998 GPS survey were compared with 

historical elevations that had been determined either by 

leveling or by estimating the historical elevations of the 

GPS stations. Ground-water-level data for areas 

indicated as having possible subsidence were analyzed 

to determine if they were near areas that had large 

ground-water-level declines. The historical elevations 

for GPS stations GOBR, HOLM, CMBR, and RAIN 

were estimated by interpolating elevations from 

topographic contours determined from aerial 

photographs taken in 1975 (GOBR) and in 1969 

(HOLM, CMBR, and RAIN). Using elevations 

determined from topographic contours to calculate land 

subsidence incorporates an error of as much as 1,500 

mm (5 ft). The historical land-surface elevations, which 

were estimated from the 1969 and 1975 topographic 

contour maps were compared with elevations 

determined from the 1998 GPS survey. Results of the 

comparison indicate that about 600 mm (2 ft) of 

subsidence occurred at GPS stations GOBR, HOLM, 

and RAIN for the two periods of comparison (1969–98 

and 1975–98), but these results are essentially nullified 

by the 1,500 mm (5 ft) error associated with estimating 

the historical elevations (table 1). These stations are in 

the center of the GPS network, southeast of Lucerne 

Lake. The historical land-surface elevations for the 

remaining stations were determined from historical 

leveling measurements (made as early as 1944 at some 

stations). Results of that comparison indicated that 

little or no change had occurred at these stations since 

the historical leveling measurements were made 

(table 1).
Global Positioning System (GPS) Survey of Lucerne Valley Area 13

Figure 6. Fissures near Lucerne Lake (dry) in San Bernardino County, Mojave Desert, California. A, View to the southwest, with 5-gallon bucket for scale. 

B, View to the northeast, with 5-gallon bucket for scale. See figure 4 for approximate location and orientation. Photographs taken in May 2001 by Loren 

Metzger, U.S. Geological Survey.

A

B
14 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Inspection of the southern Lucerne Lake (dry) 

area in May 2001 revealed fissures trending 

northeast/southwest across State Route 247 (fig. 4). In 

some instances, the fissures were more than 1 m (3.3 ft) 

in width and in depth (fig. 6); the fissures probably 

have enlarged as a result of erosion. Fissuring often is 

associated with localized differential compaction of 

unconsolidated sediment. Fissures formed by this 

mechanism are caused by the stretching of the aquifersystem structure owing to the bending of the overlying 

sediment of the differentially compacting zone (Holzer, 

1984). The orientation of the fissures is consistent with 

subsidence to the northwest or southeast. Because 

bedrock crops out at land surface to the northwest 

(Granite Mountains), which indicates a small thickness 

of unconsolidated sediment, the most likely area of 

subsidence is to the southeast where unconsolidated 

sediment thickens. The GPS monitoring network is 

located in this area of possible subsidence.

The ellipsoid heights of the GPS stations 

determined for 1998 will serve as baseline 

measurements that can be used for comparisons with 

measurements from future surveys. Errors resulting 

from comparisons of ellipsoid heights from this study 

with those determined during future studies may be as 

small as plus or minus (±) 20 mm (± 0.07 ft) because 

errors associated with orthometric-height control 

stations, as well as those associated with modeled 

geoid separations that convert the ellipsoid heights to 

orthometric heights, will become irrelevant.

GPS measurements for the GPS stations in the 

monitoring network indicate that subsidence may have 

occurred at three stations—GOBR, HOLM, and RAIN 

(fig. 4). About 600 mm (2 ft) ± 1,500 mm (±5 ft) of 

subsidence occurred at GOBR between 1975 and 1998 

and at HOLM and RAIN between 1969 and 1998. 

Between 1977 and 1998, water levels declined about 

11 m (36 ft) in well 5N/1W-25G1, which is about 2.1 

km (1.3 mi) southwest of GOBR, and about 10 m (33 

ft) in well 5N/1E-17D1, which is about 3.2 km (2 mi) 

north of GOBR (figs. 4 and 5). The screened intervals 

of these wells are unknown, but well 5N/1E-17D1 is 

only about 52 m (170 ft) deep. Water levels declined 

about 9 m (30 ft) in well 4N/1W-1M1 [screened 

interval 11 to 102 m (36 to 336 ft) below land surface] 

between 1977 and 1997; this well is near HOLM and 

RAIN (figs. 4 and 5). Only three water-level 

measurements were available for wells 4N/1W-1R1 

and -1H1, near HOLM and RAIN, for the period 

between 1954 and the late 1990s. The measurements 

for well 4N/1W-1R1 for 1954 and 1998 and for well 

4N/1W-1H1 for 1954 and 1997 indicate that water 

levels declined about 29 and 19 m (95 and 62 ft), 

respectively (fig. 5). The screened interval of well 

4N/1W-1R1 is unknown, but the screened interval of 

well 4N/1W-1H1 is 76 to 119 m (250 to 390 ft) below 

land surface.

During the 1990s, the water-level measurements 

for these wells were near or lower than the previously 

recorded low levels for these wells (Trayler and 

Koczot, 1995; Smith and Pimentel, 2000) (fig. 5). The 

relation between subsidence and the record low water 

levels in the wells in the central part of the GPS 

network suggests that the preconsolidation stress of the 

aquifer system may have been exceeded during the 

1969–98 and 1975–98 periods and that compaction 

may be permanent in these areas.
Interferometric Synthetic Aperture Radar (InSAR) 15

INTERFEROMETRIC SYNTHETIC 

APERTURE RADAR (INSAR)

InSAR Methods

InSAR is a powerful technique that uses 

differences in reflected radar signals acquired at 

different times to measure ground-surface deformation. 

This technique has been used to investigate 

deformation resulting from earthquakes (Massonnet 

and others, 1993), volcanoes (Massonnet and others, 

1995), and land subsidence (Massonnet and others, 

1997; Fielding and others, 1998; Galloway and others, 

1998; Amelung and others, 1999; Hoffmann and 

others, 2001; Sneed and others, 2001). Twenty-four 

interferograms with temporal baselines ranging from 

3 to 41 months were developed for this study using 14 

synthetic aperture radar (SAR) scenes acquired by 

European Earth Remote-Sensing (ERS) satellites. Five 

interferograms were developed for the El Mirage area, 

six for the Lockhart–Harper Lake (dry) area, six for the 

Newberry Springs area, and seven for the Lucerne 

Valley area. Each interferogram was produced by 

combining two SAR scenes that had nearly identical 

acquisition geometries to form a “change” 

interferogram. The amplitude component of the change 

interferogram shows the intensity of the radar 

backscatter and reveals features of the land surface, 

such as mountains, roads, drainage ways, and 

engineered structures. The phase component of the 

change interferogram contains information about the 

coherent displacements imaged by radar and about the 

topography. The topographic component was removed 

using an interferogram produced from SAR scenes 

acquired on 2 successive days (tandum interferogram).

For landscapes that have more or less stable 

radar reflectors (such as buildings or other engineered 

structures, or undisturbed rocks and ground surfaces) 

over a period of time, it is possible to make highprecision measurements of changes in position or 

displacements of the reflectors caused by deforming 

aquifer systems (Galloway and others, 2000). 

Displacements are calculated from a phase change at 

each point in the interferogram. The phase change is 

determined by differencing or “interfering” two radar 

scans made of the same area at different times 

(Galloway and others, 2000).

Because the phase of the radar echo is 

proportional to the distance traveled by the pulse, any 

motion of the ground surface that occurs between two 

SAR scenes causes a phase difference in the 

interferogram. Phase differences can also be caused by 

propagation delays of the radar signal, such as delays 

caused by the variable water vapor in the atmosphere, 

also known as atmospheric artifacts (Zebker and 

others, 1997). Phase differences caused by propagation 

delays and not by deformation of the land surface can 

be identified using independent interferograms. 

Independent interferograms are interferograms that do 

not share a common SAR scene. For this study, if a 

particular signal—for example an indication of an area 

of subsidence—was evident in only one interferogram 

or in multiple interferograms that shared a common 

SAR scene, that signal was attributed to a propagation 

delay in the shared SAR scene rather than to 

deformation of the land surface. Because atmospheric 

artifacts were not evident in the change interferograms, 

except where noted, the coherent phase differences 

were attributed to range displacements of the ground 

surface, which were assumed vertical.

On the phase images, an area of coherent 

displacements, for example an area of subsidence, is 

shown by color fringes that define a shape; more color 

fringes indicate more change. For the interferograms in 

this report, one color cycle, for example blue to blue, 

indicates 28 mm (0.09 ft) of range displacement or 

change. The direction of change—subsidence or 

uplift—is indicated by the color progression of the 

fringes toward the center of the shape. The color-fringe 

progression of red-orange-yellow-green-blue-purple 

indicates subsidence; the opposite progression 

indicates uplift.

InSAR cannot be used to make high-precision 

measurements over fairly long time periods for 

landscapes that lack substantial stable radar reflectors; 

such landscapes include agricultural land where 

farming practices disturb the ground surface or dry lake 

beds where episodic flooding occurs. The phase image 

of such landscapes will show an incoherent speckled 

pattern rather than coherent color fringes; this speckled 

pattern indicates decorrelation. Developing images for 

shorter temporal baselines often will increase image 

coherency because there generally will be less 

disturbance during shorter time periods.
16 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

The phase component of the interferograms 

presented in this report was “unwrapped” to construct 

the displacement profiles, or cross sections, of the 

interferograms. Unwrapping of the phase component 

was done using a “branch cut” approach developed by 

Goldstein and others (1988). This approach is 

discussed in detail in Rosen and others (2000). The 

locations of the cross sections of the coherent 

interferograms were selected using a set of 

interferograms for each area of interest (for example, a 

set of five interferograms were used for the El Mirage 

area), and, therefore, the cross sections do not always 

intersect the areas of maximum subsidence in some of 

the interferograms. Cross sections of the fairly 

incoherent interferograms are not included in this 

report. 

All the features that indicate subsidence on the 

interferograms are not discussed in this report. Reasons 

for omitting these features from the discussion are (1) 

the feature is not evident in independent 

interferograms, (2) the feature is suspect owing to its 

proximity to mountains, (3) the feature is poorly 

correlated, and (4) the feature is small in magnitude 

and (or) spatial distribution.

InSAR Results

InSAR results are presented for the El Mirage, 

Lockhart-Harper Lake (dry), and Newberry Springs 

areas in the Mojave River ground-water basin and for 

the Lucerne Valley area in the Morongo ground-water 

basin. Available ground-water-level data for areas 

undergoing vertical land-surface changes were 

examined to determine whether the vertical landsurface changes may be related to aquifer-system 

deformation caused by ground-water-level changes. 

More often than not, the water-level data were 

insufficient for determining if deformation was related 

to the water-level changes. Additional water-level 

measurements, perhaps made as frequently as 

seasonally, from depth-dependent or aquifer-dependent 

wells are needed to determine if the land-surface 

deformations evident in the interferograms are related 

to changes in water levels.

Mojave River Ground-Water Basin

El Mirage Area

Five interferograms were developed for the El 

Mirage area between April 1995 and November 1999; 

they have temporal baselines of 5, 6, 12, 16, and 21 

months (fig. 7). Four of the five interferograms—the 

interferograms that have adjacent temporal baselines of 

12 months [April 21, 1995, to April 6, 1996 (fig. 7B)]; 

16 months [April 6, 1996, to August 9, 1997 (fig. 7D)]; 

21 months [August 9, 1997, to May 1, 1999 (fig. 7E)]; 

and 6 months [May 1, 1999, to November 27, 1999 

(fig. 7F)]—compose time series 1 in figure 8. The fifth 

interferogram, which spans 5 months [April 6, 1996, to 

September 28, 1996 (fig. 7C)] is a temporal subset of 

the 16-month interferogram (fig. 7D) and composes the 

single interferogram in figure 8. Although the 

approximately 100-km2 radar scene includes parts of 

Antelope Valley where subsidence is occurring, only 

the El Mirage area of this radar scene is discussed in 

this report. For a detailed discussion of subsidence in 

Antelope Valley, see Galloway and others (1998).

All five interferograms show a subsidence 

pattern south of the southeastern tip of El Mirage Lake 

(dry). The persistent pattern indicates three areas of 

subsidence that together form an approximate L 

shape—the long limb is about 5 km (3.1 mi) north to 

south along the cross-section line V1–V1′, and the 

short limb is about 2.5 km (1.6 mi) west to east along 

the cross-section line H2–H2′. The 12-, 5-, and 16-

month interferograms (fig. 7B, C, and D, respectively) 

show this pattern best; the 21-month interferogram (fig. 

7E) is not as coherent (although the pattern is still 

evident), and the 6-month interferogram (fig. 7F)

shows almost no subsidence. The interferograms for 

the El Mirage area indicate that three areas subsided as 

much as 50 mm (0.16 ft) cumulatively during the 48-

month period between April 21, 1995, and May 1, 

1999, and that very little vertical change occurred 

during the 6-month period between May 1, 1999, and 

November 27, 1999 (figs. 7 and 8).
Interferometric Synthetic Aperture Radar (InSAR) 17

Figure 7. Amplitude image showing land-surface features and locations of wells used to evaluate subsurface geology or to monitor ground-water levels, 

and phase images and graphs showing vertical land-surface changes in the El Mirage area, San Bernardino County, California. Amplitude image (A) and 

phase images and graphs showing land-surface change for (B) April 21, 1995, to April 6, 1996; (C) April 6, 1996, to September 28, 1996; (D) April 6, 1996, to 

August 9, 1997; (E) August 9, 1997, to May 1, 1999; and (F) May 1, 1999, to November 27, 1999. (See figure 1 for location of area; see figure 8 for 

hydrographs of selected wells.)

N

6N/6W-6Q3

6N/6W-6Q3

6N/6W-18L2

6N/6W-18P4

T. 7 N.

R. 7 W.

R. 6 W.

T. 6 N.

T. 5 N.

0

0

5 Miles

5 Kilometers

A

EXPLANATION

Single well and identifier

6N/6W-30M3

6N/6W-30M1

6N/7W-23C3

6N/7W-23J1

El Mirage Lake

(dry)

H1 H1'

H2 H2'

V1'

V1
18 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 7.—Continued.

20

0.10

-0.10

 0 0

0.10

-0.10

 0

0.10

-0.10

 0

0

-20

-40

20

 0

-20

-40

20

 0

-20

-40

DISTANCE, IN KILOMETERS

A Raw data veraged data

H1 H1'

H2 H2'

V1'

V1

V1

V1'

V1'

V1

H1

H1 H2

H1' H2'

H1'

H2 H2'

V1 V1'

APRIL 21,1995–APRIL 6,1996

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

(12-month interferogram)

B

N

T. 7 N.

R. 7 W.

R. 6 W.

T. 6 N.

T. 5 N.

0

0

5 Miles

5 Kilometers

5 10 15 20 20.5 

+28 mm 0 -28 mm

relative 

uplift subsidence

El Mirage Lake

(dry)
Interferometric Synthetic Aperture Radar (InSAR) 19

Figure 7.—Continued.

0

DISTANCE, IN KILOMETERS

5 10 15 20 20.5 

0.10

-0.10

 0

0.10

-0.10

 0

0.10

-0.10

 0

H1 H1'

H2 H2'

V1'

V1

20

 0

-20

-40

20

 0

-20

-40

20

 0

-20

-40

H1' H1

H2 H2'

V1 V1'

APRIL 6,1996–SEPTEMBER 28,1996

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

(5-month interferogram)

N

T. 7 N.

R. 7 W.

R. 6 W.

T. 6 N.

T. 5 N.

C

Raw data Averaged data

0

0

5 Miles

5 Kilometers

+28 mm 0 -28 mm

relative 

uplift subsidence

El Mirage Lake (dry)

V1

V1

V1'

V1'

H1 H2

H1' H2'
20 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 7.—Continued.

0

DISTANCE, IN KILOMETERS

5 10 15 20 20.5 

H1 H1'

H2 H2'

V1'

V1

H1 H1'

H2 H2'

V1 V1'

20

 0

-20

-40

20

 0

-20

-40

20

 0

-20

-40

APRIL 6,1996–AUGUST 9,1997

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

(16-month interferogram)

N

T. 7 N.

R. 7 W.

R. 6 W.

T. 6 N.

T. 5 N.

D

0.10

-0.10

 0

0.10

-0.10

 0

0.10

-0.10

 0

Raw data

Averaged data

0

0

5 Miles

5 Kilometers

+28 mm 0 -28 mm

relative 

uplift subsidence

El Mirage Lake (dry)

V1

V1

V1'

V1'

H1 H2

H1' H2'
Interferometric Synthetic Aperture Radar (InSAR) 21

Figure 7.—Continued.

V1

V1

V1'

V1'

H1 H2

H1' H2'

H1 H1'

H2 H2'

V1'

V1

H1 H1'

H2 H2'

V1 V1'

20

 0

-20

-40

20

 0

-20

-40

20

 0

-20

-40

AUGUST 9,1997–MAY 1,1999

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

(21-month interferogram)

N

T. 7 N.

R. 7 W.

R. 6 W.

T. 6 N.

T. 5 N.

E

0.10

-0.10

 0

0.10

-0.10

 0

0.10

-0.10

 0

Raw data

Averaged data

0

0

5 Miles

5 Kilometers

+28 mm 0 -28 mm

relative 

uplift subsidence

0

DISTANCE, IN KILOMETERS

5 10 15 20 20.5 

El Mirage Lake (dry)
22 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 7.—Continued.

H1 H1'

H2 H2'

V1'

V1

H1 H1'

H2 H2'

V1 V1'

20

 0

-20

-40

20

 0

-20

-40

20

 0

-20

-40

MAY 1,1999–NOVEMBER 27,1999

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

(6-month interferogram)

N

T. 7 N.

R. 7 W.

R. 6 W.

T. 6 N.

T. 5 N.

F

0.10

-0.10

 0

0.10

-0.10

 0

0.10

-0.10

 0

Raw data

Averaged data

0

0

5 Miles

5 Kilometers

+28 mm 0 -28 mm

relative 

uplift subsidence

0

DISTANCE, IN KILOMETERS

5 10 15 20 20.5 

El Mirage Lake (dry)

V1

V1

V1'

V1'

H1 H2

H1' H2'
Interferometric Synthetic Aperture Radar (InSAR) 23

Figure 8. Depth to water for selected wells and relative land-surface change in the El Mirage area, San Bernardino County, California. (See figure 7A for 

locations of wells.)

6N/6W-30M1

113

115

117

119

121

123

6N/6W-6Q3

113

115 35

35

36

37

36

37

94

86

88

90

92

117

119

121

123

6N/7W-23C3

280

290

300

310

YEAR

DEPTH TO WATER, IN METERS BELOW LAND SURFACE

DEPTH TO WATER, IN FEET BELOW LAND SURFACE

1990

199119921993199419951996199719981999

 April 21, 1995,

 to April 6, 1996 

 

 April 6, 1996,

 to Sept. 28, 1996

 (dashed area) 

 

 April 6, 1996

 to Aug. 9, 1997 

 

 , Aug. 9, 1997,

 to May 1, 1999 

 

 May 1, 1999,

 to Nov. 27, 1999 

 

-50

-40

-30

-20

-10

0

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

Time series 1 Single interferogram

0

-0.10

-0.05

-0.15

-0.165
24 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Ground-water level data were examined for 

wells near El Mirage Lake (dry), an area where the 

interferograms show that as much as 50 mm (0.16 ft) of 

subsidence occurred south of the southeastern tip of El 

Mirage Lake (dry) during 1995–99 (fig. 8). Water-level 

data are sparse for this period; only three wells near the 

subsiding area had temporally relevant data. Two 

wells—6N/6W-6Q3 and -30M1—are screened in the 

perched zone (Smith and Pimentel, 2000). Well 

6N/6W-6Q3 is just north of the southeastern tip of El 

Mirage Lake (fig. 7A). Only two water-level 

measurements were made at well 6N/6W-6Q3; these 

measurements indicate a water-level decline of about 

2.4 m (8 ft) between the spring of 1993 and the spring 

of 1996 (fig. 8). Well 6N/6W-30M1 is about 5.5 km 

(3.4 mi) south of the southeastern tip of El Mirage 

Lake (dry) (fig. 7A). At least one water-level 

measurement was made at this well each spring 

between 1992 and 1999; these measurements indicate 

that water levels were stable, declining less than 0.3 m 

(1 ft) (fig. 8). Well 6N/7W-23C3 is screened 85 to 213 

m (280 to 700 ft) below land surface in the regional 

aquifer about 4 km (2.5 mi) south of El Mirage Lake 

(dry) and about 3.7 km (2.3 mi) northwest of well 

6N/6W-30M1 (fig. 7A). The two available water-level 

measurements for this well indicate a water-level 

decline of about 5.2 m (17 ft) between the spring of 

1990 and the spring of 1998 (fig. 8). Much of this 

decline may have occurred between the spring of 1990 

and the spring of 1993, before the adjudication began 

that resulted in decreased pumpage (Stamos and others, 

2001). (The adjudication of the Mojave Basin area was 

the legal process that allocated the right to produce 

water from the available natural water supply. Until the 

Mojave Water Agency initiated the adjudication and an 

independent court issued the judgement, water 

production rights and obligations had never been 

defined in the Mojave Basin. The court’s final decision 

was reached in January 1996.) The location of well 

6N/7W-23C3 is nearly coincident with the water-level 

depression indicated by the 1998 water-level contours 

reported by Smith and Pimentel (2000). Ground-water 

flow simulations of the Mojave River ground-water 

basin show that water levels declined as much as 53 m 

(175 ft) south of El Mirage Lake (dry) between the late 

1950s and 1999 (Stamos and others, 2001). The waterlevel declines in the regional aquifer indicated by 

recent measurements in well 6N/7W-23C3 and 

simulations for historical periods may have been large 

enough to cause the measured subsidence

Lockhart–Harper Lake (Dry) Area

Six interferograms were produced for the 

Lockhart–Harper Lake (dry) area. The interferograms 

compose two temporally overlapping time-series maps 

of vertical land-surface deformation. The six 

interferograms have temporal baselines of 3, 5, 8, 14, 

24, and 41 months for the period April 1992 to 

November 1999 (fig. 9). The 14-month [April 24, 

1992, to June 18, 1993 (fig. 9B)], 24-month [June 18, 

1993, to June 11, 1995 (fig. 9C)], 3-month [June 11, 

1995, to September 24, 1995 (fig. 9D)], and 8-month 

[September 24, 1995, to May 26, 1996 (fig. 9E)] 

interferograms form time series 1 in figure 10; the 41-

month [January 8, 1996, to June 21, 1999 (fig. 9F)] and 

the 5-month [June 21, 1999, to November 8, 1999 (fig. 

9G)] interferograms form time series 2 in figure 10. 

Three of the six interferograms, the 14-month [April 

24, 1992, to June 18, 1993 (fig. 9B)], 24-month 

[June 18, 1993, to June 11, 1995 (fig. 9C)], and 

41-month [January 8, 1996, to June 21, 1999 (fig. 9F)] 

clearly show a deformation pattern on the northeastern 

shore of Harper Lake (dry). The 3-month [June 11, 

1995, to September 24, 1995 (fig. 9D)], 8-month 

[September 24, 1995, to May 26, 1996 (fig. 9E)], and 

5-month [June 21, 1999, to November 8, 1999 

(fig. 9G)] interferograms do not show this pattern 

clearly. At least two of the six interferograms for the 

Lockhart–Harper Lake (dry) area—the 3-month (June 

11, 1995, to September 24, 1995) and the 5-month 

(June 21, 1999, to November 8, 1999) 

interferograms—show atmospheric artifacts (fig. 9D

and G, respectively) that may have affected the 

interpretations of vertical land-surface changes. 
Interferometric Synthetic Aperture Radar (InSAR) 25

Figure 9. Amplitude image showing land-surface features and locations of wells used to evaluate subsurface geology or to monitor ground-water levels, 

and phase images and graphs showing vertical land-surface changes in the Lockhart–Harper Lake (dry) area, San Bernardino County, California. Amplitude 

image (A) and phase images and graphs showing land-surface change for (B) April 24 1992, to June 18, 1993; (C) June 18, 1993, to June 11, 1995; (D) June 

11, 1995, to September 24, 1995; (E) September 24, 1995, to May 26, 1996, (F) January 8, 1996, to June 21, 1999, and (G) June 21, 1999, to November 8, 

1999. (See figure 1 for location of area; see figure 10 for hydrographs of selected wells.)

A

N

117°15'

11N/3W-16D1

11N/3W-8Z1

11N/3W-28L5

R. 5 W.

R. 4 W.

R. 3 W.

0

0

5 Miles

5 Kilometers

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

11N/3W-28R5

11N/3W-28R5

11N/3W-7D1

11N/3W-28M1

11N/3W-28L4

11N/3W-28R2

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

EXPLANATION

Single well and identifier
26 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 9.—Continued.

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

APRIL 24, 1992–JUNE 18, 1993 (14-month interferogram)

B

N

117

R. 5 W.

R. 4 W.

°15'

R. 3 W.

0

0

5 Miles

5 Kilometers

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 27

Figure 9.—Continued.

APRIL 24, 1992–JUNE 18, 1993 H1

H1'

H2 H2'

H3 H3'

V1 V1'

V2 V2'

40

20

0

0.10

-0.10

-0.20

0

0.10

-0.10

-0.20

0

0.10

-0.10

-0.20

0

0.10

-0.10

-0.20

0

0.10

-0.10

-0.20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

DISTANCE, IN KILOMETERS

Raw data

Averaged data

0

B

5 10 14.5

0 5 10 15 20 22.1

V2 V1

V2 V1

V2' V1'

V2' V1'

V2 V1

V2' V1'

H3' H2' H1'

H3' H2' H1'

H3 H2 H1

H3 H2 H1
28 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 9.—Continued.

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

JUNE 18, 1993–JUNE 11, 1995 (24-month interferogram)

C

N

117°15'

R. 5 W.

R. 4 W.

R. 3 W.

0

0

5 Miles

5 Kilometers

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 29

Figure 9.—Continued.

JUNE 18, 1993–JUNE 11, 1995

H1 H1'

H2 H2'

H3 H3'

V1 V1'

V2 V2'

0.10

40

20

0 0

-20

-0.10

-40

-60 -0.20

0.10

40

20

0 0

-20

-0.10

-40

-60 -0.20

0.10

40

20

0 0

-20

-0.10

-40

-60 -0.20

0.10

40

20

0 0

-20

-0.10

-40

-60 -0.20

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE, IN FEET

DISTANCE, IN KILOMETERS

Raw data

Averaged data

C

0 5 10 14.5

0 5 10 15 20 22.1

V2 V1

V2 V1

V2' V1'

V2' V1'

V2 V1

V2' V1'

H3' H2' H1'

H3' H2' H1'

H3 H2 H1

H3 H2 H1
30 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 9.—Continued.

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

JUNE 11, 1995–SEPTEMBER 24, 1995 (3-month interferogram)

D

N

117°15'

R. 4 W.

R. 3 W.

R. 5 W.

0

0

5 Miles

5 Kilometers

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 31

Figure 9.—Continued.

JUNE 11, 1995–SEPTEMBER 24, 1995

H1 H1'

H2 H2'

H3 H3'

V1 V1'

V2 V2'

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE, IN FEET

DISTANCE, IN KILOMETERS

Raw data Averaged data

D

0 5 10 14.5

0 5 10 15 20 22.1

H3' H2' H1'

H3' H2' H1'

H3 H2 H1

H3 H2 H1

V2 V1

V2 V1

V2' V1'

V2' V1'

V2 V1

V2' V1'
32 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 9.—Continued.

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

SEPTEMBER 24, 1995–MAY 26, 1996 (8-month interferogram)

E

N

117°15'

R. 5 W.

R. 4 W.

R. 3 W.

0

0

5 Miles

5 Kilometers

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 33

Figure 9.—Continued.

SEPTEMBER 24, 1995–MAY 26, 1996

H1 H1'

H2 H2'

H3 H3'

V1 V1'

V2 V2'

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

DISTANCE, IN KILOMETERS

Raw data

Averaged data

E

0 5 10 14.5

0 5 10 15 20 22.1

H3' H2' H1'

H3' H2' H1'

H3 H2 H1

H3 H2 H1

V2 V1

V2 V1

V2' V1'

V2' V1'

V2 V1

V2' V1'
34 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 9.—Continued.

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

JANUARY 8,1996–JUNE 21, 1999 (41-month interferogram)

F

N

117°15'

R. 5 W.

R. 4 W.

R. 3 W.

0

0

5 Miles

5 Kilometers

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 35

Figure 9.—Continued.

JANUARY 8, 1996–JUNE 21, 1999

H1 H1'

H2 H2'

H3 H3'

V1 V1'

V2 V2'

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE,IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

DISTANCE, IN KILOMETERS

Raw data

Averaged data

F

0 5 10 14.5

0 5 10 15 20 22.1

H3' H2' H1'

H3' H2' H1'

H3 H2 H1

H3 H2 H1

V2 V1

V2 V1

V2' V1'

V2' V1'

V2 V1

V2' V1'
36 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 9.—Continued.

H1 H1'

H2 H2'

H3 H3'

V1

V1'

V2

V2'

JUNE 21, 1999–NOVEMBER 8, 1999 (5-month interferogram)

G

N

117°15'

R. 5 W.

R. 4 W.

R. 3 W.

0

0 5 Kilometers

5 Miles

T. 11 N.

T. 12 N.

T. 10 N.

Harper Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 37

Figure 9.—Continued.

G

JUNE 21, 1999–NOVEMBER 8, 1999

H1 H1'

H2 H2'

H3 H3'

V1 V1'

V2 V2'

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

40

20

0

-20

-40

-60

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

DISTANCE, IN KILOMETERS

Raw data

Averaged data

0 5 10 14.5

0 5 10 15 20 22.1

H3' H2' H1'

H3' H2' H1'

H3 H2 H1

H3 H2 H1

V2 V1

V2 V1

V2' V1'

V2' V1'

V2 V1

V2' V1'
38 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 10. Depth to water for selected wells and relative land-surface change in the Lockhart–Harper Lake (dry) area, San Bernardino County, California.

(See figure 9A for locations of wells.)

70

22

74

78

82

24

26 86

90

11N/3W-28R2

50

54

58

62

66

18

16

20

70

25

80

84

88

92

29

27

96

100

11N/3W-7D1

11N/3W-16D1

YEAR

19901991199219931994199519961997

1998

1999

April 24, 1992,

to June 18, 1993

June 18, 1993,

to June 11, 1995

June 11, 1995,

to Sept. 24, 1995

June 21, 1999,

to Nov. 8, 1999

Sept. 24, 1995,

to May 26, 1996

Jan. 8, 1996,

to June 21, 1999

(dashed area)

DEPTH TO WATER, IN FEET BELOW LAND SURFACE

DEPTH TO WATER, IN METERS BELOW LAND SURFACE

-60

-50

-40

-30

-20

-10

0 0

RELATIVE LAND-SURFACE CHANGE,

IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE,

IN FEET

-0.05

-0.10

-0.15

-0.19

Time series 1

Time series 2
Interferometric Synthetic Aperture Radar (InSAR) 39

The interferograms of the Lockhart–Harper Lake 

(dry) area indicate that the northern and eastern shores 

of the playa subsided as much as 85 mm (0.28 ft) 

between 1992 and 1999 (fig. 10). The interferograms 

show a persistent pattern of deformation along the 

northern and eastern shores of the playa indicating as 

much as 60 mm (0.20 ft) of subsidence (net) between 

April 24, 1992, and May 26, 1996 (fig. 9B, C, D and E

and time series 1 in figure 10). The 41-month 

interferogram [January 8, 1996, to June 21, 1999 (fig. 

9F)] indicates that this area subsided about 30 mm (0.1 

ft), and the 5-month interferogram [June 21, 1999, to 

November 8, 1999 (fig. 9G)] shows almost no change 

(time series 2 in figure 10). 

Three wells in this area have water-level records 

for the 1990s; the screened intervals of all three of 

these wells are unknown (fig. 10). Three measurements 

were made at wells 11N/3W-7D1 and -16D1 during the 

1990s; both wells were measured in autumn 1992, 

spring 1996, and spring 1998. Water levels in these two 

wells declined about 2 m (6.5 ft) between 1992 and 

1998 (fig. 10). Water-level data for well 11N/3W-7D1 

indicate that water levels during the 1990s were at their 

lowest recorded levels (measurements were first made 

in 1953). Thirteen measurements were made at well 

11N/3W-28R2 during 1992–99; measurements 

generally were made twice a year—once in the autumn 

and once in spring. The water-level data for this well 

indicate a decline of about 2.1 m (7 ft) during the 

1992–99 period (fig. 10); records of water level, which 

date from as early as 1953, indicate that the water 

levels in the late 1990s were at their lowest levels. 

Ground-water flow simulations of the Mojave River 

ground-water basin show that water levels declined as 

much as 27 m (90 ft) between the late 1960s and 1999 

(Stamos and others, 2001). The relation between 

concurrently declining water levels—some that were 

lower in the 1990s than previously recorded lows—and 

subsidence suggests that if declining water levels are 

the stresses causing the subsidence, the 

preconsolidation stress may have been exceeded and 

subsidence may be permanent in this area.

Newberry Springs Area

Six interferograms were produced for the 

Newberry Springs area. The interferograms comprise 

two temporally overlapping time-series maps of 

vertical land-surface deformation. The six 

interferograms have temporal baselines of 3, 5, 8, 14, 

24, and 41 months for the period April 1992 to 

November 1999 (fig. 11). The 14-month [April 24, 

1992, to June 18, 1993 (fig. 11F)], 24-month [June 18, 

1993, to June 11, 1995 (fig. 11B)], 3-month [June 11, 

1995, to September 24, 1995 (fig. 11C)], and 8-month 

[September 24, 1995, to May 26, 1996 (fig. 11D)], 

form time series 1 in figure 12; the 41-month [January 

8, 1996, to June 21, 1999 (fig. 11G)] and 5-month 

[June 21, 1999, to November 8, 1999 (fig. 11E)] 

interferograms form time series 2 in figure 12. 

Four of the six interferograms for the Newberry 

Springs area show a persistent deformation pattern 

about 10 km (6 mi) east of Newberry Springs near Troy 

Lake (dry) (fig. 11B, C, D, and E). A noticeable 

deformation pattern also exists about 5 km (3.1 mi) east 

of Newberry Springs, but it is evident only in two 

dependent interferograms—the 3-month [June 11, 

1995, to September 24, 1995 (fig. 11C)] and the 8-

month [September 24, 1995, to May 26, 1996 (fig. 

11D)]—and therefore will not be discussed further. All 

six interferograms for the Newberry Springs area show 

atmospheric artifacts that may have affected the 

interpretations of the vertical land-surface changes. 

Because these atmospheric artifacts are in all the 

images for this area, it is likely that the tandum 

interferogram used to remove the topographic 

component of the data is the source of these artifacts. 

The 14-month interferogram [April 24, 1992, to June 

18, 1993 (fig. 11F)] shows the deformation caused by 

the June 28, 1992, earthquake at Landers, California, 

and the 5-month interferogram [June 21, 1999, to 

November 8, 1999 (fig. 11E)] shows deformation 

caused by motion from the October 16, 1999, Hector 

Mine earthquake, as indicated by the many residual 

fringes. Many areas in the 24-month [June 18, 1993, to 

June 11, 1995 (fig. 11B)] and 41-month [January 8, 

1996, to June 21, 1999 (fig. 11G)] interferograms have 

decorrelation problems owing to their fairly long 

temporal baselines and the agricultural land use in the 

area. A cross section could not be constructed for the 

41-month interferogram because there was too much 

decorrelation. 

The interferograms for the Newberry Springs 

area indicate that as much as 45 mm (0.15 ft) of 

subsidence occurred approximately 10 km (6 mi) east 

of Newberry Springs between 1993 and 1999 (fig. 12). 

Time series 1 (June 18, 1993–May 26, 1996) indicates 

about 5 mm (0.02 ft) of subsidence and time series 2 

(September 24, 1995–November 8, 1999) indicates 

about 40 mm (0.13 ft) of subsidence.
40 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 11. Amplitude image showing land-surface features and locations of wells and piezometers used to evaluate subsurface geology or to monitor 

ground-water levels, and phase images and graphs showing vertical land-surface changes in the Newberry Springs area, San Bernardino County, California. 

Amplitude image (A) and phase images and graphs showing land-surface change for (B) June 18, 1993, to June 11, 1995; (C) June 11, 1995, to September 

24, 1995; (D) September 24, 1995, to May 26, 1996; (E) June 21, 1999, to November 8, 1999, (F) April 24, 1992, to June 18, 1993, and (G) January 8, 1996, to 

June 21, 1999. (See figure 1 for location of area; see figure 12 for hydrographs of selected wells.)

H1 H1'

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

0

0

5

5

10 Miles

10 Kilometers

N

T. 10 N.

T. 9 N.

116°45'

35°00'

A

Daggett

9N/3E-35D3

9N/3E-35D3

9N/3E-15E4

9N/4E-10E1

9N/3E-22R4–7

Newberry

Springs

Mojave

River

Single well and identifier

Cluster well and identifier—Site at which two or more

wells are installed at different depths

EXPLANATION

Troy

Lake

(dry)

9N/3E-22R4–7

9N/4E-18N1
Interferometric Synthetic Aperture Radar (InSAR) 41

Figure 11.—Continued.

H1 H1'

transect locations are approximate

H1 H1'

JUNE 18,1993–JUNE 11,1995

20

0 0

0

-20

-40

RELATIVE LAND-SURFACE

CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE

CHANGE, IN FEET

DISTANCE, IN KILOMETERS

Raw data Averaged data

(24-month interferogram)

N

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

T. 10 N.

T. 9 N.

116°45'

35°00'

Daggett Newberry

Springs

B

0.10

-0.10

5 10 15 20 25 30 35 40 42.5

+28 mm 0 -28 mm

relative

uplift subsidence

0

0

5

5

10 Miles

10 Kilometers

Troy

Lake

(dry)

Mojave

River
42 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 11.—Continued.

transect locations are approximate

20

0

-20

-40

RELATIVE LAND-SURFACE

CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE

CHANGE, IN FEET

JUNE 11, 1995–SEPTEMBER 24, 1995

C

(3-month interferogram)

N

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

T. 10 N.

T. 9 N.

116°45'

35°00'

Daggett

Newberry

Springs

0

0.10

-0.10

H1 H1'

H1 H1'

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

0

5

5

10 Miles

10 Kilometers

0 5 10 15 20 25 30 35 40 42.5

+28 mm 0 -28 mm

relative

uplift subsidence

Mojave

River

Troy

Lake

(dry)
Interferometric Synthetic Aperture Radar (InSAR) 43

Figure 11.—Continued.

transect locations are approximate

20

0

-20

-40

SEPTEMBER 24,1995–MAY 26,1996

RELATIVE LAND-SURFACE

CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE

CHANGE, IN FEET

(8-month interferogram)

N

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

T. 10 N.

T. 9 N.

116°45'

35°00'

Daggett

Newberry

Springs

0

0.10

-0.10

D

H1 H1'

H1 H1'

DISTANCE, IN KILOMETERS

Raw data

Averaged data

0

0

5

5

10 Miles

10 Kilometers

5 10 15 20 25 30 35 40 42.5

Mojave

River

Troy

Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
44 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 11.—Continued.

transect locations are approximate

20

0

-20

-40

JUNE 21,1999–NOVEMBER 8,1999

RELATIVE LAND-SURFACECHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE

CHANGE, IN FEET

(5-month interferogram)

N

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

T. 10 N.

T. 9 N.

116°45'

35°00'

Daggett

Newberry

Springs

0

0.10

-0.10

E

H1 H1'

H1 H1'

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

0

5

5

10 Miles

10 Kilometers

5 10 15 20 25 30 35 40 42.5

Mojave

River

Troy

Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
Interferometric Synthetic Aperture Radar (InSAR) 45

Figure 11.—Continued.

APRIL 24, 1992–JUNE 18, 1993

JANUARY 8, 1996–JUNE 21, 1999

G

F

deformation

caused by the

June 28, 1992,

earthquake at

Landers

N

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

T. 10 N.

T. 9 N.

116°45'

35°00'

Daggett

Newberry

Springs

R. 1 E.

R. 2 E.

R. 3 E.

R. 4 E.

T. 10 N.

T. 9 N.

116°45'

35°00'

Daggett

Newberry

Springs

0

0

5

5

10 Miles

10 Kilometers

(14-month interferogram)

(41-month interferogram)

Mojave

River

Mojave

River

Troy

Lake

(dry)

Troy

Lake

(dry)

+28 mm 0 -28 mm

relative

uplift subsidence
46 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 12. Depth to water for selected wells and piezometers, and relative land-surface change in the Newberry Springs area, San Bernardino County, 

California. (See figure 11A for locations of wells.)

80

85

90

29 95

27

25

31

33

35

100

105

110

115

9N/3E-22R4

9N/3E-22R5

9N/3E-22R6

9N/3E-22R7

95

32

32

34

36

30

38

100

105

110

115

120

125

130

9N/3E-15E4

95

100

105

110

115

120

125

130

34

36

30

38

YEAR

1990199119921993199419951996199719981999

April 24, 1992,

to June 18, 1993

June 18, 1993,

to June 11, 1995

June 11, 1995,

to Sept. 24, 1995

Sept. 24, 1995,

to May 26, 1996

Jan. 8, 1996,

to June 21, 1999

(dashed area)

June 21, 1999,

to Nov. 8, 1999

9N/3E-35D3

DEPTH TO WATER, IN FEET BELOW LAND SURFACE

DEPTH TO WATER, IN METERS BELOW LAND SURFACE

-40

-35

-30

-25

-20

-15

-10

-0.10

-0.13

-0.05

-5

0 0

RELATIVE LAND-SURFACE CHANGE,

IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE,

IN FEET

Time series 1

Time series 2
Interferometric Synthetic Aperture Radar (InSAR) 47

Although there are no wells in the immediate 

vicinity of the measured subsidence, water-level data 

from the closest wells were available for the 1990s (fig. 

12). Water-level data for piezometers 9N/3E-22R4–7 

indicate seasonal fluctuations of as much as 5.8 m 

(19 ft) and a long-term decline of about 3 m (10 ft) 

during 1993–99 (fig. 12). Piezometers 9N/3E-22R4–6 

are perforated in the regional aquifer and 9N/3E-22R7 

is perforated in the flood-plain aquifer; the screened 

intervals for these piezometers range from 30 to 183 m 

(100 to 600 ft) below land surface (fig. 2). Water-level 

data for well 9N/3E-15E4, screened in the flood-plain 

aquifer about 18 to 46 m (60 to 150 ft) below land 

surface, indicate that water levels declined about 3 m 

(10 ft) during 1993–99, but because water levels were 

measured infrequently for this well, seasonal 

fluctuations could not be determined (fig. 12). Waterlevel data for well 9N/3E-35D3, screened in the floodplain aquifer about 18 to 67 m (60 to 219 ft) below land 

surface, indicate seasonal fluctuations of as much as 

4 m (13 ft) during some years and longer term waterlevel declines of 3 m (10 ft) during 1993–99 (fig. 12). 

Ground-water flow simulations of the Mojave River 

ground-water basin show that water levels declined as 

much as 40 m (130 ft) in this area between the early 

1940s and 1999 (Stamos and others, 2001).

Because the water levels in the six wells near 

Newberry Springs declined about 3 m (10 ft) between 

1993 and 1999, the preconsolidation stress probably 

was exceeded when water levels were at their seasonal 

lows during each summer. Subsidence that occurred 

during these periods may be permanent. The 

geophysical and lithologic logs of piezometers 9N/3E22R4–7 indicate that sediments more susceptible to 

deformation (clay and silt) are present at depths greater 

than 70 m (225 ft). However, lithologic logs for wells 

9N/4E-10E1 and -18N1 near Troy Lake (dry) (fig. 11A)

indicate a predominance of clay throughout the profile.

Morongo Ground-Water Basin—Lucerne Valley Area

Seven interferograms were produced for the 

Lucerne Valley area. The interferograms compose two 

temporally overlapping time-series maps of vertical 

land-surface deformation. The seven interferograms 

have temporal baselines of 3, 5, 8, 14, 24, 41 and 41 

months for the period April 1992 to November 1999 

(fig. 13). The 14-month [April 24, 1992, to June 18, 

1993 (fig. 13B)], 24-month [June 18, 1993, to June 11, 

1995 (fig. 13C)], 3-month (June 11, 1995, to 

September 24, 1995 (fig. 13D)], and 8-month 

[September 24, 1995, to May 26, 1996 (fig. 13F)] 

interferograms form time series 1 in figure 14. The 41-

month (April 24, 1992, to September 24, 1995 

(fig. 13E)] interferogram temporally envelopes much 

of this time series. The 41-month [January 8, 1996, to 

June 21, 1999 (fig. 13G)] and 5-month [June 21, 1999, 

to November 8, 1999 (fig. 13H)] interferograms form 

time series 2 in figure 14. 

The seven interferograms for Lucerne Valley 

(fig. 13) show two deformation patterns: one just 

southeast of the southeastern shore of the playa near 

the intersection of cross-section lines H2–H2′ and V2–

V2′ and one along the western shore of Lucerne Lake 

(dry) near the intersection of cross-section lines H1–

H1′ and V1–V1′ (fig. 13). The location of the former 

pattern coincides with the location of an area that 

subsided about 600 mm (2 ft) ±1,500 mm (5 ft) 

(determined from topographic maps and GPS 

measurements for the 1969–98 or the 1975–98 period). 

All seven interferograms for Lucerne Valley (fig. 13)

have decorrelation problems, as evidenced by the 

speckled patterns appearing in the interferograms, 

because much of the land surface has been disturbed 

owing to agricultural practices. The decorrelation also 

can be attributed to wet periods during which flooding 

and (or) deposition occurred on the playa, movement 

along faults, or strong winds. Additionally, the 14-

month [April 24, 1992, to June 18, 1993 (fig. 13B)] and 

the 41-month [April 24, 1992, to September 24, 1995 

(fig. 13E)] interferograms show deformation caused by 

motion from the June 28, 1992, earthquake at Landers. 

Deformation caused by the motion from the October 

16, 1999, Hector Mine earthquake is evident in the 5-

month [June 21, 1999, to November 8, 1999 (fig. 13H)] 

interferogram.
48 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 13. Amplitude image showing land-surface features and locations of wells and piezometers used to evaluate subsurface geology or to monitor 

ground-water levels, and phase images and graphs showing vertical land-surface changes in the Lucerne Valley area, San Bernardino County, California. 

Amplitude image (A) and phase images and graphs showing land-surface change for (B) April 24, 1992, to June 18, 1993; (C) June 18, 1993, to June 11, 

1995; (D) June 11, 1995, to September 24, 1995; (E) April 24, 1992, to September 24, 1995, (F) September 24, 1995, to May 26, 1996, and (G) January 8, 

1996, to June 21, 1999, and (H) June 21, 1999, to November 8, 1999. (See figure 1 for location of area; see figure 14 for hydrographs of selected wells.)

4N/1W-1R4–9

4N/1W-1R4–9

5N/1W-28F1

4N/1W-2J1

4N/1W-2J1

4N/1W-1R1

SAN BERNARDINO MERIDIAN

Lucerne

Lake

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

Lucerne

Valley

(dry)

A

0

0

5 Miles

5 Kilometers

RAIN

RAIN

HOLM

Single well and identifier

Global Positioning System (GPS) station and identifier

Cluster well and identifier—Site at which two or more

wells are installed at different depths

EXPLANATION

H2 H2'

V2

H1 H1'

V1

V1' V2'

GOBR

Approximate location

and orientation of

fissures in figure 6
Interferometric Synthetic Aperture Radar (InSAR) 49

Figure 13.—Continued.

DISTANCE, IN KILOMETERS

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

Raw data Averaged data

0

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

40

0

0

-0.10

-0.20

0

-0.10

-0.20

-40

-80

B

H2 H2'

V2

V2'

H2 H2'

V2 V2'

APRIL 24, 1992–JUNE 18, 1993

transect locations are approximate

H1 H1'

V1

V1

V1'

H1 H1'

V1'

(14-month interferogram)

0.10

0.10

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

SAN

BERNARDINO

MERIDIAN

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

0

0

5 Miles

5 Kilometers

5 10 13.8

Lucerne

Valley

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1'

H1

H2'

H2

V1 V2

V1' V2'
50 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 13.—Continued.

JUNE 18, 1993–JUNE 11, 1995

transect locations are approximate

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

(24-month interferogram)

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

C

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

Lucerne

Valley

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

H2 H2'

V2

V2'

H2 H2'

V2 V2'

H1 H1'

V1

V1

V1'

H1 H1'

V1'

0

0

5 Miles

5 Kilometers

5 10 13.8

SAN

BERNARDINO

MERIDIAN

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1'

H1

H2'

H2

V1 V2

V1' V2'
Interferometric Synthetic Aperture Radar (InSAR) 51

Figure 13.—Continued.

JUNE 11, 1995–SEPTEMBER 24, 1995

transect locations are approximate

D

(3-month interferogram)

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

40

RELATIVE LAND-SURFACE CHANGE, IN FEET

0

-40

-80

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

H2 H2'

V2

V2'

H2 H2'

V2 V2'

H1 H1'

V1

V1

V1'

H1 H1'

V1'

SAN

BERNARDINO

MERIDIAN

0

0

5 Miles

5 Kilometers

5 10 13.8

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1'

H1

H2'

H2

V1 V2

V1' V2'

Lucerne

Valley
52 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 13.—Continued.

APRIL 24, 1992–SEPTEMBER 24, 1995

transect locations are approximate

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

(41-month interferogram)

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

E DISTANCE, IN KILOMETERS

Raw data Averaged data

0

H2 H2'

V2

V2'

H2 H2'

V2 V2'

H1 H1'

V1

V1

V1'

H1 H1'

V1'

SAN

BERNARDINO

MERIDIAN

0

0

5 Miles

5 Kilometers

5 10 13.8

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1'

H1

H2'

H2

V1 V2

V1' V2'

Lucerne

Valley
Interferometric Synthetic Aperture Radar (InSAR) 53

Figure 13.—Continued.

F

SEPTEMBER 24, 1995–MAY 26, 1996

transect locations are approximate

(8-month interferogram)

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

Lucerne

Valley

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

H2 H2'

V2

V2'

H2 H2'

V2 V2'

H1 H1'

V1

V1

V1'

H1 H1'

V1'

SAN

BERNARDINO

MERIDIAN

0

0

5 Miles

5 Kilometers

5 10 13.8

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1'

H1

H2'

H2

V1 V2

V1' V2'
54 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 13.—Continued.

JANUARY 8, 1996–JUNE 21, 1999

transect locations are approximate

(41-month interferogram)

GRELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

40

0

-40

40

0

-40

-80

-80

40

0

-40

-80

40

0

-40

-80

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

Lucerne

Valley

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

H2 H2'

V2

V2'

H2 H2'

V2 V2'

H1 H1'

V1

V1

V1'

H1 H1'

V1'

SAN

BERNARDINO

MERIDIAN

0

0

5 Miles

5 Kilometers

5 10 13.8

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1'

H1

H2'

H2

V1 V2

V1' V2'
Interferometric Synthetic Aperture Radar (InSAR) 55

Figure 13.—Continued.

JUNE 21, 1999–NOVEMBER 8, 1999

transect locations are approximate

RELATIVE LAND-SURFACE CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE CHANGE, IN FEET

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

40

0

-40

-80

(5-month interferogram)

H

N

T. 5 N.

T. 4 N.

R. 1 W.

R. 1 E.

Lucerne

Valley

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

0.10

0

-0.10

-0.20

DISTANCE, IN KILOMETERS

Raw data Averaged data

0

H2 H2'

V2

V2'

H2 H2'

V2 V2'

H1 H1'

V1

V1

V1'

V1 V2

V1'

H1'

H1

H2'

H2

V2'

H1 H1'

V1'

SAN

BERNARDINO

MERIDIAN

0

0

5 Miles

5 Kilometers

5 10 13.8

+28 mm 0 -28 mm

relative

uplift subsidence

Lucerne

Lake

(dry)

deformation

caused by the

October 16,1999,

earthquake at

Hector Mine

H1'

H1

H2'

H2

V1 V2

V1' V2'
56 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

Figure 14. Depth to water for selected wells and piezometers and relative land-surface change in the Lucerne Valley area, San Bernardino County, 

California. (See figure 13A for locations of wells.)

145

150

155

160

165

170

175

4N/1W-1R5

110

115

120

125

130

135

140

4N/1W-1R8

110

115

120

125

130

135

140

34

36

38

40

42

34

36

38

40

42

45

47

49

51

53

130

135

40

42

44

46

48

140

145

150

155

160

6 20

25

30

35

40

45

50

8

10

12

14

Jan. 8, 1996,

to June 21, 1999

(dashed area)

Jan. 8, 1996,

to June 21, 1999

(dashed area)

4N/1W-1R1

4N/1W-1R7

YEAR

4N/1W-1R4

4N/1W-2J1

DEPTH TO WATER, IN METERS BELOW LAND SURFACE

DEPTH TO WATER, IN FEET BELOW LAND SURFACE

DEPTH TO WATER, IN FEET

BELOW LAND SURFACE

1990199119921993199419951996199719981999

1990199119921993199419951996199719981999

5N/1W-28F1

4N/1W-1R9

April 24,1992,

to June 18, 1993

June 18,1993,

to June 11, 1995

June 11,1995,

to Sept. 24, 1995

June 21,1999,

to Nov. 8, 1999

Sept. 24,1995,

to May 26, 1996 April 24,1992,

to June 18, 1993

June 18,1993,

to June 11, 1995

June 11,1995,

to Sept. 24, 1995

June 21,1999,

to Nov. 8, 1999

Sept. 24,1995,

to May 26, 1996

-50

-40

-30 -0.10

-0.15

-0.16

-0.05

-0.10

-0.115

-0.05 -20

-10

0 0

-35

-30

-25

-20

-15

-10

-5

0 0

RELATIVE LAND-SURFACE

CHANGE, IN MILLIMETERS

RELATIVE LAND-SURFACE

CHANGE, IN FEET

Time series 1

Single

interferogram

Single

interferogram Time series 2 Time series 2

Time series 1

Subsidence detected

southeast of Lucerne Lake (dry) Subsidence detected along western shore of Lucerne Lake (dry)
Future Monitoring 57

The interferograms for the Lucerne Valley area 

indicate that an area southeast of Lucerne Lake (dry) 

subsided about 90 mm (0.3 ft) between April 24, 1992, 

and November 8, 1999 (fig. 14). The area of subsidence 

is near GPS stations RAIN and HOLM, where as much 

as 600 mm (2 ft) ± 1,500 (5 ft) of subsidence occurred 

between 1969 and 1998. Water-level data for wells in 

the area are sparse, especially prior to 1997, before the 

construction of and data collection for cluster wells 

4N/1W-1R4–9. The apparent water-level rise in well 

4N/1W-2J1 and decline in 4N/1W-1R1 may be due to 

seasonal effects and thus may not represent a longer 

term trend. Water levels in wells 4N/1W-1R7 and -1R9 

declined linearly less than 1.5 m (5 ft) between 1997 

and 1999; wells 4N/1W-1R4, -1R5, and -1R8 show a 

1.5 to 3 m (5 to 10 ft) seasonal change for 1997–99, a 

slight decline from winter to winter, but almost no 

change from summer to summer (fig. 14; see figure 3

for screened intervals).

Although the limited amount of water-level data 

for the periods coincident with the interferograms 

hinders a meaningful analysis of a possible relation 

between ground-water levels in the 1990s and land 

subsidence, historical water-level data provide insights 

into the relation. Water levels in wells in the area 

declined 30 m (100 ft) between the 1950s and early 

1990s as shown by the hydrographs for wells 5N/1W25G1 and 5N/1E-17D1 in figure 5. In 1993, the 

adjudication began, requiring ground-water pumpage 

to be reduced by 20 percent (Stamos and others, 2001). 

As a result, ground-water levels southeast of Lucerne 

Lake (dry) rose and then stabilized (fig. 5). Stable 

ground-water levels and temporally coincident 

subsidence indicates that the fine-grained parts of the 

aquifer system may be compacting residually, still 

equilibrating with reduced pressures in the coarser 

grained parts of the aquifer system (fig. 3) caused by 

ground-water-level declines that occurred prior to 

1993.

The interferograms for the Lucerne Valley area 

indicate that the area along the western shore of the 

lake subsided about 60 mm (0.2 ft) between April 24, 

1992, and November 8, 1999 (fig. 14). Only one well, 

5N/1W-28F1 (unknown screened interval), which had 

data for the 1990s, is near the area of subsidence along 

the western shore of Lucerne Lake (fig. 13A). Water 

levels in this well declined less than 0.15 m (0.5 ft) 

between 1994 and 1996 (fig. 14). Because of the 

limited amount of water-level data for periods 

coincident with the interferograms, a meaningful 

analysis of a possible relation between ground-water 

levels and InSAR-detected subsidence was not 

possible.

FUTURE MONITORING

The population of the southwestern Mojave 

Desert will undoubtedly continue to grow, thus 

increasing the demand for ground water. The demand 

on the ground-water resources will result in groundwater-level declines and, probably, continued or new 

land subsidence in some areas. Periodic landsubsidence monitoring will be needed to prevent the 

adverse affects of land subsidence. 

InSAR can be used to develop spatially detailed 

seasonal, annual, or multi-year maps of ground 

displacements. Such maps can show changes as small 

as 5 mm (0.02 ft) in the vertical position of land surface 

(Hoffmann and others, 2001). In addition, the InSAR 

measurements could be compared with ground-waterlevel data to better define a possible relation between 

aquifer-system deformation (expressed as vertical 

changes at land surface) and changes in ground-water 

levels. The ground-water levels should be measured at 

least twice annually from depth-dependent or aquiferdependent wells in areas where vertical land-surface 

changes occurred during 1992–99, as documented in 

this study. For future land-based surveys, modifications 

could be made to the existing GPS network in Lucerne 

Valley and (or) new GPS networks could be established 

in areas where the InSAR maps indicated areas of 

vertical land-surface changes, such as in the El Mirage 

and Newberry Springs areas. Future monitoring of the 

GPS network (or networks) combined with the InSAR 

maps could be used to provide ground truth for the 

more spatially detailed and higher resolution InSAR 

measurements. For the amounts of subsidence detected 

in the interferograms for the Lucerne Valley area, an 

interval of 3 to 5 years between GPS surveys may be 

appropriate for detecting measurable changes in the 

vertical position of monuments for changes that are 

significantly larger than the expected GPS 

measurement error (figs. 13 and 14). 
58 Detection and Measurement of Land Subsidence using InSAR and GPS, San Bernardino County, Mojave Desert, California

CONCLUSIONS

Ground water has been the primary source of 

domestic, agricultural, and municipal water supplies in 

the Mojave Desert, California, since the early 1900s. 

Owing to increasing urbanization, demands on local 

water supplies have caused overdraft conditions in 

some areas of the Mojave River and Morongo groundwater basins and caused declines in water levels in 

some wells of more than 30 meters (100 feet) between 

the 1950s and the 1990s. These water-level declines 

have the potential to induce or renew land subsidence 

(the lowering of land-surface elevations) in these 

Mojave Desert ground-water basins.

Leveling data for the Lucerne Valley area have 

been available since as early as 1944. These data were 

used with 1998 Global Positioning System (GPS) data 

to determine the location, extent, and magnitude of 

vertical land-surface changes in Lucerne Valley in the 

Morongo ground-water basin. GPS measurements for 

three geodetic monuments in the GPS network indicate 

that about 600 millimeters (2 feet) [plus or minus 1,500 

millimeters (5 feet)] of subsidence occurred southeast 

of Lucerne Lake (dry) during the two comparison 

periods (1969–98 and 1975–98) for this study but the 

GPS measurements for seven other monuments in the 

area indicated very little or no change in vertical 

position. Water levels in this area of subsidence 

declined about 15 meters (50 feet) during 1970–98; the 

water levels in many wells were at their lowest 

recorded levels during the 1990s. The relation between 

subsidence and the record low water levels suggests 

that the preconsolidation stress of the aquifer system 

may have been exceeded during this period and that 

compaction may be permanent in these areas.

Interferometric synthetic aperture radar (InSAR) 

methods were used to determine the location, extent, 

and magnitude of vertical land-surface changes in the 

Mojave River and Morongo ground-water basins for 

various time intervals between 1992 and 1999. The 

interferograms show subsidence ranging from 45 to 90 

mm (0.15 to 0.3 ft) in four areas of these two groundwater basins—the El Mirage, Lucerne Valley, 

Newberry Springs, and Lockhart–Harper Lake (dry) 

areas.

Water-level data for the areas undergoing vertical 

land-surface changes (detected using InSAR) were 

examined to determine whether these changes may be 

related to aquifer-system deformation caused by 

ground-water-level changes. Because of the limited 

water-level data available, much of which was from 

wells with unknown screened intervals, and a lack of 

temporally coincident water-level and InSAR data, the 

relation between the ground-water-level changes and 

the vertical land-surface changes that occurred during 

1992–99 could not be clearly defined for the four areas. 

However, in all four areas, water-level data indicate 

that water levels in the 1990s were near or below 

historically low levels. This decline in ground-water 

levels can cause land subsidence. In the Lucerne Valley 

area, about 90 mm (0.3 ft) of subsidence was measured 

between 1992 and 1999 in an area where ground-water 

levels declined 30 m (100 ft) between the 1950s and 

1993 but stabilized in the mid and late 1990s. Stable 

ground-water levels and temporally coincident 

subsidence indicates that fine-grained parts of the 

aquifer system may be compacting residually, still 

equilibrating with reduced pressures in the coarser 

grained parts of the aquifer system caused by groundwater-level declines that occurred prior to 1993.

This study supports part of a cooperative 

program with the Mojave Water Agency to monitor 

water resources in the Mojave River and Morongo 

ground-water basins. Land-subsidence monitoring will 

continue to be an important component of this program 

because of continued reliance on ground water in these 

ground-water basins.

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