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1.
Silvia Ceramicola Daniel Praeg Andrea Cova Daniela Accettella Massimo Zecchin 《Geo-Marine Letters》2014,34(2-3):111-129
Mud volcanoes (MVs) are abundant along the eastern Mediterranean subduction zones, recording mud breccia extrusion over long timescales (106 years), but to date relatively few have been recognised in the northern Ionian Sea on the Calabrian accretionary prism (CAP). In the present study, the seafloor distribution and recent activity of MVs is investigated across a 35,600 km2 sector of the CAP using a regional acoustic dataset (multibeam bathymetric and backscatter imagery, integrated with subbottom profiles) locally ground-truthed by sediment cores. A total of 54 MVs are identified across water depths of 150–2,750 m using up to four geophysical criteria: distinctive morphology, high backscatter, unstratified subbottom facies and, in one case, a hydroacoustic flare. Fourteen MVs are identified from 3–4 criteria, of which five have been previously proven by cores containing mud breccia beneath up to 1.6 m of hemipelagic sediments (Madonna dello Ionio MVs 1–3, Pythagoras MV and the newly named Sartori MV), while nine others are identified for the first time (Athena, Catanzaro, Cerere, Diana, Giunone, Minerva, ‘right foot’, Venere 1 and 2). Forty other as yet unnamed MVs are inferred from 1–2 geophysical criteria (three from distinctive morphology alone). All but one possible MV lie on the inner plateau of the CAP, landwards of the Calabrian Escarpment in a zone up to 120 km wide that includes the inner pre-Messinian wedge and the fore-arc basins, where they are interpreted to record the ascent from depth of overpressured fluids that interacted with tectonic structures and with evaporitic or shale seals within the fore-arc basins. The rise of fluids may have been triggered by post-Messinian out-of-sequence tectonism that affected the entire pre-Messinian prism, but Plio-Quaternary sedimentation rates and depositional styles support the inference that significant mud volcanism has taken place only on the inner plateau. Sedimentation rates across the CAP applied to a 12 khz sonar detection depth of 225 cm imply that all MVs with backscatter signatures (50 of 54) have erupted mud breccias within the last 56 ka, and within the last 12.5 ka in the fore-arc basins. Ages of eruption estimated from the depth of cored mud breccias at five MVs, and a seismo-stratigraphic relationship at a sixth, indicate episodes at the last glacial maximum ca. 20 ka BP and during the postglacial period. Eruptive episodes within the Calabrian MV province constitute recurrent geohazards, separated by longer periods of quiescent (subdued) fluid seepage that are likely to support gas hydrate formation and chemosynthetic ecosystems. 相似文献
2.
An evacuation trigger is a point on the landscape that, once crossed by a wildfire, triggers an evacuation for a community.
The Wildland-Urban Interface Evacuation (WUIVAC) model can be used to create evacuation trigger buffers around a community
using fuels, weather, and topographic inputs. A strategic, community-scale application of WUIVAC for the town of Julian, California
was investigated. Eight years of wind measurements were used to determine the worst-case (strongest) winds in 16 directions.
Surface fire rate of spread was used to calculate evacuation trigger buffers for the communities of Julian and nearby Whispering
Pines, and for three potential evacuation routes. Multiple trigger buffers were combined to create fire planning areas, and
trigger buffers that predict the closure of all evacuation routes were explored. WUIVAC trigger buffers offer several potential
benefits for strategic evacuation planning, including determination of when to evacuate and locating potential evacuation
routes. 相似文献
3.
There is an increasing need for a quick, simple method to represent diurnal population change in metropolitan areas for effective emergency management and risk analysis. Many geographic studies rely on decennial U.S. Census data that assume that urban populations are static in space and time. This has obvious limitations in the context of dynamic geographic problems. The U.S. Department of Transportation publishes population data at the transportation analysis zone level in fifteen-minute increments. This level of spatial and temporal detail allows for improved dynamic population modeling. This article presents a methodology for visualizing and analyzing diurnal population change for metropolitan areas based on this readily available data. Areal interpolation within a geographic information system is used to create twenty-four (one per hour) population surfaces for the larger metropolitan area of Salt Lake County, Utah. The resulting surfaces represent diurnal population change for an average workday and are easily combined to produce an animation that illustrates population dynamics throughout the day. A case study of using the method to visualize population distributions in an emergency management context is provided using two scenarios: a chemical release and a dirty bomb in Salt Lake County. This methodology can be used to address a wide variety of problems in emergency management. 相似文献
4.
D. Civile E. Lodolo H. Alp Z. Ben-Avraham A. Cova L. Baradello D. Accettella M. Burca J. Centonze 《Marine Geophysical Researches》2014,35(1):37-53
Within the central Mediterranean, the northwestern sector of the Sicily Channel is the unique area where two independent tectonic processes can be analyzed: the building of the Sicilian–Maghrebian Chain occurred in Late Miocene and the continental lithospheric rifting of the northern African margin occurred since Early Pliocene. These two geodynamic processes generated a peculiar structural style that is largely recognizable in the Adventure Plateau. This plateau is the shallowest part of the Sicily Channel, where water depths do not generally exceed 150 m. It hosts several areas of geomorphic relief, which in some cases rise up to less than 20 m beneath sea-level. A series of submarine magmatic manifestations occur in this area, mainly associated with the extensional phase which produced the rift-related depressions of Pantelleria, Malta and Linosa. Seismic-stratigraphic and structural analyses, based on a large set of multichannel seismic reflection profiles and well information acquired mostly for commercial purposes in the 1970s and 1980s, have allowed us to reconstruct the Triassic-Quaternary sedimentary succession of the Adventure Plateau and define its structural setting. A broad lithological distinction can be made between the successions ranging from Triassic to Paleogene, predominantly carbonate, and the successions ranging from Miocene to Quaternary, predominantly siliciclastic. Three main structural belts have been identified within the Adventure Plateau: (1) the northern belt, affected during Late Miocene time by ESE-verging thrusts belonging to the External Thrust System orogenic domain, which represents the lowermost structural level of the Sicilian–Maghrebian Orogen; (2) the Apenninic–Maghrebian domain of the Sicilian–Maghrebian Orogen, which occupies the northwestern sector of the Adventure Plateau, and that is overthrusted on the External Thrust System orogenic domain during the Late Miocene; (3) the extensional belt of the southwestern sector of the Adventure Plateau, affected by broad NW-trending, high-angle normal faults associated with the Early Pliocene continental rifting phase. The eastern boundary of the Adventure Plateau corresponds to a broadly N–S trending lithospheric transfer zone separating two sectors of the Sicily Channel characterized by a different tectonic evolution. 相似文献
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Warning communities in the path of an advancing wildfire is a challenging problem. Decision makers need the most current information available to determine who should evacuate, when they should leave and what type of order to issue (e.g. mandatory, recommended, voluntary). This paper presents a new method for delimiting wildfire evacuation trigger points using fire spread modeling and GIS. Using data on wind, topography, and fuel in conjunction with estimated evacuation time, a trigger buffer can be computed for a community whereby an evacuation is recommended if a fire crosses the edge of the buffer. A case study is presented for the Corral Canyon section of the 1996 Calabasas Fire near Malibu, California, USA. The paper concludes with a discussion of the strengths and weaknesses of this approach. 相似文献
7.
Zlatina Anguelova Douglas A. Stow John Kaiser Philip E. Dennison Tom Cova 《The Professional geographer》2013,65(2):230-247
Wildfires create a risk to pedestrians traveling through rural areas, because they might not be aware of the presence of a wildfire or its direction and rate of spread until is too late to successfully evacuate. In wildland areas of southern San Diego County, immigrants crossing the U.S.–Mexico border and border security agents are particularly at risk to wildfires. The objective of this study is to develop a framework of analysis and associated tools for examining the combined behavior of wildfires and pedestrian mobility to assess the potential threat of fire to pedestrians in wildland areas. Outputs from a geographic information system (GIS) overlay model for determining potentially dangerous fire zones, the Wildland–Urban Interface Evacuation (WUIVAC) model, and a model of pedestrian mobility in wildland areas were combined to generate wildfire risk to pedestrian maps. The key technical contributions of the study are the development and testing of the pedestrian mobility model and the framework and logic for integrating the results of three GIS-based models. The applied geography contribution is the testing of two scenarios of high risk from wildfires to pedestrians within the U.S.–Mexico border zone of San Diego County, California. The study results show that the travel times calculated by the pedestrian mobility model appear to be realistic and are affected by the terrain and vegetation characteristics of a study site, whereas the evacuation trigger buffers (ETBs) from WUIVAC are mostly influenced by the wind speed and direction parameters of the FlamMap fire spread model. A moderate fire danger to pedestrians in the most remote wildland locations of the study area is determined. The scenario test results suggest that if a wildfire occurs within 2 km (extreme southwesterly winds) or 6 km (extreme northeasterly wind) of pedestrians in the worst case location within the San Diego border region they would likely not have a sufficient amount of time to reach a nearby safety zone. 相似文献
8.
Dynamic GIS Case Studies: Wildfire Evacuation and Volunteered Geographic Information 总被引:1,自引:0,他引:1
Edward Pultar Martin Raubal Thomas J Cova Michael F Goodchild 《Transactions in GIS》2009,13(S1):85-104
Incorporating the temporal element into traditional GIS is a challenge that has been researched for many years and has many proposed solutions. The implemented system "Extended Dynamic GIS" or EDGIS is based on the "geo-atom" and Space Time Point (STP). EDGIS provides a platform for spatiotemporal data representation, storage, and query in order to address the need for a dynamic GIS to manage complex geographic data types. The system has the capability of executing spatiotemporal object interaction queries (OIQs) such as crossing and coincidence of field-objects and object-fields. In this article existing dynamic GIS analysis techniques are further improved and enhanced through exploration of more in-depth case studies. Further examined here are applications to wildfire evacuation modeling and travel scenarios of urban environments with individuals providing volunteered geographic information (VGI). The EDGIS platform provides a means for interacting with a range of dynamic geographic phenomena. The areas of transportation, location based services (LBS), hazards, and geo-sensor networks provide challenges intertwined with the above applications as well as additional challenges pertinent to the ongoing GIScience research topic of spatiotemporal GIS. Using EDGIS to explore the described case studies of wildfire evacuation as well as VGI provides the advancements described above and demonstrates implemented uses for dynamic GIS. 相似文献
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Volcanic ash can cause physical damage to an aircraft to the point of mechanical and electrical malfunction. In the event of an ash plume, aircraft would likely be diverted or grounded, leading to economic losses. This article presents two indices to compare the economic vulnerability of flight paths to volcanic ash plumes. The first index includes three factors for a flight path: wind direction, distance to the volcano, and flight‐path attributes (i.e., number of flights per day, number of potential passengers, and average ticket cost). The second index compares the threat posed by different volcanoes to an airline flight‐path network. A case study is presented for two airlines in the northwest United States to a Mt. Adams eruption. The results show that although the first airline has more flight paths in the region, the second airline is slightly more vulnerable due to the spatial relationships of its flight paths to the volcano and their attributes. 相似文献