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Update on ITU Focus Group on AI for Natural Disaster Management GNSS-Enhanced Tsunami Early Warning Topic Group
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Numerical Modeling of Tsunami‐Generated Acoustic‐Gravity Waves in Mesopause Airglow
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Marine debris induced by the Great East Japan Earthquake and Tsunami: A multi-sensor remote sensing assessment
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The Effect of Earthquake Kinematics on Tsunami Propagation
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Tsunami Squares: Earthquake driven inundation mapping and validation by comparison to the Regional Ocean Modeling System
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Real‐Time Seismogeodetic Earthquake Magnitude Estimates for Local Tsunami Warnings
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Parallelization of the Coupled Earthquake Model
This Web-based tsunami simulation system allows users to remotely run a model on JPL s supercomputers for a given undersea earthquake. At the time of this reporting, predicting tsunamis on the Internet has never happened before. This new code directly couples the earthquake model and the ocean model on parallel computers and improves simulation speed. Seismometers can only detect information from earthquakes; they cannot detect whether or not a tsunami may occur as a result of the earthquake. When earthquake-tsunami models are coupled with the improved computational speed of modern, high-performance computers and constrained by remotely sensed data, they are able to provide early warnings for those coastal regions at risk. The software is capable of testing NASA s satellite observations of tsunamis. It has been successfully tested for several historical tsunamis, has passed all alpha and beta testing, and is well documented for users.
Consequences of impacts of small asteroids and comets with Earth
The fragmentation of a small asteroid in the atmosphere greatly increases its cross sections for aerodynamic braking and energy dissipation. At a typical impact velocity of 22 km/s, the atmosphere absorbs more than half the kinetic energy of stony meteoroids with diameters, D(sub m), less than 220 m and iron meteoroids with D(sub m) less than 80 m. The corresponding diameter for comets with impact velocity 50 km/s is D(sub m) less than 1600 m. Most of the atmospheric energy dissipation occurs in a fraction of a scale height, so large meteors appear to 'explode' or 'flare' at the end of their visible paths. This dissipation of energy in the atmosphere protects the earth from direct impact damage (e.g., craters), but it produces a blast wave that can do considerable damage. The area of destruction around the impact point in which the over-pressure in the blast wave exceeds 4 lb/sq in = 2.8 x 10(exp 5) dynes/cu cm, which is enough to knock over trees and destroy buildings, increases rapidly from zero for chondritic meteoroids less than 56 m in diameter (15 megatons) to about 200 sq km for those 80 m in diameter (48 megatons); the probable diameter of the tunguska impactor of 1908 is about 80 m. Crater formation and earthquakes are not significant in land impacts by stony asteroids less than about 200 m in diameter because of the air protection. A tsunami is probably the most devastating type of damage for asteroids 200 m to 1 km in diameter. An impact by an asteroid this size anywhere in the Atlantic would devastate coastal areas on both sides of the ocean. An asteroid a few kilometers across would produce a tsunami that would reach the foothills of the Appalachian Mountains in the upper half of the East Coast of the United States. Most of Florida is protected from a tsunami by the gradual slope of the ocean off its coast, which causes most of the tsunami energy to be reflected back into the Atlantic. The atmosphere plume produced by asteroids with diameters exceeding about 120 m cannot be contained by the atmosphere, so this bubble of high-temperature gas forms a new layer on top of the atmosphere. The dust entrapped in this hot gas is likely to have optical depths exceeding tau = 10 for asteroids with diameters exceeding about 0.5 to 1 km. The optical flux from asteroids 60 m or more in diameter is enough to ignite pine forests. However, the blast wave from an impacting asteroid goes beyond the radius in which the fire starts. The blast wave tends to blow out the fire, so it is likely that the impact will char the forest, as at Tunguska, but the impact will not produce a sustained fire. Because comets dissipate their energy much higher in the atmosphere than asteroids, they illuminate a much larger region and their blast wave is weaker. So they are much more effective in producing large fires. This suggests that the KT impactor was a comet rather than an asteroid.
Field guide to Cretaceous-tertiary boundary sections in northeastern Mexico
This guide was prepared for the field trip to the KT elastic sequence of northeastern Mexico, 5-8 February 1994, in conjunction with the Conference on New Developments Regarding the KT Event and Other Catastrophes in Earth History, held in Houston, Texas. The four-day excursion offers an invaluable opportunity to visit three key outcrops: Arroyo El Mimbral, La Lajilla, and El Pinon. These and other outcrops of this sequence have recently been interpreted as tsunami deposits produced by the meteorite impact event that produced the 200 to 300-km Chicxulub basin in Yucatan, and distributed ejecta around the world approximately 65 m.y. ago that today is recorded as a thin clay layer found at the K/T boundary. The impact tsunami interpretation for these rocks has not gone unchallenged, and others examining the outcrops arrive at quite different conclusions: not tsunami deposits but turbidites; not KT at all but 'upper Cretaceous.' Indeed, it is in hopes of resolving this debate through field discussion, outcrop evaluation, and sampling that led the organizers of the conference to sanction this field trip. This field guide provides participants with background information on the KT clastic sequence outcrops and is divided into two sections. The first section provides regional and logistical context for the outcrops and a description of the clastic sequence. The second section presents three representative interpretations of the outcrops by their advocates. There is clearly no way that these models can be reconciled and so two, if not all three, must be fundamentally wrong. Readers of this guide should keep in mind that many basic outcrop observations that these models are based upon remain unresolved. While great measures were taken to ensure that the information in the description section was as objective as possible, many observations are rooted in interpretations and the emphasis placed on certain observations depends to some degree upon the perspective of the author.
Spherule Beds 3.47-3.24 Billion Years Old in the Barberton Greenstone Belt, South Africa: A Record of Large Meteorite Impacts and Their Influence on Early Crustal and Biological Evolution
Four layers, S1-S4, containing sand-sized spherical particles formed as a result of large meteorite impacts, occur in 3.47-3.24 Ga rocks of the Barberton Greenstone Belt, South Africa. Ir levels in S3 and S4 locally equal or exceed chondritic values but in other sections are at or only slightly above background. Most spherules are inferred to have formed by condensation of impact-produced rock vapor clouds, although some may represent ballistically ejected liquid droplets. Extreme Ir abundances and heterogeneity may reflect element fractionation during spherule formation, hydraulic fractionation during deposition, and/or diagenetic and metasomatic processes. Deposition of S1, S2, and S3 was widely influenced by waves and/or currents interpreted to represent impact-generated tsunamis, and S1 and S2 show multiple graded layers indicating the passage of two or more wave trains. These tsunamis may have promoted mixing within a globally stratified ocean, enriching surface waters in nutrients for biological communities. S2 and S3 mark the transition from the 300-million-year-long Onverwacht stage of predominantly basaltic and komatiitic volcanism to the late orogenic stage of greenstone belt evolution, suggesting that regional and possibly global tectonic reorganization resulted from these large impacts. These beds provide the oldest known direct record of terrestrial impacts and an opportunity to explore their influence on early life, crust, ocean, and atmosphere. The apparent presence of impact clusters at 3.26-3.24 Ga and approx. 2.65-2.5 Ga suggests either spikes in impact rates during the Archean or that the entire Archean was characterized by terrestrial impact rates above those currently estimated from the lunar cratering record.
Lunar and Planetary Science XXXV: Impact-Related Deposits
The session "Impact-Related Deposits" included:Evidence for a Lightning-Strike Origin of the Edeowie Glass; 57Fe M ssbauer Spectroscopy of Fulgurites: Implications for Chemical Reduction; Ca-Metasomatism in Crystalline Target Rocks from the Charlevoix Structure, Quebec, Canada: Evidence for Impact-related Hydrothermal Activity; Magnetic Investigations of Breccia Veins and Basement Rocks from Roter Kamm Crater and Surrounding Region, Namibia; Petrologic Complexities of the Manicouagan Melt Sheet: Implications for 40Ar-39Ar Geochronology; Laser Argon Dating of Melt Breccias from the Siljan Impact Structure, Sweden: Implications for Possible Relationship to Late Devonian Extinction Events; Lunar Impact Crater, India: Occurrence of a Basaltic Suevite?; Age of the Lunar Impact Crater, India: First Results from Fission Track Dating; The Fluidized Chicxulub Ejecta Blanket, Mexico: Implications for Mars; Low Velocity Ejection of Boulders from Small Lunar Craters: Ground Truth for Asteroid Surfaces; Ejecta and Secondary Crater Distributions of Tycho Crater: Effects of an Oblique Impact; Potassium Isotope Systematics of Crystalline Lunar Spherules from Apollo 16; Late Paleocene Spherules from the North Sea: Probable Sea Floor Precipitates: A Silverpit Provenance Unproven; A Lithological Investigation of Marine Strata from the Triassic-Jurassic Boundary Interval, Queen Charlotte Islands, British Columbia, Including a Search for Shocked Quartz; Triassic Cratered Cobbles: Shock Effects or Tectonic Pressure?; Regional Variations of Trace Element Composition Within the Australasian Tektite Strewn Field; Cretaceous-Tertiary Boundary Microtektite-bearing Sands and Tsunami Beds, Alabama Gulf Coastal Plain; Sand Lobes on Stewart Island as Probable Impact-Tsunami Deposits; Distal Impact Ejecta, Uppermost Eocene, Texas Coastal Plain; and Continental Impact Debris in the Eltanin Impact Layer.
ldentifying Episodes of Earth Science Phenomena Using a Big-Data Technology
A significant portion of Earth Science investigations is phenomenon- (or event-) based, such as the studies of Rossby waves, volcano eruptions, tsunamis, mesoscale convective systems, and tropical cyclones. However, except for a few high-impact phenomena, e.g. tropical cyclones, comprehensive records are absent for the occurrences or events of these phenomena. Phenomenon-based studies therefore often focus on a few prominent cases while the lesser ones are overlooked. Without an automated means to gather the events, comprehensive investigation of a phenomenon is at least time-consuming if not impossible. We have constructed a prototype Automated Event Service (AES) system that is used to methodically mine custom-defined events in the reanalysis data sets of atmospheric general circulation models. Our AES will enable researchers to specify their custom, numeric event criteria using a user-friendly web interface to search the reanalysis data sets. Moreover, we have included a social component to enable dynamic formation of collaboration groups for researchers to cooperate on event definitions of common interest and for the analysis of these events. An Earth Science event (ES event) is defined here as an episode of an Earth Science phenomenon (ES phenomenon). A cumulus cloud, a thunderstorm shower, a rogue wave, a tornado, an earthquake, a tsunami, a hurricane, or an El Nino, is each an episode of a named ES phenomenon, and, from the small and insignificant to the large and potent, all are examples of ES events. An ES event has a duration (often finite) and an associated geo-location as a function of time; it's therefore an entity embedded in four-dimensional (4D) spatiotemporal space. Earth Science phenomena with the potential to cause massive economic disruption or loss of life often rivet the attention of researchers. But, broader scientific curiosity also drives the study of phenomena that pose no immediate danger, such as land/sea breezes. Due to Earth System's intricate dynamics, we are continuously discovering novel ES phenomena. We generally gain understanding of a given phenomenon by observing and studying individual events. This process usually begins by identifying the occurrences of these events. Once representative events are identified or found, we must locate associated observed or simulated data prior to commencing analysis and concerted studies of the phenomenon. Knowledge concerning the phenomenon can accumulate only after analysis has started. However, as mentioned previously, comprehensive records only exist for a very limited set of high-impact phenomena; aside from these, finding events and locating associated data currently may take a prohibitive amount of time and effort on the part of an individual investigator. The reason for the lack of comprehensive records for most of the ES phenomena is mainly due to the perception that they do not pose immediate and/or severe threat to life and property. Thus they are not consistently tracked, monitored, and catalogued. Many phenomena even lack precise and/or commonly accepted criteria for definitions. Moreover, various Earth Science observations and data have accumulated to a previously unfathomable volume; NASA Earth Observing System Data Information System (EOSDIS) alone archives several petabytes (PB) of satellite remote sensing data, which are steadily increasing. All of these factors contribute to the difficulty of methodically identifying events corresponding to a given phenomenon and significantly impede systematic investigations. We have not only envisioned AES as an environment for identifying customdefined events but also aspired for it to be an interactive environment with quick turnaround time for revisions of query criteria and results, as well as a collaborative environment where geographically distributed experts may work together on the same phenomena. A Big Data technology is thus required for the realization of such a system. In the following, we first introduce the technology selected for AES in the next section. We then demonstrate the utility of AES using a use case, Blizzard, before we conclude.
Scaling Laws for Impact Craters in Water
Tsunami waves from asteroid impacts into water are of concern from asteroids in the 200 m to 1 km diameter range because this spans the range from asteroids that will likely hit the surface and not airburst, but also be small enough that global climate effects will hopefully be minimal. Current estimates of impact tsunamis depend on either hydrocode simulations or on semi-analytical models. Unfortunately there is significant disagreement between these methods. One of the main reasons for the disparity is that the semi-analytical models such as Holsapple (1993) rely on experimental impacts into deep water. However for asteroids in the 200 - 1000 m range even the deep ocean basins can appear as shallow water impacts where the crater formed in the water reaches all the way to the sea floor. Another reason for the disparity arises from the linear interpolation of data across many orders of magnitude difference between Froude number (ratio of kinetic to gravitational energy) used in the laboratory experiments and what would be seen in an asteroid impact. The Gault & Sonett (1982) experiment shot millimeter sized glass spheres into water at 1 to 6 km/s and the Olevson (1969) experiment dropped millimeter sized water drops at a few meters per second. The goal of this work was to fill in the gaps and conduct experiments and simulations at the correct Froude numbers of interest, and in both deep and shallow water, to help resolve the disparity and extend the semi-analytical models.
Circumpolar Ocean Stability on Mars 3 Gy Ago
What was the nature of the Late Hesperian climate, warm and wet or cold and dry? Formulated this way the question leads to an apparent paradox since both options seem implausible. A warm and wet climate would have produced extensive fluvial erosion but few valley networks have been observed at the age of the Late Hesperian. A too cold climate would have kept any northern ocean frozen most of the time. A moderate cold climate would have transferred the water from the ocean to the land in the form of snow and ice. But this would prevent tsunami formation, for which there is some evidence. Here, we provide insights from numerical climate simulations in agreement with surface geological features to demonstrate that the Martian climate could have been both cold and wet. Using an advanced general circulation model (GCM), we demonstrate that an ocean can be stable, even if the Martian mean surface temperature is lower than 0 ∘C. Rainfall is moderate near the shorelines and in the ocean. The southern plateau is mostly covered by ice with a mean temperature below 0 ∘C and a glacier return flow back to the ocean. This climate is achieved with a 1-bar CO2-dominated atmosphere with 10% H2. Under this scenario of 3 Ga, the geologic evidence of a shoreline and tsunami deposits along the ocean/land dichotomy are compatible with ice sheets and glacial valleys in the southern highlands.
Oceanographic applications of radar altimetry from a spacecraft.
Spacecraft radar altimetry applied to study of sea surface slopes, tides, tsunamis, storm surges and submarine geology
First geosynchronous weather satellite prepared for launch
The Synchronous Meteorological Satellite (SMS), which is scheduled for launch 16 May 1974 is described along with the data transmission system. The Carrier Balloon System is discussed. The primary type of data to be obtained in conjunction with SMS and Nimbus F are meteorological, oceanographic, seismic, and tsunami information. The Space Environment Monitoring System is also described.