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Geology topics

Bruce M. Richmond

Publications and source records attributed to Bruce M. Richmond.

47 records · Page 3Linked to original sources
USGS2003

Data report: geology of reef-front carbonate sediment deposits around Oahu, Hawaii

This Open-File Report presents data and derivative products from an investigation of carbonate sediment deposits on the reef front in four areas around the island of Oahu, Hawaii - in Kailua Bay off Oahu's windward (east) side, off the leeward (west) coast from Makua to Kahe Point, off the north coast from Waimea to Camp Erdman, and off the south coast around Waikiki (Figure 1). The primary purpose of the investigation was to assess the resource potential of the deposits, particularly as a source of sand for beach nourishment. This work builds on previous studies by researchers from the University of Hawaii (Moberly et al., 1975; Coulbourn et al., 1988; Barry, 1995). The field program included collection of high-resolution acoustic-reflection profiles and vibracore sediment samples in Kailua Bay and off the leeward and north coasts. In a related project, in collaboration with the Hawaii State Department of Land and Natural Resources and the University of Hawaii, sidescan images and vibracores were collected in the Halekulani channel and on the adjacent Makua Terrace off Waikiki along the south coast.

Hawai'i↗
USGS2002

Atlas of natural hazards in the Hawaiian coastal zone

The purpose of this report is to communicate to citizens and regulatory authorities the history and relative intensity of coastal hazards in Hawaii. This information is the key to the wise use and management of coastal resources. The information contained in this document,we hope,will improve the ability of Hawaiian citizens and visitors to safely enjoy the coast and provide a strong data set for planners and managers to guide the future of coastal resources. This work is largely based on previous investigations by scientific and engineering researchers and county, state, and federal offices and agencies. The unique aspect of this report is that, to the extent possible, it assimilates prior efforts in documenting Hawaiian coastal hazards and combines existing knowledge into a single comprehensive coastal hazard data set. This is by no means the final word on coastal hazards in Hawaii. Every hazardous phenomenon described here, and others such as slope failure and rocky shoreline collapse, need to be more carefully quantified, forecast, and mitigated. Our ultimate goal, of course, is to make the Hawaiian coast a safer place by educating the people of the state, and their leaders, about the hazardous nature of the environment. In so doing, we will also be taking steps toward improved preservation of coastal environments, because the best way to avoid coastal hazards is to avoid inappropriate development in the coastal zone. We have chosen maps as the medium for both recording and communicating the hazard history and its intensity along the Hawaiian coast.Two types of maps are used: 1) smallscale maps showing a general history of hazards on each island and summarizing coastal hazards in a readily understandable format for general use, and 2) a large-scale series of technical maps (1:50,000) depicting coastal sections approximately 5 to 7 miles in length with color bands along the coast ranking the relative intensity of each hazard at the adjacent shoreline.

Hawaii↗
USGS2002

Map Showing Seacliff Response to Climatic and Seismic Events, Depot Hill, Santa Cruz County, California

INTRODUCTION The coastal cliffs along much of the central California coast are actively retreating. Large storms and periodic earthquakes are responsible for most of the documented seacliff slope failures. Long-term average erosion rates calculated for this section of coast (Moore and others, 1999) do not provide the spatial or temporal data resolution necessary to identify the processes responsible for retreat of the seacliffs, where episodic retreat threatens homes and community infrastructure. Research suggests that more erosion occurs along the California coast over a short time scale, during periods of severe storms or seismic activity, than occurs during decades of normal weather or seismic quiescence (Griggs and Scholar, 1998; Griggs, 1994; Plant and Griggs, 1990; Griggs and Johnson, 1979 and 1983; Kuhn and Shepard, 1979). This is the first map in a series of maps documenting the processes of short-term seacliff retreat through the identification of slope failure styles, spatial variability of failures, and temporal variation in retreat amounts in an area that has been identified as an erosion hotspot (Moore and others, 1999; Griggs and Savoy, 1985). This map presents seacliff failure and retreat data from Depot Hill, California, which is located five kilometers east of Santa Cruz (fig.1) near the town of Capitola, along the northern Monterey Bay coast. The data presented in this map series provide high-resolution spatial and temporal information on the location, amount, and processes of seacliff retreat in Santa Cruz, California. These data show the response of the seacliffs to both large magnitude earthquakes and severe climatic events such as El NiOos; this information may prove useful in predicting the future response of the cliffs to events of similar magnitude. The map data can also be incorporated into Global Information System (GIS) for use by researchers and community planners. Four sets of vertical aerial photographs (Oct. 18, 1989; Jan. 27, 1998; Feb. 9, 1998; and March 6, 1998) were orthorectified and digital terrain models (DTMs) were generated and edited for this study (see Hapke and Richmond, 2000, for description of techniques). The earliest set of photography is from 1989, taken immediately following the Loma Prieta earthquake. These photographs are used to document the response of the seacliffs to seismic shaking, as well as to establish an initial cliff-edge position to measure the amount of retreat of the cliff edge over the following decade. The remaining three sets of photographs were collected using the U.S. Geological Survey Coastal Aerial Mapping System (CAMS) during the 1997-98 El NiOo (see Hapke and Richmond, 1999, 2000). The CAMS photographs were taken before, during, and after severe storms and are used to examine seacliff response to these storms. In addition to the analyses of photogrammetrically processed data, field mapping identified joints, faults, and lithologic variations along this section of seacliff.

Miscellaneous Field Studies Map↗
USGS2002

Map Showing Seacliff Response to Climatic and Seismic Events, Seacliff State Beach, Santa Cruz County, California

INTRODUCTION The coastal cliffs along much of the central California coast are actively retreating. Large storms and periodic earthquakes are responsible for most of the documented seacliff slope failures. Long-term average erosion rates calculated for this section of coast (Moore and others, 1999) do not provide the spatial or temporal data resolution necessary to identify the processes responsible for retreat of the seacliffs, where episodic retreat threatens homes and community infrastructure. Research suggests that more erosion occurs along the California coast over a short time scale, during periods of severe storms or seismic activity, than occurs during decades of normal weather or seismic quiescence (Griggs and Scholar, 1998; Griggs, 1994; Plant and Griggs, 1990; Griggs and Johnson, 1979 and 1983; Kuhn and Shepard, 1979). This is the second map in a series of maps documenting the processes of short-term seacliff retreat through the identification of slope failure styles, spatial variability of failures, and temporal variation in retreat amounts in an area that has been identified as an erosion hotspot (Moore and others, 1999; Griggs and Savoy, 1985). This map presents seacliff failure and retreat data from Seacliff State Beach, California, which is located seven kilometers east of Santa Cruz (fig. 1) along the northern Monterey Bay coast. The data presented in this map series provide high-resolution spatial and temporal information on the location, amount, and processes of seacliff retreat in Santa Cruz, California. These data show the response of the seacliffs to both large magnitude earthquakes and severe climatic events such as El Ni?os; this information may prove useful in predicting the future response of the cliffs to events of similar magnitude. The map data can also be incorporated into Global Information System (GIS) for use by researchers and community planners. Four sets of vertical aerial photographs (Oct. 18, 1989; Jan. 27, 1998; Feb. 9, 1998; and March 6, 1998) were orthorectified and digital terrain models (DTMs) were generated and edited for this study (see Hapke and Richmond, 2000, for description of techniques). The earliest set of photography is from 1989, taken immediately following the Loma Prieta earthquake. These photographs are used to document the response of the seacliffs to seismic shaking, as well as to establish a baseline cliff-edge position to measure the amount of retreat of the cliff edge over the following decade. The remaining three sets of photographs were collected using the U.S. Geological Survey Coastal Aerial Mapping System (CAMS) during the 1997-98 El Ni?o (see Hapke and Richmond, 1999; 2000). The CAMS photographs were taken before, during, and after severe storms and are used to examine seacliff response to these storms. In addition to the analyses of photogrammetrically processed data, field mapping identified joints, faults, and lithologic variations along this section of seacliff.

Miscellaneous Field Studies Map↗
USGS2002

Map Showing Seacliff Response to Climatic and Seismic Events, Seabright Beach, Santa Cruz County, California

Introduction The coastal cliffs along much of the central California coast are actively retreating. Large storms and periodic earthquakes are responsible for most of the documented sea cliff slope failures. Long-term average erosion rates calculated for this section of coast do not provide the spatial or temporal data resolution necessary to identify the processes responsible for retreat of the sea cliffs where episodic retreat threatens homes and community infrastructure. Research suggests that more erosion occurs along the California coast over a short time scale, during periods of severe storms or seismic activity, than occurs during decades of normal weather or seismic quiescence. This is the third map in a series of maps prepared to document the processes of short-term sea cliff retreat through the identification of slope failure styles, spatial variability of failures, and temporal variation in retreat amounts in an area that has been identified as an erosion hotspot. This map presents sea cliff failure and retreat data from the Seabright Beach section, California, which is located on the east side of Santa Cruz along the northern Monterey Bay coast. The data presented in this map series provide high-resolution spatial and temporal information on the location, amount, and processes of sea cliff retreat in Santa Cruz, California. These data show the response of the sea cliffs to both large magnitude earthquakes and severe climatic events such as El Ni?os; this information may prove useful in predicting the future response of the cliffs to events of similar magnitude. The map data can also be incorporated into Global Information System (GIS) for use by researchers and community planners. During this study we developed a method for investigating short-term processes of sea cliff evolution using rectified photographic stereo models. This method allows us to document the linear extent of cliff failures, the spatial and temporal relationship between failures, and the type or style of slope failure. Seabright Beach extends 0.9 km from San Lorenzo Point on the west to the Santa Cruz Yacht Harbor on the east. The cliffs at Seabright Beach are completely protected from wave attack by a wide beach. The protective beach is a relatively recent feature that formed after the emplacement of the Santa Cruz Yacht Harbor jetty in 1963-1964. Prior to the completion of the jetty, the cliffs at Seabright Beach were subject to daily wave attack. The data in this study are post-jetty construction; therefore, the sea cliff failures and cliff retreat are the result of nonmarine processes (rainfall, groundwater and seismic shaking). The 8 to 15 m high cliffs at Seabright Beach are composed of the Miocene to Pliocene Purisima Formation, which is overlain by unconsolidated Pleistocene terrace deposits. The relative thickness of these units varies along the length of the cliff. At the west end of Seabright Beach, including San Lorenzo Point, nearly the entire cliff section is composed of Purisima Formation and is capped by less than 2 m of terrace deposits. In this exposure, the Purisima Formation is a moderately weathered, moderately indurated massive sandstone. The height of the cliffs and the thickness of the Purisima Formation decrease to the east. In the cliffs immediately adjacent to the harbor, the entire exposure is composed of terrace deposits. Toe-slope debris and wind-blown sand form a nearly continuous fan along the cliff base that obscure the lower portion of the cliff. This study documents the impacts of earthquakes and large storms to the sea cliffs in the Seabright Beach section. The first event is the 1989 Loma Prieta earthquake, a M7.1 earthquake that caused widespread damage to the area stretching from Santa Cruz to the San Francisco Bay. The epicenter of the earthquake was located in the Santa Cruz Mountains, approximately 9 km inland from the coast. Extensive block and debris falls, induced by the seismic shaking, occ

Miscellaneous Field Studies Map↗
USGS2001

Coastal-zone hazard maps and recommendations: Eastern Puerto Rico

A series of coastal zone hazard maps cover the area impacted by Hurricane Hugo (1989) in eastern Puerto Rico. The mapping strategy was to develop a tool for quick visualization of multiple hazards for use by coastal planners, managers, property owners, and potential property owners. The Puerto Rico shoreline is heavily developed in places and also highly compartmentalized in terms of shoreline types, geology, and adjacent shelf conditions. Hazards such as coastal erosion, storm surge, riverine flooding, landsliding, and seismic impact also may be compartmentalized. From a management perspective, resources therefore can be allocated on a compartment-by-compartment basis. Six types of hazards were considered in this investigation: (1) shoreline-setting hazards (long-term coastal problems), (2) marine hazards (short-term impacts of coastal storms), (3) earthquake and slope hazards (ground shaking, landslides, and liquefaction), (4) riverine hazards (historical floods), (5) development hazards (high-density development at risk or lowdensity development in extreme-hazard settings), and (6) engineering hazards (special cases in which shoreline engineering projects such as breakwaters or sand mining have significant detrimental effects on portions of the shoreline). Shoreline segments were ranked as being at extreme, high, moderate, or low risk, depending on the number of hazards present within that segment. These rankings are likely to change, gradually over decades with natural coastal evolution, more rapidly as human development infringes on the coastal zone, or in an instant during a severe storm. The hazard maps provide a basis for hazard mitigation and management recommendations.

Puerto Rico↗
USGS2000

Monitoring beach morphology changes using small-format aerial photography and digital softcopy photogrammetry

Current methods of monitoring beach morphology changes commonly involve the establishment of Global Positioning System profiles that are surveyed on a regular basis. Although this method produces precise measurements of coastal topography, it is costly in time and effort and may result in large data gaps between profiles. Much of our understanding of coastal dynamics is thus limited by profile spacing and survey frequency. Softcopy photogrammetry is increasingly being used as an alternative to assess shoreline change and study beach morphodynamics. This method of producing three-dimensional topographic models and orthophotographs from digitized aerial photography can aid in filling in the gaps between established profiles. A limiting factor to this technology is the cost of obtaining high-resolution aerial photography. We have developed an aerial mapping system designed to collect data in an efficient and cost-effective way. We use a small-format aerial photography system that can be mounted on a variety of small aircraft on short notice. After a flight, the photographs are scanned, and softcopy photogrammetry software is used to create both DTMs (Digital Terrain Models) and orthophotographs. The DTMs can be compared with existing profiles for accuracy, and volumetric changes can be computed. The orthophotos are used to make precise measurements of the position and morphology of shoreline features. This aerial mapping system is advantageous over previous methods of beach morphology change monitoring because it allows for rapid response to storm events and provides a cost-effective method of establishing a continual monitoring program in erosion hazard areas.

Environmental Geosciences↗
USGS1997

Beach loss along armored shorelines on Oahu, Hawaiian Islands

An analysis of an aerial photographic time series of Oahu's shoreline reveals that historical seawall and revetment construction (coastal armoring) to protect eroding lands has caused the narrowing of 17.3 ± 1.5 km and loss of 10.4 ± 0.9 km of sandy beach over the period 1928 or 1949 to 1995. This is ~24% of the 115.6 ± 9.8 km of originally sandy shoreline of Oahu. All narrowed and lost beaches occur in front of coastal armoring structures that fix the position of the shoreline. In addition, nearly all narrowed and lost beaches show a history of recent (5% of narrowed and lost beaches) or long-term (92% of narrowed and lost beaches) retreat. We conclude from this study that using a wall or revetment to fix the position of a shoreline undergoing retreat will cause the narrowing and eventual loss of the adjoining beach.

Hawai'i↗
USGS1988

Daily cycles in coastal dunes

Daily cycles of summer sea breezes produce distinctive cyclic foreset deposits in dune sands of the Texas and Oregon coasts. In both areas the winds are strong enough to transport sand only during part of the day, reach a peak during the afternoon, and vary little in direction during the period of sand transport. Cyclicity in the foreset deposits is made evident by variations in the type of sedimentary structure, the texture, and the heavy-mineral content of the sand. Some of the cyclic deposits are made up entirely of one basic type of structure, in which the character of the structure varies cyclically; for example, the angle of climb in a climbing-wind-ripple structure may vary cyclically. Other cyclic deposits are characterized by alternations of two or more structural types. Variations in the concentration of fine-grained heavy minerals, which account for the most striking cyclicity, arise mainly because of segregation on wind-rippled depositional surfaces: where the ripples climb at low angles, the coarsegrained light minerals, which accumulate preferentially on ripple crests, tend to be excluded from the local deposit. Daily cyclic deposits are thickest and best developed on small dunes and are least recognizable near the bases of large dunes.

California, Oregon, Texas↗
USGS1984

High-frequency sediment-level oscillations in the swash zone

Sediment-level oscillations with heights of about 6 cm and shore-normal lengths of order 10 m have been measured in the swash zone of a high-energy, coarse-sand beach. Crests of oscillations were shore parallel and continuous alongshore. The oscillations were of such low steepness (height-to-length ratio approximately 0.006) that they were difficult to detect visually. The period of oscillation ranged between 6 and 15 min and decreased landward across the swash zone. The sediment-level oscillations were progressive landward with an average migration rate in the middle to upper swash zone of 0.8 m min-1. Migration was caused mostly by erosion on the seaward flank of the crest of an oscillation during a period of net seaward sediment transport. Thus, the observed migration was a form migration landward rather than a migration involving net landward sediment transport. The observed sediment-level oscillations were different than sand waves or other swash-zone bedforms previously described.

Marine Geology↗