U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY 

Comments on Potential Geologic and Seismic Hazards Affecting Mare Island, Solano 

County, California 

by

T.L. Holzer, C.M. Wentworth, W.H. Bakun, J. Boatwright, T.E. Brocher, M. Çelebi, W.L. 

Ellsworth, J.P.B. Fletcher, E.L. Geist, R. W. Graymer, R.E. Kayen, D. K. Keefer, D. H. 

Oppenheimer, W.U. Savage, D.P. Schwartz, and R. W. Simpson 

 

Open-File Report 02-425 

2002

 

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards 

or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes 

only and does not imply endorsement by the U.S. Government. 
Executive Summary 

This report was prepared in response to a written request from the City of Vallejo, 

California, to the U.S. Geological Survey (USGS). By letter of October 4, 2002, the City 

requested that the USGS “provide advice to the City’s LNG Health and Safety Committee on its 

review of a potential liquid natural gas project” on the southern portion of Mare Island. The City 

specifically requested that the USGS advise the committee on potential hazards including fault 

rupture, earthquake ground motion, soil failure during earthquakes, tsunami and seiche, and 

landslides. The City requested that the USGS: (1) comment on these hazards, (2) describe its 

degree of confidence in its opinions, and (3) describe the scope of additional studies that will be 

needed if the City enters into an agreement with project sponsors. Advice was also requested on 

the selection of the safe shutdown and operating basis earthquakes as specified in the NFPA 59A 

standard (NFPA, 2001). 

This review of published reports and other publicly available information indicates that 

all of the hazards on which the USGS was asked to comment should be considered for the 

proposed project on the southern portion of Mare Island. Available information differs greatly 

for each of these potential hazards, and adequate understanding for design will require detailed 

site-specific investigations. 

• Surface fault rupture: Available data are inconclusive regarding the precise location and 

recency of faulting on the Franklin Fault, although there is considerable evidence that it 

does not pass directly through the site on southern Mare Island proposed for the liquefied 

natural gas (LNG) project. Clarification of the recency of faulting on the Franklin Fault 

and the possibility of minor surface faulting at the site is necessary to resolve the 

potential for faulting at the land surface. 

• Near-source ground motion: The proposed LNG project site may be as close as about 7 

km (4 miles) from the Hayward/Rodgers Creek Fault system, one of the major active 

fault systems in the San Francisco Bay region. This fault system has a 32 percent 

probability of producing a magnitude 6.7 or greater earthquake in the next 30 years and 

may be capable of producing an earthquake with a magnitude as large as 7.4. Shaking 

typically is greater closer to the earthquake source. In addition, the proposed site is close 

enough to this fault system to experience large near-source ground-motion phenomena. 

The phenomena include elevated levels of ground motion produced by propagation of the 

earthquake fault rupture toward the site (rupture directivity) and potentially large tectonic 

displacements of the land (static offset). Estimates of design ground motions at the 

proposed LNG project should consider near-source ground-motion effects, particularly 

for evaluating the ground displacement levels in the design of base-isolated systems. 

• Foundation conditions: Portions of the proposed site appear to be underlain by artificial 

fill and by soft bay mud deposited in San Pablo Bay. Both of these materials historically 

have performed poorly in earthquakes and should receive special investigation at the site. 

Artificial fill, if not properly engineered, may fail and cause large displacements at the 

land surface. Bay mud typically modifies the amplitude and frequency of seismic waves 

as they propagate upwards from bedrock. These modifications should be included in 

estimates of ground motion. 

• Tsunami and seiche: Fluctuations of water level in the San Francisco Bay system

associated with both distant and local earthquakes have been observed. While the 

2
fluctuations have been small, their effect could be compounded by adverse tidal 

conditions. The potential effects of tsunamis and seiche should be included in design and 

operational considerations of the proposed project. 

• Landslides: The steep bedrock slope adjacent to the proposed site may be susceptible to 

both earthquake and rainfall-induced landslides. Possible effect of such slope failures on 

proposed project structures should be considered. 

Selection of the Safe Shutdown Earthquake (SSE) and Operating Basis Earthquake (OBE) 

should consider the potential effects of rupture directivity, static offset, and site-specific soil 

conditions. 

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Introduction

This report was prepared at the written request of the City of Vallejo to the U.S. 

Geological Survey (USGS). By letter of October 4, 2002, the USGS was requested to “provide 

advice to the City’s LNG Health and Safety Committee on its review of a potential liquid natural 

gas project” on the southern portion of Mare Island. The City specifically requested that the 

USGS advise the committee on potential hazards including fault rupture, earthquake ground 

motion, soil failure during earthquakes, tsunami and seiche, and landslides. Advice was also 

requested on the selection of the safe shutdown and operating basis earthquakes as described in 

NFPA 59A standard (NFPA, 2001). 

This report reviews the geologic and seismic hazards that may affect the southern portion 

of Mare Island. It includes a summary of findings, followed by more extensive and technical 

discussion of issues and evidence. This report is neither a study of the proposed LNG project nor 

an evaluation of any aspect of the project. 

This report is based on regional studies of the San Francisco Bay region conducted by the 

USGS and on other published sources. In addition, the City of Vallejo provided the USGS with a 

report prepared for Bechtel Enterprises/Shell by William Lettis & Associates, “Interim Report on 

Surface Investigations of the Potential for Earthquake-related Surface Deformation at Proposed 

LNG and Power Plant Facilities, Southern Mare Island, Vallejo, California”, dated October 14, 

2002 (WLA, 2002). Discussions were also held with representatives of William Lettis & 

Associates and the California Geological Survey. No new field investigations or surveys were 

conducted by the USGS in the preparation of this report. For the purposes of this report, it is 

assumed that the proposed LNG project site is as shown in Figure 1 of WLA (2002). 

Feasibility studies and the design of engineering projects begin with assessments of the 

conditions at and near the project site that may influence design and operation. The purpose of 

this report is to comment on potential hazards and geologic conditions pertaining to Mare Island. 

Design of the proposed facility should consider these hazards and conditions. 

Setting

The proposed LNG project lies within a 70-km-wide (44 miles) set of major faults of the 

San Andreas Fault system that forms the boundary between the Pacific and North American 

tectonic plates (Figure 1). The persistent northwestward movement of the Pacific plate relative to 

North America primarily causes right-lateral slip across the major faults, but also causes 

deformation between the major faults. The ongoing complex deformation field is revealed by 

modern geodetic surveys and earthquake patterns as well as the regional geologic structure. The 

proposed site is located at the eastern shore of San Pablo Bay between two major active fault 

systems: the Hayward-Rodgers Creek Fault system on the west and the Concord-Green Valley 

Fault system on the east. The site lies near the middle of the 65-km-long (40 miles) CarnerosFranklin Faults, which juxtapose different suites of rocks, and for which the earthquake potential 

is unknown. 

4
Shaking sufficient to seriously damage structures at Mare Island occurred during the 

M6.81 1868 Hayward Fault earthquake, the M7.8 1906 San Andreas Fault earthquake, and 

particularly during the M6.3 1898 Mare Island earthquake (Appendix 1). The 1898 earthquake 

may have occurred about 20 km (12 miles) to the northwest on the southern Rodgers Creek 

Fault. Even larger nearby events than the 1898 earthquake can be expected in the future. In 

addition, the site is depicted on the USGS National Seismic Hazard Maps to have a high 

probability of strong shaking in the future (http://geohazards.cr.usgs.gov/eq/; Frankel and others, 

1997).

The regional geology of the proposed site is shown in Figure 2. The proposed site lies 

near sea level at the southern end of Mare Island adjacent to a steep slope underlain by relatively 

hard fractured rock. The island is surrounded by soft mud deposited in San Pablo Bay. Portions 

of the proposed site are underlain by artificial fill (Figure 2). In general, areas in the San 

Francisco Bay region that are underlain by fill and bay mud have experienced disproportionately 

greater damage during historic earthquakes. Such damage is caused by soil failure in the fills and 

amplification of ground shaking by the soft bay mud. 

Earthquake Sources 

This section of the report describes potential earthquake sources that may cause shaking 

at the proposed site. Earthquake sources occur throughout the San Francisco Bay region on faults 

with a broad range of slip rates, lengths, and styles of movement. The proposed site is at a 

location where earthquakes on some of these faults have the potential to produce ground motions 

that may be important for engineering design. These faults can be grouped into three categories: 

• Well-documented strike-slip faults that produce large earthquakes in the region: The site 

is located between two major, largely strike-slip fault systems (Figure 1). The HaywardRodgers Creek Fault system, which is approximately 7 km (4 miles) west of the site, 

generated damaging earthquakes in 1868 and probably in 1898. The Concord-Green 

Valley Fault system, which is12 km (7 miles) east of the site, produced a M5.5 

earthquake in 1954; while it has not generated a large historical event, there is strong 

evidence for recent pre-historic activity. The 1999 Working Group on California 

Earthquake Probabilities (WG99, 1999) concluded that the Hayward-Rodgers Creek 

Fault system has a 32 percent probability of generating a large earthquake (M6.7 to 7.4) 

by the year 2030, and the Concord-Green Valley Fault system has a 6 percent chance of 

generating a large earthquake (M≥6.7) in the same time period (Figure 1). 

• Insufficiently characterized faults closer to the site that may produce moderate to large 

earthquakes: The crustal block between the two major faults is broken by several other 

faults that could be active (Figure 3), including the Pinole, West Napa, Franklin, 

Southhampton, Lake Herman, and Sky Valley Faults. Although only the West Napa Fault 

is known to have displaced Holocene-age sediment — which is positive evidence of 

surface fault rupture in the last 11,000 years (Hart and Bryant, 1999; CDMG, 1983) — no 

evidence demonstrates that any of these other faults are not active. Small earthquakes 

recorded in the area over the past 34 years indicate that the crustal block is being actively 

deformed by small slippage on faults at depth (Figure 4). Notable among these small 

 

1

 M refers to earthquake magnitude 

5
earthquakes is a tabular subvertical grouping at depths of 5-12 km just east of the surface 

trace of the Franklin Fault (a in Figure 4, map and cross section). 

Among these faults, the Franklin Fault is particularly relevant because of its 

proximity to Mare Island. The fault does not appear to have surface geomorphic features 

that are typical of very active faults and is not classified as an active fault by the 

California Geological Survey (CDMG, 1983). While the long-term rate of fault slip is 

thus low, the seismicity and geologic data suggest that it might be capable of generating 

earthquakes. 

Further site studies should include analysis of these faults with regard to their 

activity, orientation, and type of deformation in order to estimate the size, type, and 

probability of earthquakes they can produce.

• Unknown blind faults that may be earthquake sources: Some recent damaging 

earthquakes in California, including the M6.5 Coalinga (1983), M6.9 Loma Prieta (1989), 

and M6.7 Northridge (1994) events, have occurred on blind faults — that is, on faults that 

have no primary surface rupture. Most of these faults are thrusts, but the Loma Prieta 

earthquake indicated that other types of active faults may not extend to the ground 

surface. Although no blind faults are recognized in the Mare Island area, they are known 

beneath Grizzly Island north of Suisun Bay (Unruh and Hector, 1999), and deformation 

evident in the geologic record of the past 5 million years makes their presence in the 

subsurface near Mare Island possible. The grouping of small earthquakes (a in Figure 4) 

described above could be related to an unknown blind fault. Further studies should 

include evaluation of the presence and activity of blind faults near the proposed site. Such 

studies would evaluate the presence of blind faults and their slip rates and ages by 

constructing structural models from surface geology, subsurface data from wells, seismicreflection profiles, seismicity, and gravity and magnetics. 

 

Surface Faulting 

This section addresses the potential for surface faulting near and at the proposed site. 

Surface faulting at the site would pose a serious hazard, and therefore has been the subject of a 

preliminary study by William Lettis & Associates (WLA, 2002). There are two issues: (1) the 

location of faults near or at the site, and (2) whether they are active. The WLA work addressed 

the potential for surface faulting on Mare Island and along the western and inferred eastern traces 

of the Franklin Fault using the record of deformation in the bedrock core of Mare Island, the 

elevation of marine terraces, and the continuity of subsurface horizons in seismic-reflection 

profiles. 

Fault location: 

• The WLA study presents considerable evidence that no major fault passes through the 

exposed bedrock next to the site. The regional distribution of geologic units requires that 

the main (western) trace of the Franklin Fault lies west of the bedrock exposed on Mare 

Island, as shown on geologic maps (for example, see Figure 3). The WLA (2002) 

mapping of the bedrock places the inferred eastern trace of the Franklin Fault east of the 

island. The bedrock next to the site, however, contains faults with small displacements 

and is locally concealed by landslides (WLA, 2002). Thus, the possibility of minor 

6
surface faulting at the site in association with a large event on the Franklin Fault cannot 

be precluded with present information. 

Activity of faults: 

• Terrace deformation: The shoreline angle of an uplifted marine terrace — the 

intersection of a former sea cliff with its wave-cut platform (Figure 6 of WLA, 2002) — 

defines an originally horizontal line from which to evaluate subsequent tectonic 

deformation. WLA (2002) mapped remnants of the Qt2 terrace, with an estimated age of 

120,000 years, and graphed the elevations of its shoreline angle (Figure 9 of WLA, 

2002). These elevations are given as ranges of values that reflect the uncertainties in the 

techniques of field measurement and reconstruction. The reported elevations of the 

shoreline angle are similar throughout Mare Island and thus show no evidence of 

deformation within the 8-9 m (25-30 ft) ranges of values. The reported range in 

elevations of the shoreline angle of the Qt2 terrace east of Mare Island, however, 

averages about 4.6 m (15 ft) lower. This observation would be consistent with relative 

vertical uplift of about 4.6 m (15 ft) across the inferred east trace of the Franklin Fault. 

• Seismic-reflection profiles: Seismic-reflection profiles can provide the highest resolution 

for subsurface structure and deformation, short of drilling or trenching. Profiles acquired 

as part of the WLA (2002) study across the south end of Mare Island and east of the 

island across Mare Island Strait to examine the Franklin Fault typically image shallow 

reflecting horizons to depths of several meters (WLA, 2002, Figures 12-16). Most of the 

profiles show disruption of shallow reflections where they cross the inferred eastern trace 

of the Franklin Fault. Although WLA (2002) interprets these disruptions as fluvial cutand-fill structures, a reasonable alternative with present information would be to consider 

them to represent faulting. In reflection profile G-3 across Mare Island Strait (WLA, 

2002, Figure 16), a shallow horizon above the first multiple at the eastern trace of the 

Franklin Fault is vertically displaced about 3 to 4 m (10 to 13 ft). This occurs where there 

is also a change in the slope of the seafloor. The possibility that the displacement is real, 

and not an artifact of data processing, warrants further investigation. The vertical 

resolution of the data is about 2 m (7 ft), which implies that faulting associated with a 

sizeable prehistoric earthquake could remain undetected. 

• Seismicity: The tabular grouping of small earthquakes shown at a in Figure 4 may occur 

on the Franklin Fault. This may indicate that the fault is active, although this alone would 

not indicate whether it could produce larger earthquakes and surface faulting. 

The principal traces of the Franklin Fault do not pass through the exposed bedrock next 

to the site. Refinement of the marine terrace data around the northern margin of Mare Island and 

exploration of the continuity of young sedimentary layers at the southern margin of Mare Island 

will help constrain the possibility of any minor surface faulting through the bedrock. At present 

the evidence is insufficient to conclude that the Franklin Fault is inactive, and three lines of

evidence — possible vertical displacement of the Qt2 terrace, disruption of a shallow reflection 

horizon near the east Franklin Fault, and possible spatial association with small earthquakes — 

suggest the contrary may be true. Further studies will be needed to resolve whether or not the 

Franklin Fault is active. These should include more intensive investigation of the marine terraces 

to refine the estimates of shoreline angle elevations, imaging of the deeper subsurface with 

seismic-reflection profiling to examine any persistence with depth of the disruption of shallow 

7
reflections and their relation to bedrock structure, and refinement of the analysis of the 

instrumental seismicity. 

Earthquake Ground Motions 

This section addresses the potential for and level of earthquake shaking at the southern 

end of Mare Island. The proposed site lies about 7 km (4 miles) east of the southernmost Rodgers 

Creek Fault where it overlaps with the Hayward Fault. The proximity of the proposed site to this 

active fault system implies the possibility of high levels of ground motion or earthquake shaking 

as well as special ground-motion phenomena that are only observed close to rupturing faults. 

These special phenomena include two effects, both of which could further increase levels of 

ground motion at the site. One effect, known as directivity, is associated with the direction in 

which a fault ruptures during an earthquake. The other effect, known as static offset, is a large 

sudden permanent ground displacement close to an earthquake. 

Although the Hayward-Rodgers Creek Fault system will probably be the most important 

seismic source for the proposed LNG project, the earthquake potential of the Franklin Fault and 

possible blind faults near the site is unknown. 

Soil conditions beneath a structure can significantly influence shaking by modifying the 

amplitude of the seismic waves as they propagate upward from depth. Soils with low shear-wave 

velocity, like the soft mud deposited in San Pablo Bay, have the greatest influence. The effect 

varies with both the level and the frequency of shaking. For example, ground motion may be 

increased at lower levels of shaking and decreased at higher levels of shaking. Many earthquakes 

in the San Francisco Bay region have demonstrated that shaking and damage are greater in areas 

underlain by soft soils than in nearby rock areas. 

Estimating ground motion at the proposed LNG project should include the following 

considerations: 

• Directivity: Large earthquakes result from a rupture propagating a considerable distance 

along a fault. In front of the rupture, seismic waves effectively pile up, causing large 

amplitudes in the direction in which the rupture is propagating (directivity). 

Consequently, if a rupture initiated at some distance from a site and propagated toward it, 

large amplitude seismic waves could affect the site (Somerville et al., 1997). For 

example, large-amplitude velocity pulses greater than 100 cm/s (39 inches/s) were 

recorded at two stations in Turkey during the M7.4 Kocaeli earthquake on August 17, 

1999 (Figures 5 and 6). Both stations were less than 5 km (3 miles) from the fault on 

which the earthquake occurred. This effect could be significant at the proposed site if a 

rupture on the Hayward/Rodgers Creek Faults were to propagate toward it. 

• Static offset: When faults rupture, the ground experiences large sudden permanent 

movements near the fault, called static offsets. If the Hayward and Rodgers Creek Faults 

ruptured in a single M7.4 earthquake, the static offset at the proposed site could be as 

large as 1 m (3 ft) and would be reached in several seconds (see examples in Figures 5 

and 6). Such static offset is relevant to the selection of the maximum lateral displacement 

limit of base-isolated structures. 

• Site amplification: The docking area for the proposed LNG project presumably is 

underlain by bay mud that overlies stiff soil or hard fractured rock of the Great Valley 

Complex (see Fumal, 1991, p. 140). This could result in a marked shear-wave velocity 

8
contrast. Site amplification or resonance of the bay mud above such a contrast would be 

significant and the frequency response would depend explicitly on the shape of the 

contact or interface between these geologic units. Such strong amplification and the 

potential spatial variability of the ground motion would need to be considered in the 

design of long structures.

• Deviation from standard ground-motion attenuation relations: Estimates of ground 

motion for engineered structures near active faults are commonly based on curves 

(known as attenuation relations) that are fitted to recorded observations of ground motion 

from large earthquakes (for example, Boore and others, 1997, Campbell, 1997). Because 

relatively few recordings of ground motions close to faults during large earthquakes are 

available, the standard curves for predicting ground motion should be used with caution. 

Tsunami and Seiche 

This section addresses the potential for temporary changes of water level in water bodies, 

such as oceans and bays, that are observed during many earthquakes. This phenomenon is known 

as either tsunami or seiche, depending on its characteristics. A tsunami is a series of waves of 

long wavelength generated by earthquakes, landslides, and volcanic eruptions beneath the ocean. 

Hazards from tsunamis include: (1) runup where tsunami waves wash ashore at heights above 

normal wave action, and (2) strong currents. A tsunami-induced seiche is generated where the 

tsunami reflects off shorelines and oscillates in an enclosed body of water. 

Tsunamis generated from distant sources arrive at the Golden Gate many hours after the 

causal event. Although the narrow Golden Gate admits only a portion of such tsunami energy 

into San Francisco Bay, measurable wave heights have been reported along the shore of San 

Pablo Bay from past events (Lander and others, 1993). The Great 1964 Alaska earthquake 

generated a tsunami with reported wave heights of 0.67 m (2.2 ft) at Point San Pablo and 0.98 m

(3.2 ft) at the San Pablo yacht harbor (see Figure 7 for tide gauge records in San Francisco and 

Alameda). 

Few records of local tsunami generated by earthquakes are available because most of the 

active faults in the San Francisco Bay region are onshore and display primarily horizontal slip. In 

offshore areas where there are lateral steps in fault trends, earthquakes may produce local 

tsunamis. For example, the M7.8 1906 San Francisco earthquake generated a small 0.08-m-high 

(0.25 ft) tsunami at Fort Point (Figure 8) that may have been generated by a lateral step on the 

San Andreas Fault near the Golden Gate. Such a lateral step also occurs between the Hayward 

and Rodgers Creek Faults beneath San Pablo Bay. 

Tsunami and seiche issues that could potentially affect the proposed site include: 

• Earthquakes that are on faults that rupture beneath San Pablo Bay as well as fast-moving 

coastal landslides or bluff failures near the proposed site (for example, bluffs bordering 

Carquinez Strait) may generate local tsunamis. Warnings of local tsunamis will not be 

available because the time interval between the earthquake or slope failure and arrival of 

tsunamis at Mare Island will be only a few minutes. 

• Design earthquakes for tsunami hazards at the proposed site may be different than those 

for ground motion and foundation stability. 

• Maximum runup and currents from a tsunami will be affected by tidal stage (ebb, flood, 

or slack; spring or neap tide). 

9
Standard hydrodynamic models exist to evaluate potential hazards from tsunamis. 

Foundation Stability 

This section addresses the stability of the ground at the proposed site. Foundation 

stability refers to the ability of underlying geologic materials and fills — referred to as soils in 

geotechnical engineering — to support both buried and surface engineering works. Both static 

loading and earthquake shaking may cause vertical and horizontal ground displacements. 

Portions of the proposed project may be developed on artificial fill (Figure 2), which generally 

performs poorly during earthquakes if not properly engineered. The potential for earthquakeinduced liquefaction of wet and loose sandy material and several other potential causes of 

instability should be addressed for the proposed LNG project, including base-isolated structures. 

Stability considerations should include: 

• Liquefaction—horizontal displacements: Horizontal ground displacement is an 

important potential hazard when soils liquefy. Displacements as large as tens of feet 

may occur. 

• Liquefaction—vertical displacements: Venting of ground water as it is expelled from

the liquefied sands during the liquefaction process causes the land surface to settle 

vertically. Although differential displacements and tilting, which can affect both 

buried and surface structures are the primary concern, large areas that already are 

only slightly above sea level could lose elevation and be submerged. 

• Liquefaction—venting of toxic subsurface material: Discharge (or venting) of 

subsurface material to the land surface is a common manifestation of liquefaction. 

Although such venting usually is just an inconvenience, it could be hazardous where 

toxic material present in the subsurface either in or above the liquefiable material is 

vented to the surface. 

• Displacements in clayey soils: Earthquake shaking may cause large displacements in 

clayey soil, such as bay mud. 

• Displacements at soil boundaries: Earthquake shaking can result in ground cracking 

and permanent displacements even if general landsliding does not occur. In past 

earthquakes cracking has been observed at soil-unit boundaries and soil-rock 

contacts. 

• Soil consolidation: Geologically young clay soils, like bay mud, may consolidate 

slowly when subjected to new surface loads, causing structures to settle. This process 

involves the slow expulsion of pore water and can occur over decades. 

• Tsunami and seiche: A secondary effect of earthquake-induced tsunamis and seiches 

is the rapid temporary lowering of water level, which can cause soil instability along 

shorelines. Such failures can occur when a submerged slope rapidly emerges from

water without adequate time for pore water to drain and equilibrate to the temporarily 

lower sea level. 

For all of these aspects of foundation stability, routine and well-developed siteinvestigation techniques are available to characterize the physical properties of soils, and widely 

accepted geotechnical engineering models exist to evaluate potential deformation hazards. 

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Landslides

This section addresses the potential hazard of slope failure on Mare Island. The steep 

flanks of the bedrock core of Mare Island may be subject to landslides that could affect 

foundations or impact facilities with falling or sliding rock debris from above. Numerous small 

to moderate-sized landslides and debris-flow chutes have been recognized on the steep bedrock 

slopes adjacent to the site (WLA, 2002, Figure 17). The fractured and jointed rock of the bedrock 

core may also be subject to large failures as rockfalls or large landslides triggered by earthquake 

shaking. Considerations relevant to the proposed LNG project include: 

• Rainfall-related landslides: Existing and new landslides as well as debris flows can be 

activated or caused by a single large storm or during a particularly rainy winter. 

• Earthquake-induced landslides: Both rock falls, rock slides, and debris slides — which 

are highly disrupted and can travel far beyond the slopes on which they originate — and 

deeper-seated slumps and block slides, can be caused by strong earthquake shaking of 

steep slopes in fractured rock (Keefer, 1984). 

Routine and widely accepted geotechnical techniques are available by which to 

characterize the rock and soil and to evaluate the potential for such landslides. Detailed 

geotechnical and analytical site investigations that include dynamic engineering-based slopestability analyses may be necessary to ensure adequate understanding of the potential hazard 

from earthquake-induced failures. 

Selection of SSE and OBE 

The Operating Basis Earthquake (OBE) and Safe Shutdown Earthquake (SSE) as 

described in NFPA 59A (NFPA, 2001) are estimated from probabilistic estimates of ground 

motion. Near-source effects on ground motion are not specifically described in the NFPA 59A 

standard. The large near-source effects discussed in this report could produce much larger 

ground motions than those yielded by conventional probabilistic seismic hazard analysis. It is 

therefore important that estimates of ground motions for the OBE and SSE explicitly consider 

near-source effects. Both OBE and SSE earthquake considerations should also include sitespecific aspects when defining design response spectra. 

Conclusions 

Extensive geologic and seismologic data are available for the region surrounding the 

proposed Mare Island LNG project. These data and modern understanding of earthquake 

processes indicate that several geologic and seismic hazards may be present at the proposed site 

and need improved characterization and clarification. Ground motions from large earthquakes on 

the nearby Hayward/Rodgers Creek Fault system present a hazard for project structures and 

should be addressed in the design of project facilities. The potential for a significant earthquake 

on the Franklin Fault and possible blind faults near the site is not known, and additional data and 

analysis are needed. Additional potential hazards deserving attention are foundation stability, 

landslides, and tsunamis and seiche. The selection of the Safe Shutdown and Operational Basis 

11
Earthquakes as described in the NFPA 59A standard (NFPA, 2001) should include consideration 

of near-source ground motions and site conditions in defining site-specific design response 

spectra. 

Appendix 1. Historical Earthquakes and Mare Island 

The following historical earthquakes with estimated magnitudes (Bakun, 1999) are 

known to have shaken Mare Island severely: 

M6.3 near Mare Island — March 31, 1898 

 No surface rupture was observed, making the causative fault uncertain. The probable 

epicenter is on the southern part of the Rodgers Creek Fault because of the distribution of MMI ≥

VIII damage and reports of aftershocks at sites near there (Toppozada et al., 1992). Toppozada et 

al. (1992) do not suggest a specific epicenter location. They note that the strongest and most 

numerous reports of aftershocks were from Sonoma and Lakeville; the adjacent section of the 

Rodgers Creek Fault is about 20 km (12 miles) from Mare Island. Other aftershock reports (in 

order of decreasing severity) noted by Toppozada et al. (1992): Tubbs Island, Vallejo, Napa, 

Petaluma, Martinez, and Santa Rosa. The reports of a tsunami associated with the 1898 

earthquake listed in Toppozada et al (1992), which might suggest a blind causative fault beneath 

San Pablo Bay, are not convincing. 

MMI IX effects were reported at Mare Island (Toppozada et al., 1981). Two-story 

sawmill and other buildings collapsed; Partial collapse of other brick buildings. Nearly every 

brick building was more or less damaged. The ground all around the navy yard was seamed and 

creviced. 

M6.8 on southern Hayward Fault — October 21, 1868 

At Mare Island, “Chimneys were thrown, and some buildings were considerably shaken. 

Shock accompanied by a rumbling sound.” (Lawson, 1908, p.439) 

M7.8 on San Andreas Fault — April 18, 1906 

At Mare Island, “The earthquake was much less severe than that of 1898, which wrecked 

many of the Government buildings in the navy-yard. None of the government buildings was 

wrecked this time, nor was the damage at all serious except in the case of two or three new 

buildings recently erected on the “made” land near the water-front.” (Lawson, 1908, p.212-213) 

References 

Bakun, W.H., 1999, Seismic activity of the San Francisco bay region: Seismological Society of 

America Bulletin, v. 89, no. 3, p. 764-784. 

Boore, D.M., Joyner, W.B., and Fumal. T.E., 1997, Equations for estimating horizontal response 

spectra and peak acceleration from western North American earthquakes — A summary of 

recent work: Seismological Research Letters, v. 68, p. 128-153. 

Campbell, K.W., 1997, Empirical near-source attenuation relationships for horizontal and 

vertical components of peak ground acceleration, peak velocity, and pseudo-absolute 

acceleration response spectra: Seismological Research Letters, v. 68, p. 154-179. 

12
CDMG, 1983, Cuttings Wharf quadrangle, State of California Special Studies Zones Map: 

California Division of Mines and Geology, Digital images of official maps of Alquist-Priolo 

earthquake fault zones of California Central Coast Region, CD 2000-04. 

Frankel, A., Mueller, C., Barnhard, T., Perkins, D., Leyendecker, E., Dickman, N., Hanson, S., 

and Hopper, M., 1997, Seismic hazard maps for California, Nevada and western Utah and 

Nevada, USGS Open-File Report 97-130, 12 sheets. 

Fumal, T.E., 1991, A compilation of the geology and measured and estimated shear-wave 

velocity profiles at strong-motion stations that recorded the Loma Prieta, California, 

earthquake: U.S. Geological Survey Open-file Report 91-311, 163 p. 

Graymer, R.W., Jones, D.L., and Brabb, E.E., 2002, Geologic map and map database of 

northeastern San Francisco Bay region, California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-2402, 1 sheet, scale 1:100,000, 29 p., 10 ArcInfo databases. 

Keefer, D. K., 1984, Landslides caused by earthquakes: Geological Society of America Bulletin, 

v. 95, no. 4, p. 406-421. 

Hart, E.W., and Bryant, W.A., 1999, Fault-rupture hazard zones in California: California 

Division of Mines and Geology Special Publication 42, revised 1997 (supplements 1 and 2 

added 1999), 38 p. 

Holzer, T.L., and others, 1999, Implications for earthquake risk reduction in the United States 

from the Kocaeli, Turkey, earthquake of August 17, 1999: U.S. Geological Survey Circular 

1193, 64 p. 

Lander, J. F., Lockridge, P.A., and Kozuch, M.J., 1993, Tsunamis affecting the west coast of the 

United States 1806-1992: NGDC Key to Geophysical Records Documentation No. 29, 242 p. 

Lawson, A. C. (ed.), 1908, The California earthquake of April 18,1906: Report of the State 

Earthquake Investigation Commission: Carnegie Institution of Washington Publication 87, v. 

1, part 1, 451 p. 

Michael, A.J., Ross, S.L., Schwartz, D.P., Hendley J.W., II, Stauffer, P.W., 1999, Major quake 

likely to strike between 2000 and 2030: U.S. Geological Survey Fact Sheet 152-99. 

NFPA, 2001, NFPA 59A — Standard for the production, storage, and handling of liquefied 

natural gas (LNG), 2001 edition: National Fire Protection Association, Quincy 

Massachusetts, 50 p. 

Somerville, P.G., Smith, N.F., Graves, R.W., and Abrahamson, N.A., 1997, Modification of 

empirical strong ground motion attenuation relations to include the amplitude and duration of 

effects of rupture directivity: Seismological Research Letters, v. 68, no. 1, p. 199-222. 

Toppozada, T. R., Real, C.R. and Parke, D.L., 1981, Preparation of isoseismal maps and 

summaries of reported effects for pre-1900 California earthquakes: California Department of 

Conservation, Division of Mines and Geology Open-file Report 81-11 SAC, 182 p. 

Toppozada, T. R., Borchardt, G., Hallstrom, C.L., and Youngs, L.G., 1992, 1898, “Mare Island” 

earthquake at the southern end of the Rodgers Creek Fault, in, Conference on Earthquake 

Hazards in Eastern San Francisco Bay Area, 2nd, Hayward, Calif., Proceedings, Borchardt, 

G., and others, eds.: California Department of Conservation, Division of Mines and Geology 

Special Publication 113, p. 385-392. 

Unruh, J.R., and Hector, Scott, 1999, Subsurface characterization of the Potrero-Ryer Island 

thrust system, western Sacramento-San Joaquin Delta, Northern California: U.S. Geological 

Survey National Earthquake Hazards Reduction Program Technical Report, 34 p. 

13
WG99 (Working Group on California Earthquake Probabilities), 1999, Earthquake probabilities 

in the San Francisco Bay area: 2000-2030—A summary of findings: U.S. Geological Survey 

Open-file Report 9-517, 36 p. 

WLA, 2002, Interim report on surface investigations of the potential for earthquake-related 

surface deformation at proposed LNG and power plant facilities, Southern Mare Island, 

Vallejo, California: William Lettis & Associates, Walnut Creek, Calif., unpublished report to 

Bechtel Enterprises/Shell, 55 p, 17 figs. 

Wright, T.L., and Smith, N., 1992, Right step from the Hayward Fault to the Rodgers Creek 

Fault beneath San Pablo Bay, in Conference on Earthquake Hazards in Eastern San Francisco 

Bay Area, 2nd, Hayward, Calif., Proceedings, Borchardt, G., and others, eds.: California 

Department of Conservation, Division of Mines and Geology Special Publication 113, p. 

407-417. 

14
US SG

280

580

880

680

17

1

1

80

101

101

101

21%

6%

10%

18%

6%

32%

odds ( 10%) for one or more

magnitude 6.7 or greater

earthquakes from 2000 to 2030.

This result incorporates 9% odds

of quakes not on shown faults. 

SAN FRANCISCO BAY REGION

EARTHQUAKE PROBABILITY

70%

4%

CALAVERAS FAULT

RODGERS CREEK FAULT

CONCORD–GREEN VALLEY FAULT

HAYWARD

FAULT

GREENVILLE 

 FAULT

THRUST FAULT

MT. DIABLO

CALAVERAS FAULT

 FAULT

CONCOR

D–GREEN

VALLEY FAULT

SAN ANDREAS

FAULT

P a c i f i c

O

c

e

a

n

SAN GREGORIO

FAULT

RODGERS CREEK

FAULT

HAYWARD

FAULT

Monterey

Bay

San

Francisco

Bay

New odds of magnitude 

 6.7 or greater quakes

 before 2030 on the

 indicated fault 

Odds for faults that were

 not previously included

 in probability studies

Expanding urban areas

Increasing quake odds

 along fault segments

Individual fault probabilities are

 uncertain by 5 to 10%

0

0 20 KILOMETERS

20 MILES

N

21%

18%

San Francisco

Half Moon

Bay

Pacifica

Oakland

Sacramento

Stockton

Danville

Antioch

Palo

Alto

San

Mateo

Walnut

Creek

Livermore

Pleasanton Hayward

Tracy

Santa Cruz

Watsonville

Gilroy

Monterey

Salinas

San

Jose

Santa

Rosa

Petaluma

Novato

San

Rafael

Napa Sonoma

Vallejo

EXTENT OF RUPTURE

IN LOMA PRIETA QUAKE

Figure 1. Major faults in the San Francisco Bay region and their probabilities of earthquakes with M > 6.7 from 2000 to 2030. From Michael 

and others (1999).
SAN PABLO BAY

SUISUN BAY

MARE ISLAND

SF

FF

WEST NAPA FAULT

LHF

SVF

GREEN VALLEY FAULT

CONCORD FAULT HAYWARD FAULT

RODGERS CREEK FAULT

PF

CF

TF

?

?

?

?

?

?

?

?

Figure 2. Simplified geologic map of Mare Island and the surrounding region with superimposed earthquake epicenters for the period 1971-2002. Known Holocene-active faults are shown in red. Other named faults are labelled (CF = Carneros Fault, FF = Franklin Fault, LHF = Lake Herman Fault, PF = Pinole Fault, SF = Southhampton Fault, SVF = Sky Valley Fault, TF = Tolay Fault). Epicenters are marked with squares sized in proportion to earthquake magnitude (1.1-4.1), and are color coded according to the depth (0-2.5 km = yellow, 2.5-5 km = orange, 5-7.5 km = red, 7.5-10 km = magenta, 10-12.5 km = purple, 12.5-15 km = blue, >15 km = green). Bedrock older than one million years is shown as light green, surficial deposits less than one million years old are shown as yellow, bay mud less than ten thousand years old is shown as light cream, artificial fill is shown as gray. (Modified from Graymer and others, 2002; Wright and Smith, 1992; California Division of Mines and Geology, 1983; epicenters from Northern California Seismic Network catalog, maintained jointly by the USGS-Menlo Park and the Berkeley Seismological Laboratory, University of California, Berkeley. Events in this catalog can be obtained from the Northern California Earthquake Data Center, a joint project of the University of California Berkeley Seismological Laboratory and the USGS).

Bay mud

Artificial

fill

1 .5 0 1 2 3 4 5 6 7 MILES

1 .5 0 1 2 3 4 5 6 7 KILOMETERS

0 2 4 6 8 10 12 14 THOUSAND FEET

Proposed site
SAN PABLO BAY

SUISUN BAY

Bay mud

Artificial

fill

FF

WEST NAPA FAULT

LHF

SVF

GREEN VALLEY FAULT

CONCORD FAULT HAYWARD FAULT

RODGERS CREEK FAULT

PF

SF

CF

TF

GRIZZLY ISLAND

Mare Island

Figure 3. Geologic map of Mare Island and the surrounding region with superimposed earthquake epicenters. Other named faults are labelled (CF = Carneros Fault, FF = Franklin Fault, 

LHF = Lake Herman Fault, PF = Pinole Fault, SF = Southhampton Fault, SVF = Sky Valley Fault, TF = Tolay Fault). (Modified from Graymer and others, 2002; Wright and Smith, 1992; California Division of Mines and Geology, 1983)

1 .5 0 1 2 3 4 5 6 7 MILES

1 .5 0 1 2 3 4 5 6 7 KILOMETERS

0 2 4 6 8 10 12 14 THOUSAND FEET

?

?

?

?

?

?

?

??

Proposed site
Boundary of proposed LNG site

SURFICIAL DEPOSITS

Artificial channel deposits (Historic)

Artificial fill (Historic)

Artificial fill over Bay Mud (Historic)

Artificial levee fill (Historic)

Alluvium (Holocene)

Alluvial fan deposits (Holocene)

Fine-grained alluvial fan deposits

(Holocene)

Stream channel deposits (Holocene)

Natural levee deposits (Holocene)

Floodplain deposits (Holocene)

Basin deposits (Holocene)

Bay mud deposits (Holocene)

Alluvium (Holocene and late Pleistocene)

Alluvial fan deposits (Holocene and

late Pleistocene)

Landslide deposits (Holocene and

Pleistocene)

Alluvial fan deposits (late Pleistocene)

Pediment deposits (late and early

Pleistocene)

Alluvium (late and early Pleistocene)

BLACK POINT ASSEMBLAGE

Great Valley Complex

Novato Conglomerate (Early Cretaceous)

PINOLE POINT ASSEMBLAGE

Orinda Formation (late Miocene)

HERCULES ASSEMBLAGE

Conglomerate (late Miocene)

Tuffaceous sandstone (late Miocene)

Diatomite (middle to early Miocene)

Sandstone (middle to early Miocene)

RODEO ASSEMBLAGE

Pinole Tuff (late Miocene)

Neroly Sandstone (late Miocene)

Cierbo Sandstone (late Miocene)

Briones Sandstone (late and middle

Miocene)

Upper member

Hercules shale member

Lower member

Rodeo Shale (middle Miocene)

Hambre Sandstone (middle Miocene)

Tice Shale (middle Miocene)

MARTINEZ ASSEMBLAGE

Briones Sandstone (late and middle

Miocene)

Sobrante Sandstone (early Miocene)

San Ramon Sandstone (early

Miocene and/or Oligocene)

Escobar Sandstone of Weaver (1953,

Eocene)

Basal shale member

Muir Sandstone of Weaver (1953,

Eocene)

Upper member

Lower member

Las Juntas Shale of Weaver (1953,

Eocene and Paleocene)

Upper member

Lower member

Vine Hill Sandstone of Weaver (1953,

Paleocene)

Upper member

Lower member

Great Valley Complex

Undivided sandstone, siltstone, and

shale (Late Cretaceous)

Massive sandstone

Sandstone, siltstone, and shale

Massive sandstone

Sandstone and shale (Early Cretaceous

and Late Jurassic)

SEARS POINT ASSEMBLAGE

Huichica and Glen Ellen Formations,

undivided (early Pleistocene and

Pliocene)

Sonoma Volcanics (Pliocene and late

Miocene)

Andesite to basalt flows

Rhyolite flows

Ash-flow tuff

Volcanic sand and gravel

Petaluma Formation (early Pliocene and

late Miocene)

Mudrock, sandstone, and conglomerate

Claystone

Donall Ranch volcanics of Youngman

(1989, late Miocene)

Mafic member

Rhyolite member

SONOMA ASSEMBLAGE

Huichica Formation (early Pleistocene

and Pliocene)

Sonoma Volcanics (Pliocene and late

Miocene)

Ash-flow tuff

CORDELIA ASSEMBLAGE

Huichica Formation (early Pleistocene

and Pliocene)

Sonoma Volcanics (Pliocene and late

Miocene)

Andesite to basalt flows

Andesite to dacite plugs and dikes

Rhyolite flows

Rhyolite plugs and dikes

Rhyolite and perlitic flows and plugs

Ash-flow tuff

Welded ash-flow tuff

Lithic tuff

Volcanic sandstone, siltstone, and

conglomerate

Diatomite

Cierbo Sandstone (late Miocene)

Intercalated basalt

Claremont Shale (Miocene)

Markley Sandstone (Eocene)

Jameson shale member

Nortonville Shale Member of

Kreyenhagen Formation (Eocene)

Domingene Sandstone (Eocene)

Great Valley Complex

Sandstone and shale (Late Cretaceous)

Sandstone and shale (Early Cretaceous

and Late Jurassic)

Keratophyre (Jurassic)

Massive and pillow basalt (Jurassic)

Gabbro (Jurassic)

Serpentinite (Jurassic)

Silica-carbonate rock

Limestone (age unknown)

PITTSBURG ASSEMBLAGE

Sandstone, siltstone, and gravel (early

Pleistocene and late Pliocene)

Tehama Formation (Pliocene)

Lawlor Tuff (Pliocene)

Cierbo Sandstone (late Miocene)

Markley Sandstone (Eocene)

Upper member

Lower member

Franciscan Complex

Sandstone (Late Cretaceous)

Metagraywacke (Early Cretaceous and Late

Jurassic)

Melange

Contact-- Depositional or intrusive contact,

dashed where approximately located,

dotted where concealed

Fault-- Dashed where approximately located,

small dashes where inferred, dotted where

concealed, queried where location

is uncertain.

Reverse or thrust fault-- Dashed where

approximately located, dotted where

concealed

LIST OF MAP UNITS

Figure 3 (continued).
-15.

-15.

-10.

-10.

-5.

-5.

0.

0.

5.

5.

10.

10.

15.

15.

20.

20.

25.

25.

-20. -20.

-15. -15.

-10. -10.

-5. -5.

0. 0.

-15.

-15.

-10.

-10.

-5.

-5.

0.

0.

5.

5.

10.

10.

15.

15.

20.

20.

25.

25.

-10. -10.

-5. -5.

0. 0.

5. 5.

-15.

-15.

-10.

-10.

-5.

-5.

0.

0.

5.

5.

10.

10.

15.

15.

20.

20.

25.

25.

-20. -20.

-15. -15.

-10. -10.

-5. -5.

0. 0.

Figure 4. Map and cross section showing 1967-2001 seismicity (M 0.0 - 4.1) in the vicinity of Mare Island. The cross section line is oriented 

perpendicular to the trace of the Hayward Fault (shown as a red line in map view and a red dot at the surface in cross section). The cross 

section projects hypocenters within a 7.5-km-wide box into a single vertical plane at the center of the box. Focal mechanisms are shown 

as lower hemisphere (map view) or far hemisphere (cross-section view). A tabular group of hypocenters (labeled a) is present which is 

roughly aligned with, below and slightly east of the surface trace of the Franklin Fault (labeled FF and schematically shown as a pair of 

black lines on the map and pair of black dots on the cross section). A single focal mechanism indicating largely right-lateral strike-slip on 

a steeply east-dipping fault has been calculated from the tabular group and is shown. 

a

A A'

A A'

N

HAYWARD FAULT

a

SAN PABLO BAY

Mare

Island

Proposed Site

FF
 TIME, IN SECONDS

ACCELERATION, IN cm/sec

2

0 10 20 30 40 50 60

 TIME, IN SECONDS

0 10 20 30 40 50 60

 TIME, IN SECONDS

0 10 20 30 40 50 60

-400 -200 0.0 200

VELOCITY, IN cm/sec

-20 0 20 40 60 80

DISPLACEMENT, IN cm

0 50 100 150 200

A

BC

Figure 5. A, Recorded east-west accelerations at the Turkish National Strong Motion Network station, SKR, in Adapazari. Turkey, during the August 17, 1999, M7.4 main shock. Station is 

about 3.5 km from the surface rupture. B, Velocities computed from acceleration time history showing large velocity pulse. C. Displacements computed for acceleration time history showing large displacement pulse. (From Holzer and others (1999), Figure 3).
TIME, IN SECONDS

ACCELERATION, IN cm/sec2

0 5 10 15 20 25 30

-300 -200 -100 0 100 200 300

VELOCITY, IN cm/sec

-100 -50 0 50 100

DISPLACEMENT, IN cm

-50 0 50 100 150 200 250

TIME, IN SECONDS

0 5 10 15 20 25 30

TIME, IN SECONDS

A

B

0 5 10 15 20 25 30

C

Figure 6. A, Recorded east-west accelerations at the Kandilli Observatory and Earthquake Research Institute strong motion station, YPT, at the Petro-Chemical Plant in Korfez, Turkey, during 

the August 17, 1999, M7.4 main shock. Station is about 4 km from the surface rupture. B, Velocities computed from acceleration time history showing large velocity pulse. C, Displacements 

computed for acceleration time history showing large displacement pulse. (From Holzer and others (1999), Figure 4).
Figure 7. Example of tsunami observations in San Francisco Bay from a distant tsunami. Tsunami was generated by the M9.2 Great 

Alaska earthquake of 1964. Note that tsunami waves continue for many hours and occur at all stages of the tidal cycle. Tsunami 

amplitudes diminish as the tsunami travels through the Golden Gate and into San Francisco Bay toward Oakland. (From Lander and

others, 1993). Tsunami Arrival Tsunami Arrival
Figure 8. Example of tsunami observations in San Francisco from a local tsunami. Tsunami was generated by the 1906 San Francisco 

earthquake where the San Andreas Fault trends offshore of San Francisco. Note that the tsunami amplitude in this case is much 

smaller than the amplitudes from a distant tsunami (Figure 7). Tsunami waves from the local source continue for several hours, but 

not as long as a distant tsunami. (From Lawson, 1908.)Tsunami Arrival