Ruppert, N. A.; Hansen, R. A.
The Alaska Earthquake Information Center (AEIC) receives data from over 400 seismic sites located within the state boundaries and the surrounding regions and serves as a regional data center. In 2007, the AEIC reported ~20,000 seismic events, with the largest event of M6.6 in Andreanof Islands. The real-time earthquake detection and data processing systems at AEIC are based on the Antelope system from BRTT, Inc. This modular and extensible processing platform allows an integrated system complete from data acquisition to catalog production. Multiple additional modules constructed with the Antelope toolbox have been developed to fit particular needs of the AEIC. The real-time earthquake locations and magnitudes are determined within 2-5 minutes of the event occurrence. AEIC maintains a 24/7 seismologist-on-duty schedule. Earthquake alarms are based on the real- time earthquake detections. Significant events are reviewed by the seismologist on duty within 30 minutes of the occurrence with information releases issued for significant events. This information is disseminated immediately via the AEIC website, ANSS website via QDDS submissions, through e-mail, cell phone and pager notifications, via fax broadcasts and recorded voice-mail messages. In addition, automatic regional moment tensors are determined for events with M>=4.0. This information is posted on the public website. ShakeMaps are being calculated in real-time with the information currently accessible via a password-protected website. AEIC is designing an alarm system targeted for the critical lifeline operations in Alaska. AEIC maintains an extensive computer network to provide adequate support for data processing and archival. For real-time processing, AEIC operates two identical, interoperable computer systems in parallel.
Thoms, Evan E.; Haeussler, Peter J.; Anderson, Rebecca D.; McGimsey, Robert G.
On March 27, 1964, at 5:36 p.m., a magnitude 9.2 earthquake, the largest recorded earthquake in U.S. history, struck southcentral Alaska (fig. 1). The Great Alaska Earthquake (also known as the Good Friday Earthquake) occurred at a pivotal time in the history of earth science, and helped lead to the acceptance of plate tectonic theory (Cox, 1973; Brocher and others, 2014). All large subduction zone earthquakes are understood through insights learned from the 1964 event, and observations and interpretations of the earthquake have influenced the design of infrastructure and seismic monitoring systems now in place. The earthquake caused extensive damage across the State, and triggered local tsunamis that devastated the Alaskan towns of Whittier, Valdez, and Seward. In Anchorage, the main cause of damage was ground shaking, which lasted approximately 4.5 minutes. Many buildings could not withstand this motion and were damaged or collapsed even though their foundations remained intact. More significantly, ground shaking triggered a number of landslides along coastal and drainage valley bluffs underlain by the Bootlegger Cove Formation, a composite of facies containing variably mixed gravel, sand, silt, and clay which were deposited over much of upper Cook Inlet during the Late Pleistocene (Ulery and others, 1983). Cyclic (or strain) softening of the more sensitive clay facies caused overlying blocks of soil to slide sideways along surfaces dipping by only a few degrees. This guide is the document version of an interactive web map that was created as part of the commemoration events for the 50th anniversary of the 1964 Great Alaska Earthquake. It is accessible at the U.S. Geological Survey (USGS) Alaska Science Center website: http://alaska.usgs.gov/announcements/news/1964Earthquake/. The website features a map display with suggested tour stops in Anchorage, historical photographs taken shortly after the earthquake, repeat photography of selected sites, scanned documents
Black Porto, N.; Nyst, M.
Alaska is one of the most seismically active and tectonically diverse regions in the United States. To examine risk, we have updated the seismic hazard model in Alaska. The current RMS Alaska hazard model is based on the 2007 probabilistic seismic hazard maps for Alaska (Wesson et al., 2007; Boyd et al., 2007). The 2015 RMS model will update several key source parameters, including: extending the earthquake catalog, implementing a new set of crustal faults, updating the subduction zone geometry and reoccurrence rate. First, we extend the earthquake catalog to 2013; decluster the catalog, and compute new background rates. We then create a crustal fault model, based on the Alaska 2012 fault and fold database. This new model increased the number of crustal faults from ten in 2007, to 91 faults in the 2015 model. This includes the addition of: the western Denali, Cook Inlet folds near Anchorage, and thrust faults near Fairbanks. Previously the subduction zone was modeled at a uniform depth. In this update, we model the intraslab as a series of deep stepping events. We also use the best available data, such as Slab 1.0, to update the geometry of the subduction zone. The city of Anchorage represents 80% of the risk exposure in Alaska. In the 2007 model, the hazard in Alaska was dominated by the frequent rate of magnitude 7 to 8 events (Gutenberg-Richter distribution), and large magnitude 8+ events had a low reoccurrence rate (Characteristic) and therefore didn't contribute as highly to the overall risk. We will review these reoccurrence rates, and will present the results and impact to Anchorage. We will compare our hazard update to the 2007 USGS hazard map, and discuss the changes and drivers for these changes. Finally, we will examine the impact model changes have on Alaska earthquake risk. Consider risk metrics include average annual loss, an annualized expected loss level used by insurers to determine the costs of earthquake insurance (and premium levels), and the
Hansen, Wallace R.; Kachadoorian, Reuben; Coulter, Henry W.; Migliaccio, Ralph R.; Waller, Roger M.; Stanley, Kirk W.; Lemke, Richard W.; Plafker, George; Eckel, Edwin B.; Mayo, Lawrence R.
This is the second in a series of six reports that the U.S. Geological Survey published on the results of a comprehensive geologic study that began, as a reconnaissance survey, within 24 hours after the March 27, 1964, Magnitude 9.2 Great Alaska Earthquake and extended, as detailed investigations, through several field seasons. The 1964 Great Alaska earthquake was the largest earthquake in the U.S. since 1700. Professional Paper 542, in 7 parts, describes the effects of the earthquake on Alaskan communities.
Caplan-Auerbach, J.; Petersen, T.
Since it last erupted in 1999, Shishaldin Volcano, Aleutian Islands, Alaska, has produced hundreds to thousands of long-period (1-2 Hz; LP) earthquakes every day with no other sign of volcanic unrest. In 2002, the earthquakes also exhibited a short-period (4-7 Hz; SP) signal occurring between 3 and 15 s before the LP phase. Although the SP phase contains higher frequencies than the LP phase, its spectral content is still well below that expected of brittle failure events. The SP phase was never observed without the LP phase, although LP events continued to occur in the absence of the precursory signal. The two-phased events are termed "coupled events", reflecting a triggered relationship between two discrete event types. Both phases are highly repetitive in time series, suggestive of stable, non-destructive sources. Waveform cross-correlation and spectral coherence are used to extract waveforms from the continuous record and determine precise P-wave arrivals for the SP phase. Although depths are poorly constrained, the SP phase is believed to lie at shallow (<4 km) depths just west of Shishaldin's summit. The variable timing between the SP and LP arrivals indicates that the trigger mechanism between the phases itself moves at variable speeds. A model is proposed in which the SP phase results from fluid moving within the conduit, possibly around an obstruction and the LP phase results from the coalescence of a shallow gas bubble. The variable timing is attributed to changes in gas content within the conduit. The destruction of the conduit obstacle on November 21, 2002 resulted in the abrupt disappearance of the SP phase.
Desherevskii, A. V.; Sidorin, A. Ya.
The Alaska earthquake catalog has been analyzed in detail to find and study the diurnal periodicity of earthquake events. For this purpose, a set of spatially and temporally homogeneous samples of earthquakes with the well-known magnitude of completeness ( M c) has been prepared. For each sample, the spectra have been considered, the average diurnal variations in the number of earthquakes have been calculated, and their amplitudes were determined. The average diurnal variations were compared. For representative earthquakes in Alaska, no significant diurnal variation has been found. In subrepresentative samples, either the diurnal variation is insignificant or the signal-to-noise ratio only slightly exceeds 1.3-1.9. The diurnal variation is significant (a signal-to-noise ratio of 2.0-4.5) only for the samples of weak earthquakes with magnitudes of no more than 1.4, which is 0.5 units less than the strong (i.e., guaranteed for the entire sample area) completeness threshold. The results are consistent with the hypothesis explaining the diurnal periodicity of earthquakes by noise-discrimination effects. However, a comparative analysis of the diurnal variation parameters estimated over a large number of spatially and temporally homogeneous samples of earthquakes in the Alaska, southern California, and Greece catalogs shows that all of these results cannot be explained by this model.
IAEMIS (Integrated Automated Emergency Management Information System) is the principal tool of an earthquake preparedness program developed by Martin Marietta and the Mid-America Remote Sensing Center (MARC). It is a two-component set of software, data and procedures to provide information enabling management personnel to make informed decisions in disaster situations. The NASA-developed program ELAS, originally used to analyze Landsat data, provides MARC with a spatially-oriented information management system. Additional MARC projects include land resources management, and development of socioeconomic data.
Ruppert, N. A.; Holtkamp, S. G.
An unusual sequence of earthquakes in NW Brooks Range region of Alaska began with two magnitude 5.7 earthquakes within minutes of each other on April 18, 2014. These events were followed by a vigorous aftershock sequence with many aftershocks reaching magnitude 4 and higher. Later, three more magnitude 5.7 earthquakes occurred in the same source region on May 3, June 7 and June 16. Earthquake source mechanisms indicate normal faulting on SE-NW striking fault planes. The source region is located ~20 km NE of the Noatak village and ~40 km S of the Red Dog Mine. A magnitude 5.5 occurred in this area in 1981. The 1981 sequence also exhibited a swarm-like behavior over the course of 6 months. Detection and reporting of these earthquakes is complicated by sparseness of seismic network in NW Alaska. At the time of April 18 earthquake the nearest seismic site was located at the Red Dog Mine, with the next nearest station 350 km away. Following the May 3 event, the Alaska Earthquake Center installed two additional temporary stations, one in Noatak and another in Kotzebue, 85 km S of the source area. Overall, 450 events were reported in this sequence through end of July. The catalog magnitude of completeness with the additional stations was about ~2.2. We applied waveform template matching algorithm to detect additional events in this sequence that could not be detected with the standard network processing. The template matching resulted in ~600 additional event detections. The waveform cross-correlation indicates that most of the events are not repeating sources. From the catalogued events, only 6% of event pairs have correlation coefficients of 0.75 or higher. We were able to identify only a few families of repeating events. Only one family seemed to be present throughout the entire sequence, while other event families were mostly short-lived. We find preliminary evidence that the earthquakes migrated to shallower depths throughout the sequence, consistent with the
West, Michael E.; Haeussler, Peter J.; Ruppert, Natalia A.; Freymueller, Jeffrey T.; Alaska Seismic Hazards Safety Commission
Spring was returning to Alaska on Friday 27 March 1964. A two‐week cold snap had just ended, and people were getting ready for the Easter weekend. At 5:36 p.m., an earthquake initiated 12 km beneath Prince William Sound, near the eastern end of what is now recognized as the Alaska‐Aleutian subduction zone. No one was expecting this earthquake that would radically alter the coastal landscape, influence the direction of science, and indelibly mark the growth of a burgeoning state.
Doser, D.I.; Ratchkovski, N.A.; Haeussler, P.J.; Saltus, R.
We calculated seismic moment rates from crustal earthquake information for the upper Cook Inlet region, including Anchorage, Alaska, for the 30 yr prior to and 36 yr following the 1964 Great Alaska earthquake. Our results suggest over a factor of 1000 decrease in seismic moment rate (in units of dyne centimeters per year) following the 1964 mainshock. We used geologic information on structures within the Cook Inlet basin to estimate a regional geologic moment rate, assuming the structures extend to 30 km depth and have near-vertical dips. The geologic moment rates could underestimate the true rates by up to 70% since it is difficult determine the amount of horizontal offset that has occurred along many structures within the basin. Nevertheless, the geologic moment rate is only 3-7 times lower than the pre-1964 seismic moment rate, suggesting the 1964 mainshock has significantly slowed regional crustal deformation. If we compare the geologic moment rate to the post-1964 seismic moment rate, the moment rate deficit over the past 36 yr is equivalent to a moment magnitude 6.6-7.0 earthquake. These observed differences in moment rates highlight the difficulty in using seismicity in the decades following a large megathrust earthquake to adequately characterize long-term crustal deformation.
Kayen, R.; Thompson, E.; Minasian, D.; Moss, R.E.S.; Collins, B.D.; Sitar, N.; Dreger, D.; Carver, G.
The 2002 M7.9 Denali fault earthquake resulted in 340 km of ruptures along three separate faults, causing widespread liquefaction in the fluvial deposits of the alpine valleys of the Alaska Range and eastern lowlands of the Tanana River. Areas affected by liquefaction are largely confined to Holocene alluvial deposits, man-made embankments, and backfills. Liquefaction damage, sparse surrounding the fault rupture in the western region, was abundant and severe on the eastern rivers: the Robertson, Slana, Tok, Chisana, Nabesna and Tanana Rivers. Synthetic seismograms from a kinematic source model suggest that the eastern region of the rupture zone had elevated strong-motion levels due to rupture directivity, supporting observations of elevated geotechnical damage. We use augered soil samples and shear-wave velocity profiles made with a portable apparatus for the spectral analysis of surface waves (SASW) to characterize soil properties and stiffness at liquefaction sites and three trans-Alaska pipeline pump station accelerometer locations. ?? 2004, Earthquake Engineering Research Institute.
Gomberg, J; Bodin, P; Larson, K; Dragert, H
The permanent and dynamic (transient) stress changes inferred to trigger earthquakes are usually orders of magnitude smaller than the stresses relaxed by the earthquakes themselves, implying that triggering occurs on critically stressed faults. Triggered seismicity rate increases may therefore be most likely to occur in areas where loading rates are highest and elevated pore pressures, perhaps facilitated by high-temperature fluids, reduce frictional stresses and promote failure. Here we show that the 2002 magnitude M = 7.9 Denali, Alaska, earthquake triggered widespread seismicity rate increases throughout British Columbia and into the western United States. Dynamic triggering by seismic waves should be enhanced in directions where rupture directivity focuses radiated energy, and we verify this using seismic and new high-sample GPS recordings of the Denali mainshock. These observations are comparable in scale only to the triggering caused by the 1992 M = 7.4 Landers, California, earthquake, and demonstrate that Landers triggering did not reflect some peculiarity of the region or the earthquake. However, the rate increases triggered by the Denali earthquake occurred in areas not obviously tectonically active, implying that even in areas of low ambient stressing rates, faults may still be critically stressed and that dynamic triggering may be ubiquitous and unpredictable. PMID:14961117
Gomberg, J.; Bodin, P.; Larson, K.; Dragert, H.
The permanent and dynamic (transient) stress changes inferred to trigger earthquakes are usually orders of magnitude smaller than the stresses relaxed by the earthquakes themselves, implying that triggering occurs on critically stressed faults. Triggered seismicity rate increases may therefore be most likely to occur in areas where loading rates are highest and elevated pore pressures, perhaps facilitated by high-temperature fluids, reduce frictional stresses and promote failure. Here we show that the 2002 magnitude M = 7.9 Denali, Alaska, earthquake triggered wide-spread seismicity rate increases throughout British Columbia and into the western United States. Dynamic triggering by seismic waves should be enhanced in directions where rupture directivity focuses radiated energy, and we verify this using seismic and new high-sample GPS recordings of the Denali mainshock. These observations are comparable in scale only to the triggering caused by the 1992 M = 7.4 Landers, California, earthquake, and demonstrate that Landers triggering did not reflect some peculiarity of the region or the earthquake. However, the rate increases triggered by the Denali earthquake occurred in areas not obviously tectonically active, implying that even in areas of low ambient stressing rates, faults may still be critically stressed and that dynamic triggering may be ubiquitous and unpredictable.
Brocher, Thomas M.; Filson, John R.; Fuis, Gary S.; Haeussler, Peter J.; Holzer, Thomas L.; Plafker, George; Blair, J. Luke
The magnitude 9.2 Great Alaska Earthquake that struck south-central Alaska at 5:36 p.m. on Friday, March 27, 1964, is the largest recorded earthquake in U.S. history and the second-largest earthquake recorded with modern instruments. The earthquake was felt throughout most of mainland Alaska, as far west as Dutch Harbor in the Aleutian Islands some 480 miles away, and at Seattle, Washington, more than 1,200 miles to the southeast of the fault rupture, where the Space Needle swayed perceptibly. The earthquake caused rivers, lakes, and other waterways to slosh as far away as the coasts of Texas and Louisiana. Water-level recorders in 47 states—the entire Nation except for Connecticut, Delaware, and Rhode Island— registered the earthquake. It was so large that it caused the entire Earth to ring like a bell: vibrations that were among the first of their kind ever recorded by modern instruments. The Great Alaska Earthquake spawned thousands of lesser aftershocks and hundreds of damaging landslides, submarine slumps, and other ground failures. Alaska’s largest city, Anchorage, located west of the fault rupture, sustained heavy property damage. Tsunamis produced by the earthquake resulted in deaths and damage as far away as Oregon and California. Altogether the earthquake and subsequent tsunamis caused 129 fatalities and an estimated $2.3 billion in property losses (in 2013 dollars). Most of the population of Alaska and its major transportation routes, ports, and infrastructure lie near the eastern segment of the Aleutian Trench that ruptured in the 1964 earthquake. Although the Great Alaska Earthquake was tragic because of the loss of life and property, it provided a wealth of data about subductionzone earthquakes and the hazards they pose. The leap in scientific understanding that followed the 1964 earthquake has led to major breakthroughs in earth science research worldwide over the past half century. This fact sheet commemorates Great Alaska Earthquake and
Tuthill, Samuel J.; Laird, Wilson M.
The Alaska earthquake of March 27, 1964, caused widespread geomorphic changes in the Martin-Bering Rivers area-900 square miles of uninhabited mountains, alluvial flatlands, and marshes north of the Gulf of Alaska, and east of the Copper River. This area is at lat 60°30’ N. and long 144°22’ W., 32 miles east of Cordova, and approximately 130 miles east-southeast of the epicenter of the earthquake. The geomorphic effects observed were: (1) earthquake-induced ground fractures, (2) mudvent deposits, (3) “earthquake-fountain” craters, (4) subsidence, (5) mudcones, (6) avalanches, (7) subaqueous landslides, (8) turbidity changes in ice-basined lakes on the Martin River glacier, (9) filling of ice-walled sinkholes, (10) gravel-coated snow cones, (11) lake ice fractures, and (12) uplift accompanied the earthquake. In addition to geomorphic effects, the earthquake affected the animal populations of the area. These include migratory fish, terrestrial mollusks, fur-bearing animals, and man. The Alaska earthquake clearly delineated areas of alluvial fill, snow and rock avalanche corridors, and deltas of the deeper lakes as unsuitable for future construction.
Logan, Malcolm H.; Burton, Lynn R.; Eckel, Edwin B.; Kachadoorian, Reuben; McCulloch, David S.; Bonilla, Manuel G.
This is the forth in a series of six reports that the U.S. Geological Survey published on the results of a comprehensive geologic study that began, as a reconnaissance survey, within 24 hours after the March 27, 1964, Magnitude 9.2 Great Alaska Earthquake and extended, as detailed investigations, through several field seasons. The 1964 Great Alaska earthquake was the largest earthquake in the U.S. since 1700. Professional Paper 545, in 4 parts, describes the effects on transportation, communications, and utilities.
Parsons, Tom; Geist, Eric L.; Ryan, Holly F.; Lee, Homa J.; Haeussler, Peter J.; Lynett, Patrick; Hart, Patrick E.; Sliter, Ray; Roland, Emily
Like many subduction zone earthquakes, the deadliest aspects of the 1964 M = 9.2 Alaska earthquake were the tsunamis it caused. The worst of these were generated by local submarine landslides induced by the earthquake. These caused high runups, engulfing several coastal towns in Prince William Sound. In this paper, we study one of these cases in detail, the Port Valdez submarine landslide and tsunami. We combine eyewitness reports, preserved film, and careful posttsunami surveys with new geophysical data to inform numerical models for landslide tsunami generation. We review the series of events as recorded at Valdez old town and then determine the corresponding subsurface events that led to the tsunami. We build digital elevation models of part of the pretsunami and posttsunami fjord-head delta. Comparing them reveals a ~1500 m long region that receded 150 m to the east, which we interpret as the primary delta landslide source. Multibeam imagery and high-resolution seismic reflection data identify a ~400 m wide chute with hummocky deposits at its terminus, which may define the primary slide path. Using these elements we run hydrodynamic models of the landslide-driven tsunamis that match observations of current direction, maximum inundation, and wave height at Valdez old town. We speculate that failure conditions at the delta front may have been influenced by manmade changes in drainage patterns as well as the fast retreat of Valdez and other glaciers during the past century.
West, Michael; Sánchez, John J; McNutt, Stephen R
As surface waves from the 26 December 2004 earthquake in Sumatra swept across Alaska, they triggered an 11-minute swarm of 14 local earthquakes near Mount Wrangell, almost 11,000 kilometers away. Earthquakes occurred at intervals of 20 to 30 seconds, in phase with the largest positive vertical ground displacements during the Rayleigh surface waves. We were able to observe this correlation because of the combination of unusually long surface waves and seismic stations near the local earthquakes. This phase of Rayleigh wave motion was dominated by horizontal extensional stresses reaching 25 kilopascals. These observations imply that local events were triggered by simple shear failure on normal faults. PMID:15905395
Chapman, James B.; Elliott, Julie; Doser, Diane I.; Pavlis, Terry L.
The Suckling Hills in southern Alaska experienced localized, anomalously large coseismic uplift in the Mw 9.2, 1964 Alaska earthquake. Large uplift at the Suckling Hills can be explained by increased slip, or an asperity, on the Alaska-Aleutian megathrust; however, this paper suggests that increased uplift may be a result of slip on the Suckling Hills splay fault. We present a series of models that demonstrate how the inclusion of the Suckling Hills fault improves the fit between modeled vertical displacement and measured coseismic uplift in comparison to slip on the Alaska-Aleutian megathrust alone. Our results suggest that ~ 3 m of average slip on the Suckling Hills fault during the 1964 earthquake can help explain the large coseismic uplift data. These results are consistent with recent studies indicating Pleistocene slip on the Suckling Hills fault and together highlight the potential seismic and tsunami risk associated with this segment of the Alaskan subduction complex.
Hansen, Wallace R.; Eckel, Edwin B.; Schaem, William E.; Lyle, Robert E.; George, Warren; Chance, Genie
One of the greatest geotectonic events of our time occurred in southern Alaska late in the afternoon of March 27, 1964. Beneath a leaden sky, the chill of evening was just settling over the Alaskan countryside. Light snow was falling on some communities. It was Good Friday, schools were closed, and the business day was ending. Suddenly without warning half of Alaska was rocked and jarred by the most violent earthquake to occur in North America this century. The descriptive summary that follows is based on the work of many investigators. A large and still-growing scientific literature has accumulated since the earthquake, and this literature has been freely drawn upon here. In particular, the writers have relied upon the findings of their colleagues in the Geological Survey. Some of these findings have been published, but some are still being prepared for publication. Moreover, some field investigations are still in progress. This is the first in a series of six reports that the U.S. Geological Survey published on the results of a comprehensive geologic study that began, as a reconnaissance survey, within 24 hours after the March 27, 1964, Magnitude 9.2 Great Alaska Earthquake and extended, as detailed investigations, through several field seasons. The 1964 Great Alaska earthquake was the largest earthquake in the U.S. since 1700. Professional Paper 541, in 1 part, describes Field Investigations and Reconstruction Effort.
Page, R.A.; Plafker, G.; Pulpan, H.
Geologic and seismic data reveal a set of parallel, active, strike-slip faults in east-central Alaska between the Denali and Tintina fault systems. The faults strike northeast to north-northeast, at a high angle to the bounding dextral fault systems, and exhibit sinistral slip. This hypothesizes that this set of faults divides the crust into long blocks that are rotating clockwise in response to northerly compression resulting from Pacific-North American plate convergence. It is suggested that these faults have produced most of the large historical earthquakes in east-central Alaska between the Alaska Range and the Yukon River. -Authors
The recorded responses of an Anchorage, Alaska, building during four significant earthquakes that occurred in 2002 are studied. Two earthquakes, including the 3 November 2002 M7.9 Denali fault earthquake, with epicenters approximately 275 km from the building, generated long trains of long-period (>1 s) surface waves. The other two smaller earthquakes occurred at subcrustal depths practically beneath Anchorage and produced higher frequency motions. These two pairs of earthquakes have different impacts on the response of the building. Higher modes are more pronounced in the building response during the smaller nearby events. The building responses indicate that the close-coupling of translational and torsional modes causes a significant beating effect. It is also possible that there is some resonance occurring due to the site frequency being close to the structural frequency. Identification of dynamic characteristics and behavior of buildings can provide important lessons for future earthquake-resistant designs and retrofit of existing buildings. ?? 2004, Earthquake Engineering Research Institute.
Tan, Y. J.; Tolstoy, M.
Significant tidal triggering of earthquakes has been observed precursory to the Tohoku and Sumatra megathrust earthquakes (Tanaka 2010; 2012). The appearance of high correlation between tidally-induced stresses and earthquake occurrence frequency several to ten years before these megathrust earthquakes suggests that such statistical analysis could be useful in improving forecasting of future subduction zone earthquakes. Using this statistical method, we analyzed the Alaska-Aleutian subduction zone which has been known to produce devastating tsunamigenic earthquakes, and specifically the Semidi Segment that is probably late in its earthquake cycle (Davies et. al. 1981). Our study aims to understand if significant tidal triggering of earthquakes were present precursory to historical great earthquakes in this region. We also aim to understand if any segment along the subduction zone is currently displaying statistically significant tidal triggering of earthquakes and whether such observations are indicative of the stress state of the segment. Finally, we test if the strength of tidal triggering captured by this statistical method is sensitive to the tidal stress azimuth used. Such sensitivity could be indicative of the predominant fault slip direction in the specific segment.
von Huene, Roland; Miller, John J.; Weinrebe, Wilhelm
Three destructive earthquakes along the Alaska subduction zone sourced transoceanic tsunamis during the past 70 years. Since it is reasoned that past rupture areas might again source tsunamis in the future, we studied potential asperities and barriers in the subduction zone by examining Quaternary Gulf of Alaska plate history, geophysical data, and morphology. We relate the aftershock areas to subducting lower plate relief and dissimilar materials in the seismogenic zone in the 1964 Kodiak and adjacent 1938 Semidi Islands earthquake segments. In the 1946 Unimak earthquake segment, the exposed lower plate seafloor lacks major relief that might organize great earthquake rupture. However, the upper plate contains a deep transverse-trending basin and basement ridges associated with the Eocene continental Alaska convergent margin transition to the Aleutian island arc. These upper plate features are sufficiently large to have affected rupture propagation. In addition, massive slope failure in the Unimak area may explain the local 42-m-high 1946 tsunami runup. Although Quaternary geologic and tectonic processes included accretion to form a frontal prism, the study of seismic images, samples, and continental slope physiography shows a previous history of tectonic erosion. Implied asperities and barriers in the seismogenic zone could organize future great earthquake rupture.
Witter, R. C.; Zhang, Y. J.; Wang, K.; Priest, G. R.; Goldfinger, C.; Stimely, L. L.
We develop 15 full-margin rupture models for Cascadia subduction zone earthquakes that define vertical seafloor deformation used to simulate tsunami inundation at Bandon, Oregon. We consider rupture models that include slip partitioned to a splay fault in the accretionary wedge and models that vary the updip limit of slip on the megathrust. The design of coseismic slip models is based on the interpretation of paleoseismic and paleotsunami data, especially turbidite records offshore and a tsunami deposit sequence at Bradley Lake in southern Oregon. Alternative scenarios are evaluated using a logic tree that ranks model consistency with geophysical and geological data. The hydrodynamic computer model, SELFE, is used to simulate tsunami generation, propagation and inundation for the 15 Cascadia earthquake sources and two Alaska earthquake sources: the 1964 Mw 9.2 Prince William Sound earthquake and a maximum hypothetical earthquake beneath the Gulf of Alaska. Results describe levels of confidence (in percent) that a Cascadia tsunami will not exceed simulated wave runup. Maximum Cascadia tsunami wave elevations at the shoreline vary between ˜4 and ˜25 m above the model tide (mean higher high water) for earthquakes with 9 to 44 m slip and moment magnitude (Mw) 8.7 to 9.2. The simulated inundation for all Cascadia scenarios is consistent with minimum constraints from the spatial extent of deposits left by the AD 1700 Cascadia tsunami and older predecessors. Simulations of the 1964 Alaska tsunami agree with limited historical observations of wave heights and runup in Bandon. We recommend using the maximum Cascadia tsunami scenario and the maximum Alaska tsunami scenario for delineating evacuation zones for the Oregon coast. The tsunami scenario most consistent with paleoseismic data or the larger splay fault scenario, which encompass ~80 to 95 percent of the hazard, should be considered for land use planning and future revisions to building codes along the coast.
... Bureau of Ocean Energy Management Information Collection: Southern Alaska Sharing Network and Subsistence... in Alaska, ``Southern Alaska Sharing Network and Subsistence Study.'' DATES: Submit written comments.... Title: Southern Alaska Sharing Network and Subsistence Study. Abstract: The Bureau of Ocean...
Lahr, John C.; Plafker, George; Stephens, C.D.; Foglean, K.A.; Blackford, M.E.
On 28 February 1979 an earthquake with surface wave magnitude (Ms) of 7.7 (W. Person, personal communication, 1979) occurred beneath the Chugach and St. Elias mountains of southern Alaska (fig. 1). This is a region of complex tectonics resulting from northwestward convergence between the Pacific and North American plates. To the east, the northwest-trending Fairweather fault accommodates the movement with dextral slip of about 5.5 cm/yr (Plafker, Hudson, and others, 1978); to the west, the Pacific plate underthrusts Alaska at the Aleutian trench, which trends southwestward (Plafker 1969). The USGS has operated a telemetered seismic network in southern Alaska since 1971 and it was greatly expanded along the eastern Gulf of Alaska in September 1974. The current configuration of stations is shown in Figure 9. Technical details of the network are available in published earthquake catalogs (Lahr, Page, and others, 1974; Fogleman, Stephens, and others, 1978). Preliminary analysis of the data from this network covering the time period September 1, 1978 through March 10, 1979, as well as worldwide data for the main shock will be discussed in this paper.
Cohen, Steven C.; Freymueller, Jeffrey T.
This article, for Advances in Geophysics, is a summary of crustal deformation studies in southcentral Alaska. In 1964, southcentral Alaska was struck by the largest earthquake (moment magnitude 9.2) occurring in historical times in North America and the second largest earthquake occurring in the world during the past century. Conventional and space-based geodetic measurements have revealed a complex temporal-spatial pattern of crustal movement. Numerical models suggest that ongoing convergence between the North America and Pacific Plates, viscoelastic rebound, aseismic creep along the tectonic plate interface, and variable plate coupling all play important roles in controlling both the surface and subsurface movements. The geodetic data sets include tide-gauge observations that in some cases provide records back to the decades preceding the earthquake, leveling data that span a few decades around the earthquake, VLBI data from the late 1980s, and GPS data since the mid-1990s. Geologic data provide additional estimates of vertical movements and a chronology of large seismic events. Some of the important features that are revealed by the ensemble of studies that are reviewed in this paper include: (1) Crustal uplift in the region that subsided by up 2 m at the time of the earthquake is as much as 1 m since the earthquake. In the Turnagain Arm and Kenai Peninsula regions of southcentral Alaska, uplift rates in the immediate aftermath of the earthquake reached 150 mm/yr , but this rapid uplift decayed rapidly after the first few years following the earthquake. (2) At some other locales, notably those away the middle of the coseismic rupture zone, postseismic uplift rates were initially slower but the rates decay over a longer time interval. At Kodiak Island, for example, the uplift rates have been decreasing at a rate of about 7mm/yr per decade. At yet other locations, the uplift rates have shown little time dependence so far, but are thought not to be sustainable
Haeussler, P. J.; Witter, R. C.; Liberty, L. M.; Brothers, D. S.; Briggs, R. W.; Armstrong, P. A.; Freymueller, J. T.; Parsons, T.; Ryan, H. F.; Lee, H. J.; Roland, E. C.
Earthquakes and tsunamis are the principal geohazards of southern Alaska. The entire margin has ruptured in megathrust earthquakes, including the M9.2 1964 event, and these earthquakes have launched deadly local and trans-Pacific tsunamis. Tsunamis have been by far the largest killer in these earthquakes. Moreover, the subduction zone displays a range in locking behavior from completely locked beneath Prince William Sound, to nearly freely slipping beneath the Shumagin Islands. Characterizing earthquake-related tsunami sources requires a diverse set of methods, and we discuss several examples. One important source for tsunamis is from megathrust splay faults. The Patton Bay splay fault system ruptured during the 1964 earthquake and generated a tsunami that impacted coastlines tens of minutes after the earthquake. A combination of multibeam mapping, high-resolution and crustal-scale seismic data, thermochronology, and detrital zircon geochronology show focused exhumation along this splay fault system for the last 2-3 Ma. Moreover, this long term pattern of exhumation mimics the pattern of uplift in 1964. Submarine landslides are another example of a tsunami source. Numerous devastating slides were triggered by the 1964 earthquake. Multibeam bathymetry, bathymetry difference maps, high-resolution seismic data, and records of paleotsunamis in coastal marshes reveal a long history of submarine landsliding in the coastal fjords of Alaska. The Little Ice Age appears to have had a significant influence on the submarine landslides in the 1964 earthquake through increased sediment production, transport to fjord margins, and, locally, compaction by glacier advances. Glacial retreat before 1964 gave rise to over-steepened slopes susceptible to dynamic failure. Numerous blocks in the submarine landslides were particularly effective in generating high tsunami run up. Finally, regional tectonic displacements of the seafloor have launched trans-Pacific tsunamis. Coastal
Liberty, L. M.; Haeussler, P. J.; Moeller, M.
Using tsunami run up, seismic reflection and bathymetric data, we identify tsunamigenic sea floor ruptures that resulted from the 1964 Great Alaska earthquake. These sea floor lineaments are rooted in megathrust splay faults that appear across the 500-km wide Gulf of Alaska continental shelf. Based on estimated tsunami travel times, we identify two splay faults that produced 5-10 m wave heights in the coastal town of Seward and remote settlements along the Kenai Peninsula. These faults splay from the megathrust along the trailing edge of the subducted Yakutat terrane that is sandwiched between the Pacific and North American plates. Duplexing along the megathrust likely transferred lateral motion along the decollement to vertical splay fault motion that resulted in multi-meter sea floor uplifts. We identify the Cape Cleare fault as the source of the earliest tsunami arrival for Seward, Puget Bay and Whidbey Bay. Sparker seismic data, pre- and post-earthquake bathymetry and crustal seismic data characterize the along-strike Holocene motion on this 70-km long fault that parallels the Patton Bay fault that ruptured on nearby Montague Island. We define a strand of the Middleton Island fault system as the source of the second arrival in Puget and Whidbey Bays and the earliest tsunami source on Middleton Island and other sites in the eastern Gulf of Alaska. Sea floor displacements of more than 20 m suggest both of these faults have repeatedly ruptured during Holocene earthquakes. Additionally, we identify a series of active thrust faults along the length of the Gulf of Alaska to Kodiak Island that likely initiated tsunami waves from smaller sea floor displacements. Sea floor offsets and splay faults that are mapped along the length of the continental shelf suggest Holocene coseismic rupture patterns are not reflected in interseismic GPS measurements along the Kenai Peninsula, but are consistent with seismic, tsunami, and geodetic measurements from the 1964 earthquake
Lee, H. J.; Ryan, H. F.; Suleimani, E.; Haeussler, P. A.; Kayen, R. E.; Hampton, M. A.
The M9.2 Alaska earthquake of 1964 caused major damage to the port facilities and town of Valdez, resulting in a total of 32 deaths. Most of the damage and deaths in Valdez were caused by submarine-landslide generated tsunamis that occurred immediately after the earthquake. Some post-earthquake investigations were conducted in the 1960's. Dramatic changes in bathymetry were observed, including several hundred meters of deepening below the head of Port Valdez fjord, and these were attributed to submarine landsliding. Recent multibeam surveys of Port Valdez provide much more information about the morphology of landslide deposits. Also, we collected high-resolution (chirp) surveys over apparent landslide debris to evaluate the chronology and three-dimensional character of the deposits, and we performed quantitative evaluations of pre- and post-earthquake bathymetric data. Landslide morphologies include several forms. In the western part of the fjord, there is a field of large blocks (up to 40-m high) on the fjord floor near the location of the greatest tsunami-wave runup estimated for the 1964 earthquake (~50 m). The runup direction for the waves (northeast) is consistent with the failure of these blocks being the trigger. Surrounding the fields of blocks are lobes from two debris flows that likely occurred at the same time as the block slides. Both debris flows and block slides appear to have resulted from the failure of a large moraine front, formed by Shoup Glacier on the northwest side of Port Valdez. At the fjord head, near the location of the badly damaged old town of Valdez, is an intricate series of gullies, channels, and talus, although these features display little evidence for the large-scale mass movement that occurred. However, near the center of the fjord is the front of a large debris lobe that flowed from the east end of the fjord half-way down the fjord and stopped. This huge deposit represents material that failed at the fjord head, mobilized into a
Lee, H.; Ryan, H.F.; Suleimani, E.; Kayen, R.E.; Hampton, M.A.
The M9.2 Alaska earthquake of 1964caused major damage to the port facilities and town of Valdez, resulting in a total of 32 deaths. Most of the damage and deaths in Valdez were caused by submarine-landslide generated tsunamis that occurred immediately after the earthquake. Some post-earthquake investigations were conducted in the 1960's. Dramatic changes in bathymetry were observed, including several hundred meters of deepening below the head of Port Valdezfjord, and these were attributed to submarine landsliding. Recent multibeam surveys of Port Valdez provide much more information about the morphology of landslide deposits. Also, we collected high-resolution (chirp) surveys over apparent landslide debris to evaluate the chronology and three-dimensional character of the deposits, and we performed quantitative evaluations of pre- and post-earthquake bathymetric data. Landslide morphologies include several forms. In the western part of the fjord, there is a field of large blocks (up to 40-m high) on the fjord floor near the location of the greatest tsunami-wave runup estimated for the 1964 earthquake (~50 m). The runup direction for the waves (northeast) is consistent with the failure of these blocks being the trigger. Surrounding the fields of blocks are lobes from two debris flows that likely occurred at the same time as the block slides. Both debris flows and block slides appear to have resulted from the failure of a large moraine front, formed by Shoup Glacier on the northwest side of Port Valdez. At the fjord head, near the location of the badly damaged old town of Valdez, is an intricate series of gullies, channels, and talus, although these features display little evidence for the large-scale mass movement that occurred. However, near the center of the fjord is the front of a large debris lobe that flowed from the east end of the fjord half-way down the fjord and stopped. This huge deposit represents material that failed at the fjord head
Sauber, Jeanne M.
The glaciers of southern Alaska are extensive, and many of them have undergone gigatons of ice wastage on time scales on the order of the seismic cycle. Since the ice loss occurs directly above a shallow main thrust zone associated with subduction of the Pacific-Yakutat plate beneath continental Alaska, the region between the Malaspina and Bering Glaciers is an excellent test site for evaluating the importance of recent ice wastage on earthquake faulting potential. We demonstrate the influence of cumulative glacial mass loss following the 1899 Yakataga earthquake (M=8.1) by using a two dimensional finite element model with a simple representation of ice fluctuations to calculate the incremental stresses and change in the fault stability margin (FSM) along the main thrust zone (MTZ) and on the surface. Along the MTZ, our results indicate a decrease in FSM between 1899 and the 1979 St. Elias earthquake (M=7.4) of 0.2 - 1.2 MPa over an 80 km region between the coast and the 1979 aftershock zone; at the surface, the estimated FSM was larger but more localized to the lower reaches of glacial ablation zones. The ice-induced stresses were large enough, in theory, to promote the occurrence of shallow thrust earthquakes. To empirically test the influence of short-term ice fluctuations on fault stability, we compared the seismic rate from a reference background time period (1988-1992) against other time periods (1993-2006) with variable ice or tectonic change characteristics. We found that the frequency of small tectonic events in the Icy Bay region increased in 2002-2006 relative to the background seismic rate. We hypothesize that this was due to a significant increase in the rate of ice wastage in 2002-2006 instead of the M=7.9, 2002 Denali earthquake, located more than 100km away.
The great earthquake that struck Alaska about 5:36 p.m., Alaska standard time, Friday, March 27, 1964 (03:36:1.3.0, Greenwich mean time, March 28, 1964), severely crippled the highway system in the south-central part of the State. All the major highways and most secondary roads were impaired. Damage totaled more than $46 million, well over $25 million to bridges and nearly $21 million to roadways. Of the 204 bridges in south-central Alaska, 141 were damaged; 92 were severely damaged or destroyed. The earthquake damaged 186 of the 830 miles of roadway in south-central Alaska, 83 miles so severely that replacement or relocation was required. Earthquake damage to the roadways and bridges was chiefly by (1) seismic shaking, (2) compaction of fills as well as the underlying sediments, (3) lateral displacement of the roadway and bridges, (4) fractures, (5) landslides, (6) avalanches, (7) inundation by seismic sea waves, (8) scouring by seismic sea waves, (9) regional tectonic subsidence, causing inundation and erosion by high tides in subsided areas. The intensity of damage was controlled primarily by the geologic environment (including the depth of the water table) upon which the highway structures rested, and secondarily by the engineering characteristics of the structures. Structures on bedrock were only slightly damaged if at all, whereas those on unconsolidated sediments were slightly to severely damaged, or were completely destroyed by seismic shaking. The low-lying areas underlain by saturated sediments, such as the Snow River Crossing and Turnagain Arm sections of the Seward-Anchorage Highway, were the most severely damaged stretches of the highway system in south-central Alaska. At Snow River and Turnagain Arm, the sediments underlying the roadway are fine grained and the water table is shallow. These factors were responsible for the intense damage along this stretch of the highway. All the bridges on the Copper River Highway except for one on bedrock were
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Gorum, Tolga; Korup, Oliver; van Westen, Cees J.; van der Meijde, Mark; Xu, Chong; van der Meer, Freek D.
The 2002 Mw 7.9 Denali Fault earthquake, Alaska, provides an unparalleled opportunity to investigate in quantitative detail the regional hillslope mass-wasting response to strong seismic shaking in glacierized terrain. We present the first detailed inventory of ∼1580 coseismic slope failures, out of which some 20% occurred above large valley glaciers, based on mapping from multi-temporal remote sensing data. We find that the Denali earthquake produced at least one order of magnitude fewer landslides in a much narrower corridor along the fault ruptures than empirical predictions for an M ∼8 earthquake would suggest, despite the availability of sufficiently steep and dissected mountainous topography prone to frequent slope failure. In order to explore potential controls on the reduced extent of regional coseismic landsliding we compare our data with inventories that we compiled for two recent earthquakes in periglacial and formerly glaciated terrain, i.e. at Yushu, Tibet (Mw 6.9, 2010), and Aysén Fjord, Chile (2007 Mw 6.2). Fault movement during these events was, similarly to that of the Denali earthquake, dominated by strike-slip offsets along near-vertical faults. Our comparison returns very similar coseismic landslide patterns that are consistent with the idea that fault type, geometry, and dynamic rupture process rather than widespread glacier cover were among the first-order controls on regional hillslope erosional response in these earthquakes. We conclude that estimating the amount of coseismic hillslope sediment input to the sediment cascade from earthquake magnitude alone remains highly problematic, particularly if glacierized terrain is involved.
Dixon, James P.; Power, John A.
On January 8, 2006, a swarm of volcanic-tectonic earthquakes began beneath Mount Martin at the southern end of the Katmai volcanic cluster. This was the first recorded swarm at Mount Martin since continuous seismic monitoring began in 1996. The number of located earthquakes increased during the next four days, reaching a peak on January 11. For the next two days, the seismic activity decreased, and on January 14, the number of events increased to twice the previous day's total. Following this increase in activity, seismicity declined, returning to background levels by the end of the month. The Alaska Volcano Observatory located 860 earthquakes near Mount Martin during January 2006. No additional signs of volcanic unrest were noted in association with this earthquake swarm. The earthquakes in the Mount Martin swarm, relocated using the double difference technique, formed an elongated cluster dipping to the southwest. Focal mechanisms beneath Mount Martin show a mix of normal, thrust, and strike-slip solutions, with normal focal mechanisms dominating. For earthquakes more than 1 km from Mount Martin, all focal mechanisms showed normal faulting. The calculated b-value for the Mount Martin swarm is 0.98 and showed no significant change before, during, or after the swarm. The triggering mechanism for the Mount Martin swarm is unknown. The time-history of earthquake occurrence is indicative of a volcanic cause; however, there were no low-frequency events or observations, such as increased steaming associated with the swarm. During the swarm, there was no change in the b-value, and the distribution and type of focal mechanisms were similar to those in the period before the anomalous activity. The short duration of the swarm, the similarity in observed focal mechanisms, and the lack of additional signs of unrest suggest this swarm did not result from a large influx of magma within the shallow crust beneath Mount Martin.
Ferrians, Oscar J., Jr.
The Copper River Basin area is in south-central Alaska and covers 17,800 square miles. It includes most of the Copper River Basin and parts of the surrounding Alaska Range and the Talkeetna, Chugach, and Wrangell Mountains. On March 27, 1964, shortly after 5:36 p.m. Alaska standard time, a great earthquake having a Richter magnitude of about 8.5 struck south-central Alaska. Computations by the U.S. Coast and Geodetic Survey place the epicenter of the main shock at lat 61.1° N. and long 147.7° W., and the hypocenter, or actual point of origin, from 20 to 50 kilometers below the surface. The epicenter is near the western shore of Unakwik Inlet in northern Prince William Sound; it is 30 miles from the closest point within the area of study and 180 miles from the farthest point. Releveling data obtained in 1964 after the earthquake indicates that broad areas of south-central Alaska were warped by uplift and subsidence. The configuration of these areas generally parallels the trend of the major tectonic elements of the region. Presumably a large part of this change took place during and immediately after the 1964 earthquake. The water level in several wells in the area lowered appreciably, and the water in many became turbid; generally, however, within a few days after the earthquake the water level returned to normal and the suspended sediment settled out. Newspaper reports that the Copper River was completely dammed and Tazlina Lake drained proved erroneous. The ice on most lakes was cracked, especially around the margins of the lakes where floating ice broke free from the ice frozen to the shore. Ice on Tazlina, Klutina, and Tonsina Lakes was intensely fractured by waves generated by sublacustrine landslides off the fronts of deltas. These waves stranded large blocks of ice above water level along the shores. River ice was generally cracked in the southern half of the area and was locally cracked in the northern half. In the area of study, the majority of the
Cohen, Steven; Holdahl, Sandford; Caprette, Douglas; Hilla, Stephen; Safford, Robert; Schultz, Donald
Using Global Positioning System (GPS) receivers, we reoccupied several leveling benchmarks on the Kenai Peninsula of Alaska which had been surveyed by conventional leveling immediately following the March 27, 1964, Prince William Sound earthquake (M(sub w) = 9.3). By combining the two sets of measurements with a new, high-resolution model of the geoid in the region, we were able to determine the cumulative 1993-1964 postseismic vertical displacement. We find uplift at all of our benchmarks, relative to Seward, Alaska, a point that is stable according to tide gauge data. The maximum uplift of about 1 m occurs near the middle of the peninsula. The region of maximum uplift appears to be shifted northwest relative to the point of maximum coseismic subsidence. If we use tide gauge data at Nikishka and Seward to constrain the vertical motion, then the observed uplift has a trenchward tilt (down to the southeast) as well as an arching component. To explain the observations, we use creep-at-depth models. Most acceptable models require a fault slip of about 2.75 m, although this result is not unique. If the slip has been continuous since the 1964 earthquake, then the average slip rate is nearly 100 mm/yr, twice the plate convergence rate. Comparing the net uplift achieved in 29 years with that observed over 11 years in an adjacent region southeast of Anchorage, Alaska, we conclude that the rate of uplift is decreasing. A further decrease in the uplift rate is expected as the 29-year averaged displacement rate is about twice the plate convergence rate and therefore cannot be sustained over the entire earthquake cycle.
Stanley, Kirk W.
Some 10,000 miles of shoreline in south-central Alaska was affected by the subsidence or uplift associated with the great Alaska earthquake of March 27, 1964. The changes in shoreline processes and beach morphology that were suddenly initiated by the earthquake were similar to those ordinarily caused by gradual changes in sea level operating over hundreds of years, while other more readily visible changes were similar to some of the effects of great but short-lived storms. Phenomena became available for observation within a few hours which would otherwise not have been available for many years. In the subsided areas—including the shorelines of the Kenai Peninsula, Kodiak Island, and Cook Inlet—beaches tended to flatten in gradient and to recede shoreward. Minor beach features were altered or destroyed on submergence but began to reappear and to stabilize in their normal shapes within a few months after the earthquake. Frontal beach ridges migrated shoreward and grew higher and wider than they were before. Along narrow beaches backed by bluffs, the relatively higher sea level led to vigorous erosion of the bluff toes. Stream mouths were drowned and some were altered by seismic sea waves, but they adjusted within a few months to the new conditions. In the uplifted areas, generally around Prince William Sound, virtually all beaches were stranded out of reach of the sea. New beaches are gradually developing to fit new sea levels, but the processes are slow, in part because the material on the lower parts of the old beaches is predominantly fine grained. Streams were lengthened in the emergent areas, and down cutting and bank erosion have increased. Except at Homer and a few small villages, where groins, bulkheads, and cobble-filled baskets were installed, there has been little attempt to protect the postearthquake shorelines. The few structures that were built have been only partially successful because there was too little time to study the habits of the new shore
Argus, Donald F.; Lyzenga, Gregory A.
We use geodetic data from Very Long Baseline Interferometry (VLBI) to determine the pre- and postseismic velocities of two sites. We then place limits on variations in interseismic strain buildup. The 1987 and 1988 Gulf of Alaska earthquakes (each Ms = 7.6) broke the Pacific plate interior. During the earthquakes the Cape Yakataga site moved 78 mm toward southwest. During the 1989 Loma Prieta earthquake (Ms = 7.1) the Fort Ord site moved 48 mm toward north. Baselines (a) from Fairbanks to Cape Yakataga and (b) from Mojave to Fort Ord change at nearly the same rate before and after the earthquakes. Postseismic transients, which we determine from differences between post- and preseismic rates, are minor: at Cape Yakataga the transient is 3 +/- 4 mm in a postseismic interval of 23 months, and at Fort Ord the transient is 6 +/- 5 mm in 21 months. The slip beneath the Loma Prieta rupture needed to generate the Fort Ord transient is 0.22 +/- 0.19 m, one-tenth the coseismic slip (2 m). We analyze elastic lithosphere-viscous asthenosphere models to determine that the characteristic time describing exponential decay in deep fault slip is longer than 6 years. The VLBI measurements are consistent with uniform interseismic strain buildup. They disagree with fast postseismic rates caused by an asthenosphere with very low viscosity.
Haeussler, P.J.; Lee, H.J.; Ryan, H.F.; Labay, K.; Kayen, R.E.; Hampton, M.A.; Suleimani, E.
Following the 1964 M9.2 megathrust earthquake in southern Alaska, Seward was the only town hit by tsunamis generated from both submarine landslides and tectonic sources. Within 45 seconds of the start of the earthquake, a 1.2-km-long section of waterfront began sliding seaward, and soon after, ~6-8-m high waves inundated the town. Studies soon after the earthquake concluded that submarine landslides along the Seward waterfront generated the tsunamis that occurred immediately after the earthquake. We analyze pre- and post-earthquake bathymetry data to assess the location and extent of submarine mass failures and sediment transport. New NOAA multibeam bathymetry shows the morphology of the entire fjord at 15 m resolution. We also assembled all older soundings from smooth sheets for comparison to the multibeam dataset. We gridded the sounding data, applied corrections for coseismic subsidence, post-seismic rebound, unrecovered co-seismic subsidence, sea-level rise (vertical datum shift), and measurement errors. The difference grids show changes resulting from the 1964 earthquake. We estimate the total volume of slide material to be about 211 million m3. Most of this material was transported to a deep, flat area, which we refer to as “the bathtub”, about 6 to 13 km south of Seward. Sub-bottom profiling of the bathtub shows an acoustically transparent unit, which we interpret as a sediment flow deposit resulting from the submarine landslides. The scale of the submarine landslides and the distance over which sediment was transported is much larger than previously appreciated.
Kilgore, W.; Roman, D. C.; Power, J. A.; Hansen, R. A.; Biggs, J.
Microearthquake (< M3.0) swarms occur frequently in volcanic environments, but do not always culminate in an eruption. Such non-eruptive swarms may be caused by stresses induced by magma intrusion, hydrothermal fluid circulation, or regional tectonic processes, such as slow-slip earthquakes. Strandline Lake, located 30 km northeast of Mount Spurr volcano in south-central Alaska, experienced a strong earthquake swarm between August 1996 and August 1998. The Alaska Volcano Observatory (AVO) catalog indicates that a total of 2,999 earthquakes were detected during the swarm period, with a maximum magnitude of Mw 3.1 and a depth range of 0-30 km below sea level (with the majority of catalog hypocenters located between 5-10 km BSL). The cumulative seismic moment of the swarm was 2.03e15 N m, equivalent to a cumulative magnitude of Mw 4.2. Because of the swarm's distance from the nearest Holocene volcanic vent, seismic monitoring was poor and gas and deformation data for the swarm period do not exist. However, combined waveforms from a dense seismic network on Mount Spurr and from several regional seismic stations allowed us to re-analyze the swarm earthquakes. We first developed a new 1-D velocity model for the Strandline Lake region by re-picking and inverting precise arrival times for 27 large Strandline Lake earthquakes. The new velocity model reduced the average RMS for these earthquakes from 0.16 to 0.11s, and the average horizontal and vertical location errors from 3.3 to 2.5 km and 4.7 to 3.0 km, respectively. Depths of the 27 earthquakes ranged from 10.5 to 22.1 km with an average depth of 16.6 km. A moderately high b-value of 1.33 was determined for the swarm period, possibly indicative of magmatic activity. However, a similarly high b-value of 1.25 was calculated for the background period. 28 well-constrained fault plane solutions for both swarm and background earthquakes indicate a diverse mixture of strike-slip, dip-slip, and reverse faulting beneath
Fogleman, Kent A.; Lahr, John C.; Stephens, Christopher D.; Page, Robert A.
This report describes the instrumentation and evolution of the U.S. Geological Survey's regional seismograph network in southern Alaska, provides phase and hypocenter data for seismic events from October 1971 through May 1989, reviews the location methods used, and discusses the completeness of the catalog and the accuracy of the computed hypocenters. Included are arrival time data for explosions detonated under the Trans-Alaska Crustal Transect (TACT) in 1984 and 1985. The U.S. Geological Survey (USGS) operated a regional network of seismographs in southern Alaska from 1971 to the mid 1990s. The principal purpose of this network was to record seismic data to be used to precisely locate earthquakes in the seismic zones of southern Alaska, delineate seismically active faults, assess seismic risks, document potential premonitory earthquake phenomena, investigate current tectonic deformation, and study the structure and physical properties of the crust and upper mantle. A task fundamental to all of these goals was the routine cataloging of parameters for earthquakes located within and adjacent to the seismograph network. The initial network of 10 stations, 7 around Cook Inlet and 3 near Valdez, was installed in 1971. In subsequent summers additions or modifications to the network were made. By the fall of 1973, 26 stations extended from western Cook Inlet to eastern Prince William Sound, and 4 stations were located to the east between Cordova and Yakutat. A year later 20 additional stations were installed. Thirteen of these were placed along the eastern Gulf of Alaska with support from the National Oceanic and Atmospheric Administration (NOAA) under the Outer Continental Shelf Environmental Assessment Program to investigate the seismicity of the outer continental shelf, a region of interest for oil exploration. Since then the region covered by the network remained relatively fixed while efforts were made to make the stations more reliable through improved electronic
Power, John A.; March, Gail D.; Lahr, John C.; Jolly, Arthur D.; Cruse, Gina R.
Following a 23 year period of quiescence, Redoubt Volcano erupted between December 14,1989 and April 21,1990. The eruption was accompanied by thousands of earthquakes (Alaska Volcano Observatory Staff, 1990). Throughout the eruption sequence, data from the PC/AT system provided the primary means of determining earthquake hypocenters. This report catalogs the earthquake hypocenters and magnitudes calculated from data collected between October 12, 1989 and December 31, 1990 on the PC/AT acquisition system, provides station locations, statistics, and calibrations, and outlines which stations were recorded and used in triggering the PC/AT system.
Roland, E. C.; Gulick, S. P.; Levoir, M. A.; Haeussler, P. J.
We present initial results from a rapid-response ocean bottom seismometer (OBS) deployment that recorded aftershock activity on the Queen Charlotte-Fairweather (QC-F) fault following the Mw 7.5 earthquake on January 5th 2013 near Craig, Alaska. This earthquake was the second of two Mw > 7 events on this fault system in a 3 month time period; the Craig earthquake followed a Mw 7.8 thrust event that occurred in October 2012, west of Haida Gwaii, British Columbia. Although the QC-F is a major plate boundary fault, little is known about the regional fault structure, interseismic coupling, and rheological controls on the depth distribution of seismic slip along the continent-ocean transform. The majority of the QC-F fault system extends offshore western British Columbia and southeast Alaska, making it difficult to characterize earthquakes and fault deformation with land-based seismic and geodetic instruments. This experiment is the first ever offshore seismometer deployment to record earthquake activity along this northern segment of the QC-F system, and was set in motion with help from the US Coast Guard, who provided a vessel and crew to deploy and recover the OBS array on short notice. The seismic array utilized 6 GeoPro short period OBS from the University of Texas Institute for Geophysics, which recorded approximately 3 weeks of aftershock activity in April-May of 2013. Combining high-quality local OBS recordings with land-based seismic observations from Alaska Earthquake Information Center (AEIC) stations to the east, we present more precise aftershock locations and depths that help to better characterize fault zone architecture along the northern section of the QC-F. Although moment tensor solutions indicate that the January 5th mainshock sustained slip consistent with Pacific-North America plate motions, aftershock focal mechanisms indicate some interaction with neighboring faults, such as the Chatham Straight fault. This new OBS dataset will also help to
Johnson, K. M.; Burgmann, R.; Freymueller, J.
We investigate the processes of postseismic deformation following the 2002 Denali Fault, Alaska earthquake using 4.5 years of continuous and campaign GPS data. Afterslip is modeled on a fault in an elastic lithosphere overlying a Maxwell (linear) viscoelastic asthenosphere. We assume afterslip is governed by a nonlinear velocity- strengthening friction law. Postseismic GPS time-series are best explained by a combination of two mechanisms: viscous flow in the lower crust and upper mantle with viscosity of about 1019 Pa s, and afterslip on the fault above 30-40 km depth. Models with afterslip only (no distributed viscous flow) underestimate displacements at sites more than 100 km from the fault. The rate-state frictional parameter a-b, is estimated to be in the range 10-3-10-2, consistent experimental values for granite at conditions near the transition from velocity weakening to velocity strengthening. It has been suggested previously that nonlinear rheology of the upper mantle is necessary to explain the observed evolution of surface displacement rates with time. However, the displacement rates at continuous GPS sites are reproduced remarkably well by our model with afterslip in a fault zone with nonlinear rheology and a linear viscous upper mantle. The Denali earthquake may have caused increased locking at the interface of the subducting Pacific plate south of the Denali Fault. Northeast directed horizontal surface velocities at GPS sites over 100 km south of the Denali fault increased following the earthquake. The magnitude of the acceleration at these sites in southern Alaska cannot be explained with our simple models of postseismic deformation associated with afterslip and viscous flow directly below the Denali fault. The Denali earthquake reduced the reverse-sense of shear stress on the subduction interface, promoting increased coupling on the interface. Simple spring-slider models with rate-state friction confirm the possibility of increased coupling of the
Jordan, T. H.; Scec/Itr Collaboration
The Southern California Earthquake Center (SCEC), in collaboration with the San Diego Supercomputer Center, the USC Information Sciences Institute,IRIS, and the USGS, has received a large five-year grant from the NSF's ITR Program and its Geosciences Directorate to build a new information infrastructure for earthquake science. In many respects, the SCEC/ITR Project presents a microcosm of the IT efforts now being organized across the geoscience community, including the EarthScope initiative. The purpose of this presentation is to discuss the experience gained by the project thus far and lay out the challenges that lie ahead; our hope is to encourage cross-discipline collaboration in future IT advancements. Project goals have been formulated in terms of four "computational pathways" related to seismic hazard analysis (SHA). For example, Pathway 1 involves the construction of an open-source, object-oriented, and web-enabled framework for SHA computations that can incorporate a variety of earthquake forecast models, intensity-measure relationships, and site-response models, while Pathway 2 aims to utilize the predictive power of wavefield simulation in modeling time-dependent ground motion for scenario earthquakes and constructing intensity-measure relationships. The overall goal is to create a SCEC "community modeling environment" or collaboratory that will comprise the curated (on-line, documented, maintained) resources needed by researchers to develop and use these four computational pathways. Current activities include (1) the development and verification of the computational modules, (2) the standardization of data structures and interfaces needed for syntactic interoperability, (3) the development of knowledge representation and management tools, (4) the construction SCEC computational and data grid testbeds, and (5) the creation of user interfaces for knowledge-acquisition, code execution, and visualization. I will emphasize the increasing role of standardized
Johnson, Jessica H.; Prejean, Stephanie; Savage, Martha K.; Townend, John
We use shear wave splitting (SWS) analysis and double-difference relocation to examine temporal variations in seismic properties prior to and accompanying magmatic activity associated with the 2008 eruption of Okmok volcano, Alaska. Using bispectrum cross-correlation, a multiplet of 25 earthquakes is identified spanning five years leading up to the eruption, each event having first motions compatible with a normal fault striking NE–SW. Cross-correlation differential times are used to relocate earthquakes occurring between January 2003 and February 2009. The bulk of the seismicity prior to the onset of the eruption on 12 July 2008 occurred southwest of the caldera beneath a geothermal field. Earthquakes associated with the onset of the eruption occurred beneath the northern portion of the caldera and started as deep as 13 km. Subsequent earthquakes occurred predominantly at 3 km depth, coinciding with the depth at which the magma body has been modeled using geodetic data. Automated SWS analysis of the Okmok catalog reveals radial polarization outside the caldera and a northwest-southeast polarization within. We interpret these polarizations in terms of a magma reservoir near the center of the caldera, which we model with a Mogi point source. SWS analysis using the same input processing parameters for each event in the multiplet reveals no temporal changes in anisotropy over the duration of the multiplet, suggesting either a short-term or small increase in stress just before the eruption that was not detected by GPS, or eruption triggering by a mechanism other than a change of stress in the system.
Data from the 2002 Denali fault earthquake recorded at 26 sites in and near Anchorage, Alaska, show a number of systematic features important in studies of site response and in constructing long-period spectra for use in earthquake engineering. The data demonstrate that National Earthquake Hazards Reduction Program (NEHRP) site classes are a useful way of grouping stations according to site amplification. In general, the sites underlain by lower shear-wave velocities have higher amplification. The amplification on NEHRP class D sites exceeds a factor of 2 relative to an average of motions on class C sites. The amplifications are period dependent. They are in rough agreement with those from previous studies, but the new data show that the amplifications extend to at least 10 sec, periods longer than considered in previous studies. At periods longer than about 14 sec, all sites have motion of similar amplitude, and the ground displacements are similar in shape, polarization, and amplitude for all stations. The displacement ground motion is dominated by a series of four pulses, which are associated with the three subevents identified in inversion studies (the first pulse is composed of P waves from the first subevent). Most of the high-frequency ground motion is associated with the S waves from subevent 1. The pulses from subevents 1 and 2, with moment releases corresponding to M 7.1 and 7.0, are similar to the pulse of displacement radiated by the M 7.1 Hector Mine earthquake. The signature from the largest subevent (M 7.6) is more subdued than those from the first two subevents. The two largest pulses produce response spectra with peaks at a period of about 15 sec. The spectral shape at long periods is in good agreement with the recent 2003 NEHRP code spectra but is in poor agreement with the shape obtained from Eurocode 8.
An integrated seismic monitoring system with a total of 53 channels of accelerometers is now operating in and at the nearby free-field site of the 20-story steel-framed Atwood Building in highly seismic Anchorage, Alaska. The building has a single-story basement and a reinforced concrete foundation without piles. The monitoring system comprises a 32-channel structural array and a 21-channel site array. Accelerometers are deployed on 10 levels of the building to assess translational, torsional, and rocking motions, interstory drift (displacement) between selected pairs of adjacent floors, and average drift between floors. The site array, located approximately a city block from the building, comprises seven triaxial accelerometers, one at the surface and six in boreholes ranging in depths from 15 to 200 feet (???5-60 meters). The arrays have already recorded low-amplitude shaking responses of the building and the site caused by numerous earthquakes at distances ranging from tens to a couple of hundred kilometers. Data from an earthquake that occurred 186 km away traces the propagation of waves from the deepest borehole to the roof of the building in approximately 0.5 seconds. Fundamental structural frequencies [0.58 Hz (NS) and 0.47 Hz (EW)], low damping percentages (2-4%), mode coupling, and beating effects are identified. The fundamental site frequency at approximately 1.5 Hz is close to the second modal frequencies (1.83 Hz NS and 1.43 EW) of the building, which may cause resonance of the building. Additional earthquakes prove repeatability of these characteristics; however, stronger shaking may alter these conclusions. ?? 2006, Earthquake Engineering Research Institute.
Gulick, S. S.; LeVoir, M. A.; Haeussler, P. J.; Saustrup, S.
On September 10th the largest of four earthquakes (Mw 8.2) that occurred in southeast Alaska on 1899 produced a 6 m tsunami and may have produced as much as 14 m of co-seismic uplift. This earthquake had an epicenter somewhere near Yakutat or Disenchantment Bays. These bays lie at the transition between the Fairweather Fault (the Pacific-North American strike-slip plate boundary), and the Yakutat Terrane-North American subduction zone. The deformation front of this subduction zone is thought to include the eastern fault in the Pamplona Zone offshore, the Malaspina Fault onshore, and the Esker Creek Fault near Yakutat Bay. The 10 September 1899 event could have taken place on a Yakutat-North American megathrust that daylights in Yakutat or Disenchantment Bay. Alternatively, the 10 September 1899 earthquake could have originated from the Fairweather-Boundary and Yakutat faults, transpressive components of the Fairweather strike-slip system present in the Yakutat Bay region, or from thrusting along the Yakutat and Otemaloi Faults on the southeast flank of Yakutat Bay. Characterizing fault slip during the Alaskan earthquakes of 1899 is vital to assessing both subduction zone structure and seismic hazards in the Yakutat Bay area. Each possible fault model has a different implication for modern hazards. These results will be used to update seismic hazard and fault maps and assess future risk to the Yakutat Bay and surrounding communities. During Aug. 6-17th, we anticipate acquiring high-resolution, marine multichannel seismic data aboard the USGS vessel Alaskan Gyre in Yakutat and Disenchantment Bays to search for evidence of recent faulting and directly test these competing theories for the 10 September 1899 event. This survey uses the University of Texas Institute for Geophysics' mini-GI gun, 24-channel seismic streamer, portable seismic compressor system, and associated gun control and data acquisition system to acquire the data. The profiles have a nominal common
Oglesby, D.D.; Dreger, Douglas S.; Harris, R.A.; Ratchkovski, N.; Hansen, R.
We perform inverse kinematic and forward dynamic models of the M 7.9 2002 Denali fault, Alaska, earthquake to shed light on the rupture process and dynamics of this event, which took place on a geometrically complex fault system in central Alaska. We use a combination of local seismic and Global Positioning System (GPS) data for our kinematic inversion and find that the slip distribution of this event is characterized by three major asperities on the Denali fault. The rupture nucleated on the Susitna Glacier thrust fault, and after a pause, propagated onto the strike-slip Denali fault. Approximately 216 km to the east, the rupture abandoned the Denali fault in favor of the more southwesterly directed Totschunda fault. Three-dimensional dynamic models of this event indicate that the abandonment of the Denali fault for the Totschunda fault can be explained by the Totschunda fault's more favorable orientation with respect to the local stress field. However, a uniform tectonic stress field cannot explain the complex slip pattern in this event. We also find that our dynamic models predict discontinuous rupture from the Denali to Totschunda fault segments. Such discontinuous rupture helps to qualitatively improve our kinematic inverse models. Two principal implications of our study are (1) a combination of inverse and forward modeling can bring insight into earthquake processes that are not possible with either technique alone, and (2) the stress field on geometrically complex fault systems is most likely not due to a uniform tectonic stress field that is resolved onto fault segments of different orientations; rather, other forms of stress heterogeneity must be invoked to explain the observed slip patterns.
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Kirby, Stephen; Scholl, David; von Huene, Roland; Wells, Ray
Tsunami modeling has shown that tsunami sources located along the Alaska Peninsula segment of the Aleutian-Alaska subduction zone have the greatest impacts on southern California shorelines by raising the highest tsunami waves for a given source seismic moment. The most probable sector for a Mw ~ 9 source within this subduction segment is between Kodiak Island and the Shumagin Islands in what we call the Semidi subduction sector; these bounds represent the southwestern limit of the 1964 Mw 9.2 Alaska earthquake rupture and the northeastern edge of the Shumagin sector that recent Global Positioning System (GPS) observations indicate is currently creeping. Geological and geophysical features in the Semidi sector that are thought to be relevant to the potential for large magnitude, long-rupture-runout interplate thrust earthquakes are remarkably similar to those in northeastern Japan, where the destructive Mw 9.1 tsunamigenic earthquake of 11 March 2011 occurred. In this report we propose and justify the selection of a tsunami source seaward of the Alaska Peninsula for use in the Tsunami Scenario that is part of the U.S. Geological Survey (USGS) Science Application for Risk Reduction (SAFRR) Project. This tsunami source should have the potential to raise damaging tsunami waves on the California coast, especially at the ports of Los Angeles and Long Beach. Accordingly, we have summarized and abstracted slip distribution from the source literature on the 2011 event, the best characterized for any subduction earthquake, and applied this synoptic slip distribution to the similar megathrust geometry of the Semidi sector. The resulting slip model has an average slip of 18.6 m and a moment magnitude of Mw = 9.1. The 2011 Tohoku earthquake was not anticipated, despite Japan having the best seismic and geodetic networks in the world and the best historical record in the world over the past 1,500 years. What was lacking was adequate paleogeologic data on prehistoric earthquakes
Bernardino, M. J.; Hayes, G. P.; Dannemann, F.; Benz, H.
summaries provide the public with immediate background information useful for teaching and media related purposes and are an essential component to many NEIC products. As part of the NEIC's earthquake response, rapid earthquake summary posters are created in the hours following a significant global earthquake. These regional tectonic summaries are included in each earthquake summary poster along with a discussion of the event, written by research scientists at the NEIC, often with help from regional experts. Now, through the efforts of this and related studies, event webpages will automatically contain a regional tectonic summary immediately after an event has been posted. These new summaries include information about plate boundary interactions and other associated tectonic elements, trends in seismicity and brief descriptions of significant earthquakes that have occurred in a region. The tectonic summaries for the following regions have been updated as part of this work: South America, the Caribbean, Alaska and the Aleutians, Kuril-Kamchatka, Japan and vicinity, and Central America, with newly created summaries for Sumatra and Java, the Mediterranean, Middle East, and the Himalayas. The NEIC is currently planning to integrate concise stylized maps with each tectonic summary for display on the USGS website.
Waller, Roger M.
The Anchorage hydrologic system was greatly affected by the seismic shock. Immediate but temporary effects included increased stream discharge, seiche action on lakes, and fluctuations in ground-water levels. Generally, ground-water levels were residually lowered after the initial period of fluctuation. This lowering is attributed either to changes in the discharge zones offshore or to a change in the permeability of the aquifers by seismically induced strain. Water supplies were disrupted temporarily by snowslides on streams and by sanding or turbidity in wells. Salt-water encroachment to wells on Fire Island seems to have increased. The approximate 3.7-foot lowering of land level and the diminished artesian head may permit further salt-water encroachment. Increased pore pressure in the Pleistocene Bootlegger Cove Clay led to liquefaction in silt and sand lenses that contributed to the disastrous bluff landslides. Measurements after the earthquake indicate that most pore pressures are declining, whereas some remain high or are increasing. Subsidence in the area was caused principally by tectonic readjustment, but differential compaction within the Bootlegger Cove Clay contributed to subsidences estimated to be as much as 0.6 foot beneath Anchorage.
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Kirkby, M.J.; Kirkby, Anne V.
During the 1964 Alaska earthquake, tectonic deformation uplifted the southern end of Montague Island as much as 33 feet or more. The uplifted shoreline is rapidly being modified by subaerial and marine processes. The new raised beach is formed in bedrock, sand, gravel, and deltaic bay-head deposits, and the effect of each erosional process was measured in each material. Fieldwork was concentrated in two areas—MacLeod Harbor on the northwest side and Patton Bay on the southeast side of Montague Island. In the unconsolidated deltaic deposits of MacLeod Harbor, 97 percent of the erosion up to June 1965, 15 months after the earthquake, was fluvial, 2.2 percent was by rainwash, and only 0.8 percent was marine; 52 percent of the total available raised beach material had already been removed. The volume removed by stream erosion was proportional to low-flow discharge raised to the power of 0.75 to 0.95, and this volume increased as the bed material became finer. Stream response to the relative fall in base level was very rapid, most of the downcutting in unconsolidated materials occurring within 48 hours of the uplift for streams with low flows greater than 10 cubic feet per second. Since then, erosion by these streams has been predominantly lateral. Streams with lower discharges, in unconsolidated materials, still had knickpoints after 15 months. No response to uplift could be detected in stream courses above the former preearthquake sea level. Where the raised beach is in bedrock, it is being destroyed principally by marine action but at such a low rate that no appreciable erosion of bedrock was found 15 months after the earthquake. A dated rock platform raised earlier has eroded at a mean rate of 0.49 foot per year. In this area the factor limiting the rate of erosion was rock resistance rather than the transporting capacity of the waves. The break in slope between the top of the raised beach and the former seacliff is being obliterated by debris which is
Vinson, T. S.; Hulsey, L.; Ma, J.; Connor, B.; Brooks, T. E.
More than two dozen major bridges were subjected to severe ground motions during the October-November 2002 Earthquake Sequence on the Denali Fault, Alaska. The bridges represented a number of conventional designs constructed over the past three to four decades. The objective of the field investigation presented herein was to determine the extent of the damage, if any, to the bridge structures, foundations and approach embankments. This was accomplished by direct inspection of the bridges by the authors (or employees of their organizations) along the Richardson, Alaska, Parks, and Denali Highways, the Tok Cutoff, and the railroad bridges for the railroad alignment between Trapper Creek and Fairbanks. More specifically, the members of the investigation team (represented by the authors) conducted more than three days of field inspections of bridges within the zone of severe ground shaking during the M6.7 and M7.9 Denali fault events. The primary conclusion noted was that while a substantial number of bridges were subjected to intense shaking they all performed very well and were not damaged to the extent that remedial repairs to the bridge structure were necessary. There were occurrences of lateral spreading/liquefaction related damage to the approach embankments and slight separation of the approach embankment from the abutment foundation systems. Overall, considering the severity of ground shaking, much greater damage to the bridge structures, foundations and approach embankments would be predicted. Had the earthquakes occurred during winter when the ground was frozen and the ductility of the structures was substantially reduced events comparable to the October-November 2002 Earthquake Sequence on the Denali Fault, Alaska could have resulted in significant damage to bridges. This reconnaissance was supported by the National Science Foundation, Alaska Dept. of Transportation and Public Facilities, and the Alaska Railroad Corporation.
Bossu, R.; Lefebvre, S.; Mazet-Roux, G.; Steed, R.
The Euro-Med Seismological Centre (EMSC) operates the second global earthquake information website (www.emsc-csem.org) which attracts 2 million visits a month from about 200 different countries. We collect information about earthquakes' effects from eyewitnesses such as online questionnaires, geolocated pics to rapidly constrain impact scenario. At the beginning, the collection was purely intended to address a scientific issue: the rapid evaluation of earthquake's impact. However, it rapidly appears that the understanding of eyewitnesses' expectations and motivations in the immediate aftermath of an earthquake was essential to optimise this data collection. Crowdsourcing information on earthquake's effects does not apply to a pre-existing community. By definition, eyewitnesses only exist once the earthquake has struck. We developed a strategy on social networks (Facebook, Google+, Twitter...) to interface with spontaneously emerging online communities of eyewitnesses. The basic idea is to create a positive feedback loop: attract eyewitnesses and engage with them by providing expected earthquake information and services, collect their observations, collate them for improved earthquake information services to attract more witnesses. We will present recent examples to illustrate how important the use of social networks is to engage with eyewitnesses especially in regions of low seismic activity where people are unaware of existing Internet resources dealing with earthquakes. A second type of information collated in our information services is derived from the real time analysis of the traffic on our website in the first minutes following an earthquake occurrence, an approach named flashsourcing. We show, using the example of the Mineral, Virginia earthquake that the arrival times of eyewitnesses of our website follows the propagation of the generated seismic waves and then, that eyewitnesses can be considered as ground motion sensors. Flashsourcing discriminates felt
Bender, A. M.; Witter, R. C.; Rogers, M.; Saenger, C. P.
Subsidence during the Mw 9.2, 1964 great Alaska earthquake lowered Turnagain Arm near Girdwood, Alaska by ~1.5m and caused rapid relative sea-level (RSL) rise that shifted estuary mud flats inland over peat-forming wetlands. Sharp mud-over-peat contacts record these environment shifts at sites along Turnagain Arm including Bird Point, 11km west of Girdwood. Transfer functions based on changes in intertidal microfossil populations across these contacts accurately estimate earthquake subsidence at Girdwood, but poor preservation of microfossils hampers this method at other sites in Alaska. We test a new method that employs compositions of stable carbon and nitrogen isotopes in intertidal sediments as proxies for elevation. Because marine sediment sources are expected to have higher δ13C and δ15N than terrestrial sources, we hypothesize that these values should decrease with elevation in modern intertidal sediment, and should also be more positive in estuarine mud above sharp contacts that record RSL rise than in peaty sediment below. We relate δ13C and δ15N values above and below the 1964 mud/peat contact to values in modern sediment of known elevation, and use these values qualitatively to indicate sediment source, and quantitatively to estimate the amount of RSL rise across the contact. To establish a site-specific sea level datum, we deployed a pressure transducer and compensatory barometer to record a 2-month tide series at Bird Point. We regressed the high tides from this series against corresponding NOAA verified high tides at Anchorage (~50km west of Bird Point) to calculate a high water datum within ×0.14m standard error (SE). To test whether or not modern sediment isotope values decrease with elevation, we surveyed a 60-m-long modern transect, sampling surface sediment at ~0.10m vertical intervals. Results from this transect show a decrease of 4.64‰ in δ13C and 3.97‰ in δ15N between tide flat and upland sediment. To evaluate if δ13C and δ15N
Bartsch-Winkler, S.; Schmoll, H.R.
During the great 1964 earthquake, parts of coastal southern Alaska subsided tectonically as much as 2 m, and this led to burial of high-intertidal organic-rich marshes by low-intertidal and tidal silt. In the tectonically active parts of upper Cook Inlet, the presence of stratigraphic sections containing numerous prehistoric interbedded layers of peat and silt suggests that such stratigraphy resulted when marshes and forests were similarly inundated and buried by intertidal and tidal sediment as a result of great, prehistoric earthquakes. This study tests the feasibility of using buried, radiocarbon-dated, late Holocene peat layers that are exposed in the intertidal zone of upper Cook Inlet to determine earthquake recurrence intervals. Because of problems associated with conventional radiocarbon dating, the complex stratigraphy of the study area, the tectonic setting, and regional changes in sea level, conclusions from the study do not permit precise identification of the timing and recurrence of paleoseismic events. -from Authors
McNutt, S. R.; Sanchez, J. J.; Moran, S. C.; Power, J. A.
The Mw7.9 Denali Fault earthquake provided an opportunity to look for intermediate-term (days to weeks) responses of Alaskan volcanoes to shaking from a large regional earthquake. The Alaska Volcano Observatory monitors 24 volcanoes with seismic networks. We examined one station for each volcano, generally the closest (typically 5 km from the vent) unless noise, site response, or other factors made the data unusable. Data were digitally bandpass filtered between 0.8 and 5 Hz to reduce noise from microseisms and wind. Data for the period three days before to three days after the Mw7.9 earthquake were then plotted at a standard scale used for AVO routine monitoring. Shishaldin volcano, which has a background rate of several hundred seismic events per day on station SSLS, showed no change from before to after the earthquake. Veniaminof volcano, which has had recent mild eruptions and a rate of several dozen seismic events per day on station VNNF, suffered a drop in seismicity at the time of the earthquake by a factor of 2.5; this lasted for 15 days. We tested this result using a different station, VNSS, and a different method of counting (non-filtered data on helicorder records) and found the same result. We infer that Veniaminof's activity was modified by the Mw7.9 earthquake. Wrangell, the closest volcano, had a background rate of about 10 events per day. Data from station WANC could not be measured for 8 days after the Mw7.9 earthquake because the large number of aftershocks precluded identification of local seismicity. For the following eight days, however, its seismicity rate was 30 percent lower than before. While subtle, we infer that this may be related to the earthquake. It is known that Wrangell increased its heat output after the Mw9.2 Alaska earthquake of 1964 and again after the Ms7.1 St. Elias earthquake of 1979. The other 21 volcanoes showed no changes in seismicity from 3 days before to 3 days after the Mw7.9 event. We conclude that intermediate
Ye, Lingling; Lay, Thorne; Kanamori, Hiroo
On 23 June 2014, the largest intermediate depth earthquake (Mw 7.9) of the last 100 years ruptured within the subducting Pacific plate about 100 km below the Rat Islands archipelago of the Western Aleutian Islands, Alaska. The unusual faulting orientation, strike = 206°, dip = 24°, and rake = -14°, is possibly related to curvature of the underthrust slab and high obliquity of the relative plate motions. The first ~15 s of the rupture generated relatively weak seismic waves, followed by strong energy release for the next 25 s. The seismic moment is 1.0 × 1021 Nm, and slip of up to ~10 m is concentrated within a 50 km × 50 km region. The radiated energy is 1.1 to 2.7 × 1016 J, assuming attenuation t* of 0.4 to 0.7 s. This type of intraplate faulting can be very damaging for populated regions above subduction zones such as Japan, Taiwan, Chile, and Indonesia.
Fisher, M.A.; Ratchkovski, N.A.; Nokleberg, W.J.; Pellerin, L.; Glen, J.M.G.
Geophysical information, including deep-crustal seismic reflection, magnetotelluric (MT), gravity, and magnetic data, cross the aftershock zone of the 3 November 2002 Mw 7.9 Denali fault earthquake. These data and aftershock seismicity, jointly interpreted, reveal the crustal structure of the right-lateral-slip Denali fault and the eastern Alaska Range orogen, as well as the relationship between this structure and seismicity. North of the Denali fault, strong seismic reflections from within the Alaska Range orogen show features that dip as steeply as 25?? north and extend downward to depths between 20 and 25 km. These reflections reveal crustal structures, probably ductile shear zones, that most likely formed during the Late Cretaceous, but these structures appear to be inactive, having produced little seismicity during the past 20 years. Furthermore, seismic reflections mainly dip north, whereas alignments in aftershock hypocenters dip south. The Denali fault is nonreflective, but modeling of MT, gravity, and magnetic data suggests that the Denali fault dips steeply to vertically. However, in an alternative structural model, the Denali fault is defined by one of the reflection bands that dips to the north and flattens into the middle crust of the Alaska Range orogen. Modeling of MT data indicates a rock body, having low electrical resistivity (>10 ??-m), that lies mainly at depths greater than 10 km, directly beneath aftershocks of the Denali fault earthquake. The maximum depth of aftershocks along the Denali fault is 10 km. This shallow depth may arise from a higher-than-normal geothermal gradient. Alternatively, the low electrical resistivity of deep rocks along the Denali fault may be associated with fluids that have weakened the lower crust and helped determine the depth extent of the after-shock zone.
Effects of the earthquake of March 27, 1964, on air and water transport, communications, and utilities systems in south-central Alaska: Chapter B in The Alaska earthquake, March 27, 1964: effects on transportation, communications, and utilities
Eckel, Edwin B.
The earthquake of March 27, 1964, wrecked or severely hampered all forms of transportation, all utilities, and all communications systems over a very large part of south-central Alaska. Effects on air transportation were minor as compared to those on the water, highway, and railroad transport systems. A few planes were damaged or wrecked by seismic vibration or by flooding. Numerous airport facilities were damaged by vibration or by secondary effects of the earthquake, notably seismic sea and landslide-generated waves, tectonic subsidence, and compaction. Nearly all air facilities were partly or wholly operational within a few hours after the earthquake. The earthquake inflicted enormous damage on the shipping industry, which is indispensable to a State that imports fully 90 percent of its requirements—mostly by water—and whose largest single industry is fishing. Except for those of Anchorage, all port facilities in the earthquake-affected area were destroyed or made inoperable by submarine slides, waves, tectonic uplift, and fire. No large vessels were lost, but more than 200 smaller ones (mostly crab or salmon boats) were lost or severely damaged. Navigation aids were destroyed, and hitherto well-known waterways were greatly altered by uplift or subsidence. All these effects wrought far-reaching changes in the shipping economy of Alaska, many of them to its betterment. Virtually all utilities and communications in south-central Alaska were damaged or wrecked by the earthquake, but temporary repairs were effected in remarkably short times. Communications systems were silenced almost everywhere by loss of power or by downed lines; their place was quickly taken by a patchwork of self-powered radio transmitters. A complex power-generating system that served much of the stricken area from steam, diesel, and hydrogenerating plants was disrupted in many places by vibration damage to equipment and by broken transmission lines. Landslides in Anchorage broke gas
Gardine, L.; Tape, C.; West, M. E.
Despite residing in a state with 75% of North American earthquakes and three of the top 15 ever recorded, most Alaskans have limited knowledge about the science of earthquakes. To many, earthquakes are just part of everyday life, and to others, they are barely noticed until a large event happens, and often ignored even then. Alaskans are rugged, resilient people with both strong independence and tight community bonds. Rural villages in Alaska, most of which are inaccessible by road, are underrepresented in outreach efforts. Their remote locations and difficulty of access make outreach fiscally challenging. Teacher retention and small student bodies limit exposure to science and hinder student success in college. The arrival of EarthScope's Transportable Array, the 50th anniversary of the Great Alaska Earthquake, targeted projects with large outreach components, and increased community interest in earthquake knowledge have provided opportunities to spread information across Alaska. We have found that performing hands-on demonstrations, identifying seismological relevance toward career opportunities in Alaska (such as natural resource exploration), and engaging residents through place-based experience have increased the public's interest and awareness of our active home.
McCulloch, David S.; Bonilla, Manuel G.
In the 1964 Alaska earthquake, the federally owned Alaska Railroad sustained damage of more than $35 million: 54 percent of the cost for port facilities; 25 percent, roadbed and track; 9 percent, buildings and utilities; 7 percent, bridges and culverts; and 5 percent, landslide removal. Principal causes of damage were: (1) landslides, landslide-generated waves, and seismic sea waves that destroyed costly port facilities built on deltas; (2) regional tectonic subsidence that necessitated raising and armoring 22 miles of roadbed made susceptible to marine erosion; and (3), of greatest importance in terms of potential damage in seismically active areas, a general loss of strength experienced by wet waterlaid unconsolidated granular sediments (silt to coarse gravel) that allowed embankments to settle and enabled sediments to undergo fiowlike displacement toward topographic depressions, even in fiat-lying areas. The term “landspreading” is proposed for the lateral displacement and distension of mobilized sediments; landspreading appears to have resulted largely from liquefaction. Because mobilization is time dependent and its effects cumulative, the long duration of strong ground motion (timed as 3 to 4 minutes) along the southern 150 miles of the rail line made landspreading an important cause of damage. Sediments moved toward natural and manmade topographic depressions (stream valleys, gullies, drainage ditches, borrow pits, and lakes). Stream widths decreased, often about 20 inches but at some places by as much as 6.5 feet, and sediments moved upward beneath stream channels. Landspreading toward streams and even small drainage ditches crushed concrete and metal culverts. Bridge superstructures were compressed and failed by lateral buckling, or more commonly were driven into, through, or over bulkheads. Piles and piers were torn free of superstructures by moving sediments, crowded toward stream channels, and lifted in the center. The lifted piles arched the
In this spectacular MODIS image from November 7, 2001, the skies are clear over Alaska, revealing winter's advance. Perhaps the most interesting feature of the image is in its center; in blue against the rugged white backdrop of the Alaska Range, Denali, or Mt. McKinley, casts its massive shadow in the fading daylight. At 20,322 ft (6,194m), Denali is the highest point in North America. South of Denali, Cook Inlet appears flooded with sediment, turning the waters a muddy brown. To the east, where the Chugach Mountains meet the Gulf of Alaska, and to the west, across the Aleutian Range of the Alaska Peninsula, the bright blue and green swirls indicate populations of microscopic marine plants called phytoplankton. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC
In this spectacular MODIS image from November 7, 2001, the skies are clear over Alaska, revealing winter's advance. Perhaps the most interesting feature of the image is in its center; in blue against the rugged white backdrop of the Alaska Range, Denali, or Mt. McKinley, casts its massive shadow in the fading daylight. At 20,322 ft (6,194m), Denali is the highest point in North America. South of Denali, Cook Inlet appears flooded with sediment, turning the waters a muddy brown. To the east, where the Chugach Mountains meet the Gulf of Alaska, and to the west, across the Aleutian Range of the Alaska Peninsula, the bright blue and green swirls indicate populations of microscopic marine plants called phytoplankton.
Alaska's Good Friday earthquake of 27 March 1964 was accompanied by vertical tectonic deformation over an area of 170,000 to 200,000 square kilometers in south-central Alaska. The deformation included two major northeast-trending zones of uplift and subsidence situated between the Aleutian Trench and the Aleutian Volcanic Arc; together they are 700 to 800 kilometers long and from 150 to 250 kilometers wide. The seaward zone is one in which uplift of as much as 10 meters on land and 15 meters on the sea floor has occurred as a result of both crustal warping and local faulting. Submarine uplift within this zone generated a train of seismic sea waves with half-wave amplitudes of more than 7 meters along the coast near the source. The adjacent zone to the northwest is one of subsidence that averages about 1 meter and attains a measured maximum of 2.3 meters. A second zone of slight uplift may exist along all or part of the Aleutian and Alaska ranges northwest of the zone of subsidence. PMID:17819412
Hagerty, M. T.; Lomax, A.; Hellman, S. B.; Whitmore, P.; Weinstein, S.; Hirshorn, B. F.; Knight, W. R.
Tsunami warning centers must rapidly decide whether an earthquake is likely to generate a destructive tsunami in order to issue a tsunami warning quickly after a large event. For very large events (Mw > 8 or so), magnitude and location alone are sufficient to warrant an alert. However, for events of smaller magnitude (e.g., Mw ~ 7.5), particularly for so-called "tsunami earthquakes", magnitude alone is insufficient to issue an alert and other measurements must be rapidly made and used to assess tsunamigenic potential. The Tsunami Information technology Modernization (TIM) is a National Oceanic and Atmospheric Administration (NOAA) project to update and standardize the earthquake and tsunami monitoring systems currently employed at the U.S. Tsunami Warning Centers in Ewa Beach, Hawaii (PTWC) and Palmer, Alaska (NTWC). We (ISTI) are responsible for implementing the seismic monitoring components in this new system, including real-time seismic data collection and seismic processing. The seismic data processor includes a variety of methods aimed at real-time discrimination of tsunamigenic events, including: Mwp, Me, slowness (Theta), W-phase, mantle magnitude (Mm), array processing and finite-fault inversion. In addition, it contains the ability to designate earthquake scenarios and play the resulting synthetic seismograms through the processing system. Thus, it is also a convenient tool that integrates research and monitoring and may be used to calibrate and tune the real-time monitoring system. Here we show results of the automated processing system for a large dataset of subduction zone earthquakes containing recent tsunami earthquakes and we examine the accuracy of the various discrimation methods and discuss issues related to their successful real-time application.
Sauber, J.; Ruppert, N.; Muskett, R.
In southern Alaska between the Malaspina and Bering Glaciers large ice fluctuations occur directly above a shallow main thrust zone associated with subduction of the Pacific-Yakutat plate beneath continental Alaska. Recently the southern Alaskan glaciers have shown a tendency toward earlier glacier melt onset and longer ablation season resulting in increased glacier wastage. Although these glaciers are generally undergoing ice mass loss, the temporal and spatial pattern of surface elevation change is complex and many of the larger glaciers undergo quasi-periodic surges. We have used ICESat-derived elevations along with InSAR-derived digital elevation models (DEM), such as the SRTM-C,-X DEMs, to detect general patterns in ice elevation change for surfaces with variable slope and roughness with exact and near-repeat ICESat tracks. Rather than averaging over large regions or relying on crossovers, we exploited the potential of individual ICESat waveform returns to estimate glacier elevations and surface characteristics. Careful interpretation of the ICESat waveforms must take into account the potential effects of signal saturation, forward scattering due to clouds, and field of view shadowing on pulse shape and the resulting errors in elevation and relief measurements. We have used our ICESat minus ICESat and ICESat minus InSAR-derived DEM elevation change results, along with earlier ice change studies, to estimate ice load changes from 1988-2006 for the southern coastal Alaska glaciers between the Malaspina and Bering Glaciers. The ice load changes were input to finite element models to calculate displacement rates, incremental stresses, and change in the fault stability margin. In 2002-2006, for instance, the predicted displacement rates of the solid Earth due to average annual change in ice loads were up to 20 mm/yr for the vertical and 3 mm/yr for the horizontal. To empirically evaluate the influence of short-term ice fluctuations on fault stability, we compared
Ratchkovski, N. A.; Hansen, R. A.; Kore, K. R.
The largest earthquake ever recorded on the Denali fault system (magnitude 7.9) struck central Alaska on November 3, 2002. It was preceded by a magnitude 6.7 earthquake on October 23. This earlier earthquake and its zone of aftershocks were located ~20 km to the west of the 7.9 quake. Aftershock locations and surface slip observations from the 7.9 quake indicate that the rupture was predominately unilateral in the eastward direction. The geologists mapped a ~300-km-long rupture and measured maximum offsets of 8.8 meters. The 7.9 event ruptured three different faults. The rupture began on the northeast trending Susitna Glacier Thrust fault, a splay fault south of the Denali fault. Then the rupture transferred to the Denali fault and propagated eastward for 220 km. At about 143W the rupture moved onto the adjacent southeast-trending Totschunda fault and propagated for another 55 km. The cumulative length of the 6.7 and 7.9 aftershock zones along the Denali and Totschunda faults is about 380 km. The earthquakes were recorded and processed by the Alaska Earthquake Information Center (AEIC). The AEIC acquires and processes data from the Alaska Seismic Network, consisting of over 350 seismograph stations. Nearly 40 of these sites are equipped with the broad-band sensors, some of which also have strong motion sensors. The rest of the stations are either 1 or 3-component short-period instruments. The data from these stations are collected, processed and archived at the AEIC. The AEIC staff installed a temporary seismic network of 6 instruments following the 6.7 earthquake and an additional 20 stations following the 7.9 earthquake. Prior to the 7.9 Denali Fault event, the AEIC was locating 35 to 50 events per day. After the event, the processing load increased to over 300 events per day during the first week following the event. In this presentation, we will present and interpret the aftershock location patterns, first motion focal mechanism solutions, and regional seismic
Wright, Tim J.; Lu, Zhong; Wicks, Chuck
The 23 October 2002 Nenana Mountain Earthquake (Mw ∼ 6.7) occurred on the Denali Fault (Alaska), to the west of the Mw ∼ 7.9 Denali Earthquake that ruptured the same fault 11 days later. We used 6 interferograms, constructed using radar images from the Canadian Radarsat-1 and European ERS-2 satellites, to determine the coseismic surface deformation and a source model. Data were acquired on ascending and descending satellite passes, with incidence angles between 23 and 45 degrees, and time intervals of 72 days or less. Modeling the event as dislocations in an elastic half space suggests that there was nearly 0.9 m of right-lateral strike-slip motion at depth, on a near-vertical fault, and that the maximum slip in the top 4 km of crust was less than 0.2 m. The Nenana Mountain Earthquake increased the Coulomb stress at the future hypocenter of the 3 November 2002, Denali Earthquake by 30–60 kPa.
Ellsworth, W.L.; Celebi, M.; Evans, J.R.; Jensen, E.G.; Kayen, R.; Metz, M.C.; Nyman, D.J.; Roddick, J.W.; Spudich, P.; Stephens, C.D.
A free-field recording of the Denali fault earthquake was obtained by the Alyeska Pipeline Service Company 3 km from the surface rupture of the Denali fault. The instrument, part of the monitoring and control system for the trans-Alaska pipeline, was located at Pump Station 10, approximately 85 km east of the epicenter. After correction for the measured instrument response, we recover a seismogram that includes a permanent displacement of 3.0 m. The recorded ground motion has relatively low peak acceleration (0.36 g) and very high peak velocity (180 cm/s). Nonlinear soil response may have reduced the peak acceleration to this 0.36 g value. Accelerations in excess of 0.1 g lasted for 10 s, with the most intense motion occurring during a 1.5-s interval when the rupture passed the site. The low acceleration and high velocity observed near the fault in this earthquake agree with observations from other recent large-magnitude earthquakes. ?? 2004, Earthquake Engineering Research Institute.
Ji, C.; Helmberger, D.V.; Wald, D.J.
Slip histories for the 2002 M7.9 Denali fault, Alaska, earthquake are derived rapidly from global teleseismic waveform data. In phases, three models improve matching waveform data and recovery of rupture details. In the first model (Phase I), analogous to an automated solution, a simple fault plane is fixed based on the preliminary Harvard Centroid Moment Tensor mechanism and the epicenter provided by the Preliminary Determination of Epicenters. This model is then updated (Phase II) by implementing a more realistic fault geometry inferred from Digital Elevation Model topography and further (Phase III) by using the calibrated P-wave and SH-wave arrival times derived from modeling of the nearby 2002 M6.7 Nenana Mountain earthquake. These models are used to predict the peak ground velocity and the shaking intensity field in the fault vicinity. The procedure to estimate local strong motion could be automated and used for global real-time earthquake shaking and damage assessment. ?? 2004, Earthquake Engineering Research Institute.
Ross, S.; Jones, L. M.; Wilson, R. I.; Bahng, B.; Barberopoulou, A.; Borrero, J. C.; Brosnan, D.; Bwarie, J. T.; Geist, E. L.; Johnson, L. A.; Hansen, R. A.; Kirby, S. H.; Knight, E.; Knight, W. R.; Long, K.; Lynett, P. J.; Miller, K. M.; Mortensen, C. E.; Nicolsky, D.; Oglesby, D. D.; Perry, S. C.; Porter, K. A.; Real, C. R.; Ryan, K. J.; Suleimani, E. N.; Thio, H. K.; Titov, V. V.; Wein, A. M.; Whitmore, P.; Wood, N. J.
inform decision makers. The SAFRR Tsunami Scenario is organized by a coordinating committee with several working groups, including Earthquake Source, Paleotsunami/Geology Field Work, Tsunami Modeling, Engineering and Physical Impacts, Ecological Impacts, Emergency Management and Education, Social Vulnerability, Economic and Business Impacts, and Policy. In addition, the tsunami scenario process is being assessed and evaluated by researchers from the Natural Hazards Center at the University of Colorado at Boulder. The source event, defined by the USGS' Tsunami Source Working Group, is an earthquake similar to the 2011 Tohoku event, but set in the Semidi subduction sector, between Kodiak Island and the Shumagin Islands off the Pacific coast of the Alaska Peninsula. The Semidi sector is probably late in its earthquake cycle and comparisons of the geology and tectonic settings between Tohoku and the Semidi sector suggest that this location is appropriate. Tsunami modeling and inundation results have been generated for many areas along the California coast and elsewhere, including current velocity modeling for the ports of Los Angeles, Long Beach, and San Diego, and Ventura Harbor. Work on impacts to Alaska and Hawaii will follow. Note: Costas Synolakis (USC) is also an author of this abstract.
Plafker, G.; Savage, J. C.; Lee, W. H.
The Mw 9.5 Chile earthquake sequence (21-22/05/1960), the largest instrumentally-recorded seismic event in history, was generated by a megathrust rupture of the southern end of the Peru-Chile Arc about 850 km long and 60-150 km wide down dip. Within Chile, the accompanying tsunami reached 15 m high and took an estimated 1,000 of the more than 2,000 lives lost. The trans-Pacific tsunami killed 230 people in Japan, Hawaii and the Philippine Islands. The tsunami source was primarily due to regional offshore upwarp, with possible superimposed larger local uplift due to displacement on splay faults. The Mw 9.2 Alaska earthquake (27/03/1964) ruptured major segments of the eastern Aleutian Arc 800 km long by 250-350 km wide down dip. Coseismic uplift along splay faults offshore generated a major near-field tsunami reaching 13 m high in Alaska that took at least 21 lives. Local earthquake-triggered submarine landslides in fiords along the rugged Kenai and Chugach mountains generated local (non-tsunami) waves with run up to 52 m high that took about 77 lives and caused major damage to coastal communities. Tectonically-generated tsunami waves were also generated over the continental shelf and slope due to regional uplift that averaged about 2 m; these waves added to the damage in coastal Alaska and caused 15 deaths and local property damage as far away as Oregon and California. The Mw 9.15 Sumatra earthquake (26/12/2004) ruptured segments of the Sunda Arc more than 1200 km long by 150-200 km wide down dip. The accompanying near-field tsunami was as high as 36 m in northern Sumatra where it caused 169,000 casualties along 200 km of shoreline while the far-field tsunami took an additional 63,000 lives throughout the Indian Ocean region. This made it the deadliest tsunami in recorded history. In addition to a few meters of regional uplift caused by slip on the megathrust, large-slip splay fault sources are inferred from intraplate seismicity, and from early tsunami arrival
Reviews the setting of the 1964 earthquake and the unprecedented tectonic deformation that accompanied it. Outlines research directed towards defining the deformation that occurs between great earthquakes (interseismic part of the seismic cycle) and the longterm history of deformation over repeated seismic cycles in the earthquake-affected region, emphasizing work in progress. An understanding of this record of deformation is basic for evaluating how frequently 1964-type events recur in this same region, for improved understanding for the earthquake cycle in great subduction-zone seismotectonic events, and for predicting future great earthquakes in this and tectonically similar regions elsewhere. -from Author
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A learning unit about earthquakes includes activities for primary grade students, including making inferences and defining operationally. Task cards are included for independent study on earthquake maps and earthquake measuring. (CB)
An earthquake happens when two blocks of the earth suddenly slip past one another. Earthquakes strike suddenly, violently, and without warning at any time of the day or night. If an earthquake occurs in a ...
An earthquake happens when two blocks of the earth suddenly slip past one another. Earthquakes strike suddenly, violently, and without warning at any time of the day or night. If an earthquake occurs in a populated area, it may cause ...
Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.
Cassidy, J. F.; Rogers, G. C.; Bird, A. L.; Mulder, T. L.
The 3 November 2002 M=7.9 Alaska earthquake was one of the largest earthquakes recorded in North America during the past 100 years. This earthquake occurred at 2:12 p.m. PST (on a Sunday) and was located 330 km to the west of the Yukon-Alaska border. Surface rupture and aftershocks extended to within about 100 km of the Canadian border. More than 250 "felt" reports were submitted to the Geological Survey of Canada website (http://www.pgc.nrcan.gc.ca/seismo/table.htm) within a few days of the earthquake. Here, we summarize those reports which include typical high-frequency shaking effects to distances of about 1500 km, as well as numerous long-period effects, such as human effects (nausea), swaying highrises, telephone poles and chandeliers, seiches in lakes and inlets, water sloshing from swimming pools, and instances of dirty well-water to distances of nearly 3500 km across Western Canada. Felt intensities (MMI)of about IV were observed across the Yukon Territory at distances of 350 km to 750 km. There were a few reports of minor damage in this region, as well as numerous reports of items knocked from shelves and parked vehicles rocking noticeably. The most distant felt reports in western Canada were from southern Alberta (2400 km distance) where people in highrises felt the swaying. More than 30 reports of human effects were received. These ranged from people feeling dizzy, seasick or nauseated (to distances of 2400 km), to difficulty standing and maintaining balance (to distances of 1000 km). Long-period effects of houses "swaying", large signs flexing, and telephone poles and tall trees swaying were reported to distances of more than 1000 km. Swinging of chandeliers, hanging plants and lights were reported to distances of 2400 km. There were more than 30 reports of seiches. Most reports came from southern British Columbia (2200-2400 km) where, although no ground shaking was noticed, water surges up to 1 m were observed. In one case a cabin held by cables near
Haeussler, P. J.; Parsons, T.; Lee, H. J.; Ryan, H. F.; Brothers, D. S.; Liberty, L. M.; Hart, P. E.; Geist, E. L.; Roland, E. C.; Witter, R. C.; Kayen, R. E.
Submarine landslide-generated tsunamis were the single largest cause of fatalities in the Mw9.2 1964 Great Alaska earthquake. In the last decade, we studied the submarine slope failures in six fjords: Resurrection Bay, Port Valdez, Passage Canal, southern Dangerous Passage, Aialik Bay, and Harris Bay. The six fjords lie 20 to 30 km above the Alaska-Aleutian megathrust, which provides an ideal landslide trigger mechanism. To characterize the landslides, we used multibeam bathymetry data, pre- and post-event bathymetry differencing, sparker and chirp seismic data, wave runup directions and heights, shear wave velocity profiles, the onland sedimentary record of the tsunamis, observations during the earthquake, and tsunami models. All slides originated at the margins of the fjords, mostly in unconsolidated sediment of the fjord-head deltas(?), and transported sediment to the deepest part of the fjords. The slides transported material up to ~15 km, resulting in slide deposits up to 20 m thick, and a subsequent megaturbidite deposit up to 15 m thick. These slides resurfaced the entire fjord bottom and the resultant flow of sediment and water brought numerous deep dwelling fish to the surface, killed by the sudden pressure changes. Typical fjord sedimentation resulted in conditions primed for slope failures. Fjord-head deltas deposited unconsolidated sediment at the upper margins of the fjords, which composed the majority of sediment that failed during the earthquake. We find that the highest tsunami runups were correlated with blocky landslides that required unique depositional conditions. The Little Ice Age (LIA) occurred between the penultimate megathrust earthquake ~900 yr ago and 1964, with the most recent maximum extent around 1875AD. The LIA glacial expansion led to significant sedimentation at the margins of the fjords. Near Shoup Bay in Port Valdez, in Passage Canal, and probably in southern Dangerous Passage, ice overrode till and sediment deposited in front of
Earle, P. S.; Wald, D. J.; Benz, H.; Sipkin, S.; Dewey, J.; Allen, T.; Jaiswal, K.; Buland, R.; Choy, G.; Hayes, G.; Hutko, A.
Immediately after detecting the May 12th, 2008 Mw 7.9 Wenchuan Earthquake, the USGS National Earthquake Information Center (NEIC) began a coordinated effort to understand and communicate the earthquake's seismological characteristics, tectonic context, and humanitarian impact. NEIC's initial estimates of magnitude and location were distributed within 30 minutes of the quake by e-mail and text message to 70,000 users via the Earthquake Notification System. The release of these basic parameters automatically triggered the generation of more sophisticated derivative products that were used by relief and government agencies to plan their humanitarian response to the disaster. Body-wave and centroid moment tensors identified the earthquake's mechanism. Predictive ShakeMaps provided the first estimates of the geographic extent and amplitude of shaking. The initial automated population exposure estimate generated and distributed by the Prompt Assessment of Global Earthquakes for Response (PAGER) system stated that 1.2 million people were exposed to severe-to-extreme shaking (Modified Mercalli Intensity VIII or greater), indicating a large-scale disaster had occurred. NEIC's modeling of the mainshock and aftershocks was continuously refined and expanded. The length and orientation of the fault were determined from aftershocks, finite-fault models, and back-projection source imaging. Firsthand accounts of shaking intensity were collected and mapped by the "Did You Feel It" system. These results were used to refine our ShakeMaps and PAGER exposure estimates providing a more accurate assessment of the extent and enormity of the disaster. The products were organized and distributed in an event-specific summary poster and via the USGS Earthquake Program web pages where they were viewed by millions and reproduced by major media outlets (over 1/2 billion hits were served that month). Rather than just a point showing magnitude and epicenter, several of the media's schematic maps
Jibson, R.W.; Harp, E.L.; Schulz, W.; Keefer, D.K.
The moment magnitude (M) 7.9 Denali Fault, Alaska, earthquake of 3 November 2002 triggered thousands of landslides, primarily rock falls and rock slides, that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 20 ?? 106 m3. The pattern of landsliding was unusual: the number and concentration of triggered slides was much less than expected for an earthquake of this magnitude, and the landslides were concentrated in a narrow zone about 30-km wide that straddled the fault-rupture zone over its entire 300-km length. Despite the overall sparse landslide concentration, the earthquake triggered several large rock avalanches that clustered along the western third of the rupture zone where acceleration levels and ground-shaking frequencies are thought to have been the highest. Inferences about near-field strong-shaking characteristics drawn from interpretation of the landslide distribution are strikingly consistent with results of recent inversion modeling that indicate that high-frequency energy generation was greatest in the western part of the fault-rupture zone and decreased markedly to the east. ?? 2005 Elsevier B.V. All rights reserved.
Engdahl, E.R.; Billington, S.; Kisslinger, C.
The Andreanof Islands earthquake (Mw 8.0) is the largest event to have occurred in that section of the Aleutian arc since the March 9, 1957, Aleutian Islands earthquake (Mw 8.6). Teleseismically well-recorded earthquakes in the region of the 1986 earthquake are relocated with a plate model and with careful attention to the focal depths. The data set is nearly complete for mb???4.7 between longitudes 172??W and 179??W for the period 1964 through April 1987 and provides a detailed description of the space-time history of moderate-size earthquakes in the region for that period. Additional insight is provided by source parameters which have been systematically determined for Mw???5 earthquakes that occurred in the region since 1977 and by a modeling study of the spatial distribution of moment release on the mainshock fault plane. -from Authors
Ruppert, Natalia G.; Prejean, Stephanie G.; Hansen, Roger A.
An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field.
Ruppert, N.A.; Prejean, S.; Hansen, R.A.
An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field. Copyright ?? 2011 by the American Geophysical Union.
Eberhart-Phillips, D.; Haeussler, P.J.; Freymueller, J.T.; Frankel, A.D.; Rubin, C.M.; Craw, P.; Ratchkovski, N.A.; Anderson, G.; Carver, G.A.; Crone, A.J.; Dawson, T.E.; Fletcher, H.; Hansen, R.; Harp, E.L.; Harris, R.A.; Hill, D.P.; Hreinsdottir, S.; Jibson, R.W.; Jones, L.M.; Kayen, R.; Keefer, D.K.; Larsen, C.F.; Moran, S.C.; Personius, S.F.; Plafker, G.; Sherrod, B.; Sieh, K.; Sitar, N.; Wallace, W.K.
The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali fault, then took a right step and continued with right-slip on the Totschunda fault. There is good correlation between geologically observed and geophysically inferred moment release. The earthquake produced unusually strong distal effects in the rupture propagation direction, including triggered seismicity.
Walter, Edward J.
Presents an analysis of the causes of earthquakes. Topics discussed include (1) geological and seismological factors that determine the effect of a particular earthquake on a given structure; (2) description of some large earthquakes such as the San Francisco quake; and (3) prediction of earthquakes. (HM)
Pakiser, Louis C.
One of a series of general interest publications on science topics, the booklet provides those interested in earthquakes with an introduction to the subject. Following a section presenting an historical look at the world's major earthquakes, the booklet discusses earthquake-prone geographic areas, the nature and workings of earthquakes, earthquake…
Sanchez, J. J.; McNutt, S. R.
On November 3, 2002 a Mw 7.9 earthquake ruptured segments of the Denali Fault and adjacent faults in interior Alaska providing a unique opportunity to look for intermediate-term (days to weeks) responses of Alaskan volcanoes to shaking from a large regional earthquake. The Alaska Volcano Observatory (AVO) monitors 24 volcanoes with seismograph networks. We examined one station per volcano, generally the closest to the vent (typically within 5 km) unless noise, or other factors made the data unusable. Data were digitally filtered between 0.8 and 5 Hz to enhance the signal-to-noise ratio. Data for the period four weeks before to four weeks after the Mw 7.9 earthquake were then plotted at a standard scale used for AVO routine monitoring. Mt. Veniaminof volcano, which has had recent mild eruptions and a rate of ten earthquakes per day on station VNNF, suffered a drop in seismicity by a factor of two after the earthquake; this lasted for 15 days. Wrangell, the closest volcano to the epicenter, had a background rate of about 16 earthquakes per day. Data from station WANC could not be measured for 3 days after the Mw 7.9 earthquake because the large number and size of aftershocks impeded identification of local earthquakes. For the following 30 days, however, its seismicity rate dropped by a factor of two. Seismicity then remained low for an additional 4 months at Wrangell, whereas that at Veniaminof returned to normal within weeks. The seismicity at both Mt. Veniaminof and Mt. Wrangell is dominated by low-frequency volcanic events. The detection thresholds for both seismograph networks are low and stations VNNF and WANC operated normally during the time of our study, thus we infer that the changes in seismicity may be related to the earthquake. It is known that Wrangell increased its heat output after the Mw 9.2 Alaska earthquake of 1964 and again after the Ms 7.1 St.Elias earthquake of 1979. The other volcanoes showed no changes in seismicity that can be attributable to
Foster, Helen L.; Karlstrom, Thor N.V.
The great 1964 Alaska earthquake caused considerable ground breakage in the Cook Inlet area of south-central Alaska. The breakage occurred largely in thick deposits of unconsolidated sediments. The most important types of ground breakage were (1) fracturing or cracking and the extrusion of sand and gravel with ground water along fractures in various types of landforms, and (2) slumping and lateral extension of unconfined faces, particularly along delta fronts. The principal concentration of ground breakage within the area covered by this report was in a northeast-trending zone about 60 miles long and 6 miles wide in the northern part of the Kenai Lowland. The zone cut across diverse topography and stratigraphy. Cracks were as much as 30 feet across and 25 feet deep. Sand, gravel, and pieces of coal and lignite were extruded along many fissures. It is suggested that the disruption in this zone may be due to movement along a fault in the underlying Tertiary rocks. The outwash deltas of Tustumena and Skilak Lakes in the Kenai Lowland, of Eklutna Lake and Lake George in the Chugach Mountains, of Bradley Lake in the Kenai Mountains, and at the outlet of upper Beluga Lake at the base of the Alaska Range showed much slumping, as did the delta of the Susitna River. Parts of the flood plains of the Skilak River, Fox River, and Eagle River were extensively cracked. A few avalanches and slumps occurred along the coast of Cook Inlet in scattered localities. Some tidal flats were cracked. However, in view of the many thick sections of unconsolidated sediments and the abundance of steep slopes, the cracking was perhaps less than might have been expected. Observations along the coasts indicated changes in sea level which, although caused partly by compaction of unconsolidated sediments, may largely be attributed to crus1tal deformation accompanying the earthquake. Most of the Cook Inlet area was downwarped, although the northwest side of Cook Inlet may have been slightly unwarped
Beach ridges as paleoseismic indicators of abrupt coastal subsidence during subduction zone earthquakes, and implications for Alaska-Aleutian subduction zone paleoseismology, southeast coast of the Kenai Peninsula, Alaska
Kelsey, Harvey M.; Witter, Robert C.; Engelhart, Simon E.; Briggs, Richard; Nelson, Alan R.; Haeussler, Peter J.; Corbett, D. Reide
The Kenai section of the eastern Alaska-Aleutian subduction zone straddles two areas of high slip in the 1964 great Alaska earthquake and is the least studied of the three megathrust segments (Kodiak, Kenai, Prince William Sound) that ruptured in 1964. Investigation of two coastal sites in the eastern part of the Kenai segment, on the southeast coast of the Kenai Peninsula, identified evidence for two subduction zone earthquakes that predate the 1964 earthquake. Both coastal sites provide paleoseismic data through inferred coseismic subsidence of wetlands and associated subsidence-induced erosion of beach ridges. At Verdant Cove, paleo-beach ridges record the paleoseismic history; whereas at Quicksand Cove, buried soils in drowned coastal wetlands are the primary indicators of paleoearthquake occurrence and age. The timing of submergence and death of trees mark the oldest earthquake at Verdant Cove that is consistent with the age of a well documented ∼900-year-ago subduction zone earthquake that ruptured the Prince William Sound segment of the megathrust to the east and the Kodiak segment to the west. Soils buried within the last 400–450 years mark the penultimate earthquake on the southeast coast of the Kenai Peninsula. The penultimate earthquake probably occurred before AD 1840 from its absence in Russian historical accounts. The penultimate subduction zone earthquake on the Kenai segment did not rupture in conjunction with the Prince William Sound to the northeast. Therefore the Kenai segment, which is presently creeping, can rupture independently of the adjacent Prince William Sound segment that is presently locked.
Roper, Paul J.; Roper, Jere Gerard
Describes the causes and effects of earthquakes, defines the meaning of magnitude (measured on the Richter Magnitude Scale) and intensity (measured on a modified Mercalli Intensity Scale) and discusses earthquake prediction and control. (JR)
Sigman, Marilyn; And Others
This document consists of a teacher manual and a set of information cards. The teacher manual is designed to educate Alaskan students about the important functions of Alaska's wetlands and about the fish and wildlife that live there. Part I of the manual explores Alaska's wetland habitats, the plants and animals that live there, and the…
... notice (77 FR 50712) announcing that we would submit this ICR to OMB for approval. The notice provided... Bureau of Ocean Energy Management Information Collection: Southern Alaska Sharing Network and Subsistence... networks in coastal Alaska. This notice provides the public a second opportunity to comment on...
Roman, D.C.; Power, J.A.
A significant number of volcano-tectonic(VT) earthquake swarms, some of which are accompanied by ground deformation and/or volcanic gas emissions, do not culminate in an eruption.These swarms are often thought to represent stalled intrusions of magma into the mid- or shallow-level crust.Real-time assessment of the likelihood that a VTswarm will culminate in an eruption is one of the key challenges of volcano monitoring, and retrospective analysis of non-eruptive swarms provides an important framework for future assessments. Here we explore models for a non-eruptive VT earthquake swarm located beneath Iliamna Volcano, Alaska, in May 1996-June 1997 through calculation and inversion of fault-plane solutions for swarm and background periods, and through Coulomb stress modeling of faulting types and hypocenter locations observed during the swarm. Through a comparison of models of deep and shallow intrusions to swarm observations,we aim to test the hypothesis that the 1996-97 swarm represented a shallow intrusion, or "failed" eruption.Observations of the 1996-97 swarm are found to be consistent with several scenarios including both shallow and deep intrusion, most likely involving a relatively small volume of intruded magma and/or a low degree of magma pressurization corresponding to a relatively low likelihood of eruption. ?? 2011 Springer-Verlag.
Heinrichs, T. A.; Sharpton, V. L.; Engle, K. E.; Ledlow, L. L.; Seman, L. E.
In support of the International Polar Year, the Geographic Information Network of Alaska (GINA) intends to make available to researchers three important Arctic data sets. The first is near-real-time synoptic scale data from GINA and NOAA/NESDIS satellite ground stations. GINA operates ground stations that receive direct readout from the AVHRR (1.1-km per pixel resolution) and MODIS (250- to 1000-meter) sensors carried on NOAA and NASA satellites. GINA works in partnership with NOAA/NESDIS's Fairbanks Command and Data Acquisition Station (FCDAS) to distribute real-time data captured by FCDAS facilities in Fairbanks and Barrow, Alaska. AVHRR and Feng Yun 1D (1.1-km) sensors are captured in Fairbanks by FCDAS and distributed by GINA. AVHRR data is captured by FCDAS in Barrow and distributed by GINA. Due to its high latitude, the station mask of the Barrow station extends well beyond the Pole, showing the status in real-time of Arctic basin cloud and sea ice conditions. Second, digital elevation models (DEM) for Alaska vary greatly in quality and availability. The best available DEMs for Alaska will be combined and served through a GINA gateway. Third, the best available imagery for more than three quarters of Alaska is 15-meter pan-sharpened Landsat data. Less than a quarter of the state is covered by 5-meter or better data. The best available imagery for Alaska will be combined and served through a GINA gateway. In accordance with the IPY Subcommittee on Data Policy and Management recommendations, all data will be made available via Open Geospatial Consortium protocols, including Web Mapping, Feature, and Coverage Services. Data will also be made available for download in georeferenced formats such as GeoTIFF, MrSID, or GRID. Metadata will be available though the National Spatial Data Infrastructure via Z39.50 GEO protocols and through evolving web-based metadata standards.
Takahashi, I.; Nakamura, H.; Suzuki, W.; Kunugi, T.; Aoi, S.; Fujiwara, H.
J-RISQ (Japan Real-time Information System for earthquake) has been developing in NIED for appropriate first-actions to big earthquakes. When an earthquake occurs, seismic intensities (SI) are calculated first at each observation station and sent to the Data Management Center in different timing. The system begins the first estimation when the number of the stations observing the SI of 2.5 or larger exceeds the threshold amount. It estimates SI distribution, exposed population and earthquake damage on buildings by using basic data for estimation, such as subsurface amplification factors, population, and building information. It has been accumulated in J-SHIS (Japan Seismic Information Station) developed by NIED, a public portal for seismic hazard information across Japan. The series of the estimation is performed for each 250m square mesh and finally the estimated data is converted into information for each municipality. Since October 2013, we have opened estimated SI, exposed population etc. to the public through the website by making full use of maps and tables.In the previous system, we sometimes could not inspect the information of the surrounding areas out of the range suffered from strong motions, or the details of the focusing areas, and could not confirm whether the present information was the latest or not without accessing the website. J-RISQ has been advanced by introducing the following functions to settle those problems and promote utilization in local areas or in personal levels. In addition, the website in English has been released.・It has become possible to focus on the specific areas and inspect enlarged information.・The estimated information can be downloaded in the form of KML.・The estimated information can be updated automatically and be provided as the latest one.・The newest information can be inspected by using RSS readers or browsers corresponding to RSS.・Exclusive pages for smartphones have been prepared.The information estimated
Plafker, George; Kachadoorian, Reuben
Kodiak Island and the nearby islands constitute a mountainous landmass with an aggregate area of 4,900 square miles that lies at the western border of the Gulf of Alaska and from 20 to 40 miles off the Alaskan mainland. Igneous and metamorphic rocks underlie most of the area except for a narrow belt of moderately to poorly indurated rocks bordering the Gulf of Alaska coast and local accumulations of unconsolidated alluvial and marine deposits along the streams and coast. The area is relatively undeveloped and is sparsely inhabited. About 4,800 of the 5,700 permanent residents in the area live in the city of Kodiak or at the Kodiak Naval Station. The great earthquake, which occurred on March 27, 1964, at 5:36 p.m. Alaska standard time (March 28,1964, 0336 Greenwich mean time), and had a Richter magnitude of 8.4-8.5, was the most severe earthquake felt on Kodiak Island and its nearby islands in modern times. Although the epicenter lies in Prince William Sound 250 miles northeast of Kodiak—the principal city of the area—the areal distribution of the thousands of aftershocks that followed it, the local tectonic deformation, and the estimated source area of the subsequent seismic sea wave, all suggest that the Kodiak group of islands lay immediately adjacent to, and northwest of, the focal region from which the elastic seismic energy was radiated. The duration of strong ground motion in the area was estimated at 2½ minutes. Locally, the tremors were preceded by sounds audible to the human ear and were reportedly accompanied in several places by visible ground waves. Intensity and felt duration of the shocks during the main earthquake and aftershock sequence varied markedly within the area and were strongly influenced by the local geologic environment. Estimated Mercalli intensities in most areas underlain by unconsolidated Quaternary deposits ranged from VIII to as high as IX. In contrast, intensities in areas of upper Tertiary rock ranged from VII to VIII, and in
Enders, M.; Miner, J.; Bierma, R. M.; Busby, R.
EarthScope's Transportable Array (TA) in Alaska and Canada is an ongoing deployment of 261 high quality broadband seismographs. The Alaska TA is the continuation of the rolling TA/USArray deployment of 400 broadband seismographs in the lower 48 contiguous states and builds on the success of the TA project there. The TA in Alaska and Canada is operated by the IRIS Consortium on behalf of the National Science Foundation as part of the EarthScope program. By Sept 2015, it is anticipated that the TA network in Alaska and Canada will be operating 105 stations. During the summer 2015, TA field crews comprised of IRIS and HTSI station specialists, as well as representatives from our partner agencies the Alaska Earthquake Center and the Alaska Volcano Observatory and engineers from the UNAVCO Plate Boundary Observatory will have completed a total of 36 new station installations. Additionally, we will have completed upgrades at 9 existing Alaska Earthquake Center stations with borehole seismometers and the adoption of an additional 35 existing stations. As the array doubles in Alaska, IRIS continues to collaborate closely with other network operators, universities and research consortia in Alaska and Canada including the Alaska Earthquake Center (AEC), the Alaska Volcano Observatory (AVO), the UNAVCO Plate Boundary Observatory (PBO), the National Tsunami Warning Center (NTWC), Natural Resources Canada (NRCAN), Canadian Hazard Information Service (CHIS), the Yukon Geologic Survey (YGS), the Pacific Geoscience Center of the Geologic Survey, Yukon College and others. During FY14 and FY15 the TA has completed upgrade work at 20 Alaska Earthquake Center stations and 2 AVO stations, TA has co-located borehole seismometers at 5 existing PBO GPS stations to augment the EarthScope observatory. We present an overview of deployment plan and the status through 2015. The performance of new Alaska TA stations including improvements to existing stations is described.
Jüngling, Sebastian; Schroeder, Matthias; Lühr, Birger-Gottfried; Woith, Heiko; Wächter, Joachim
The 2008 MS 8.0 Wenchuan earthquake is one of the deadliest in recent human history. This earthquake has not just united the whole world to help local people to lead their life through the difficult time, it has also fostered significant global cooperation to study this event from various aspects: including pre-seismic events (such as the seismicity, gravity, electro-magnetic fields, well water level, radon level in water etc), co-seismic events (fault slipping, landslides, man-made structure damages etc) and post-seismic events (such as aftershocks, well water level changing etc) as well as the disaster relief efforts. In the last four years, more than 300 scientific articles have been published on peer-reviewed journals, among them about 50% are published in Chinese, 30% in English, and about 20% in both languages. These researches have advanced our understanding of earthquake science in general. It has also sparked open debates in many aspects. Notably, the role of the Zipingpu reservoir (built not long ago before the earthquake) in the triggering of this monstrous earthquake is still one of many continuing debates. Given that all these articles are ssporadically spread out on different journals and numerous issues and in different languages, it can be very inefficient, sometimes impossible, to dig out the information that are in need. The Earthquake Research Group in the Chengdu University of Technology (ERGCDUT) has initiated an effort to develop an information platform to collect and analyze scientific research on or related to this earthquake, the hosting faults and the surrounding tectonic regions. A preliminary website has been setup for this purpose: http://www.wenchuaneqresearch.org. Up to this point (July 2012), articles published in 6 Chinese journals and 7 international journals have been collected. Articles are listed journal by journal, and also grouped by contents into four major categories, including pre-seismic events, co-seismic events, post
Hinckley, Kay, Comp.; Kleinert, Jean, Comp.
The product of two 1975 workshops held in Southeastern Alaska (Fairbanks and Sitka), this publication presents the following: (1) papers (written by the educators in attendance at the workshops) which address education methods and concepts relevant to the culture of Southeastern Alaska ("Tlingit Sea Lion Parable"; "Using Local Knowledge in…
Nelson, A. R.; Briggs, R. W.; Kemp, A.; Haeussler, P. J.; Engelhart, S. E.; Dura, T.; Angster, S. J.; Bradley, L.
Uncertainty in earthquake and tsunami prehistory of the Aleutian-Alaska megathrust westward of central Kodiak Island limit assessments of southern Alaska's earthquake hazard and forecasts of potentially damaging tsunamis along much of North America's west coast. Sitkinak Island, one of the Trinity Islands off the southwest tip of Kodiak Island, lies at the western end of the rupture zone of the 1964 Mw9.2 earthquake. Plafker reports that a rancher on the north coast of Sitkinak Island observed ~0.6 m of shoreline uplift immediately following the 1964 earthquake, and the island is now subsiding at about 3 mm/yr (PBO GPS). Although a high tsunami in 1788 caused the relocation of the first Russian settlement on southwestern Kodiak Island, the eastern extent of the megathrust rupture accompanying the tsunami is uncertain. Interpretation of GPS observations from the Shumagin Islands, 380 km southwest of Kodiak Island, suggests an entirely to partially creeping megathrust in that region. Here we report the first stratigraphic evidence of tsunami inundation and land-level change during prehistoric earthquakes west of central Kodiak Island. Beneath tidal and freshwater marshes around a lagoon on the south coast of Sitkinak Island, 27 cores and tidal outcrops reveal the deposits of four to six tsunamis in 2200 years and two to four abrupt changes in lithology that may correspond with coseismic uplift and subsidence over the past millennia. A 2- to 45-mm-thick bed of clean to peaty sand in sequences of tidal sediment and freshwater peat, identified in more than one-half the cores as far inland as 1.5 km, was probably deposited by the 1788 tsunami. A 14C age on Scirpus seeds, double 137Cs peaks at 2 cm and 7 cm depths (Chernobyl and 1963?), a consistent decline in 210Pb values, and our assumption of an exponential compaction rate for freshwater peat, point to a late 18th century age for the sand bed. Initial 14C ages suggest that two similar extensive sandy beds, identified
Ryan, Holly F.; von Huene, Roland; Wells, Ray E.; Scholl, David W.; Kirby, Stephen; Draut, Amy E.
During the past several years, devastating tsunamis were generated along subduction zones in Indonesia, Chile, and most recently Japan. Both the Chile and Japan tsunamis traveled across the Pacific Ocean and caused localized damage at several coastal areas in California. The question remains as to whether coastal California, in particular the California Continental Borderland, is vulnerable to more extensive damage from a far-field tsunami sourced along a Pacific subduction zone. Assuming that the coast of California is at risk from a far-field tsunami, its coastline is most exposed to a trans-Pacific tsunami generated along the eastern Aleutian-Alaska subduction zone. We present the background geologic constraints that could control a possible giant (Mw ~9) earthquake sourced along the eastern Aleutian-Alaska megathrust. Previous great earthquakes (Mw ~8) in 1788, 1938, and 1946 ruptured single segments of the eastern Aleutian-Alaska megathrust. However, in order to generate a giant earthquake, it is necessary to rupture through multiple segments of the megathrust. Potential barriers to a throughgoing rupture, such as high-relief fracture zones or ridges, are absent on the subducting Pacific Plate between the Fox and Semidi Islands. Possible asperities (areas on the megathrust that are locked and therefore subject to infrequent but large slip) are identified by patches of high moment release observed in the historical earthquake record, geodetic studies, and the location of forearc basin gravity lows. Global Positioning System (GPS) data indicate that some areas of the eastern Aleutian-Alaska megathrust, such as that beneath Sanak Island, are weakly coupled. We suggest that although these areas will have reduced slip during a giant earthquake, they are not really large enough to form a barrier to rupture. A key aspect in defining an earthquake source for tsunami generation is determining the possibility of significant slip on the updip end of the megathrust near
Case, J.E.; Barnes, D.F.; Plafker, George; Robbins, S.L.
Sedimentary and volcanic rocks of Mesozoic and early Tertiary age form a roughly arcuate pattern in and around Prince William Sound, the epicentral region of the Alaska earthquake of 1964. These rocks include the Valdez Group, a predominantly slate and graywacke sequence of Jurassic and Cretaceous age, and the Orca Group, a younger sequence of early Tertiary age. The Orca consists of a lower unit of dense-average 2.87 g per cm3 (grams per cubic centimeter) pillow basalt and greenstone intercalated with sedimentary rocks and an upper unit of lithologically variable sandstone interbedded with siltstone or argillite. Densities of the clastic rocks in both the Valdez and Orca Groups average about 2.69 g per cm3. Granitic rocks of relatively low density (2.62 g per cm3) cut the Valdez and Orca Groups at several localities. Both the Valdez and the Orca Groups were complexly folded and extensively faulted during at least three major episodes of deformation: an early period of Cretaceous or early Tertiary orogeny, a second orogeny that probably culminated in late Eocene or early Oligocene time and was accompanied or closely followed by emplacement of granitic batholiths, and a third episode of deformation that began in late Cenozoic time and continued intermittently to the present. About 500 gravity stations were established in the Prince William Sound region in conjunction with postearthquake geologic investigations. Simple Bouguer anomaly contours trend approximately parallel to the arcuate geologic structure around the sound. Bouguer anomalies decrease northward from +40 mgal (milligals) at the southwestern end of Montague Island to -70 mgal at College and Harriman Fiords. Most of this change may be interpreted as a regional gradient caused by thickening of the continental crust. Superimposed on the gradient is a prominent gravity high of as much as 65 mgal that extends from Elrington Island on the southwest, across Knight and Glacier Islands to the Ellamar Peninsula
Evans, John R.; Jensen, E. Gray; Sell, Russell; Stephens, Christopher D.; Nyman, Douglas J.; Hamilton, Robert C.; Hager, William C.
In September, 2003, the Alyeska Pipeline Service Company (APSC) and the U.S. Geological Survey (USGS) embarked on a joint effort to extract, test, and calibrate the accelerometers, amplifiers, and bandpass filters from the earthquake monitoring systems (EMS) at Pump Stations 09, 10, and 11 of the Trans-Alaska Pipeline System (TAPS). These were the three closest strong-motion seismographs to the Denali fault when it ruptured in the MW 7.9 earthquake of 03 November 2002 (22:12:41 UTC). The surface rupture is only 3.0 km from PS10 and 55.5 km from PS09 but PS11 is 124.2 km away from a small rupture splay and 126.9 km from the main trace. Here we briefly describe precision calibration results for all three instruments. Included with this report is a link to the seismograms reprocessed using these new calibrations: http://nsmp.wr.usgs.gov/data_sets/20021103_2212_taps.html Calibration information in this paper applies at the time of the Denali fault earthquake (03 November 2002), but not necessarily at other times because equipment at these stations is changed by APSC personnel at irregular intervals. In particular, the equipment at PS09, PS10, and PS11 was changed by our joint crew in September, 2003, so that we could perform these calibrations. The equipment stayed the same from at least the time of the earthquake until that retrieval, and these calibrations apply for that interval.
Schroeder, M.; Stender, V.; Jüngling, S.
Fisher, M.A.; Nokleberg, W.J.; Ratchkovski, N.A.; Pellerin, L.; Glen, J.M.; Brocher, T.M.; Booker, J.
The aftershock zone of the 3 November 2002, M = 7.9 earthquake that ruptured along the right-slip Denali fault in south-central Alaska has been investigated by using gravity and magnetic, magnetotelluric, and deep-crustal, seismic reflection data as well as outcrop geology and earthquake seismology. Strong seismic reflections from within the Alaska Range orogen north of the Denali fault dip as steeply as 25°N and extend to depths as great as 20 km. These reflections outline a relict crustal architecture that in the past 20 yr has produced little seismicity. The Denali fault is nonreflective, probably because this fault dips steeply to vertical. The most intriguing finding from geophysical data is that earthquake aftershocks occurred above a rock body, with low electrical resistivity (>10 Ω·m), that is at depths below ∼10 km. Aftershocks of the Denali fault earthquake have mainly occurred shallower than 10 km. A high geothermal gradient may cause the shallow seismicity. Another possibility is that the low resistivity results from fluids, which could have played a role in locating the aftershock zone by reducing rock friction within the middle and lower crust.
Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.
In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.
Moran, S.C.; Stihler, S.D.; Power, J.A.
On 4 March 1999, a shallow ML 5.2 earthquake occurred beneath Unimak Island in the Aleutian Arc. This earthquake was located 10-15 km west of Shishaldin Volcano, a large, frequently active basaltic-andesite stratovolcano. A Strombolian eruption began at Shishaldin roughly 1 month after the mainshock, culminating in a large explosive eruption on 19 April. We address the question of whether or not the eruption caused the mainshock by computing the Coulomb stress change caused by an inflating dike on fault planes oriented parallel to the mainshock focal mechanism. We found Coulomb stress increases of ???0.1 MPa in the region of the mainshock, suggesting that magma intrusion prior to the eruption could have caused the mainshock. Satellite and seismic data indicate that magma was moving upwards beneath Shishaldin well before the mainshock. indicating that, in an overall sense, the mainshock cannot be said to have caused the eruption. However, observations of changes at the volcano following the mainshock and several large aftershocks suggest that the earthquakes may, in turn, have influenced the course of the eruption.
Wood, Nathan J.; Schmidtlein, Mathew C.; Peters, Jeff
Pedestrian evacuation modeling for tsunami hazards typically focuses on current land-cover conditions and population distributions. To examine how post-disaster redevelopment may influence the evacuation potential of at-risk populations to future threats, we modeled pedestrian travel times to safety in Seward, Alaska, based on conditions before the 1964 Good Friday earthquake and tsunami disaster and on modern conditions. Anisotropic, path distance modeling is conducted to estimate travel times to safety during the 1964 event and in modern Seward, and results are merged with various population data, including the location and number of residents, employees, public venues, and dependent care facilities. Results suggest that modeled travel time estimates conform well to the fatality patterns of the 1964 event and that evacuation travel times have increased in modern Seward due to the relocation and expansion of port and harbor facilities after the disaster. The majority of individuals threatened by tsunamis today in Seward are employee, customer, and tourist populations, rather than residents in their homes. Modern evacuation travel times to safety for the majority of the region are less than wave arrival times for future tectonic tsunamis but greater than arrival times for landslide-related tsunamis. Evacuation travel times will likely be higher in the winter time, when the presence of snow may constrain evacuations to roads.
Describes methods to access current earthquake information from the National Earthquake Information Center. Enables students to build genuine learning experiences using real data from earthquakes that have recently occurred. (JRH)
Effects of the earthquake of March 27, 1964, on the Eklutna Hydroelectric Project, Anchorage, Alaska, with a section on television examination of earthquake damage to underground communication and electrical systems in Anchorage: Chapter A in The Alaska earthquake, March 27, 1964: effects on transportation, communications, and utilities
Logan, Malcolm H.; with a section on Television Examination of Earthquake Damage to Underground Communication and Electrical Systems in Anchorage by Burton, Lynn R.
The March 27, 1964, Alaska earthquake and its associated aftershocks caused damage requiring several million dollars worth of repair to the Eklwtna Hydroelectric Project, 34 miles northeast of Anchorage. Electric service from the Eklutna powerplant was interrupted during the early phase of the March 27 earthquake, built was restored (intermittently) until May 9,1964, when the plant was closed for inspection and repair. Water for Eklutna project is transported from Eklutna Lake to the powerplant at tidewater on Knik Arm of Cook Inlet by an underwater intake connected to a 4.46-mile tunnel penstock. The primary damage caused by the earthquake was 1at the intake structure in Eklutna Lake. No damage to the power tunnel was observed. The piles-supported powerplant and appurtenant structures, Anchorage and Palmer substations, and the transmission lines suffered minor dammage. Most damage occurred to facilities constructed on un-consolidated sediments and overburden which densified and subsided during the earthquake. Structures built on bedrock experienced little or no damage. Underground communication and electrical systems in Anchorage were examined with a small-diameter television camera to locate damaged areas requiring repair. Most of the damage was concentrated at or near valley slopes. Those parts of the systems within the major slide areas of the city were destroyed.
Examines the types of damage experienced by California State University at Northridge during the 1994 earthquake and what lessons were learned in handling this emergency are discussed. The problem of loose asbestos is addressed. (GR)
Dorr, P. M.; Gardine, L.; Tape, C.; McQuillan, P.; Cubley, J. F.; Samolczyk, M. A.; Taber, J.; West, M. E.; Busby, R.
The EarthScope Transportable Array is deploying about 260 stations in Alaska and western Canada. IRIS and EarthScope are partnering with the Alaska Earthquake Center, part of the University of Alaska's Geophysical Institute, and Yukon College to spread awareness of earthquakes in Alaska and western Canada and the benefits of the Transportable Array for people living in these regions. We provide an update of ongoing education and outreach activities in Alaska and Canada as well as continued efforts to publicize the Transportable Array in the Lower 48. Nearly all parts of Alaska and portions of western Canada are tectonically active. The tectonic and seismic variability of Alaska, in particular, requires focused attention at the regional level, and the remoteness and inaccessibility of most Alaskan and western Canadian villages and towns often makes frequent visits difficult. When a community is accessible, every opportunity to engage the residents is made. Booths at state fairs and large cultural gatherings, such as the annual convention of the Alaska Federation of Natives, are excellent venues to distribute earthquake information and to demonstrate a wide variety of educational products and web-based applications related to seismology and the Transportable Array that residents can use in their own communities. Meetings and interviews with Alaska Native Elders and tribal councils discussing past earthquakes has led to a better understanding of how Alaskans view and understand earthquakes. Region-specific publications have been developed to tie in a sense of place for residents of Alaska and the Yukon. The Alaska content for IRIS's Active Earth Monitor emphasizes the widespread tectonic and seismic features and offers not just Alaska residents, but anyone interested in Alaska, a glimpse into what is going on beneath their feet. The concerted efforts of the outreach team will have lasting effects on Alaskan and Canadian understanding of the seismic hazard and
Fisher, M.A.; Ruppert, N.A.; White, R.A.; Wilson, F.H.; Comer, D.; Sliter, R.W.; Wong, F.L.
Clustered earthquakes located 25??km northeast of Augustine Volcano began about 6??months before and ceased soon after the volcano's 2006 explosive eruption. This distal seismicity formed a dense cluster less than 5??km across, in map view, and located in depth between 11??km and 16??km. This seismicity was contemporaneous with sharply increased shallow earthquake activity directly below the volcano's vent. Focal mechanisms for five events within the distal cluster show strike-slip fault movement. Cluster seismicity best defines a plane when it is projected onto a northeast-southwest cross section, suggesting that the seismogenic fault strikes northwest. However, two major structural trends intersect near Augustine Volcano, making it difficult to put the seismogenic fault into a regional-geologic context. Specifically, interpretation of marine multichannel seismic-reflection (MCS) data shows reverse faults, directly above the seismicity cluster, that trend northeast, parallel to the regional geologic strike but perpendicular to the fault suggested by the clustered seismicity. The seismogenic fault could be a reactivated basement structure.
Thompson, K. J.; Krantz, D. H.
The Working Group on California Earthquake Probabilities (WGCEP) includes, in its introduction to earthquake rupture forecast maps, the assertion that "In daily living, people are used to making decisions based on probabilities -- from the flip of a coin (50% probability of heads) to weather forecasts (such as a 30% chance of rain) to the annual chance of being killed by lightning (about 0.0003%)."  However, psychology research identifies a large gap between lay and expert perception of risk for various hazards , and cognitive psychologists have shown in numerous studies [1,4-6] that people neglect, distort, misjudge, or misuse probabilities, even when given strong guidelines about the meaning of numerical or verbally stated probabilities . The gap between lay and expert use of probability needs to be recognized more clearly by scientific organizations such as WGCEP. This study undertakes to determine how the lay public interprets earthquake hazard information, as presented in graphical map form by the Uniform California Earthquake Rupture Forecast (UCERF), compiled by the WGCEP and other bodies including the USGS and CGS. It also explores alternate ways of presenting hazard data, to determine which presentation format most effectively translates information from scientists to public. Participants both from California and from elsewhere in the United States are included, to determine whether familiarity -- either with the experience of an earthquake, or with the geography of the forecast area -- affects people's ability to interpret an earthquake hazards map. We hope that the comparisons between the interpretations by scientific experts and by different groups of laypeople will both enhance theoretical understanding of factors that affect information transmission and assist bodies such as the WGCEP in their laudable attempts to help people prepare themselves and their communities for possible natural hazards.  Kahneman, D & Tversky, A (1979). Prospect
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Suleimani, E.; Hansen, R.; Haeussler, P.J.
We use a viscous slide model of Jiang and LeBlond (1994) coupled with nonlinear shallow water equations to study tsunami waves in Resurrection Bay, in south-central Alaska. The town of Seward, located at the head of Resurrection Bay, was hit hard by both tectonic and local landslide-generated tsunami waves during the MW 9.2 1964 earthquake with an epicenter located about 150 km northeast of Seward. Recent studies have estimated the total volume of underwater slide material that moved in Resurrection Bay during the earthquake to be about 211 million m3. Resurrection Bay is a glacial fjord with large tidal ranges and sediments accumulating on steep underwater slopes at a high rate. Also, it is located in a seismically active region above the Aleutian megathrust. All these factors make the town vulnerable to locally generated waves produced by underwater slope failures. Therefore it is crucial to assess the tsunami hazard related to local landslide-generated tsunamis in Resurrection Bay in order to conduct comprehensive tsunami inundation mapping at Seward. We use numerical modeling to recreate the landslides and tsunami waves of the 1964 earthquake to test the hypothesis that the local tsunami in Resurrection Bay has been produced by a number of different slope failures. We find that numerical results are in good agreement with the observational data, and the model could be employed to evaluate landslide tsunami hazard in Alaska fjords for the purposes of tsunami hazard mitigation. ?? Birkh??user Verlag, Basel 2009.
Lu, Zhiming; Wicks, C., Jr.; Power, J.A.; Dzurisin, D.
In March 1996 an intense swarm of volcano-tectonic earthquakes (???3000 felt by local residents, Mmax = 5.1, cumulative moment of 2.7 ??1018 N m) beneath Akutan Island in the Aleutian volcanic arc, Alaska, produced extensive ground cracks but no eruption of Akutan volcano. Synthetic aperture radar interferograms that span the time of the swarm reveal complex island-wide deformation: the western part of the island including Akutan volcano moved upward, while the eastern part moved downward. The axis of the deformation approximately aligns with new ground cracks on the western part of the island and with Holocene normal faults that were reactivated during the swarm on the eastern part of the island. The axis is also roughly parallel to the direction of greatest compressional stress in the region. No ground movements greater than 2.83 cm were observed outside the volcano's summit caldera for periods of 4 years before or 2 years after the swarm. We modeled the deformation primarily as the emplacement of a shallow, east-west trending, north dipping dike plus inflation of a deep, Mogi-type magma body beneath the volcano. The pattern of subsidence on the eastern part of the island is poorly constrained. It might have been produced by extensional tectonic strain that both reactivated preexisting faults on the eastern part of the island and facilitated magma movement beneath the western part. Alternatively, magma intrusion beneath the volcano might have been the cause of extension and subsidence in the eastern part of the island. We attribute localized subsidence in an area of active fumaroles within the Akutan caldera, by as much as 10 cm during 1992-1993 and 1996-1998, to fluid withdrawal or depressurization of the shallow hydrothermal system. Copyright 2000 by the American Geophysical Union.
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Xu, J. H.; Nie, G. Z.; Xu, X.
Acquiring disaster information quickly after an earthquake is crucial for disaster and emergency rescue management. This study examines a digital social network - an earthquake disaster information reporting network - for rapid collection of earthquake disaster information. Based on the network, the disaster information rapid collection method is expounded in this paper. The structure and components of the reporting network are introduced. Then the work principles of the reporting network are discussed, in which the rapid collection of disaster information is realised by using Global System for Mobile Communications (GSM) messages to report the disaster information and Geographic information system (GIS) to analyse and extract useful disaster information. This study introduces some key technologies for the work principles, including the methods of mass sending and receiving of SMS for disaster management, the reporting network grouping management method, brief disaster information codes, and the GIS modelling of the reporting network. Finally, a city earthquake disaster information quick reporting system is developed and with the support of this system the reporting network obtained good results in a real earthquake and earthquake drills. This method is a semi-real time disaster information collection method which extends current SMS based method and meets the need of small and some moderate earthquakes.
Ross, S.; Jones, L.; Wilson, R. I.; Bahng, B.; Barberopoulou, A.; Borrero, J. C.; Brosnan, D.; Bwarie, J.; Geist, E. L.; Johnson, L.; Kirby, S. H.; Knight, W.; Long, K.; Lynett, P. J.; Miller, K.; Mortensen, C. E.; Nicolsky, D.; Oglesby, D. D.; Perry, S. C.; Plumlee, G. S.; Porter, K. A.; Real, C. R.; Ryan, K. J.; Suleimani, E.; Thio, H. K.; Titov, V.; Wein, A. M.; Whitmore, P.; Wood, N. J.
The SAFRR Tsunami Scenario models a hypothetical but plausible tsunami, created by an Mw9.1 earthquake occurring offshore from the Alaskan peninsula, and its impacts on the California coast. We present the likely inundation areas, current velocities in key ports and harbors, physical damage and repair costs, economic consequences, environmental impacts, social vulnerability, emergency management, and policy implications for California associated with the tsunami scenario. The intended users are those who must make mitigation decisions before and rapid decisions during future tsunamis. Around a half million people would be present in the scenario's inundation area in residences, businesses, public venues, parks and beaches. Evacuation would likely be ordered for the State of California's maximum mapped tsunami inundation zone, evacuating an additional quarter million people from residences and businesses. Some island and peninsula communities would face particular evacuation challenges because of limited access options and short warning time, caused by the distance between Alaska and California. Evacuations may also be a challenge for certain dependent-care populations. One third of the boats in California's marinas could be damaged or sunk, costing at least 700 million in repairs to boats and docks, and potentially much more to address serious issues due to sediment transport and environmental contamination. Fires would likely start at many sites where fuel and petrochemicals are stored in ports and marinas. Tsunami surges and bores may travel several miles inland up coastal rivers. Debris clean-up and recovery of inundated and damaged areas will take days, months, or years depending on the severity of impacts and the available resources for recovery. The Ports of Los Angeles and Long Beach (POLA/LB) would be shut down for a miniμm of two days due to strong currents. Inundation of dry land in the ports would result in 100 million damages to cargo and additional
Gardine, L.; Dorr, P. M.; Tape, C.; McQuillan, P.; Taber, J.; West, M. E.; Busby, R. W.
The EarthScopeTransportable Array is working to locate over 260 stations in Alaska and western Canada. In this region, new tactics and partnerships are needed to increase outreach exposure. IRIS and EarthScope are partnering with the Alaska Earthquake Center, part of University of Alaska Geophysical Institute, to spread awareness of Alaska earthquakes and the benefits of the Transportable Array for Alaskans. Nearly all parts of Alaska are tectonically active. The tectonic and seismic variability of Alaska requires focused attention at the regional level, and the remoteness and inaccessibility of most Alaska villages and towns often makes frequent visits difficult. For this reason, Alaska outreach most often occurs at community events. When a community is accessible, every opportunity to engage the residents is made. Booths at state fairs and large cultural gatherings, such as the annual convention of the Alaska Federation of Natives, are excellent venues to distribute earthquake information and to demonstrate a wide variety of educational products and web-based applications related to seismology and the Transportable Array that residents can use in their own communities. Region-specific publications have been developed to tie in a sense of place for residents of Alaska. The Alaska content for IRIS's Active Earth Monitor will emphasize the widespread tectonic and seismic features and offer not just Alaska residents, but anyone interested in Alaska, a glimpse into what is going on beneath their feet. The concerted efforts of the outreach team will have lasting effects on Alaskan understanding of the seismic hazard and tectonics of the region. Efforts to publicize the presence of the Transportable Array in Alaska, western Canada, and the Lower 48 also continue. There have been recent articles published in university, local and regional newspapers; stories appearing in national and international print and broadcast media; and documentaries produced by some of the world
Loyd, R.; Walter, S.; Fenton, J.; Tubbesing, S.; Greene, M.
In the rush to remove debris after a damaging earthquake, perishable data related to a wide range of impacts on the physical, built and social environments can be lost. The California Post-Earthquake Information Clearinghouse is intended to prevent this data loss by supporting the earth scientists, engineers, and social and policy researchers who will conduct fieldwork in the affected areas in the hours and days following the earthquake to study these effects. First called for by Governor Ronald Reagan following the destructive M6.5 San Fernando earthquake in 1971, the concept of the Clearinghouse has since been incorporated into the response plans of the National Earthquake Hazard Reduction Program (USGS Circular 1242). This presentation is intended to acquaint scientists with the purpose, functions, and services of the Clearinghouse. Typically, the Clearinghouse is set up in the vicinity of the earthquake within 24 hours of the mainshock and is maintained for several days to several weeks. It provides a location where field researchers can assemble to share and discuss their observations, plan and coordinate subsequent field work, and communicate significant findings directly to the emergency responders and to the public through press conferences. As the immediate response effort winds down, the Clearinghouse will ensure that collected data are archived and made available through "lessons learned" reports and publications that follow significant earthquakes. Participants in the quarterly meetings of the Clearinghouse include representatives from state and federal agencies, universities, NGOs and other private groups. Overall management of the Clearinghouse is delegated to the agencies represented by the authors above.
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Cowen, A R; Denney, J P
On January 25, 1 week after the most devastating earthquake in Los Angeles history, the Southern California Hospital Council released the following status report: 928 patients evacuated from damaged hospitals. 805 beds available (136 critical, 669 noncritical). 7,757 patients treated/released from EDs. 1,496 patients treated/admitted to hospitals. 61 dead. 9,309 casualties. Where do we go from here? We are still waiting for the "big one." We'll do our best to be ready when Mother Nature shakes, rattles and rolls. The efforts of Los Angeles City Fire Chief Donald O. Manning cannot be overstated. He maintained department command of this major disaster and is directly responsible for implementing the fire department's Disaster Preparedness Division in 1987. Through the chief's leadership and ability to forecast consequences, the city of Los Angeles was better prepared than ever to cope with this horrendous earthquake. We also pay tribute to the men and women who are out there each day, where "the rubber meets the road." PMID:10133439
Martirosyan, A.; Hansen, R.; Robinson, M.
The ShakeMap (SM) system was developed by the USGS for generating and distributing real-time ground- shaking maps in the aftermath of significant earthquakes. SMs provide vital information within minutes after an earthquake to emergency response agencies, the media and the general public. It is also a tool to produce earthquake planning scenarios and to estimate losses from hypothetical strong earthquakes. SM production in Alaska is based on observed ground motion data (maximum peak ground accelerations and velocities of two horizontal components) and complemented by calculated values using empirical attenuation relationships. These data are collected from more than 80 broadband and 25 strong motion stations throughout the state. The real-time seismic operations in Alaska, including the SM system, are maintained at the Alaska Earthquake Information Center (AEIC) of the Geophysical Institute in Fairbanks. The earthquake parameters and waveform measurements are obtained within the Antelope seismic monitoring system. Currently, SMs are produced for events with magnitudes greater that M3.5 with at least 10 associated arrival picks. Moreover, the calculated intensity of the eligible events should be greater than 2.5 at the epicenter. With these settings, about 20 to 30 SMs are triggered in Alaska per month. The maps are generated and posted on the AEIC website 2-3 minutes after the event. The processing time mostly depends on the number of waveforms utilized in the calculation. Several SM updates may be issued for the same event as more reliable data become available. A manual run may be executed afterwards for significant events in order to utilize any additional information, such as extended source geometry or data from external sources.
Heath, Melissa Allen; Dean, Brenda
Over the past decade, catastrophic earthquakes have garnered international attention regarding the need for improving immediate and ongoing support services for disrupted communities. Following the December 26, 2004 Indonesian earthquake, the Indian Ocean tsunami was responsible for displacing millions and taking the lives of an estimated 320,000…
Vinson, T. S.; Carlson, R.; Hansen, R.; Hulsey, L.; Ma, J.; White, D.; Barnes, D.; Shur, Y.
A National Science Foundation (NSF) Small Grant Exploratory Research Grant was awarded to the University of Alaska Fairbanks to archive bedrock and ground motions and fault offsets and their effects for the October-November 2002 earthquake sequence on the Denali Fault, Alaska. The scope of work included the accumulation of all strong motion records, satellite imagery, satellite remote sensing data, aerial and ground photographs, and structural response (both measured and anecdotal) that would be useful to achieve the objective. Several interesting data sets were archived including ice cover, lateral movement of stream channels, landslides, avalanches, glacial fracturing, "felt" ground motions, and changes in water quantity and quality. The data sources may be spatially integrated to provide a comprehensive assessment of the bedrock and ground motions and fault offsets for the October-November 2002 earthquake sequence. In the aftermath of the October-November 2002 earthquake sequence on the Denali fault, the Alaskan engineering community expressed a strong interest to understand why their structures and infrastructure were not substantially damaged by the ground motions they experienced during the October-November 2002 Earthquake Sequence on the Denali Fault. The research work proposed under this NSF Grant is a necessary prerequisite to this understanding. Furthermore, the proposed work will facilitate a comparison of Denali events with the Loma Prieta and recent Kocelli and Dozce events in Turkey, all of which were associated with strike-slip faulting. Finally, the spatially integrated data will provide the basis for research work that is truly innovative. For example, is may be possible to predict the observed (1) landsliding and avalanches, (2) changes in water quantity and quality, (3) glacial fracturing, and (4) the widespread liquefaction and lateral spreading, which occurred along the Tok cutoff and Northway airport, with the bedrock and ground motions and
Displacement waveforms and high-frequency acceleration envelopes from stations at distances of 3-300 km were inverted to determine the source process of the M 7.9 Denali fault earthquake. Fitting the initial portion of the displacement waveforms indicates that the earthquake started with an oblique thrust subevent (subevent # 1) with an east-west-striking, north-dipping nodal plane consistent with the observed surface rupture on the Susitna Glacier fault. Inversion of the remainder of the waveforms (0.02-0.5 Hz) for moment release along the Denali and Totschunda faults shows that rupture proceeded eastward on the Denali fault, with two strike-slip subevents (numbers 2 and 3) centered about 90 and 210 km east of the hypocenter. Subevent 2 was located across from the station at PS 10 (Trans-Alaska Pipeline Pump Station #10) and was very localized in space and time. Subevent 3 extended from 160 to 230 km east of the hypocenter and had the largest moment of the subevents. Based on the timing between subevent 2 and the east end of subevent 3, an average rupture velocity of 3.5 km/sec, close to the shear wave velocity at the average rupture depth, was found. However, the portion of the rupture 130-220 km east of the epicenter appears to have an effective rupture velocity of about 5.0 km/ sec, which is supershear. These two subevents correspond approximately to areas of large surface offsets observed after the earthquake. Using waveforms of the M 6.7 Nenana Mountain earthquake as empirical Green's functions, the high-frequency (1-10 Hz) envelopes of the M 7.9 earthquake were inverted to determine the location of high-frequency energy release along the faults. The initial thrust subevent produced the largest high-frequency energy release per unit fault length. The high-frequency envelopes and acceleration spectra (>0.5 Hz) of the M 7.9 earthquake can be simulated by chaining together rupture zones of the M 6.7 earthquake over distances from 30 to 180 km east of the
Nicolsky, D.; Suleimani, E.; Koehler, R. D.
The Alaska Earthquake Information Center (AEIC) participates in the National Tsunami Hazard Mitigation Program by evaluating and mapping potential tsunami inundation of coastal Alaska. We evaluate potential tsunami hazards for several coastal communities near the epicenter of the 1964 Great Alaska Earthquake and numerically model the extent of their inundation due to tsunamis generated by earthquake and landslide sources. Tsunami scenarios include a repeat of the tsunami triggered by the 1964 Great Alaska Earthquake, as well as hypothetical tsunamis generated by an extended 1964 rupture, a Cascadia megathrust earthquake, earthquakes from the Prince William Sound and Kodiak asperities of the 1964 rupture, and a hypothetical Tohoku-type rupture in the Gulf of Alaska region. Local underwater landslide events in several communities are also considered as credible tsunamigenic scenarios. We perform simulations for each of the source scenarios using AEIC's recently developed and tested numerical model of tsunami wave propagation and runup. Results of the numerical modeling are verified by simulating the tectonic and landslide-generated tsunamis observed during the 1964 earthquake. The tsunami scenarios are intended to provide guidance to local emergency management agencies in tsunami hazard assessment, evacuation planning, and public education for reducing future casualties and damage from tsunamis. During the 1964 earthquake, locally generated waves of unknown origin were identified at several communities, located in the western part of Prince William Sound. The waves appeared shortly after the shaking began and swept away most of the buildings while the shaking continued. We model the tectonic tsunami assuming different tsunami generation processes and claim the importance of including both vertical and horizontal displacement into the 1964 tsunami generation process.
This paper first evaluates the earthquake prediction method (1999 ) used by US Geological Survey as the lead example and reviews also the recent models. Secondly, points out the ongoing debate on the predictability of earthquake recurrences and lists the main claims of both sides. The traditional methods and the "frequentist" approach used in determining the earthquake probabilities cannot end the complaints that the earthquakes are unpredictable. It is argued that the prevailing "crisis" in seismic research corresponds to the Pre-Maxent Age of the current situation. The period of Kuhnian "Crisis" should give rise to a new paradigm based on the Information-Theoric framework including the inverse problem, Maxent and Bayesian methods. Paper aims to show that the information- theoric methods shall provide the required "Methodica Firma" for the earthquake prediction models.
Patton, John M.; Ketchum, David C.; Guy, Michelle R.
This document provides an overview of the capabilities, design, and use cases of the data acquisition and archiving subsystem at the U.S. Geological Survey National Earthquake Information Center. The Edge and Continuous Waveform Buffer software supports the National Earthquake Information Center’s worldwide earthquake monitoring mission in direct station data acquisition, data import, short- and long-term data archiving, data distribution, query services, and playback, among other capabilities. The software design and architecture can be configured to support acquisition and (or) archiving use cases. The software continues to be developed in order to expand the acquisition, storage, and distribution capabilities.
Bender, Adrian M; Witter, Robert C.; Rogers, Matthew
During the Mw 9.2 1964 great Alaska earthquake, Turnagain Arm near Girdwood, Alaska subsided 1.7 ± 0.1 m based on pre- and postearthquake leveling. The coseismic subsidence in 1964 caused equivalent sudden relative sea-level (RSL) rise that is stratigraphically preserved as mud-over-peat contacts where intertidal silt buried peaty marsh surfaces. Changes in intertidal microfossil assemblages across these contacts have been used to estimate subsidence in 1964 by applying quantitative microfossil transfer functions to reconstruct corresponding RSL rise. Here, we review the use of organic stable C and N isotope values and Corg:Ntot ratios as alternative proxies for reconstructing coseismic RSL changes, and report independent estimates of subsidence in 1964 by using δ13C values from intertidal sediment to assess RSL change caused by the earthquake. We observe that surface sediment δ13C values systematically decrease by ∼4‰ over the ∼2.5 m increase in elevation along three 60- to 100-m-long transects extending from intertidal mud flat to upland environments. We use a straightforward linear regression to quantify the relationship between modern sediment δ13C values and elevation (n = 84, R2 = 0.56). The linear regression provides a slope–intercept equation used to reconstruct the paleoelevation of the site before and after the earthquake based on δ13C values in sandy silt above and herbaceous peat below the 1964 contact. The regression standard error (average = ±0.59‰) reflects the modern isotopic variability at sites of similar surface elevation, and is equivalent to an uncertainty of ±0.4 m elevation with respect to Mean Higher High Water. To reduce potential errors in paleoelevation and subsidence estimates, we analyzed multiple sediment δ13C values in nine cores on a shore-perpendicular transect at Bird Point. Our method estimates 1.3 ± 0.4 m of coseismic RSL rise across the 1964 contact by taking the arithmetic mean of the
Wald, David J.; Hayes, Gavin P.; Benz, Harley M.; Earle, Paul; Briggs, Richard W.
The M 9.0 11 March 2011 Tohoku, Japan, earthquake and associated tsunami near the east coast of the island of Honshu caused tens of thousands of deaths and potentially over one trillion dollars in damage, resulting in one of the worst natural disasters ever recorded. The U.S. Geological Survey National Earthquake Information Center (USGS NEIC), through its responsibility to respond to all significant global earthquakes as part of the National Earthquake Hazards Reduction Program, quickly produced and distributed a suite of earthquake information products to inform emergency responders, the public, the media, and the academic community of the earthquake's potential impact and to provide scientific background for the interpretation of the event's tectonic context and potential for future hazard. Here we present a timeline of the NEIC response to this devastating earthquake in the context of rapidly evolving information emanating from the global earthquake-response community. The timeline includes both internal and publicly distributed products, the relative timing of which highlights the inherent tradeoffs between the requirement to provide timely alerts and the necessity for accurate, authoritative information. The timeline also documents the iterative and evolutionary nature of the standard products produced by the NEIC and includes a behind-the-scenes look at the decisions, data, and analysis tools that drive our rapid product distribution.
Amato, A.; Cultrera, G.; Margheriti, L.; Nostro, C.; Selvaggi, G.; INGVterremoti Team
A devastating earthquake had been predicted for May 11, 2011 in Rome. This prediction was never released officially by anyone, but it grew up in the Internet and was amplified by media. It was erroneously ascribed to Raffaele Bendandi, an Italian self-taught natural scientist who studied planetary motions. Indeed, around May 11, 2011, a planetary alignment was really expected and this contributed to give credibility to the earthquake prediction among people. During the previous months, INGV was overwhelmed with requests for information about this supposed prediction by Roman inhabitants and tourists. Given the considerable mediatic impact of this expected earthquake, INGV decided to organize an Open Day in its headquarter in Rome for people who wanted to learn more about the Italian seismicity and the earthquake as natural phenomenon. The Open Day was preceded by a press conference two days before, in which we talked about this prediction, we presented the Open Day, and we had a scientific discussion with journalists about the earthquake prediction and more in general on the real problem of seismic risk in Italy. About 40 journalists from newspapers, local and national tv's, press agencies and web news attended the Press Conference and hundreds of articles appeared in the following days, advertising the 11 May Open Day. The INGV opened to the public all day long (9am - 9pm) with the following program: i) meetings with INGV researchers to discuss scientific issues; ii) visits to the seismic monitoring room, open 24h/7 all year; iii) guided tours through interactive exhibitions on earthquakes and Earth's deep structure; iv) lectures on general topics from the social impact of rumors to seismic risk reduction; v) 13 new videos on channel YouTube.com/INGVterremoti to explain the earthquake process and give updates on various aspects of seismic monitoring in Italy; vi) distribution of books and brochures. Surprisingly, more than 3000 visitors came to visit INGV
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Perry, S.; Jordan, T.
Our undergraduate research program, SCEC/UseIT, an NSF Research Experience for Undergraduates site, provides software for earthquake researchers and educators, movies for outreach, and ways to strengthen the technical career pipeline. SCEC/UseIT motivates diverse undergraduates towards science and engineering careers through team-based research in the exciting field of earthquake information technology. UseIT provides the cross-training in computer science/information technology (CS/IT) and geoscience needed to make fundamental progress in earthquake system science. Our high and increasing participation of women and minority students is crucial given the nation"s precipitous enrollment declines in CS/IT undergraduate degree programs, especially among women. UseIT also casts a "wider, farther" recruitment net that targets scholars interested in creative work but not traditionally attracted to summer science internships. Since 2002, SCEC/UseIT has challenged 79 students in three dozen majors from as many schools with difficult, real-world problems that require collaborative, interdisciplinary solutions. Interns design and engineer open-source software, creating increasingly sophisticated visualization tools (see "SCEC-VDO," session IN11), which are employed by SCEC researchers, in new curricula at the University of Southern California, and by outreach specialists who make animated movies for the public and the media. SCEC-VDO would be a valuable tool for research-oriented professional development programs.
Scott, C. A.; Goldberg, M.
The National Weather Service (NWS), Alaska Region (AR) provides warnings, forecasts and information for an area greater than 20% of the size of the continental United States. This region experiences an incredible diversity of weather phenomena, yet ironically is one of the more data-sparse areas in the world. Polar orbiting satellite-borne sensors offer one of the most cost effective means of gaining repetitive information over this data-sparse region to provide insight on Alaskan weather and the environment on scales ranging from synoptic to mesoscale in a systematic manner. Because of Alaska's high latitude location, polar orbiting satellites can provide coverage about every two hours at high resolution. The Suomi National Polar-orbiting Partnership (S-NPP) Satellite, equipped with a new generation of satellite sensors to better monitor, detect, and track weather and the environment was launched October 2011. Through partnership through the with NESDIS JPSS, the University of Alaska - Geographical Information Network of Alaska (GINA), the NWS Alaska Region was able to gain timely access to the Visible Infrared Imaging Radiometer Suite (VIIRS) imagery from S-NPP. The imagery was quickly integrated into forecast operations across the spectrum of NWS Alaska areas of responsibility. The VIIRS has provided a number of new or improved capabilities for detecting low cloud/fog, snow cover, volcanic ash, fire hotspots/smoke, flooding due to river ice break up, and sea ice and ice-free passages. In addition the Alaska Region has successfully exploited the 750 m spatial resolution of the VIIRS/Near Constant Contrast (NCC) low-light visible measurements. Forecasters have also begun the integration of NOAA Unique Cross-track Infrared Sounder (CrIS)/Advanced Technology Microwave Sounder (ATMS) Processing System (NUCAPS) Soundings in AWIPS-II operations at WFO Fairbanks and Anchorage, the Alaska Aviation Weather Unit (AAWU) and the Alaska Region, Regional Operations Center (ROC
When Eric Calais, professor of geophysics in Purdue University's Department of Earth and Atmospheric Sciences, first learned about the 12 January strikeslip earthquake along a portion of the Enriquillo-Plantain Garden fault zone (EPGFZ) in Haiti, he knew right away that it would be a shallow event and a large event, very close to the capital city of Port-au-Prince. Having worked in Haiti, he also was aware that the poor nation lacks seismic and building construction codes. “My immediate reaction was, ‘This is going to be a total nightmare and a huge disaster for Haiti,’” Calais, who also is a researcher at the French National Center for Scientific Research, told Eos. The main earthquake, currently estimated at magnitude 7.0, occurred at 2153:10 UTC at a depth of 13 kilometers, just 25 kilometers outside of Port-au-Prince, the U.S. Geological Survey (USGS) reports. Since then, there have been dozens of aftershocks, many of them above magnitude 5.0; these aftershocks could continue for weeks or even months, according to USGS (see Figure 1). In recent decades, there had not been a major earthquake along the approximately 600-kilometer-long EPGFZ (named after the end points in Jamaica and the Dominican Republic), although seismologists indicate that large earthquakes in 1860, 1770, and earlier likely originated along that system.
Chen, Peng; Wu, Jian; Liu, Yaolin; Wang, Jing
At present, the extraction of earthquake disaster information from remote sensing data relies on visual interpretation. However, this technique cannot effectively and quickly obtain precise and efficient information for earthquake relief and emergency management. Collapsed buildings in the town of Zipingpu after the Wenchuan earthquake were used as a case study to validate two kinds of rapid extraction methods for earthquake-collapsed building information based on pixel-oriented and object-oriented theories. The pixel-oriented method is based on multi-layer regional segments that embody the core layers and segments of the object-oriented method. The key idea is to mask layer by layer all image information, including that on the collapsed buildings. Compared with traditional techniques, the pixel-oriented method is innovative because it allows considerably rapid computer processing. As for the object-oriented method, a multi-scale segment algorithm was applied to build a three-layer hierarchy. By analyzing the spectrum, texture, shape, location, and context of individual object classes in different layers, the fuzzy determined rule system was established for the extraction of earthquake-collapsed building information. We compared the two sets of results using three variables: precision assessment, visual effect, and principle. Both methods can extract earthquake-collapsed building information quickly and accurately. The object-oriented method successfully overcomes the pepper salt noise caused by the spectral diversity of high-resolution remote sensing data and solves the problem of same object, different spectrums and that of same spectrum, different objects. With an overall accuracy of 90.38%, the method achieves more scientific and accurate results compared with the pixel-oriented method (76.84%). The object-oriented image analysis method can be extensively applied in the extraction of earthquake disaster information based on high-resolution remote sensing.
Page, G. Andrew; Hill, Melissa
Information, communication, and educational technologies hold promise to connect geographically isolated rural communities, offering adults greater access to educational, financial, and numerous other resources. The Internet and computer-based network technologies are often seen as remedies for communities in economic decline, but they also have…
Bossu, Rémy; Steed, Robert; Mazet-Roux, Gilles; Roussel, Fréderic; Caroline, Etivant
Historical earthquakes are only known to us through written recollections and so seismologists have a long experience of interpreting the reports of eyewitnesses, explaining probably why seismology has been a pioneer in crowdsourcing and citizen science. Today, Internet has been transforming this situation; It can be considered as the digital nervous system comprising of digital veins and intertwined sensors that capture the pulse of our planet in near real-time. How can both seismology and public could benefit from this new monitoring system? This paper will present the strategy implemented at Euro-Mediterranean Seismological Centre (EMSC) to leverage this new nervous system to detect and diagnose the impact of earthquakes within minutes rather than hours and how it transformed information systems and interactions with the public. We will show how social network monitoring and flashcrowds (massive website traffic increases on EMSC website) are used to automatically detect felt earthquakes before seismic detections, how damaged areas can me mapped through concomitant loss of Internet sessions (visitors being disconnected) and the benefit of collecting felt reports and geolocated pictures to further constrain rapid impact assessment of global earthquakes. We will also describe how public expectations within tens of seconds of ground shaking are at the basis of improved diversified information tools which integrate this user generated contents. A special attention will be given to LastQuake, the most complex and sophisticated Twitter QuakeBot, smartphone application and browser add-on, which deals with the only earthquakes that matter for the public: the felt and damaging earthquakes. In conclusion we will demonstrate that eyewitnesses are today real time earthquake sensors and active actors of rapid earthquake information.
Jolly, Arthur D.; Power, John A.; Stihler, Scott D.; Rao, Lalitha N.; Davidson, Gail; Paskievitch, John F.; Estes, Steve; Lahr, John C.
The 1992 eruptions at Mount Spurr's Crater Peak vent provided the highlight of the catalog period. The crisis included three sub-plinian eruptions, which occurred on June 27, August 18, and September 16-17, 1992. The three eruptions punctuated a complex seismic sequence which included volcano-tectonic (VT) earthquakes, tremor, and both deep and shallow long period (LP) earthquakes. The seismic sequence began on August 18, 1991, with a small swarm of volcano-tectonic events beneath Crater Peak, and spread throughout the volcanic complex by November of the same year. Elevated levels of seismicity persisted at Mount Spurr beyond the catalog time period.
de Rubeis, Valerio; Sbarra, Paola; Sebaste, Beppe; Tosi, Patrizia
The experience of collection of data on earthquake effects and diffusion of information to people, carried on through the site "haisentitoilterremoto.it" (didyoufeelit) managed by the Istituto Nazionale di Geofisica e Vulcanologia (INGV), has evidenced a constantly growing interest by Italian citizens. Started in 2007, the site has collected more than 520,000 compiled intensity questionnaires, producing intensity maps of almost 6,000 earthquakes. One of the most peculiar feature of this experience is constituted by a bi-directional information exchange. Every person can record observed effects of the earthquake and, at the same time, look at the generated maps. Seismologists, on the other side, can find each earthquake described in real time through its effects on the whole territory. In this way people, giving punctual information, receive global information from the community, mediated and interpreted by seismological knowledge. The relationship amongst seismologists, mass media and civil society is, thus, deep and rich. The presence of almost 20,000 permanent subscribers distributed on the whole Italian territory, alerted in case of earthquake, has reinforced the participation: the subscriber is constantly informed by the seismologists, through e-mail, about events occurred in his-her area, even if with very small magnitude. The "alert" service provides the possibility to remember that earthquakes are a phenomenon continuously present, on the other hand it shows that high magnitude events are very rare. This kind of information is helpful as it is fully complementary to that one given by media. We analyze the effects of our activity on society and mass media. The knowledge of seismic phenomena is present in each person, having roots on fear, idea of death and destruction, often with the deep belief of very rare occurrence. This position feeds refusal and repression. When a strong earthquake occurs, surprise immediately changes into shock and desperation. A
Suleimani, E.; Nicolsky, D.J.; Haeussler, P.J.; Hansen, R.
We apply a recently developed and validated numerical model of tsunami propagation and runup to study the inundation of Resurrection Bay and the town of Seward by the 1964 Alaska tsunami. Seward was hit by both tectonic and landslide-generated tsunami waves during the Mw 9.2 1964 mega thrust earthquake. The earthquake triggered a series of submarine mass failures around the fjord, which resulted in land sliding of part of the coastline into the water, along with the loss of the port facilities. These submarine mass failures generated local waves in the bay within 5 min of the beginning of strong ground motion. Recent studies estimate the total volume of underwater slide material that moved in Resurrection Bay to be about 211 million m3 (Haeussler et al. in Submarine mass movements and their consequences, pp 269-278, 2007). The first tectonic tsunami wave arrived in Resurrection Bay about 30 min after the main shock and was about the same height as the local landslide-generated waves. Our previous numerical study, which focused only on the local land slide generated waves in Resurrection Bay, demonstrated that they were produced by a number of different slope failures, and estimated relative contributions of different submarine slide complexes into tsunami amplitudes (Suleimani et al. in Pure Appl Geophys 166:131-152, 2009). This work extends the previous study by calculating tsunami inundation in Resurrection Bay caused by the combined impact of landslide-generated waves and the tectonic tsunami, and comparing the composite inundation area with observations. To simulate landslide tsunami runup in Seward, we use a viscous slide model of Jiang and LeBlond (J Phys Oceanogr 24(3):559-572, 1994) coupled with nonlinear shallow water equations. The input data set includes a high resolution multibeam bathymetry and LIDAR topography grid of Resurrection Bay, and an initial thickness of slide material based on pre- and post-earthquake bathymetry difference maps. For
McBride, S.; Tilley, E. N.; Johnston, D. M.; Becker, J.; Orchiston, C.
This research evaluates the public education earthquake information prior to the Canterbury Earthquake sequence (2010-present), and examines communication learnings to create recommendations for improvement in implementation for these types of campaigns in future. The research comes from a practitioner perspective of someone who worked on these campaigns in Canterbury prior to the Earthquake Sequence and who also was the Public Information Manager Second in Command during the earthquake response in February 2011. Documents, specifically those addressing seismic risk, that were created prior to the earthquake sequence, were analyzed, using a "best practice matrix" created by the researcher, for how closely these aligned to best practice academic research. Readability tests and word counts are also employed to assist with triangulation of the data as was practitioner involvement. This research also outlines the lessons learned by practitioners and explores their experiences in regards to creating these materials and how they perceive these now, given all that has happened since the inception of the booklets. The findings from the research showed these documents lacked many of the attributes of best practice. The overly long, jargon filled text had little positive outcome expectancy messages. This probably would have failed to persuade anyone that earthquakes were a real threat in Canterbury. Paradoxically, it is likely these booklets may have created fatalism in publics who read the booklets. While the overall intention was positive, for scientists to explain earthquakes, tsunami, landslides and other risks to encourage the public to prepare for these events, the implementation could be greatly improved. This final component of the research highlights points of improvement for implementation for more successful campaigns in future. The importance of preparedness and science information campaigns can be not only in preparing the population but also into development of
Following the 2010 Haiti earthquake, more than two million people moved to temporary camps, most of which arose spontaneously in the days after the earthquake. This study focuses on the material assistance people in five Port-au-Prince camps reported receiving, noting the differences between assistance from formal aid agencies and from 'informal' sources such as family. Seven weeks after the earthquake, 32% of camp dwellers reported receiving no assistance whatsoever; 55% had received formal aid, typically a tent or tarpaulins; and 40% had received informal aid, usually in the form of cash transfers from family living abroad. While people were grateful for any material aid, cash was more frequently considered timely and more effective than aid-in-kind. Should this study be indicative of the greater displaced population, aid agencies should consider how they might make better use of cash transfers as an aid modality. PMID:24601934
Lu, Zhiming; Wicks, C., Jr.; Kwoun, O.; Power, J.A.; Dzurisin, D.
In March 1996, an intense earthquake swarm beneath Akutan Island, Alaska, was accompanied by extensive ground cracking but no eruption of Akutan volcano. Radar interferograms produced from L-band JERS-1 and C-band ERS-1/2 images show uplift associated with the swarm by as much as 60 cm on the western part of the island. The JERS-1 interferogram has greater coherence, especially in areas with loose surface material or thick vegetation. It also shows subsidence of similar magnitude on the eastern part of the island and displacements along faults reactivated during the swarm. The axis of uplift and subsidence strikes about N70??W, which is roughly parallel to a zone of fresh cracks on the northwest flank of the volcano, to normal faults that cut the island and to the inferred maximum compressive stress direction. A common feature of models that fit the deformation is the emplacement of a shallow dike along this trend beneath the northwest flank of the volcano. Both before and after the swarm, the northwest flank was uplifted 5-20 mm/year relative to the southwest flank, probably by magma intrusion. The zone of fresh cracks subsided about 20 mm during 1996-1997 and at lesser rates thereafter, possibly because of cooling and degassing of the intrusion. ?? 2005 CASI.
Arnold, Robert D.; And Others
Pursuant to the Native land claims within Alaska, this compilation of background data and interpretive materials relevant to a fair resolution of the Alaska Native problem seeks to record data and information on the Native peoples; the land and resources of Alaska and their uses by the people in the past and present; land ownership; and future…
Tarr, A.; Benz, H.; Earle, P.; Wald, D. J.
Earthquake Summary Posters (ESP's), a new product of the U.S. Geological Survey's Earthquake Program, are produced at the National Earthquake Information Center (NEIC) in Golden. The posters consist of rapidly-generated, GIS-based maps made following significant earthquakes worldwide (typically M>7.0, or events of significant media/public interest). ESP's consolidate, in an attractive map format, a large-scale epicentral map, several auxiliary regional overviews (showing tectonic and geographical setting, seismic history, seismic hazard, and earthquake effects), depth sections (as appropriate), a table of regional earthquakes, and a summary of the reional seismic history and tectonics. The immediate availability of the latter text summaries has been facilitated by the availability of Rapid, Accurate Tectonic Summaries (RATS) produced at NEIC and posted on the web following significant events. The rapid production of ESP's has been facilitated by generating, during the past two years, regional templates for tectonic areas around the world by organizing the necessary spatially-referenced data for the map base and the thematic layers that overlay the base. These GIS databases enable scripted Arc Macro Language (AML) production of routine elements of the maps (for example background seismicity, tectonic features, and probabilistic hazard maps). However, other elements of the maps are earthquake-specific and are produced manually to reflect new data, earthquake effects, and special characteristics. By the end of this year, approximately 85% of the Earth's seismic zones will be covered for generating future ESP's. During the past year, 13 posters were completed, comparable to the yearly average expected for significant earthquakes. Each year, all ESPs will be published on a CD in PDF format as an Open-File Report. In addition, each is linked to the special event earthquake pages on the USGS Earthquake Program web site (http://earthquake.usgs.gov). Although three formats
The 2010 earthquake in Haiti, which killed an estimated 316,000 people, offered many lessons in mass-fatality management (MFM). The dissertation defined MFM in seeking information and in recovery, preservation, identification, and disposition of human remains. Specifically, it examined how mass fatalities were managed in Haiti, how affected…
Praet, Nore; Moernaut, Jasper; Van Daele, Maarten; Kempf, Philipp; Haeussler, Peter; Strupler, Michael; De Batist, Marc
On March 27, 1964, the "Good Friday" Earthquake ruptured an 800 km-long segment of the Alaskan-Aleutian megathrust, representing the largest measured earthquake in North America (Mw 9.2). Recurrence rates of such megathrust earthquakes are typically in the order of hundreds of years. The development of a reliable assessment of seismic hazards evidently requires statistically much more robust earthquake recurrence data. For this, high-quality paleoseismological records are necessary, which are able to extend the historical evidence much further back in time. The current knowledge of the paleoseismicity along the megathrust segment around Prince William Sound is inferred from records of abrupt changes in coastal elevation. Lake sediments can also produce excellent paleoseismological records. Seismically induced subaquatic landslides generate distinct resedimentation deposits that are interbedded in between the background sediments. During a reconnaissance survey in 2012, we collected short cores and high-resolution seismic data in several glacial lakes in Southern Alaska. The short gravity cores reveal a clear sedimentary imprint of the 1964 Earthquake in different sub-basins of the investigated lakes, and the seismic profiles show the presence of older mass-wasting deposits with similar large volumes. Multiple landslide deposits and associated turbidites at several stratigraphic levels imply that these deposits were also triggered by strong earthquake shaking. The length (i.e. entire Holocene) and high-resolution chronology (i.e. Pb/Cs data reveal that the core laminations represent varves) of the lacustrine record will allow to generate a unique, high-quality dataset of megathrust earthquake recurrences along the Prince William Sound segment of the Alaskan-Aleutian subduction zone. In winter of 2014, long cores (ca. 15 meters) will be taken at key locations in Skilak Lake, Eklutna Lake and possibly Kenai Lake. Analyzing and dating these sediment cores will make it
Aagaard, B.T.; Anderson, G.; Hudnut, K.W.
We use three-dimensional dynamic (spontaneous) rupture models to investigate the nearly simultaneous ruptures of the Susitna Glacier thrust fault and the Denali strike-slip fault. With the 1957 Mw 8.3 Gobi-Altay, Mongolia, earthquake as the only other well-documented case of significant, nearly simultaneous rupture of both thrust and strike-slip faults, this feature of the 2002 Denali fault earthquake provides a unique opportunity to investigate the mechanisms responsible for development of these large, complex events. We find that the geometry of the faults and the orientation of the regional stress field caused slip on the Susitna Glacier fault to load the Denali fault. Several different stress orientations with oblique right-lateral motion on the Susitna Glacier fault replicate the triggering of rupture on the Denali fault about 10 sec after the rupture nucleates on the Susitna Glacier fault. However, generating slip directions compatible with measured surface offsets and kinematic source inversions requires perturbing the stress orientation from that determined with focal mechanisms of regional events. Adjusting the vertical component of the principal stress tensor for the regional stress field so that it is more consistent with a mixture of strike-slip and reverse faulting significantly improves the fit of the slip-rake angles to the data. Rotating the maximum horizontal compressive stress direction westward appears to improve the fit even further.
Moran, Edward H.
The report contains environmental and urban geographic information system data for 14 sites in 5 watersheds in Anchorage, Alaska. These sites were examined during summer in 1999 and 2000 to determine effects of urbanization on water quality. The data sets are Environmental Systems Research Institute, Inc., shapefiles, coverages, and images. Also included are an elevation grid and a triangulated irregular network. Although the data are intended for users with advanced geographic information system capabilities, simple images of the data also are available. ArcView? 3.2 project, an ArcGIS? project, and 16 ArcExplorer2? projects are linked to the PDF file based report. Some of these coverages are large files over 10 MB. The largest coverage, impervious cover, is 208 MB.
Context: Damages and loss of life sustained during an earthquake results from falling structures and flying glass and objects. To address these and other problems, new information technology and systems as a means can improve crisis management and crisis response. The most important factor for managing the crisis depends on our readiness before disasters by useful data. Aims: This study aimed to determine the Earthquake Information Management System (EIMS) in India, Afghanistan and Iran, and describe how we can reduce destruction by EIMS in crisis management. Materials and Methods: This study was an analytical comparison in which data were collected by questionnaire, observation and checklist. The population was EIMS in selected countries. Sources of information were staff in related organizations, scientific documentations and Internet. For data analysis, Criteria Rating Technique, Delphi Technique and descriptive methods were used. Results: Findings showed that EIMS in India (Disaster Information Management System), Afghanistan (Management Information for Natural Disasters) and Iran are decentralized. The Indian state has organized an expert group to inspect issues about disaster decreasing strategy. In Iran, there was no useful and efficient EIMS to evaluate earthquake information. Conclusions: According to outcomes, it is clear that an information system can only influence decisions if it is relevant, reliable and available for the decision-makers in a timely fashion. Therefore, it is necessary to reform and design a model. The model contains responsible organizations and their functions. PMID:23555130
Waller, Roger M.; Stanley, Kirk W.
The March 27, 1964, earthquake shook the Homer area for about 3 minutes. Land effects consisted of a 2- to 6-foot subsidence of the mainland and Homer Spit, one earthflow at the mouth of a canyon, several landslides on the Homer escarpment and along the sea bluffs, and minor fissuring of the ground, principally at the edges of bluffs and on Homer Spit. Hydrologic effects consisted of at least one and possibly two submarine landslides at the end of the spit, seiche waves in Kachemak Bay, ice breakage on Beluga Lake, sanding of wells, and a temporary loss of water in some wells. Seismic damage to the community was light in comparison with that of other communities closer to the epicenter. One submarine landslide, however, took out most of the harbor breakwater. The greatest damage was due to the subsidence of the spit, both tectonically (2–3 ft) and by differential compaction or lateral spreading (an additional 1–4 ft). Higher tides now flood much of the spit. The harbor and dock had to be replaced, and buildings on the end of the spit had to be elevated. Protection works for other buildings and the highway were needed. These works included application of fill to raise the highway and parts of the spit above high tides. Reconstruction costs and disaster loans totaled about $2½ million, but this amount includes added improvement costs over preexisting values. Homer Spit in particular and the Homer area in general rank as areas where precautions must be taken in selecting building sites. The hazards of landslides, earthflows, compaction and submarine slumping—all of which might be triggered by an earthquake—should be considered in site selection. In plan, Homer Spit resembles a scimitar with its curving blade pointed seaward. It is about 4 miles long and as much as 1,500 feet wide. The spit is composed largely of gravel intermixed with some sand. After the earthquake and the resulting tectonic subsidence and compaction, much of the spit was below high
Welling, L. A.; Winfree, R.; Mow, J.
Climate change presents unprecedented challenges for managing natural and cultural resources into the future. Impacts are expected to be highly consequential but specific effects are difficult to predict, requiring a flexible process for adaptation planning that is tightly coupled to climate science delivery systems. Scenario planning offers a tool for making science-based decisions under uncertainty. The National Park Service (NPS) is working with the Department of the Interior Climate Science Centers (CSCs), the NOAA Regional Integrated Science and Assessment teams (RISAs), and other academic, government, non-profit, and private partners to develop and apply scenarios to long-range planning and decision frameworks. In April 2012, Alaska became the first region of the NPS to complete climate change scenario planning for every national park, preserve, and monument. These areas, which collectively make up two-thirds of the total area of the NPS, are experiencing visible and measurable effects attributable to climate change. For example, thawing sea ice, glaciers and permafrost have resulted in coastal erosion, loss of irreplaceable cultural sites, slope failures, flooding of visitor access routes, and infrastructure damage. With higher temperatures and changed weather patterns, woody vegetation has expanded into northern tundra, spruce and cedar diebacks have occurred in southern Alaska, and wildland fire severity has increased. Working with partners at the Alaska Climate Science Center and the Scenario Network for Alaska Planning the NPS integrates quantitative, model-driven data with qualitative, participatory techniques to scenario creation. The approach enables managers to access and understand current climate change science in a form that is relevant for their decision making. Collaborative workshops conducted over the past two years grouped parks from Alaska's southwest, northwest, southeast, interior and central areas. The emphasis was to identify and connect
Cua, G. B.; Gasparini, P.; Giardini, D.; Zschau, J.; Filangieri, A. R.; Reakt Wp7 Team
The primary objective of European FP7 project REAKT (Strategies and Tools for Real-Time Earthquake Risk Reduction) is to improve the efficiency of real-time earthquake risk mitigation methods and their capability of protecting structures, infrastructures, and populations. REAKT aims to address the issues of real-time earthquake hazard and response from end-to-end, with efforts directed along the full spectrum of methodology development in earthquake forecasting, earthquake early warning, and real-time vulnerability systems, through optimal decision-making, and engagement and cooperation of scientists and end users for the establishment of best practices for use of real-time information. Twelve strategic test cases/end users throughout Europe have been selected. This diverse group of applications/end users includes civil protection authorities, railway systems, hospitals, schools, industrial complexes, nuclear plants, lifeline systems, national seismic networks, and critical structures. The scale of target applications covers a wide range, from two school complexes in Naples, to individual critical structures, such as the Rion Antirion bridge in Patras, and the Fatih Sultan Mehmet bridge in Istanbul, to large complexes, such as the SINES industrial complex in Portugal and the Thessaloniki port area, to distributed lifeline and transportation networks and nuclear plants. Some end-users are interested in in-depth feasibility studies for use of real-time information and development of rapid response plans, while others intend to install real-time instrumentation and develop customized automated control systems. From the onset, REAKT scientists and end-users will work together on concept development and initial implementation efforts using the data products and decision-making methodologies developed with the goal of improving end-user risk mitigation. The aim of this scientific/end-user partnership is to ensure that scientific efforts are applicable to operational
Bignami, Christian; Stramondo, Salvatore; Pierdicca, Nazzareno
The APhoRISM - Advanced PRocedure for volcanIc and Seismic Monitoring - project is an FP7 funded project, which aims at developing and testing two new methods to combine Earth Observation satellite data from different sensors, and ground data for seismic and volcanic risk management. The objective is to demonstrate that this two types of data, appropriately managed and integrated, can provide new improved products useful for seismic and volcanic crisis management. One of the two methods deals with earthquakes, and it concerns the generation of maps to address the detection and estimate of damage caused by a seism. The method is named APE - A Priori information for Earthquake damage mapping. The use of satellite data to investigate earthquake damages is not an innovative issue. Indeed, a wide literature and projects have addressed and focused such issue, but usually the proposed approaches are only based on change detection techniques and/or classifications algorithms. The novelty of APhoRISM-APE relies on the exploitation of a priori information derived by: - InSAR time series to measure surface movements - shakemaps obtained from seismological data - vulnerability information. This a priori information is then integrated with change detection map from earth observation satellite sensors (either Optical or Synthetic Aperture Radar) to improve accuracy and to limit false alarms.
Fischer, Kasper D.
Guy, Michelle R.; Patton, John M.; Fee, Jeremy; Hearne, Mike; Martinez, Eric; Ketchum, D.; Worden, Charles; Quitoriano, Vince; Hunter, Edward; Smoczyk, Gregory; Schwarz, Stan
It is important to note that this document provides a brief introduction to the work of dozens of software developers and IT specialists, spanning in many cases more than a decade. References to significant amounts of supporting documentation, code, and information are supplied within.
Degroot, R. M.; Springer, K.; Brooks, C. J.; Schuman, L.; Dalton, D.; Benthien, M. L.
In 1999 the Southern California Earthquake Center initiated an effort to expand its reach to multiple target audiences through the development of an interpretive trail on the San Andreas fault at Wallace Creek and an earthquake exhibit at Fingerprints Youth Museum in Hemet. These projects and involvement with the San Bernardino County Museum in Redlands beginning in 2007 led to the creation of Earthquake Education and Public Information Centers (EPIcenters) in 2008. The impetus for the development of the network was to broaden participation in The Great Southern California ShakeOut. In 2009 it has grown to be more comprehensive in its scope including its evolution into a statewide network. EPIcenters constitute a variety of free-choice learning institutions, representing museums, science centers, libraries, universities, parks, and other places visited by a variety of audiences including families, seniors, and school groups. They share a commitment to demonstrating and encouraging earthquake preparedness. EPIcenters coordinate Earthquake Country Alliance activities in their county or region, lead presentations or organize events in their communities, or in other ways demonstrate leadership in earthquake education and risk reduction. The San Bernardino County Museum (Southern California) and The Tech Museum of Innovation (Northern California) serve as EPIcenter regional coordinating institutions. They interact with over thirty institutional partners who have implemented a variety of activities from displays and talks to earthquake exhibitions. While many activities are focused on the time leading up to and just after the ShakeOut, most EPIcenter members conduct activities year round. Network members at Kidspace Museum in Pasadena and San Diego Natural History Museum have formed EPIcenter focus groups on early childhood education and safety and security. This presentation highlights the development of the EPIcenter network, synergistic activities resulting from this
Yin, L.; Heaton, T. H.
Most of the current Earthquake Early Warning technologies focus on time analysis of wave amplitudes. There are two major drawbacks of these waveform-based techniques: tradeoffs between magnitude and distance estimation for the onsite algorithms, and time latency in alerts for the network algorithms. We are proposing an alternative EEW algorithm that combines the efficiency of onsite algorithms and accuracy of network algorithms, which provides the fastest alert at the moment of station trigger. It is achieved by using observed seismicity from the network as prior information to predict short-term seismic hazards, and then use trigger information from the onsite station as likelihood information to estimate earthquake probability and hypocenter location. This algorithm has numbers of advantages. First, due to the independent data source of this algorithm, results can be directly multiplied to the results of other algorithms such as GPS and waveform data under Bayesian framework to achieve posterior probability function. Second, it is especially beneficial for regions with sparsely distributed station density where it takes longer time for the seismic signals to arrive at the near stations. Lastly, it can significantly speed up warning process during aftershock sequence, swarm earthquake sequence, and mainshocks that had foreshocks. The concept can be further extended to network-based algorithms to incorporate arrived waveform data at more stations.
U.S. Geological Survey; Spall, Henry, (Edited By); Schnabel, Diane C.
Earthquakes and Volcanoes is published bimonthly by the U.S. Geological Survey to provide current information on earthquakes and seismology, volcanoes, and related natural hazards of interest to both generalized and specialized readers. The Secretary of the Interior has determined that the publication of this periodical is necessary in the transaction of the public business required by law of this Department. Use of funds for printing this periodical has been approved by the Office of Management and Budget through June 30, 1989. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Kasahara, A.; Yagi, Y.
Rupture process of earthquake derived from geophysical observations is important information to understand nature of earthquake and assess seismic hazard. Finite fault inversion is a commonly applied method to construct seismic source model. In conventional inversion, fault is approximated by a simple fault surface even if rupture of real earthquake should propagate along non-planar complex fault. In the conventional inversion, complex rupture kinematics is approximated by limited model parameters that only represent slip on a simple fault surface. This over simplification may cause biased and hence misleading solution. MW 7.7 left-lateral strike-slip earthquake occurred in southwestern Pakistan on 2013-09-24 might be one of exemplar event to demonstrate the bias. For this earthquake, northeastward rupture propagation was suggested by a finite fault inversion of teleseismic body and long period surface waves with a single planer fault (USGS). However, surface displacement field measured from cross-correlation of optical satellite images and back-projection imaging revealed that rupture was unilaterally propagated toward southwest on a non-planer fault (Avouac et.al., 2014). To mitigate the bias, more flexible source parameterization should be employed. We extended multi-time window finite fault method to represent rupture kinematics on a complex fault. Each spatio-temporal knot has five degrees of freedom and is able to represent arbitrary strike, dip, rake, moment release rate and CLVD component. Detailed fault geometry for a source fault is not required in our method. The method considers data covariance matrix with uncertainty of Green's function (Yagi and Fukahata, 2011) to obtain stable solution. Preliminary results show southwestward rupture propagation and focal mechanism change that is consistent with fault trace. The result suggests usefulness of the flexible source parameterization for inversion of complex events.
Eggert, Silke; Fohringer, Joachim
Natural disasters like earthquakes require a fast response from local authorities. Well trained rescue teams have to be available, equipment and technology has to be ready set up, information have to be directed to the right positions so the head quarter can manage the operation precisely. The main goal is to reach the most affected areas in a minimum of time. But even with the best preparation for these cases, there will always be the uncertainty of what really happened in the affected area. Modern geophysical sensor networks provide high quality data. These measurements, however, are only mapping disjoint values from their respective locations for a limited amount of parameters. Using observations of witnesses represents one approach to enhance measured values from sensors ("humans as sensors"). These observations are increasingly disseminated via social media platforms. These "social sensors" offer several advantages over common sensors, e.g. high mobility, high versatility of captured parameters as well as rapid distribution of information. Moreover, the amount of data offered by social media platforms is quite extensive. We analyze messages distributed via Twitter after major earthquakes to get rapid information on what eye-witnesses report from the epicentral area. We use this information to (a) quickly learn about damage and losses to support fast disaster response and to (b) densify geophysical networks in areas where there is sparse information to gain a more detailed insight on felt intensities. We present a case study from the Mw 7.1 Philippines (Bohol) earthquake that happened on Oct. 15 2013. We extract Twitter messages, so called tweets containing one or more specified keywords from the semantic field of "earthquake" and use them for further analysis. For the time frame of Oct. 15 to Oct 18 we get a data base of in total 50.000 tweets whereof 2900 tweets are geo-localized and 470 have a photo attached. Analyses for both national level and locally for
Hirata, K.; Fujiwara, H.; Nakamura, H.; Osada, M.; Morikawa, N.; Kawai, S.; Ohsumi, T.; Aoi, S.; Yamamoto, N.; Matsuyama, H.; Toyama, N.; Kito, T.; Murashima, Y.; Murata, Y.; Inoue, T.; Saito, R.; Takayama, J.; Akiyama, S.; Korenaga, M.; Abe, Y.; Hashimoto, N.
The Earthquake Research Committee(ERC)/HERP, Government of Japan (2013) revised their long-term evaluation of the forthcoming large earthquake along the Nankai Trough; the next earthquake is estimated M8 to 9 class, and the probability (P30) that the next earthquake will occur within the next 30 years (from Jan. 1, 2013) is 60% to 70%. In this study, we assess tsunami hazards (maximum coastal tsunami heights) in the near future, in terms of a probabilistic approach, from the next earthquake along Nankai Trough, on the basis of ERC(2013)'s report. The probabilistic tsunami hazard assessment that we applied is as follows; (1) Characterized earthquake fault models (CEFMs) are constructed on each of the 15 hypothetical source areas (HSA) that ERC(2013) showed. The characterization rule follows Toyama et al.(2015, JpGU). As results, we obtained total of 1441 CEFMs. (2) We calculate tsunamis due to CEFMs by solving nonlinear, finite-amplitude, long-wave equations with advection and bottom friction terms by finite-difference method. Run-up computation on land is included. (3) A time predictable model predicts the recurrent interval of the present seismic cycle is T=88.2 years (ERC,2013). We fix P30 = 67% by applying the renewal process based on BPT distribution with T and alpha=0.24 as its aperiodicity. (4) We divide the probability P30 into P30(i) for i-th subgroup consisting of the earthquakes occurring in each of 15 HSA by following a probability re-distribution concept (ERC,2014). Then each earthquake (CEFM) in i-th subgroup is assigned a probability P30(i)/N where N is the number of CEFMs in each sub-group. Note that such re-distribution concept of the probability is nothing but tentative because the present seismology cannot give deep knowledge enough to do it. Epistemic logic-tree approach may be required in future. (5) We synthesize a number of tsunami hazard curves at every evaluation points on coasts by integrating the information about 30 years occurrence
Douglas, Dorothy, Ed.
This document consists of the two 2000 issues of "Alaska's Children," which provides information on the Alaska Head Start State Collaboration Project and updates on Head Start activities in Alaska. Regular features include a calendar of conferences and meetings, a status report on Alaska's children, reports from the Alaska Children's Trust, and…
Kruse, F. A.; Kim, A. M.; Runyon, S. C.; Carlisle, Sarah C.; Clasen, C. C.; Esterline, C. H.; Jalobeanu, A.; Metcalf, J. P.; Basgall, P. L.; Trask, D. M.; Olsen, R. C.
The Naval Postgraduate School (NPS) Remote Sensing Center (RSC) and research partners have completed a remote sensing pilot project in support of California post-earthquake-event emergency response. The project goals were to dovetail emergency management requirements with remote sensing capabilities to develop prototype map products for improved earthquake response. NPS coordinated with emergency management services and first responders to compile information about essential elements of information (EEI) requirements. A wide variety of remote sensing datasets including multispectral imagery (MSI), hyperspectral imagery (HSI), and LiDAR were assembled by NPS for the purpose of building imagery baseline data; and to demonstrate the use of remote sensing to derive ground surface information for use in planning, conducting, and monitoring post-earthquake emergency response. Worldview-2 data were converted to reflectance, orthorectified, and mosaicked for most of Monterey County; CA. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data acquired at two spatial resolutions were atmospherically corrected and analyzed in conjunction with the MSI data. LiDAR data at point densities from 1.4 pts/m2 to over 40 points/ m2 were analyzed to determine digital surface models. The multimodal data were then used to develop change detection approaches and products and other supporting information. Analysis results from these data along with other geographic information were used to identify and generate multi-tiered products tied to the level of post-event communications infrastructure (internet access + cell, cell only, no internet/cell). Technology transfer of these capabilities to local and state emergency response organizations gives emergency responders new tools in support of post-disaster operational scenarios.
Stull, E.A.; Hlohowskyj, I.; LaGory, K. E.; Environmental Science Division
The North Aleutian Basin Planning Area of the Minerals Management Service (MMS) is a large geographic area with significant natural resources. The Basin includes most of the southeastern part of the Bering Sea Outer Continental Shelf, including all of Bristol Bay. The area supports important habitat for a wide variety of species and globally significant habitat for birds and marine mammals, including several federally listed species. Villages and communities of the Alaska Peninsula and other areas bordering or near the Basin rely on its natural resources (especially commercial and subsistence fishing) for much of their sustenance and livelihood. The offshore area of the North Aleutian Basin is considered to have important hydrocarbon reserves, especially natural gas. In 2006, the MMS released a draft proposed program, 'Outer Continental Shelf Oil and Gas Leasing Program, 2007-2012' and an accompanying draft programmatic environmental impact statement (EIS). The draft proposed program identified two lease sales proposed in the North Aleutian Basin in 2010 and 2012, subject to restrictions. The area proposed for leasing in the Basin was restricted to the Sale 92 Area in the southwestern portion. Additional EISs will be needed to evaluate the potential effects of specific lease actions, exploration activities, and development and production plans in the Basin. A full range of updated multidisciplinary scientific information will be needed to address oceanography, fate and effects of oil spills, marine ecosystems, fish, fisheries, birds, marine mammals, socioeconomics, and subsistence in the Basin. Scientific staff at Argonne National Laboratory were contracted to assist MMS with identifying and prioritizing information needs related to potential future oil and gas leasing and development activities in the North Aleutian Basin. Argonne focused on three related tasks: (1) identify and gather relevant literature published since 1996, (2) synthesize and summarize the
... Region; Bering Sea and Aleutian Islands Crab Arbitration AGENCY: National Oceanic and Atmospheric... for Gulf of Alaska groundfish fisheries, arbitration system, monitoring, economic data collection, and cost recovery fee collection. The Crab Rationalization Program Arbitration System is established by...
Zoeller, G.; Holschneider, M.
In recent publications, it has been shown that earthquake catalogs are useful to estimate the maximum expected earthquake magnitude in a future time horizon Tf. However, earthquake catalogs alone do not allow to estimate the maximum possible magnitude M (Tf = ∞) in a study area. Therefore, we focus on the question, which data might be helpful to constrain M. Assuming a doubly-truncated Gutenberg-Richter law and independent events, optimal estimates of M depend solely on the largest observed magnitude μ regardless of all the other details in the catalog. For other models of the frequency-magnitude relation, this results holds in approximation. We show that the maximum observed magnitude μT in a known time interval T in the past provides provides the most powerful information on M in terms of the smallest confidence intervals. However, if high levels of confidence are required, the upper bound of the confidence interval may diverge. Geological or tectonic data, e.g. strain rates, might be helpful, if μT is not available; but these quantities can only serve as proxies for μT and will always lead to a higher degree of uncertainty and, therefore, to larger confidence intervals of M.
Fan, Hong; Guo, Dan; Li, Huaiyuan
In this paper a web information extraction method is presented which identifies a variety of thematic events utilizing the event knowledge framework derived from text training, and then further uses the syntactic analysis to extract the event key information. The method which combines the text semantic information and domain knowledge of the event makes the extraction of information people interested more accurate. In this paper, web based earthquake news extraction is taken as an example. The paper firstly briefs the overall approaches, and then details the key algorithm and experiments of seismic events extraction. Finally, this paper conducts accuracy analysis and evaluation experiments which demonstrate that the proposed method is a promising way of hot events mining.
Hayes, G.P.; Earle, P.S.; Benz, H.M.; Wald, D.J.; Briggs, R.W.
This article presents a timeline of NEIC response to a major global earthquake for the first time in a formal journal publication. We outline the key observations of the earthquake made by the NEIC and its partner agencies, discuss how these analyses evolved, and outline when and how this information was released to the public and to other internal and external parties. Our goal in the presentation of this material is to provide a detailed explanation of the issues faced in the response to a rare, giant earthquake. We envisage that the timeline format of this presentation can highlight technical and procedural successes and shortcomings, which may in turn help prompt research by our academic partners and further improvements to our future response efforts. We have shown how NEIC response efforts have significantly improved over the past six years since the great 2004 Sumatra-Andaman earthquake. We are optimistic that the research spawned from this disaster, and the unparalleled dense and diverse data sets that have been recorded, can lead to similar-and necessary-improvements in the future.
This paper delivers a brief survey of renewable energy technologies applicable to Alaska's climate, latitude, geography, and geology. We first identify Alaska's natural renewable energy resources and which renewable energy technologies would be most productive. e survey the current state of renewable energy technologies and research efforts within the U.S. and, where appropriate, internationally. We also present information on the current state of Alaska's renewable energy assets, incentives, and commercial enterprises. Finally, we escribe places where research efforts at Sandia National Laboratories could assist the state of Alaska with its renewable energy technology investment efforts.
Altan, O.; Toz, G.; Kulur, S.; Seker, D.; Volz, S.; Fritsch, D.; Sester, M.
After a catastrophe like an earthquake, one on the most important problems is to provide shelter and housing for the homeless. To this end, it is necessary to decide if a building is still habitable, or if it is has to be renovated or even torn down. A prerequisite for such decisions is the detailed knowledge about the status of the building. Earlier earthquakes revealed problems in the processes of documenting and analysing the building damage, as they demanded much effort in terms of time and manpower. The main difficulties appeared to be because of the analogue damage assessments which created a great variety of unstructured information that had to be put in a line to allow further analysis. Apart from that, documentation of damage effects was not detailed and could only be carried out on the spot of a disaster. The aim of this study is to make an improvement, using combination of Geographic Information Systems (GIS) as a management and data analysis tool and photogrammetry as a documentation method. Photogrammetric data acquisition is achieved using a CCD camera and the digital photogrammetric software package PICTRAN by Technet. The information system part is the GIS package ArcView by ESRI. The combination of rapid data acquisition and GIS offers a quick assessment of the situation and the possibility of its objective and holistic analysis. This is the prerequisite for a quick initiation of appropriate measures to help people.
In recent years, we have made significant progress in being able to recognize the long-range pattern of events that precede large earthquakes. For example, in a recent issue of the Earthquake Information Bulletin, we saw how the pioneering work of S.A. Fedotov of the U.S.S.R in the Kamchatka-Kurile Islands region has been applied worldwide to forecast where large, shallow earthquakes might occur in the next decades. Indeed, such a "seismic gap" off the coast of Alaska was filled by the 1972 Sitka earthquake. Promising results are slowly accumulating from other techniques that suggest that intermediate-term precursors might also be seen: among these are tilt and geomagnetic anomalies and anomalous land uplift. But the crucial point remains that short-term precursors (days to hours) will be needed in many cases if there is to be a significant saving of lives.
Perry, S.; Benthien, M.; Jordan, T. H.
The SCEC/UseIT internship program is training the next generation of earthquake scientist, with methods that can be adapted to other disciplines. UseIT interns work collaboratively, in multi-disciplinary teams, conducting computer science research that is needed by earthquake scientists. Since 2002, the UseIT program has welcomed 64 students, in some two dozen majors, at all class levels, from schools around the nation. Each summer''s work is posed as a ``Grand Challenge.'' The students then organize themselves into project teams, decide how to proceed, and pool their diverse talents and backgrounds. They have traditional mentors, who provide advice and encouragement, but they also mentor one another, and this has proved to be a powerful relationship. Most begin with fear that their Grand Challenge is impossible, and end with excitement and pride about what they have accomplished. The 22 UseIT interns in summer, 2005, were primarily computer science and engineering majors, with others in geology, mathematics, English, digital media design, physics, history, and cinema. The 2005 Grand Challenge was to "build an earthquake monitoring system" to aid scientists who must visualize rapidly evolving earthquake sequences and convey information to emergency personnel and the public. Most UseIT interns were engaged in software engineering, bringing new datasets and functionality to SCEC-VDO (Virtual Display of Objects), a 3D visualization software that was prototyped by interns last year, using Java3D and an extensible, plug-in architecture based on the Eclipse Integrated Development Environment. Other UseIT interns used SCEC-VDO to make animated movies, and experimented with imagery in order to communicate concepts and events in earthquake science. One movie-making project included the creation of an assessment to test the effectiveness of the movie''s educational message. Finally, one intern created an interactive, multimedia presentation of the UseIT program.
Brabets, Timothy P.
In 1906, the U.S. Geological Survey (USGS) began operating a network of streamflow-gaging stations in Alaska. The primary purpose of the streamflow- gaging network has been to provide peak flow, average flow, and low-flow characteristics to a variety of users. In 1993, the USGS began a study to evaluate the current network of 78 stations. The objectives of this study were to determine the adequacy of the existing network in predicting selected regional flow characteristics and to determine if providing additional streamflow-gaging stations could improve the network's ability to predict these characteristics. Alaska was divided into six distinct hydrologic regions: Arctic, Northwest, Southcentral, Southeast, Southwest, and Yukon. For each region, historical and current streamflow data were compiled. In Arctic, Northwest, and Southwest Alaska, insufficient data were available to develop regional regression equations. In these areas, proposed locations of streamflow-gaging stations were selected by using clustering techniques to define similar areas within a region and by spatial visual analysis using the precipitation, physiographic, and hydrologic unit maps of Alaska. Sufficient data existed in Southcentral and Southeast Alaska to use generalized least squares (GLS) procedures to develop regional regression equations to estimate the 50-year peak flow, annual average flow, and a low-flow statistic. GLS procedures were also used for Yukon Alaska but the results should be used with caution because the data do not have an adequate spatial distribution. Network analysis procedures were used for the Southcentral, Southeast, and Yukon regions. Network analysis indicates the reduction in the sampling error of the regional regression equation that can be obtained given different scenarios. For Alaska, a 10-year planning period was used. One scenario showed the results of continuing the current network with no additional gaging stations and another scenario showed the results
Bossu, R.; Etivant, C.; Roussel, F.; Mazet-Roux, G.; Steed, R.
Smartphone applications have swiftly become one of the most popular tools for rapid reception of earthquake information for the public. Wherever someone's own location is, they can be automatically informed when an earthquake has struck just by setting a magnitude threshold and an area of interest. No need to browse the internet: the information reaches you automatically and instantaneously! One question remains: are the provided earthquake notifications always relevant for the public? A while after damaging earthquakes many eyewitnesses scrap the application they installed just after the mainshock. Why? Because either the magnitude threshold is set too high and many felt earthquakes are missed, or it is set too low and the majority of the notifications are related to unfelt earthquakes thereby only increasing anxiety among the population at each new update. Felt and damaging earthquakes are the ones of societal importance even when of small magnitude. LastQuake app and Twitter feed (QuakeBot) focuses on these earthquakes that matter for the public by collating different information threads covering tsunamigenic, damaging and felt earthquakes. Non-seismic detections and macroseismic questionnaires collected online are combined to identify felt earthquakes regardless their magnitude. Non seismic detections include Twitter earthquake detections, developed by the USGS, where the number of tweets containing the keyword "earthquake" is monitored in real time and flashsourcing, developed by the EMSC, which detect traffic surges on its rapid earthquake information website caused by the natural convergence of eyewitnesses who rush to the Internet to investigate the cause of the shaking that they have just felt. We will present the identification process of the felt earthquakes, the smartphone application and the 27 automatically generated tweets and how, by providing better public services, we collect more data from citizens.
This MODIS true-color image shows the Gulf of Alaska and Kodiak Island, the partially snow-covered island in roughly the center of the image. Credit: Jacques Descloitres, MODIS Land Rapid Response Team
Obara, Kazushige; Kato, Aitaro
Slow earthquakes are characterized by a wide spectrum of fault slip behaviors and seismic radiation patterns that differ from those of traditional earthquakes. However, slow earthquakes and huge megathrust earthquakes can have common slip mechanisms and are located in neighboring regions of the seismogenic zone. The frequent occurrence of slow earthquakes may help to reveal the physics underlying megathrust events as useful analogs. Slow earthquakes may function as stress meters because of their high sensitivity to stress changes in the seismogenic zone. Episodic stress transfer to megathrust source faults leads to an increased probability of triggering huge earthquakes if the adjacent locked region is critically loaded. Careful and precise monitoring of slow earthquakes may provide new information on the likelihood of impending huge earthquakes.
Obara, Kazushige; Kato, Aitaro
Slow earthquakes are characterized by a wide spectrum of fault slip behaviors and seismic radiation patterns that differ from those of traditional earthquakes. However, slow earthquakes and huge megathrust earthquakes can have common slip mechanisms and are located in neighboring regions of the seismogenic zone. The frequent occurrence of slow earthquakes may help to reveal the physics underlying megathrust events as useful analogs. Slow earthquakes may function as stress meters because of their high sensitivity to stress changes in the seismogenic zone. Episodic stress transfer to megathrust source faults leads to an increased probability of triggering huge earthquakes if the adjacent locked region is critically loaded. Careful and precise monitoring of slow earthquakes may provide new information on the likelihood of impending huge earthquakes. PMID:27418504
Dong, Laigen; Shan, Jie; Ye, Yuanxin
It is important to grasp damage information in stricken areas after an earthquake in order to perform quick rescue and recovery activities. Recent research into remote sensing techniques has shown significant ability to generate quality damage information. The methods based on only post-earthquake data are widely researched especially because there are no pre-earthquake reference data in many cities of the world. This paper addresses a method for detection of damaged buildings using only post-event satellite imagery so that scientists and researchers can take advantage of the ability of helicopters and airplanes to fly over the damage faster. Statistical information of line segments extracted from post-event satellite imagery, such as mean length (ML) and weighted tilt angel standard deviation (WTASD), are used for discriminating the damaged and undamaged buildings.
LaBelle, J.C.; Wise, J.L.; Voelker, R.P.; Schulze, R.H.; Wohl, G.M.
A comprehensive Atlas of Alaska marine ice is presented. It includes information on pack and landfast sea ice and calving tidewater glacier ice. It also gives information on ice and related environmental conditions collected over several years time and indicates the normal and extreme conditions that might be expected in Alaska coastal waters. Much of the information on ice conditions in Alaska coastal waters has emanated from research activities in outer continental shelf regions under assessment for oil and gas exploration and development potential. (DMC)
Furlong, K. P.; Benz, H.; Hayes, G. P.; Villasenor, A.
Although most would agree that the occurrence of natural disaster events such as earthquakes, volcanic eruptions, and floods can provide effective learning opportunities for natural hazards-based courses, implementing compelling materials into the large-enrollment classroom environment can be difficult. These natural hazard events derive much of their learning potential from their real-time nature, and in the modern 24/7 news-cycle where all but the most devastating events are quickly out of the public eye, the shelf life for an event is quite limited. To maximize the learning potential of these events requires that both authoritative information be available and course materials be generated as the event unfolds. Although many events such as hurricanes, flooding, and volcanic eruptions provide some precursory warnings, and thus one can prepare background materials to place the main event into context, earthquakes present a particularly confounding situation of providing no warning, but where context is critical to student learning. Attempting to implement real-time materials into large enrollment classes faces the additional hindrance of limited internet access (for students) in most lecture classrooms. In Earth 101 Natural Disasters: Hollywood vs Reality, taught as a large enrollment (150+ students) general education course at Penn State, we are collaborating with the USGS’s National Earthquake Information Center (NEIC) to develop efficient means to incorporate their real-time products into learning activities in the lecture hall environment. Over time (and numerous events) we have developed a template for presenting USGS-produced real-time information in lecture mode. The event-specific materials can be quickly incorporated and updated, along with key contextual materials, to provide students with up-to-the-minute current information. In addition, we have also developed in-class activities, such as student determination of population exposure to severe ground
... Region Bering Sea & Aleutian Islands (BSAI) Crab Economic Data Reports AGENCY: National Oceanic and... Fisheries Service (NMFS) manages the crab fisheries in the waters off the coast of Alaska under the Fishery Management Plan (FMP) for the Bering Sea and Aleutian Islands (BSAI) Crab. The Magnuson-Stevens...
Alaska State Library, Juneau.
Everyone is responsible for the welfare of the children in our communities. Some persons, such as school teachers and peace officers, are required by law in Alaska to report known or suspected child abuse and neglect. The general public is also encouraged to report such knowledge or suspicions so that children can be protected and families can…
Alaska State Library, Juneau.
Alaska law requires that medical and health personnel report known and suspected child abuse and neglect. No one is more likely to see indicators of abuse and neglect than medical and other health-related personnel. Such indicators can include broken bones, bruises, malnutrition and other effects of neglect, infections, and other signs of sexual…
Suleimani, E. N.; Nicolsky, D. J.; Hansen, R. A.
The Alaska Earthquake Information Center (AEIC) conducts tsunami inundation mapping for coastal communities in Alaska. This activity provides local emergency officials with tsunami hazard assessment and mitigation tools. At-risk communities are spread along several segments of the Alaska-Aleutian Subduction Zone, with each segment having a unique seismic history and potential tsunami hazard. As a result, almost every community has a distinct set of potential tsunami sources that need to be considered in order to make a tsunami inundation map. Therefore, an important component of the inundation mapping effort is identification and specification of potential tsunami sources. We are creating tsunami inundation maps for Sitka, Alaska, in the scope of the National Tsunami Hazard Mitigation Program. Tsunami potential from tectonic and submarine landslide sources must be evaluated in this case for comprehensive mapping of areas at risk for inundation. The community of Sitka, the former capital of Russian Alaska, is located in Southeast Alaska, on the west coast of Baranof Island, facing the Pacific Ocean. In this area of southern Alaska, the subduction of the Pacific plate beneath the North America plate becomes a transform boundary that continues down the coast as the Fairweather - Queen Charlotte (FW-QC) transform fault system. The Sitka segment of the FW-QC fault system ruptured in large strike-slip earthquakes in 1927 (Ms7.1) and in 1972 (Ms7.6). We numerically model the extent of inundation in Sitka due to tsunami waves generated from earthquake and landslide sources. Tsunami scenarios include a repeat of the tsunami triggered by the 1964 Great Alaska earthquake, repeat of the tsunami triggered by the 2011 Tohoku earthquake, tsunami waves generated by a hypothetically extended 1964 rupture, a hypothetical Cascadia megathrust earthquake, and hypothetical earthquakes in the FW-QC fault system. Underwater landslide events off the continental shelf along the FW-QC fault
Lauro, Claudia; Avanzini, Marco
During 2009 the Natural Science Museum of Trento organized the exhibition "Attraction Earth: Earthquakes and Terrestrial Magnetism" in collaboration with the INGV (Italian National Institute of Geophysic and Volcanology). In this exhibition a particular sector has been devoted to the seismic activity and its monitoring in the Province of Trento. The purpose was to inform local people on the geological features of their territory, the monitoring activity carried out by the Civil Protection and the potential earthquake hazards, also in order to adopt a correct behaviour in case of seismic event. This sector, "The seismometric Trentino network", was organized by the Geological Service of the Trento Civil Protection and it is open till May 2010, both for general public and school students. For the latter, a particular education pack, realized by the Educational Department of the Museum and consisting of a guided tour coupled with the laboratory activity "Waves upside-down: seismology", is proposed. The whole exhibition has been also coupled with a cycle conferences targeted to adults, in which these topics have been explained by researchers and technicians of INGV and of Trento Geological Service. "The seismometric Trentino network" sector presents the daily monitoring activity of the Geological Service, that has been monitoring the seismic activity for the last 30 years, and describes the deep earth processes of the local territory, such as presence of tectonic discontinuities and their activity. It consists of display panels, a seismometer with rotating drums and a multimedia that reports the monitoring activity of the seismometric network, with real time connection to the various monitoring stations. This allows visitors to observe instantly the local seismic events recorded by each station. The seismometric network was established by the institutions of Trento Province after the earthquakes occurred in Friuli Venezia-Giulia and at Riva del Garda (1976). It started
Mortensen, Carl; Donlin, Carolyn; Page, Robert A.; Ward, Peter
In coping with recent multibillion-dollar earthquake disasters, scientists and emergency managers have found new ways to speed and improve relief efforts. This progress is founded on the rapid availability of earthquake information from seismograph networks.
... Health > American Indians/Alaska Natives Minority Women's Health American Indians/Alaska Natives Related information How to Talk to ... disease. Return to top Health conditions common in American Indian and Alaska Native women Accidents Alcoholism and drug ...
... MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Plans and Information Contents of Exploration Plans (ep) § 250.220 If I propose... exploration activities in the Alaska OCS Region, the following planning information must accompany your EP:...
The Southern California Earthquake Center's Fault Information System (FIS) provides a single point of access to fault-related data and models from multiple databases and datasets. The FIS is built of computer code, metadata and Web interfaces based on Web services technology, which enables queries and data interchange irrespective of computer software or platform. Currently we have working prototypes of programmatic and browser-based access. The first generation FIS may be searched and downloaded live, by automated processes, as well as interactively, by humans using a browser. Users get ascii data in plain text or encoded in XML. Via the Earthquake Information Technology (EIT) Interns (Juve and others, this meeting), we are also testing the effectiveness of querying multiple databases using a fault database ontology. For more than a decade, the California Geological Survey (CGS), SCEC, and the U. S. Geological Survey (USGS) have put considerable, shared resources into compiling and assessing published fault data, then providing the data on the Web. Several databases now exist, with different formats, datasets, purposes, and users, in various stages of completion. When fault databases were first envisioned, the full power of today's internet was not yet recognized, and the databases became the Web equivalents of review papers, where one could read an overview summation of a fault, then copy and paste pertinent data. Today, numerous researchers also require rapid queries and downloads of data. Consequently, the first components of the FIS are MySQL databases that deliver numeric values from earlier, text-based databases. Another essential service provided by the FIS is visualizations of fault representations such as those in SCEC's Community Fault Model. The long term goal is to provide a standardized, open-source, platform-independent visualization technique. Currently, the FIS makes available fault model viewing software for users with access to Matlab or Java3D
Li, Boren; Wu, Jianping; Pan, Mao; Huang, Jing
In hazard management, earthquake researchers have utilized GIS to ease the process of managing disasters. Researchers use WebGIS to assess hazards and seismic risk. Although they can provide a visual analysis platform based on GIS technology, they lack a general description in the extensibility of WebGIS for processing dynamic data, especially real-time data. In this paper, we propose a novel approach for real-time 3D visual earthquake information publishing model based on WebGIS and digital globe to improve the ability of processing real-time data in systems based on WebGIS. On the basis of the model, we implement a real-time 3D earthquake information publishing system—EqMap3D. The system can not only publish real-time earthquake information but also display these data and their background geoscience information in a 3D scene. It provides a powerful tool for display, analysis, and decision-making for researchers and administrators. It also facilitates better communication between researchers engaged in geosciences and the interested public.
Levy, Gad; Blumberg, Nehemia; Kreiss, Yitshak; Ash, Nachman; Merin, Ofer
Following the January 2010 earthquake in Haiti, the Israel Defense Force Medical Corps dispatched a field hospital unit. A specially tailored information technology solution was deployed within the hospital. The solution included a hospital administration system as well as a complete electronic medical record. A light-weight picture archiving and communication system was also deployed. During 10 days of operation, the system registered 1111 patients. The network and system up times were more than 99.9%. Patient movements within the hospital were noted, and an online command dashboard screen was generated. Patient care was delivered using the electronic medical record. Digital radiographs were acquired and transmitted to stations throughout the hospital. The system helped to introduce order in an otherwise chaotic situation and enabled adequate utilization of scarce medical resources by continually gathering information, analyzing it, and presenting it to the decision-making command level. The establishment of electronic medical records promoted the adequacy of medical treatment and facilitated continuity of care. This experience in Haiti supports the feasibility of deploying information technologies within a field hospital operation. Disaster response teams and agencies are encouraged to consider the use of information technology as part of their contingency plans. PMID:20962123
Douglas, Dorothy, Ed.
This document consists of four issues of the quarterly report "Alaska's Children," which provides information on the Alaska Head Start State Collaboration Project and updates on Head Start activities in Alaska. Regular features in the issues include a calendar of conferences and meetings, a status report on Alaska's children, reports from the…
Dixon, J. P.; McNutt, S. R.; Power, J. A.; West, M.
The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute at the University of Alaska Fairbanks, and the Alaska Division of Geological and Geophysical Surveys observed its 20th anniversary in 2008. The AVO seismic network, inherited from AVO partners in 1988, consisted of three small-aperture subnetworks on Mount Spurr, Redoubt Volcano and Augustine Volcano and regional stations for a total of 23 short-period instruments (two with three-components). Twenty years later, the AVO network has expanded to 192 stations (23 three-component short-period, and 15 broadband) on 33 volcanoes spanning 2500 km across the Aleutian arc in one of the most remote and challenging environments in the world. The AVO seismic network provides for a unique data set. Within the seismically active Aleutian Arc, there are instrumented volcanoes which exhibit a variety of chemical compositions and eruptive styles. With each individual volcanic center similarly instrumented and all data analyzed in a consistent manner AVO has produced a data set suitable for making seismic comparisons across a wide suite of volcanoes. In twenty years, the AVO has captured data sets for eruptions at Augustine, Kasatochi, Okmok, Pavlof, Redoubt, Shishaldin, Spurr, and Venianinof. AVO data set also includes several volcanic-tectonic swarms, most notably at Akutan, Iliamna, Mageik, Martin, Shishaldin, and Tanaga. This broad approach to volcano seismology has led to a better understanding of precursory earthquake swarms, variations in background rates, triggered seismicity, the structure of volcanoes, volcanic tremor and deep long period earthquakes, among numerous other topics. The AVO also incorporates data from seismic stations operated by both the Alaska Earthquake Information Center and West Coast and Alaska Tsunami Warning Center to help locate some of the 70,000 earthquakes in the AVO catalog. In exchange AVO provides dense seismic data from the
Thirty years old this summer, RAHI, the Rural Alaska Honors Institute is a statewide, six-week, summer college-preparatory bridge program at the University of Alaska Fairbanks for Alaska Native and rural high school juniors and seniors. This summer, in collaboration with the University of Texas Austin, the Rural Alaska Honors Institute launched a new program, GeoFORCE Alaska. This outreach initiative is designed to increase the number and diversity of students pursuing STEM degree programs and entering the future high-tech workforce. It uses Earth science to entice kids to get excited about dinosaurs, volcanoes and earthquakes, and includes physics, chemistry, math, biology and other sciences. Students were recruited from the Alaska's Arctic North Slope schools, in 8th grade to begin the annual program of approximately 8 days, the summer before their 9th grade year and then remain in the program for all four years of high school. They must maintain a B or better grade average and participate in all GeoFORCE events. The culmination is an exciting field event each summer. Over the four-year period, events will include trips to Fairbanks and Anchorage, Arizona, Oregon and the Appalachians. All trips focus on Earth science and include a 100+ page guidebook, with tests every night culminating with a final exam. GeoFORCE Alaska was begun by the University of Alaska Fairbanks in partnership with the University of Texas at Austin, which has had tremendous success with GeoFORCE Texas. GeoFORCE Alaska is managed by UAF's long-standing Rural Alaska Honors Institute, that has been successfully providing intense STEM educational opportunities for Alaskan high school students for over 30 years. The program will add a new cohort of 9th graders each year for the next four years. By the summer of 2015, GeoFORCE Alaska is targeting a capacity of 160 students in grades 9th through 12th. Join us to find out more about this exciting new initiative, which is enticing young Alaska Native
Winkler, Gary R.; Plafker, George; Goldfarb, R.J.; Case, J.E.
report summarizes recent results of integrated geological, geochemical, and geophysical field and laboratory studies conducted by the U.S. Geological Survey in the Cordova and Middleton Island 1?x3 ? quadrangles of coastal southern Alaska. Published open-file reports and maps accompanied by descriptive and interpretative texts, tables, diagrams, and pertinent references provide background information for a mineral-resource assessment of the two quadrangles. Mines in the Cordova and Middleton Island quadrangles produced copper and byproduct gold and silver in the first three decades of the 20th century. The quadrangles may contain potentially significant undiscovered resources of precious and base metals (gold, silver, copper, zinc, and lead) in veins and massive sulfide deposits hosted by Cretaceous and Paleogene sedimentary and volcanic rocks. Resources of manganese also may be present in the Paleogene rocks; uranium resources may be present in Eocene granitic rocks; and placer gold may be present in beach sands near the mouth of the Copper River, in alluvial sands within the canyons of the Copper River, and in smaller alluvial deposits underlain by rocks of the Valdez Group. Significant coal resources are present in the Bering River area, but difficult access and structural complexities have discouraged development. Investigation of numerous oil and gas seeps near Katalla in the eastern part of the area led to the discovery of a small, shallow field from which oil was produced between 1902 and 1933. The field has been inactive since, and subsequent exploration and drilling onshore near Katalla in the 1960's and offshore near Middleton Island on the outer continental shelf in the 1970's and 1980's was not successful.
This Fact Sheet provides a brief description of postearthquake tools and products provided by the Advanced National Seismic System (ANSS) through the U.S. Geological Survey Earthquake Hazards Program. The focus is on products specifically aimed at providing situational awareness in the period immediately following significant earthquake events.
Cluff, L.S.; Page, R.A.; Slemmons, D.B.; Grouse, C.B.
The discovery of oil on Alaska's North Slope and the construction of a pipeline to transport that oil across Alaska coincided with the National Environmental Policy Act of 1969 and a destructive Southern California earthquake in 1971 to cause stringent stipulations, state-of-the-art investigations, and innovative design for the pipeline. The magnitude 7.9 earthquake on the Denali fault in November 2002 was remarkably consistent with the design earthquake and fault displacement postulated for the Denali crossing of the Trans-Alaska Pipeline route. The pipeline maintained its integrity, and disaster was averted. Recent probabilistic studies to update previous hazard exposure conclusions suggest continuing pipeline integrity.
The volcanological significance of seismicity within Katmai National Park has been debated since the first seismograph was installed in 1963, in part because Katmai seismicity consists almost entirely of high-frequency earthquakes that can be caused by a wide range of processes. I investigate this issue by determining 140 well-constrained first-motion fault-plane solutions for shallow (depth < 9 km) earthquakes occuring between 1995 and 2001 and inverting these solutions for the stress tensor in different regions within the park. Earthquakes removed by several kilometers from the volcanic axis occur in a stress field characterized by horizontally oriented ??1 and ??3 axes, with ??1 rotated slightly (12??) relative to the NUVELIA subduction vector, indicating that these earthquakes are occurring in response to regional tectonic forces. On the other hand, stress tensors for earthquake clusters beneath several Katmai cluster volcanoes have vertically oriented ??1 axes, indicating that these events are occuring in response to local, not regional, processes. At Martin-Mageik, vertically oriented ??1 is most consistent with failure under edifice loading conditions in conjunction with localized pore pressure increases associated with hydrothermal circulation cells. At Trident-Novarupta, it is consistent with a number of possible models, including occurence along fractures formed during the 1912 eruption that now serve as horizontal conduits for migrating fluids and/or volatiles from nearby degassing and cooling magma bodies. At Mount Katmai, it is most consistent with continued seismicity along ring-fracture systems created in the 1912 eruption, perhaps enhanced by circulating hydrothermal fluids and/or seepage from the caldera-filling lake.
... 30 Mineral Resources 2 2010-07-01 2010-07-01 false If I propose activities in the Alaska OCS Region, what planning information must accompany the DPP? 250.251 Section 250.251 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Plans and...
... 30 Mineral Resources 2 2011-07-01 2011-07-01 false If I propose activities in the Alaska OCS Region, what planning information must accompany the DPP? 250.251 Section 250.251 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, REGULATION, AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE...
... 30 Mineral Resources 2 2011-07-01 2011-07-01 false If I propose activities in the Alaska OCS Region, what planning information must accompany the EP? 250.220 Section 250.220 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, REGULATION, AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE...
Hellman, S. B.; Lisowski, S.; Baker, B.; Hagerty, M.; Lomax, A.; Leifer, J. M.; Thies, D. A.; Schnackenberg, A.; Barrows, J.
Tsunami Information technology Modernization (TIM) is a National Oceanic and Atmospheric Administration (NOAA) project to update and standardize the earthquake and tsunami monitoring systems currently employed at the U.S. Tsunami Warning Centers in Ewa Beach, Hawaii (PTWC) and Palmer, Alaska (NTWC). While this project was funded by NOAA to solve a specific problem, the requirements that the delivered system be both open source and easily maintainable have resulted in the creation of a variety of open source (OS) software packages. The open source software is now complete and this is a presentation of the OS Software that has been funded by NOAA for benefit of the entire seismic community. The design architecture comprises three distinct components: (1) The user interface, (2) The real-time data acquisition and processing system and (3) The scientific algorithm library. The system follows a modular design with loose coupling between components. We now identify the major project constituents. The user interface, CAVE, is written in Java and is compatible with the existing National Weather Service (NWS) open source graphical system AWIPS. The selected real-time seismic acquisition and processing system is open source SeisComp3 (sc3). The seismic library (libseismic) contains numerous custom written and wrapped open source seismic algorithms (e.g., ML/mb/Ms/Mwp, mantle magnitude (Mm), w-phase moment tensor, bodywave moment tensor, finite-fault inversion, array processing). The seismic library is organized in a way (function naming and usage) that will be familiar to users of Matlab. The seismic library extends sc3 so that it can be called by the real-time system, but it can also be driven and tested outside of sc3, for example, by ObsPy or Earthworm. To unify the three principal components we have developed a flexible and lightweight communication layer called SeismoEdex.
Jordan, T. H.
In assessing their risk to society, earthquakes are best characterized as cascades that can propagate from the natural environment into the socio-economic (built) environment. Strong earthquakes rarely occur as isolated events; they usually cluster in foreshock-mainshock-aftershock sequences, seismic swarms, and extended sequences of large earthquakes that propagate along major fault systems. These cascades are regulated by stress-mediated interactions among faults driven by tectonic loading. Within these cascades, each large event can itself cause a chain reaction in which the primary effects of faulting and ground shaking induce secondary effects, including tsunami, landslides, liquefaction, and set off destructive processes within the built environment, such as fires and radiation leakage from nuclear plants. Recent earthquakes have demonstrated how the socio-economic effects of large earthquakes can reverberate for many years. To reduce earthquake risk and improve the resiliency of communities to earthquake damage, society depends on five geotechnologies for tracking earthquake cascades: long-term probabilistic seismic hazard analysis (PSHA), short-term (operational) earthquake forecasting, earthquake early warning, tsunami warning, and the rapid production of post-event information for response and recovery (see figure). In this presentation, I describe how recent advances in earthquake system science are leading to improvements in this geotechnology pipeline. In particular, I will highlight the role of earthquake simulations in predicting strong ground motions and their secondary effects before and during earthquake cascades
Britton, Joe M.
Descriptions of the mineral occurrences shown on the accompanying figure follow. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.
Leask, Linda; Killorin, Mary; Martin, Stephanie
This booklet provides data on Alaska's population, economy, health, education, government, and natural resources, including specific information on Alaska Natives. Since 1960, Alaska's population has tripled and become more diverse, more stable, older, less likely to be male or married, and more concentrated. About 69 percent of the population…
... WILDLIFE REFUGE SYSTEM HUNTING AND FISHING Refuge-Specific Regulations for Hunting and Fishing § 32.21 Alaska. Alaska refuges are opened to hunting, fishing and trapping pursuant to the Alaska National Interest Lands Conservation Act (Pub. L. 96-487, 94 Stat. 2371). Information regarding specific...
Dickerson, Daniel L; Johnson, Carrie L
American Indian/Alaska Native (AI/AN) urban youths experience significant mental health and substance use problems. However, culturally relevant treatment approaches that incorporate community perspectives within the urban setting are limited. This study analyzes community perspectives from AI/AN parents, AI/AN youths, and services providers within Los Angeles County. Information gathered was utilized to develop a needs assessment for AI/AN youths with mental health and substance use problems and to design a community-informed treatment approach. Nine focus groups and key informant interviews were conducted. The Los Angeles County community strongly expressed the need for providing urban AI/AN youths with traditional healing services and cultural activities within their treatment program. However, various barriers to accessing mental health and substance abuse treatment services were identified. An integrated treatment approach was subsequently designed as a result of input derived from community perspectives. The community believed that providing urban AI/AN youths with an integrated treatment approach has the potential to decrease the risk of mental health and substance abuse problems in addition to enhancing their cultural identity and self esteem. PMID:22400466
Oliver, Valerie Smith; Sumner, Jim
This handbook is a collection of printed materials that are available to students about the geology, weather, plants, animals and people of Alaska. Topics included are: (1) "Alaska History Line"; (2) "Geography of Alaska" (including maps, rivers, and islands); (3) "Geologic Time"; (4) "Geology" (including plates, earthquake zones, permafrost, and…
Solie, D. J.; McCarthy, S.
four times a year. Even though the in-class time per year is not large, our experience suggests that a long term, multi-year connection enhances learning by the students. We coordinate with HAARP research campaigns so as to utilize the availability of top scientists for public lectures. We do not limit our scope to only ionospheric physics, but try to meet the demands and needs of the region as they arise. Less than two weeks after the November, 2002 Denali Fault Earthquake, we traveled to the villages most strongly effected by the quake and presented basic preliminary information about the quake (Sources: Alaska Earthquake Information Center, Alaska State Geological Survey & USGS). As a teachable moment it was unparalleled, but it was also an example of where even preliminary information on an event can truly help to calm people.
Gardine, M.; West, M. E.; Ruppert, N.
As part of the Alaska Earthquake Center's effort to create customized and relevant products to diverse Alaskan communities, we have embarked on a process to take results from ShakeMap and tailor them to state needs. We have created customized ShakeMaps, produced shaking estimates for small communities that may not be obvious on large-scale maps, and greatly expanded a suite of earthquake scenarios throughout the state for use in hazard assessment and disaster preparation. These efforts have the combined goal helping Alaskans better prepare for the possibility of a damaging earthquake in their community. ShakeMap is a well-regarded system created by the U.S. Geological Survey (USGS) to produce maps of measured and predicted ground-motions for real and scenario earthquakes; many seismic networks throughout the world use it operationally. The Earthquake Center routinely uses ShakeMap to provide general information about recent earthquakes to stakeholders and the public. Customized ShakeMaps are produced for notable earthquakes near the Trans-Alaska Pipeline and made available to Alyeska, the pipeline operator. These ShakeMaps are part of a larger system to alert Alyeska of any strong motions that could cause damage to the pipeline infrastructure to help minimize economic and environmental issues. However, despite being the most seismically active state in the United States, limited work has been done to assess possible earthquake scenarios in much of the state and even fewer of the end products are known to residents, many of whom live in small towns and villages, isolated both in distance and in infrastructure from the rest of the population. ShakeMap scenarios are visual representations of earthquake data that have tremendous outreach value as a stand-alone product. For many of the scenarios, we have used earthquake parameters pulled from the numerous notable earthquakes in the history of the state, from the well-known (2004 M7.9 Denali Fault, 1964 M9.2 Good Friday
Louisiana Arts and Science Center, Baton Rouge.
THE UNIT DESCRIBED IN THIS BOOKLET DEALS WITH THE GEOGRAPHY OF ALASKA. THE UNIT IS PRESENTED IN OUTLINE FORM. THE FIRST SECTION DEALS PRINCIPALLY WITH THE PHYSICAL GEOGRAPHY OF ALASKA. DISCUSSED ARE (1) THE SIZE, (2) THE MAJOR LAND REGIONS, (3) THE MOUNTAINS, VOLCANOES, GLACIERS, AND RIVERS, (4) THE NATURAL RESOURCES, AND (5) THE CLIMATE. THE…
Kamer, Yavor; Ouillon, Guy; Sornette, Didier; Wössner, Jochen
We present the "condensation" method that exploits the heterogeneity of the probability distribution functions (PDFs) of event locations to improve the spatial information content of seismic catalogs. As its name indicates, the condensation method reduces the size of seismic catalogs while improving the access to the spatial information content of seismic catalogs. The PDFs of events are first ranked by decreasing location errors and then successively condensed onto better located and lower variance event PDFs. The obtained condensed catalog differs from the initial catalog by attributing different weights to each event, the set of weights providing an optimal spatial representation with respect to the spatially varying location capability of the seismic network. Synthetic tests on fractal distributions perturbed with realistic location errors show that condensation improves spatial information content of the original catalog, which is quantified by the likelihood gain per event. Applied to Southern California seismicity, the new condensed catalog highlights major mapped fault traces and reveals possible additional structures while reducing the catalog length by ∼25%. The condensation method allows us to account for location error information within a point based spatial analysis. We demonstrate this by comparing the multifractal properties of the condensed catalog locations with those of the original catalog. We evidence different spatial scaling regimes characterized by distinct multifractal spectra and separated by transition scales. We interpret the upper scale as to agree with the thickness of the brittle crust, while the lower scale (2.5 km) might depend on the relocation procedure. Accounting for these new results, the epidemic type aftershock model formulation suggests that, contrary to previous studies, large earthquakes dominate the earthquake triggering process. This implies that the limited capability of detecting small magnitude events cannot be used
Kamer, Yavor; Ouillon, Guy; Sornette, Didier; Wössner, Jochen
We present the "condensation" method that exploits the heterogeneity of the probability distribution functions (PDFs) of event locations to improve the spatial information content of seismic catalogs. As its name indicates, the condensation method reduces the size of seismic catalogs while improving the access to the spatial information content of seismic catalogs. The PDFs of events are first ranked by decreasing location errors and then successively condensed onto better located and lower variance event PDFs. The obtained condensed catalog differs from the initial catalog by attributing different weights to each event, the set of weights providing an optimal spatial representation with respect to the spatially varying location capability of the seismic network. Synthetic tests on fractal distributions perturbed with realistic location errors show that condensation improves spatial information content of the original catalog, which is quantified by the likelihood gain per event. Applied to Southern California seismicity, the new condensed catalog highlights major mapped fault traces and reveals possible additional structures while reducing the catalog length by ˜25 % . The condensation method allows us to account for location error information within a point based spatial analysis. We demonstrate this by comparing the multifractal properties of the condensed catalog locations with those of the original catalog. We evidence different spatial scaling regimes characterized by distinct multifractal spectra and separated by transition scales. We interpret the upper scale as to agree with the thickness of the brittle crust, while the lower scale (2.5 km) might depend on the relocation procedure. Accounting for these new results, the epidemic type aftershock model formulation suggests that, contrary to previous studies, large earthquakes dominate the earthquake triggering process. This implies that the limited capability of detecting small magnitude events cannot be
Ross, Katharyn E. K.; Shuell, Thomas J.
Some pre-instructional misconceptions held by children can persist through scientific instruction and resist changes. Identifying these misconceptions would be beneficial for science instruction. In this preliminary study, scores on a 60-item true-false test of knowledge and misconceptions about earthquakes were compared with previous interview…
Telesca, Luciano; Chamoli, Ashutosh; Lovallo, Michele; Stabile, Tony Alfredo
Revealing the tsunamigenic potential of an earthquake is very challenging in regards to minimizing the casualties a tsunami can provoke. Thus, development of methodologies that can reliably furnish a early warnings of a tsunami is crucial. In order to accomplish this aim it is important to preliminarily identify the characteristics of seismograms that can be used to distinguish tsunamigenic (TS) earthquakes from non-tsunamigenic (NTS) earthquakes. In this paper P-wave time dynamic of 17 seismograms of TS earthquakes and 26 NTS seismograms are analysed by means of two advanced statistical tools: the Fisher-Shannon method and the multifractal detrended fluctuation analysis (MFDFA). Both methods are well suited to disclosing the inner time properties of complex signals, as seismograms appear to be. Using these two methods jointly, we defined a classifier, the performance of which was tested by means of the receiver-operating characteristic curve that plots true positive rate versus false positive rate. This classifier shows a discrimination power that can be considered acceptable in comparison with the devastating effects caused by a non-alarmed tsunami. Our findings indicate that proper choice of the classifier's threshold allows correctly identification of approximately 69 % of the NTS seismograms and approximately 76 % of the TS seismograms. The presented results presented may be helpful in addressing the complex problem of early tsunami warning.
Zama, Shinsaku; Endo, Makoto; Takanashi, Ken'ichi; Araiba, Kiminori; Sekizawa, Ai; Hosokawa, Masafumi; Jeong, Byeong-Pyo; Hisada, Yoshiaki; Murakami, Masahiro
Based on the earlier study result that the gathering of damage information can be quickly achieved in a municipality with a smaller population, it is proposed that damage information is gathered and analyzed using an area roughly equivalent to a primary school district as a basic unit. The introduction of this type of decentralized system is expected to quickly gather important information on each area. The information gathered by these communal disaster prevention bases is sent to the disaster prevention headquarters which in turn feeds back more extensive information over a wider area to the communal disaster prevention bases. Concrete systems have been developed according to the above mentioned framework, and we performed large-scale experiments on simulating disaster information collection, transmission and on utilization for smooth responses against earthquake disaster with collaboration from Toyohashi City, Aichi Prefecture, where is considered to suffer extensive damage from the Tokai and Tonankai Earthquakes with very high probability of the occurrence. Using disaster information collection/transmission equipments composed of long-distance wireless LAN, a notebook computer, a Web camera and an IP telephone, city staffs could easily input and transmit the information such as fire, collapsed houses and impassable roads, which were collected by the inhabitants participated in the experiment. Headquarters could confirm such information on the map automatically plotted, and also state of each disaster-prevention facility by means of Web-cameras and IP telephones. Based on the damage information, fire-spreading, evaluation, and traffic simulations were automatically executed at the disaster countermeasure office and their results were displayed on the large screen to utilize for making decisions such as residents' evacuation. These simulated results were simultaneously displayed at each disaster-prevention facility and were served to make people understand the
Jordan, T.H.; Marzocchi, W.; Michael, A.J.; Gerstenberger, M.C.
We cannot yet predict large earthquakes in the short term with much reliability and skill, but the strong clustering exhibited in seismic sequences tells us that earthquake probabilities are not constant in time; they generally rise and fall over periods of days to years in correlation with nearby seismic activity. Operational earthquake forecasting (OEF) is the dissemination of authoritative information about these time‐dependent probabilities to help communities prepare for potentially destructive earthquakes. The goal of OEF is to inform the decisions that people and organizations must continually make to mitigate seismic risk and prepare for potentially destructive earthquakes on time scales from days to decades. To fulfill this role, OEF must provide a complete description of the seismic hazard—ground‐motion exceedance probabilities as well as short‐term rupture probabilities—in concert with the long‐term forecasts of probabilistic seismic‐hazard analysis (PSHA).
... earthquake hazard assessments and earthquake occurrence under the Earthquake Hazards Reduction Act of 1977..., Earthquake Hazards Program, (703) 648-6716. SUPPLEMENTARY INFORMATION: Title: Earthquake Hazards Program... under the Earthquake Hazards Reduction Act to develop earthquake hazard assessments and recording...
Bilek, S. L.; Lay, T.; Ruff, L.
Previous studies used seismic energy to moment ratios for datasets of large earthquakes as a useful discriminant for tsunami earthquakes. We extend this idea of a "slowness" discriminant to a large dataset of subduction zone underthrusting earthquakes. We determined estimates of energy release in these shallow earthquakes using a large dataset of source time functions. This dataset contains source time functions for 418 shallow (< 70 km depth) earthquakes ranging from Mw 5.5 - 8.0 from 14 circum-Pacific subduction zones. Also included are tsunami earthquakes for which source time functions are available. We calculate energy using two methods, a substitution of a simplified triangle and integration of the original source time function. In the first method, we use a triangle substitution of peak moment and duration to find a minimum estimate of energy. The other method incorporates more of the source time function information and can be influenced by source time function complexity. We examine patterns in source time function complexity with respect to the energy estimates. For comparison with other earthquake parameters, it is useful to remove the effect of seismic moment on the energy estimates. We use the seismic energy to moment ratio (E/Mo) to highlight variations with depth, moment, and subduction zone. There is significant scatter in this ratio using both methods of energy calculation. We observe a slight increase in E/Mo with increasing Mw. There is not much variation in E/Mo with depth seen in entire dataset. However, a slight increase in E/Mo with depth is apparent in a few subduction zones such as Alaska, Central America, and Peru. An average E/Mo of 5x10e-6 roughly characterizes this shallow earthquake dataset, although with a factor of 10 scatter. This value is within about a factor of 2 of E/Mo ratios determined by Choy and Boatwright (1995). Tsunami earthquakes suggest an average E/Mo of 2x10e-7, significantly lower than the average for the shallow
Hafner, L. A.; McNutt, S. R.
Felt reports for Alaskan earthquakes were found to be non-uniformly distributed throughout the year. With a predominantly tourist economy, the Alaskan population nearly triples in the summer months, possibly affecting the reporting of earthquakes in the historical record. Using published felt reports from the National Earthquake Information Center and the Alaska Earthquake Information Center, the percentage of events felt each month in central mainland Alaska were tabulated and compared between the summer and winter seasons. Earthquakes were selected from January 1, 1990 to October 31, 2002, from latitudes 58 to 70 degrees N and longitudes 140 to 160 degrees W, and depths 0 to 200 km. 408 events were felt out of a total of 695 that occurred. A number of parameters, including time of day, latitude, longitude, and magnitude, were additionally compared to specify possible limiting factors within each season. While a strong seasonal effect was not found in magnitude 4.0 ML events and greater, the months of May and June were consistently found to have the highest percentage of felt events with a steep drop occurring in the month of July. We ascribe this effect to the summer melting of the top layer of frozen ground to a depth of about 1.5 meters. Additionally, smaller events from magnitude 1.0 to 4.0 ML were also examined. 396 events were felt out of a total of 7,451 that occurred. We found that small earthquakes were felt, with a significant difference, more readily during summer months than in winter. This is likely an effect of the higher summer population of tourists and greater distribution of open businesses. Together these observations suggest that the historical Alaskan earthquake record is likely biased in favor of more frequent reporting of events occurring in summer months as opposed to winter.
Buland, R. P.; Guy, M.; Kragness, D.; Patton, J.; Erickson, B.; Morrison, M.; Bryon, C.; Ketchum, D.; Benz, H.
The USGS National Earthquake Information Center (NEIC) has put into operation a new generation of seismic acquisition, processing and distribution subsystems that seamlessly integrate regional, national and global seismic network data for routine monitoring of earthquake activity and response to large, damaging earthquakes. The system, Bulletin Hydra, was designed to meet Advanced National Seismic System (ANSS) design goals to handle thousands of channels of real-time seismic data, compute and distribute time-critical seismic information for emergency response applications, and manage the integration of contributed earthquake products and information, arriving from near-real-time up to six weeks after an event. Bulletin Hydra is able meet these goals due to a modular, scalable, and flexible architecture that supports on-the-fly consumption of new data, readily allows for the addition of new scientific processing modules, and provides distributed client workflow management displays. Through the Edge subsystem, Bulletin Hydra accepts waveforms in half a dozen formats. In addition, Bulletin Hydra accepts contributed seismic information including hypocenters, magnitudes, moment tensors, unassociated and associated picks, and amplitudes in a variety of formats including earthworm import/export pairs and EIDS. Bulletin Hydra has state-driven algorithms for computing all IASPEI standard magnitudes (e.g. mb, mb_BB, ML, mb_LG, Ms_20, and Ms_BB) as well as Md, Ms(VMAX), moment tensor algorithms for modeling different portions of the wave-field at different distances (e.g. teleseismic body-wave, centroid, and regional moment tensors), and broadband depth. All contributed and derived data are centrally managed in an Oracle database. To improve on single station observations, Bulletin Hydra also does continuous real-time beam forming of high-frequency arrays. Finally, workflow management displays are used to assist NEIC analysts in their day-to-day duties. All combined
Shrinking Sea Ice, Thawing Permafrost, Bigger Storms, and Extremely Limited Data - Addressing Information Needs of Stakeholders in Western Alaska Through Participatory Decisions and Collaborative Science.
Murphy, K. A.; Reynolds, J.
Communities, Tribes, and decision makers in coastal western Alaska are being impacted by declining sea ice, sea level rise, changing storm patterns and intensities, and increased rates of coastal erosion. Relative to their counterparts in the contiguous USA, their ability to plan for and respond to these changes is constrained by the region's generally meager or non-existent information base. Further, the information needs and logistic challenges are of a scale that perhaps can be addressed only through strong, strategic collaboration. Landscape Conservation Cooperatives (LCCs) are fundamentally about applied science and collaboration, especially collaborative decision making. The Western Alaska LCC has established a process of participatory decision making that brings together researchers, agency managers, local experts from Tribes and field specialists to identify and prioritize shared information needs; develop a course of action to address them by using the LCC's limited resources to catalyze engagement, overcome barriers to progress, and build momentum; then ensure products are delivered in a manner that meets decision makers' needs. We briefly review the LCC's activities & outcomes from the stages of (i) collaborative needs assessment (joint with the Alaska Climate Science Center and the Alaska Ocean Observing System), (ii) strategic science activities, and (iii) product refinement and delivery. We discuss lessons learned, in the context of our recent program focused on 'Changes in Coastal Storms and Their Impacts' and current collaborative efforts focused on delivery of Coastal Resiliency planning tools and results from applied science projects. Emphasis is given to the various key interactions between scientists and decision makers / managers that have been promoted by this process to ensure alignment of final products to decision maker needs.
Sandru, J. M.; Hansen, R. A.; Estes, S. A.; Fowler, M.
AEIC (Alaska Earthquake Information Center) has begun the task of upgrading the older regional seismic monitoring sites that have been in place for a number of years. Many of the original sites (some dating to the 1960's) are still single component analog technology. This was a very reasonable and ultra low power reliable system for its day. However with the advanced needs of today's research community, AEIC has begun upgrading to Broadband and Strong Motion Seismometers, 24 bit digitizers and high-speed two-way communications, while still trying to maintain the utmost reliability and maintaining low power consumption. Many sites have been upgraded or will be upgraded from single component to triaxial broad bands and triaxial accerometers. This provided much greater dynamic range over the older antiquated technology. The challenge is compounded by rapidly changing digital technology. Digitizersand data communications based on analog phone lines utilizing 9600 baud modems and RS232 are becoming increasingly difficult to maintain and increasingly expensive compared to current methods that use Ethernet, TCP/IP and UDP connections. Gaining a reliable Internet connection can be as easy as calling up an ISP and having a DSL connection installed or may require installing our own satellite uplink, where other options don't exist. LANs are accomplished with a variety of communications devices such as spread spectrum 900 MHz radios or VHF radios for long troublesome shots. WANs are accomplished with a much wider variety of equipment. Traditional analog phone lines are being used in some instances, however 56K lines are much more desirable. Cellular data links have become a convenient option in semiurban environments where digital cellular coverage is available. Alaska is slightly behind the curve on cellular technology due to its low population density and vast unpopulated areas but has emerged into this new technology in the last few years. Partnerships with organizations
Lahr, J.C.; Chouet, B.A.; Stephens, C.D.; Power, J.A.; Page, R.A.
Determination of the precise locations of seismic events associated with the 1989-1990 eruptions of Redoubt Volcano posed a number of problems, including poorly known crustal velocities, a sparse station distribution, and an abundance of events with emergent phase onsets. In addition, the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm. This algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations. The velocity model was calibrated on the basis of a posteruptive seismic survey, in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice. The model consists of a stack of homogeneous horizontal layers; setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice. Detailed analysis of hypocentral errors shows that the long-period (LP) events constituting the vigorous 23-hour swarm that preceded the initial eruption on December 14 could have originated from a point 1.4 km below the crater floor. A similar analysis of LP events in the swarm preceding the major eruption on January 2 shows they also could have originated from a point, the location of which is shifted 0.8 km northwest and 0.7 km deeper than the source of the initial swarm. We suggest this shift in LP activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of December. Volcano-tectonic (VT) earthquakes did not occur until after the initial 23-hour-long swarm. They began slowly just below the LP source and their rate of occurrence increased after the eruption of 01:52 AST on December 15, when they shifted to depths of 6 to 10 km. After January 2 the VT activity migrated gradually northward; this migration suggests northward propagating withdrawal of
The Great East Japan Earthquake of March 11, 2011 caused extensive damage over a widespread area. Our hospital library, which is located in the affected area, was no exception. A large collection of books was lost, and some web content was inaccessible due to damage to the network environment. This greatly hindered our efforts to continue providing post-disaster medical information services. Information support, such as free access to databases, journals, and other online content related to the disaster areas, helped us immensely during this time. We were fortunate to have the cooperation of various medical employees and library members via social networks, such as twitter, during the process of attaining this information support.
...In compliance with section 3506(c)(2)(A) of the Paperwork Reduction Act of 1995, the Indian Arts and Crafts Board announces the proposed extension of a public information collection and seeks public comments on the provisions...