Large earthquakes are catastrophic events, which can trigger tsunamis and landslides. CMG research aims to better understand the origin, frequency and distribution of earthquakes, and the geologic processes acting in the affected coastal and marine regions. High priority is given to densely populated areas with high frequency or large size earthquakes.
USGS Scientists in Samoa and American Samoa Studying Impacts of Recent Tsunami, October-November 2009 On September 29, 2009, a magnitude-8.0 submarine earthquake occurred at 6:48a.m. Samoa Standard Time approximately 190 km (120 mi) south of Samoa and triggered a tsunami that caused more than 100 deaths and widespread damage in Samoa, American Samoa, and Tonga. Observers reported four tsunami waves that ranged from approximately 1.5 to 6 m high and reached as far as 1.5 km inland. A rapid-response team of USGS scientists is traveling to American Samoa to collect data that will be quickly degraded or destroyed by recovery activity and natural processes. USGS Western Coastal and Marine Geology (WCMG) oceanographer Bruce Jaffe arrived in Pago Pago, on the island of Tutuila, American Samoa, on October 4 and was joined later in the week by fellow WCMG scientists Bruce Richmond, Mark Buckley, Guy Gelfenbaum, Steve Watt, and Alex Apotsos. Oceanographer Walter Dudley of the University of Hawai‘i, Hilo, will work with the USGS team. The team will collect time-sensitive data to help them determine the height of tsunami waves at various sites and the distances the waves traveled inland. They will study the transport of sediment and other debris, look for and measure evidence of subsidence and uplift caused by the earthquake, document erosion caused by the tsunami waves, and make other observations critical to the better understanding of tsunami impacts and processes. Posted: 2009-11-24
Cascadia Seismic Hazard Studies Investigations of Earthquake and Tsunami Hazards and History in the Pacific Northwest, specifically the Cascadia Subduction Zone. Posted: 2009-07-24
Open-File Report 2007-1437: The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2) A USGS, California Geological Survey, and Southern California Earthquake Center joint report: California’s 35 million people live among some of the most active earthquake faults in the United States. Public safety demands credible assessments of the earthquake hazard to maintain appropriate building codes for safe construction and earthquake insurance for loss protection. Seismic hazard analysis begins with an earthquake rupture forecast—a model of probabilities that earthquakes of specified magnitudes, locations, and faulting types will occur during a specified time interval. This report describes a new earthquake rupture forecast for California developed by the 2007 Working Group on California Earthquake Probabilities (WGCEP 2007). Posted: 2008-07-11
Coastal and Marine Knowledge Bank An initiative to develop and present a national-scale, interdisciplinary scientific framework for marine environments, the coastal zone, and coastal watersheds Posted: 2007-11-28
Investigation of the M6.6 Niigata-Chuetsu Oki, Japan, Earthquake of July 16, 2007 The M6.6 mainshock of the Niigata Chuetsu Oki (offshore) earthquake occurred at 10:13 a.m. local time on July 16, 2007, and was followed by a sequence of aftershocks that were felt during the entire time of the reconnaissance effort. The mainshock had an estimated focal depth of 10 km and struck in the Japan Sea offshore Kariwa. Analysis of waveforms from source inversion studies indicates that the event occurred along a thrust fault with a NE trend. The fault plane is either a strike of 34 degrees with a dip of 51 degrees or a strike of 238 degrees with a dip of 41 degrees. Which of these two planes is associated with the mainshock rupture is unresolved, although attenuation relationship analysis indicates that the northwest-dipping fault is favored. The quake affected an approximately 100-km-wide area along the coastal areas of southwestern Niigata prefecture. The event triggered ground failures as far as the Unouma Hills, located in central Niigata approximately 50 km from the shore and the source area of the 2004 Niigata Chuetsu earthquake. The primary event produced tsunami run-ups that reached maximum runup heights of about 20 centimeters along the shoreline of southern Niigata Prefecture. Posted: 2007-11-15
Professional Paper 1661-E: Seismic Stability of the Duwamish River Delta, Seattle, Washington The delta front of the Duwamish River valley near Elliott Bay and Harbor Island is founded on young Holocene deposits shaped by sea-level rise, episodic volcanism, and seismicity. These river-mouth deposits are highly susceptible to seismic soil liquefaction and are potentially prone to submarine landsliding and disintegrative flow failure. A highly developed commercial-industrial corridor, extending from the City of Kent to the Elliott Bay/Harbor Island marine terminal facilities, is founded on the young Holocene deposits of the Duwamish River valley. The deposits of this Holocene delta have been shaped not only by relative sea-level rise but also by episodic volcanism and seismicity. Ground-penetrating radar (GPR), cores, in situ testing, and outcrops are being used to examine the delta stratigraphy and to infer how these deposits will respond to future volcanic eruptions and earthquakes in the region. A geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front. Posted: 2007-11-02
USGS Open-File Report 2004-1426, RayGUI 2.0, Inversion Ray-Tracing for RAYINVR RayGUI 2.0 is a graphical user interface (GUI) to the seismic travel-time modeling program of Zelt and Smith (1992). RayGUI 2.0 represents a significant improvement over the previous version of RayGUI (RayGUI 1.04; Loss et al., 1998a, b). RayGUI 2.0 uses an updated Java version (1.3), and it can run on various operating systems (UNIX, Linux, and Mac OS X). Several new functions have been incorporated, including: execute the forward and inversion codes of Zelt and Smith (1992), create models or add new parts of models from an ASCII file, graphically add layers or points, graphically pinch layers, change the velocity value of a control point, report point location and velocity, import traveltime lists, generate postscript files, export the velocity model into an ASCII file, generate 1D velocity profiles at specified locations, calculate root-mean-square errors between observed and calculated arrivals for selected phases, access the ray trace log, and several other new display features. Posted: 2006-10-20
Coasts of Colombia Due to the complex geologic history of the northwestern part of South America, the Colombian coasts include a variety of coastline types, ranging from high-relief, steep-plunging cliffs typical of igneous and metamorphic massifs, to low, sandy barrier islands and extensive mangrove swamps characteristic of deltaic areas of both coasts. Posted: 2006-06-14
Tsunamis and Earthquakes - 2005 Sumatra Tsunami Study - USGS WCMG USGS Western Coastal and Marine Geology was part of an international team that studied sediment deposits in Sri Lanka from the tsunami generated by the magnitude 9.0 Sumatra earthquake on December 26, 2004. Posted: 2005-05-31
USGS WCMG - Notes from the field... Sumatra 2005 News and Information about the USGS West Sumatra International Tsunami Survey Team's Field Study, March 30 - April 26, 2005. These "Notes from the field" pages were created on a daily basis as a way to report findings during the ITST's field study. The effort began just as the 28 March 2005 earthquake and tsunami occurred off Sumatra. Posted: 2005-05-02
Scientific Investigations Report 2004-5183: Late Quaternary Deposition in the Inner Basins of the California Continental Borderland- Part A. Santa Monica Basin Radiocarbon dating of sediment core samples from Santa Monica Basin document Holocene (younger than approximately 11 ka) landslides and fault offsets along the basin margin. The new dates include 17 from six piston cores on the continental slope and 11 from Ocean Drilling Program Site 1015 on the basin floor. The dates, which are based on data from pelagic and benthic foraminifera in addition to several dates from mollusk shells, are used to provide chronostratigraphic control for a previously determined basin-wide seismic stratigraphy. The geologic setting at the core sites and a sediment log for each core are shown. In addition, each sediment log is accompanied by a color core photograph as well as P-wave velocity and gamma-ray density profiles. The primary purpose of the report is to make the radiocarbon dates available for other studies in the Santa Monica Basin. A comparison of sediment accumulation rates between the late Pleistocene and Holocene provides insight to the effects of sea-level change on sediment input to the basin. In addition, the results can be used to evaluate the effectiveness of wire-line piston coring in providing age control for earthquake hazard and sedimentologic studies. Posted: 2005-02-15
Tsunamis and Earthquakes - 2005 Sri Lanka Tsunami Study - USGS WCMG USGS Western Coastal and Marine Geology was part of an international team that studied sediment deposits in Sri Lanka from the tsunami generated by the magnitude 9.0 Sumatra earthquake on December 26, 2004 Posted: 2005-02-14
The Chesapeake Bay Bolide Impact: A New View of Coastal Plain Evolution - USGS Fact Sheet 049-98 A spectacular geological event took place on the Atlantic margin of North America about 35 million years ago in the late part of the Eocene Epoch. Sea level was unusually high everywhere on Earth, and the ancient shoreline of the Virginia region was somewhere in the vicinity of where Richmond is today. Tropical rain forests covered the slopes of the Appalachians. To the east of a narrow coastal plain, a broad, lime (calcium carbonate)-covered continental shelf lay beneath the ocean. Suddenly, with an intense flash of light, that tranquil scene was transformed into a hellish cauldron of mass destruction. From the far reaches of space, a bolide (comet or asteroid), 3-5 kilometers in diameter, swooped through the Earth's atmosphere and blasted an enormous crater into the continental shelf. The crater is now approximately 200 km southeast of Washington, D.C., and is buried 300-500 meters beneath the southern part of Chesapeake Bay and the peninsulas of southeastern Virginia. Posted: 2004-03-02
Monterey Bay Marine Sanctuary Geological Processes and Framework - USGS Fact Sheet The U.S. Geological Survey (USGS) will move its Pacific Marine Geology program to a new location at the University of California at Santa Cruz (UCSC) and we are excited about our role in the marine sciences community around Monterey Bay. There is much to learn in the region, not only as a result of new opportunities in the Marine Sanctuary, but also that knowledge gained here may be transferred to our studies of similar environments in other parts of the world. Posted: 2004-03-02
USGS OFR 03-110 - Cruise Report for A1-02-SC: Southern California CABRILLO project, Earthquake Hazards Task A two-week marine geophysical survey obtained sidescan-sonar images and multiple sets of high-resolution seismic-reflection profiles in the southern California offshore area between Point Arguello and Point Dume. The data were obtained to support two project activities of the United States Geological Survey (USGS) Coastal and Marine Geology (CMG) Program: (1) the evaluation of the geologic hazards posed by earthquake faults and landslides in the offshore areas of Santa Barbara Channel and western Santa Monica Basin and (2) determine the location of active hydrocarbon seeps in the vicinity of Point Conception as part of a collaborative study with the Minerals Management Service (MMS). The 2002 cruise, A1-02- SC, is the fourth major data-collection effort in support of the first objective (Normark et al., 1999a, b; Gutmacher et al., 2000). A cruise to obtain sediment cores to constrain the timing of deformation interpreted from the geophysical records is planned for the summer of 2003. Posted: 2003-10-01
Subsurface Controls on Historical Subsidence Rates and Associated
Wetland Loss in Southcentral Louisiana The Gulf Coast Basin is a region where subsidence and fault activation are common around large, mature oil and gas fields even though moderately deep hydrocarbon production has generally been disregarded as the primary cause. This project will test the hypothesis that long-term, large-volume oil and gas production in the Gulf Coast Basin has resulted in land-surface subsidence and activation of deep-seated faults around some fields. Posted: 2003-03-14
Primary Causes of Wetland Loss at Madison Bay, Terrebonne Parish, Louisiana - USGS Open File Report 03-060 The Gulf Coast Basin is a region where subsidence and fault activation are common around large, mature oil and gas fields even though moderately deep hydrocarbon production has generally been disregarded as the primary cause. This project will test the hypothesis that long-term, large-volume oil and gas production in the Gulf Coast Basin has resulted in land-surface subsidence and activation of deep-seated faults around some fields. Posted: 2003-03-11
Natural Disasters - Forecasting Hurricane Occurrence Events such as hurricanes, earthquakes, floods, tsunamis, volcanic eruptions, and tornadoes are natural disasters because they negatively impact society, and so they must be measured and understood in human-related terms. At the U.S. Geological Survey, we have developed a new method to examine fatality and dollar-loss data, and to make probabilistic estimates of the frequency and magnitude of future events. This information is vital to large sectors of society including disaster relief agencies and insurance companies. Posted: 2003-03-02
Shallow Stratigraphic Evidence of Subsidence and Faulting Induced by Hydrocarbon Production in Coastal Southeast Texas - USGS Open File Report 01-274 Wetland losses and their progressive conversion to open water around producing oil and gas fields in the Gulf Coast region have been attributed to a variety of natural and anthropogenic processes. Three large, mature hydrocarbon fields in coastal southeast Texas were examined to evaluate competing hypotheses of wetland losses and to characterize subaerial and submerged surfaces near reactivated faults and zones of subsidence. Posted: 2002-09-19
Subsidence and Fault Activation Related to Fluid Energy Production, Gulf Coast Basin The Gulf Coast Basin is a region where subsidence and fault activation are common around large, mature oil and gas fields even though moderately deep hydrocarbon production has generally been disregarded as the primary cause. This project will test the hypothesis that long-term, large-volume oil and gas production in the Gulf Coast Basin has resulted in land-surface subsidence and activation of deep-seated faults around some fields. Posted: 2002-09-18
The USGS Ocean Bottom Seismometer Facility An Ocean Bottom Seismometer (OBS) is a self contained data-acquisition system which free falls to the ocean floor and records seismic data generated by airguns and earthquakes. The OBS's are portable, self contained, inexpensive to operate, and can be deployed and retrieved off almost any size boat (including a Zodiac). They are therefore, uniquely suitable to record wide-angle reflection and refraction shots in remote areas or under primitive conditions and to be deployed on short notice to record earthquake aftershocks Posted: 2002-04-24
San Francisco Bay Earthquake Hazards Project Earthquake Hazard Studies in the San Francisco Bay area, including monitoring of faults through seismic imaging and other geophysical studies. Posted: 2000-07-25
About Gas Hydrates and a USGS gas hydrate project Questions and answers about submarine gas hydrates: an ice-like crystalline solid formed of water and gas that is found in places under the sea floor and has important implications to techniques of deep-sea drilling and future energy supplies. Posted: 1999-03-08
Chesapeake Bay Bolide: Modern Consequences of an Ancient Cataclysm The story of the Chesapeake Bay Bolide, a meteor that hit the earth and formed a crater that is now buried under the mouth of Chesapeake Bay; how it was originally discovered, its effects on the landscape, and its importance to the groundwater supply and to engineering planning in the Norfolk area of Virginia and the lower Delmarva peninsula. Posted: 1997-07-24
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