Evaluation of Intensity Prediction Equations (IPEs) for Small-Magnitude Earthquakes

2021 ◽  
Author(s):  
Ganyu Teng ◽  
Jack W. Baker ◽  
David J. Wald
Keyword(s):  
United States ◽  
Ground Truth ◽  
Site Amplification ◽  
Eastern United States ◽  
Prediction Equations ◽  
Small Magnitude ◽  
Intensity Prediction ◽  
Central United States ◽  
Hazard Disaggregation

Abstract This study assesses existing intensity prediction equations (IPEs) for small unspecified magnitude (M ≤3.5) earthquakes at short hypocentral distances (Dh) and explores such earthquakes’ contribution to the felt shaking hazard. In particular, we consider IPEs by Atkinson and Wald (2007) and Atkinson et al. (2014), and evaluate their performance based on “Did You Feel It” (DYFI) reports and recorded peak ground velocities (PGVs) in the central United States. Both IPEs were developed based on DYFI reports in the central and eastern United States with moment magnitudes above Mw 3.0. DYFI reports are often used as the ground truth when evaluating and developing IPEs, but they could be less reliable when there are limited responses for small-magnitude earthquakes. We first compare the DYFI reports with intensities interpolated from recorded PGVs. Results suggest a minimal discrepancy between the two when the intensity is large enough to be felt (i.e., M >2 and Dh<15  km). We then compare intensities from 31,617 DYFI reports of 3049 earthquakes with the two IPEs. Results suggest that both the IPEs match well with observed intensities for 2.0< M <3.0 and Dh<10  km, but the IPE by Atkinson et al. (2014) matches better for larger distances. We also observe that intensities from DYFI reports attenuate faster compared with the two IPEs, especially for distances greater than 10 km. We then group DYFI reports by inferred VS30 as a proxy for site amplification effects. We observe that intensities at sites with VS30 around 300 m/s are consistently higher than at sites with VS30 around 700 m/s and are also closer to the two IPEs. Finally, we conduct hazard disaggregation for earthquakes at close distances (Dh=7.5  km) using the observed records. Results suggest that earthquakes with magnitudes below M 3.0 contribute more than 40% to the occurrence of felt shaking.

scholarly journals Virulence of Puccinia triticina on Wheat in the United States in 1999

Plant Disease ◽  
2002 ◽  
Vol 86 (1) ◽  
pp. 15-19 ◽  
Author(s):  
D. L. Long ◽  
K. J. Leonard ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Great Plains ◽  
Gulf Coast ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
Distribution Patterns ◽  
The United States ◽  
Eastern United States ◽  
Ohio Valley ◽  
Central United States

Isolates of Puccinia triticina were obtained from wheat leaf collections made by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio Valley, and Gulf Coast states in 1999. Pathogenic races were determined from virulence/avirulence phenotypes on 14 host lines that are near-isogenic for leaf rust resistance. We found 58 races among 1,180 isolates in 1999. As in previous surveys, regional race distribution patterns showed that the central United States is a single epidemiological unit distinct from the eastern United States. The distinctive racial composition of collections from the Southeast, Northeast, and Ohio Valley indicates that populations of P. triticina in those areas are not closely connected, suggesting epidemics originate from localized overwintering sources.

Zoogeography and taxonomy of Dirofilaria scapiceps (Leidy, 1886) and D. uniformis Price, 1957 (Nematoda: Filarioidea) of lagomorphs in North America

1983 ◽  
Vol 61 (5) ◽  
pp. 1011-1022 ◽  
Author(s):  
Cheryl M. Bartlett
Keyword(s):  
United States ◽  
North America ◽  
Host Record ◽  
Sylvilagus Floridanus ◽  
Eastern United States ◽  
New Host ◽  
New Host Record ◽  
South Central ◽  
Central United States ◽  
Subcutaneous Tissues

Dirofilaria scapiceps (Leidy, 1886) was found in 62% of 404 Lepus americanus, 27% of 89 Sylvilagus floridanus, 13% of 31 Orytolagus cuniculus (domestic), 4% of 26 L. capensis, and none of 15 L. timidus, 2 L. californicus, and 50 L. townsendii collected in various regions of North America. Dirofilaria scapiceps in L. capensis is a new host record. The two species of Dirofilaria, D. scapiceps and D. uniformis Price, 1957, known from lagomorphs are redescribed. Dirofilaria scapiceps occurs predominantly in connective tissue surrounding tendons in the ankle region and rarely in intermuscular fascia near the knee joint of the hind leg; D. uniformis occurs in subcutaneous tissues of the trunk. Both D. scapiceps and D. uniformis are known only from lagomorphs in North America, D. scapiceps from L. americanus, L. capensis, S. floridanus, S. palustris and O. cuniculus and D. uniformis from S. floridanus, S. palustris and O. cuniculus. Dirofilaria scapiceps is present in lagomorphs in Alaska, Canada, eastern United States and Wyoming whereas D. uniformis is known only from lagomorphs in southeastern and south central United States. Dirofilaria uniformis may have evolved, through paedomorphosis, from D. scapiceps.

scholarly journals Observations of Hail–Wind Ratios from Convective Storm Reports across the Continental United States

2020 ◽  
Vol 35 (2) ◽  
pp. 635-656 ◽  
Author(s):  
Matthew J. Bunkers ◽  
Steven R. Fleegel ◽  
Thomas Grafenauer ◽  
Chauncy J. Schultz ◽  
Philip N. Schumacher
Keyword(s):  
United States ◽  
Late Summer ◽  
Weather Forecast ◽  
Eastern United States ◽  
Convective Storm ◽  
Convective Storms ◽  
Warm Summer ◽  
Central United States ◽  
Spatiotemporal Analyses ◽  
Convective Mode

Abstract The objective of this study is to provide guidance on when hail and/or wind is climatologically most likely (temporally and spatially) based on the ratio of severe hail reports to severe wind reports, which can be used by National Weather Forecast (NWS) forecasters when issuing severe convective warnings. Accordingly, a climatology of reported hail-to-wind ratios (i.e., number of hail reports divided by the number of wind reports) for observed severe convective storms was derived using U.S. storm reports from 1955 to 2017. Owing to several temporal changes in reporting and warning procedures, the 1996–2017 period was chosen for spatiotemporal analyses, yielding 265 691 hail and 294 449 wind reports. The most notable changes in hail–wind ratios occurred around 1996 as the NWS modernized and deployed new radars (leading to more hail reports relative to wind) and in 2010 when the severe hail criterion increased nationwide (leading to more wind reports relative to hail). One key finding is that hail–wind ratios are maximized (i.e., relatively more hail than wind) during the late morning through midafternoon and in the spring (March–May), with geographical maxima over the central United States and complex/elevated terrain. Otherwise, minimum ratios occur overnight, during the late summer (July–August) as well as November–December, and over the eastern United States. While the results reflect reporting biases (e.g., fewer wind than hail reports in low-population areas but more wind reports where mesonets are available), meteorological factors such as convective mode and cool spring versus warm summer environments also appear associated with the hail–wind ratio climatology.

The Precipitation Response over the Continental United States to Cold Tropical Pacific Sea Surface Temperatures

2014 ◽  
Vol 27 (13) ◽  
pp. 5036-5055 ◽  
Author(s):  
Hailan Wang ◽  
Siegfried Schubert
Keyword(s):  
United States ◽  
Warm Season ◽  
The United States ◽  
Tropical Pacific ◽  
Eastern United States ◽  
North Atlantic Subtropical High ◽  
Sst Variability ◽  
The Pacific ◽  
Central United States ◽  
Atmospheric Circulation Anomalies

The dominant pattern of SST variability in the Pacific during its cold phase produces pronounced precipitation deficits over the continental United States throughout the annual cycle. This study investigates the observed physical and dynamical processes through which the cold Pacific pattern affects U.S. precipitation, particularly the causes for the peak dry impacts in fall, as well as the nature of the differences between the summer and fall responses. Results show that the peak precipitation deficit over the United States during fall is primarily due to reduced atmospheric moisture transport from the Gulf of Mexico into the central and eastern United States and secondarily a reduction in local evaporation from land–atmosphere feedback. The former is associated with a strong and systematic low-level northeasterly flow anomaly over the southeastern United States that counteracts the northwest branch of the climatological North Atlantic subtropical high. The above northeasterly anomaly is maintained by both diabatic heating anomalies in the nearby intra-American seas and diabatic cooling anomalies in the tropical Pacific. In contrast, the modest summertime precipitation deficit over the central United States is mainly an intensification of the local dry anomaly in the preceding spring from local land–atmosphere feedback; the rather weak and disorganized atmospheric circulation anomalies over and to the south of the United States make little contribution. An evaluation of the NASA Seasonal-to-Interannual Prediction Project (NSIPP-1) AGCM simulations shows it to be deficient in simulating the warm season tropical convection responses over the intra-American seas to the cold Pacific pattern and thereby the precipitation responses over the United States, a problem that appears to be common to many AGCMs.

scholarly journals Warm Season Response over North America to a Shutdown of the Atlantic Meridional Overturning Circulation and CO2 Increases

2012 ◽  
Vol 25 (19) ◽  
pp. 6701-6720 ◽  
Author(s):  
Bing Pu ◽  
Edward K. Vizy ◽  
Kerry H. Cook
Keyword(s):  
United States ◽  
North Atlantic ◽  
Warm Season ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Eastern United States ◽  
The North ◽  
Central United States ◽  
Moisture Fluxes ◽  
Meridional Overturning

Abstract Paleo-proxy and modeling evidence suggest that a shutdown of the Atlantic meridional overturning circulation (AMOC) would decrease North Atlantic Ocean sea surface temperatures and have far-reaching climate impacts. The authors use a regional climate model to examine the warm season response over North America to a hypothetical late-twenty-first-century shutdown of the AMOC with increased atmospheric CO2. In the future simulation, precipitation decreases over the western and central United States by up to 40% and over eastern Mexico by up to 50%. Over the eastern United States rainfall generally increases except during July. Variations in the moisture convergence associated with large-scale circulation changes dominate the rainfall variations, while evaporation plays a critical role over the northeastern United States in spring and the north-central United States in summer. During April–June the westward extension of the North Atlantic subtropical high enhances southwesterly moisture fluxes from the Gulf of Mexico into the eastern and south-central United States. Increases in low-level moisture content reduce the stability of the atmosphere. Enhanced southerly winds promote convergence over the eastern United States through the Sverdrup vorticity balance and precipitation increases. In July–August anomalous anticyclonic moisture fluxes associated with an anomalous high over the Gulf of Mexico and eastern Pacific decrease the moisture supply into the United States and Mexico. Over the central United States decreases in evaporation support decreases in low-level moisture content and increases in atmospheric stability. Over the eastern United States the Sverdrup balance weakens in summer and anomalous moisture convergence is mainly located over the East Coast.

scholarly journals Virulence of Puccinia triticina on Wheat in the United States from 1996 to 1998

Plant Disease ◽  
2000 ◽  
Vol 84 (12) ◽  
pp. 1334-1341 ◽  
Author(s):  
D. L. Long ◽  
K. J. Leonard ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Great Plains ◽  
Gulf Coast ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
Distribution Patterns ◽  
The United States ◽  
Eastern United States ◽  
Ohio Valley ◽  
Central United States

Isolates of Puccinia triticina were obtained from wheat leaf collections made by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio Valley, and Gulf Coast states in 1996, 1997, and 1998. Virulence-avirulence phenotypes were determined on 14 host lines that are near-isogenic for leaf rust resistance. We found 31 phenotypes among 277 single uredinial isolates in 1996, 56 phenotypes among 989 isolates in 1997, and 43 phenotypes among 989 isolates in 1998. As in previous surveys, regional race distribution patterns showed that the central United States is a single epidemiological unit distinct from the eastern United States. The distinctive racial composition of collections from the southeast, northeast, and Ohio Valley indicate that populations of P. triticina in those areas are not closely connected, suggesting that epidemics originate from localized overwintering sources.

scholarly journals Future Changes in Hail Occurrence in the United States Determined through Convection-Permitting Dynamical Downscaling

2019 ◽  
Vol 32 (17) ◽  
pp. 5493-5509 ◽  
Author(s):  
Robert J. Trapp ◽  
Kimberly A. Hoogewind ◽  
Sonia Lasher-Trapp
Keyword(s):  
United States ◽  
Dynamical Downscaling ◽  
The United States ◽  
Lower Atmosphere ◽  
Eastern United States ◽  
Environmental Support ◽  
Convective Storms ◽  
Four Seasons ◽  
Central United States ◽  
Storm Frequency

AbstractThe effect of anthropogenically enhanced greenhouse gas concentrations on the frequency and intensity of hail depends on a range of physical processes and scales. These include the environmental support of the hail-generating convective storms and the frequency of their initiation, the storm volume over which hail growth is promoted, and the depth of the lower atmosphere conducive to melting. Here, we use high-resolution (convection permitting) dynamical downscaling to simultaneously account for these effects. We find broad geographical areas of increases in the frequency of large hail (≳35-mm diameter) over the United States, during all four seasons. Increases in very large hail (≳50-mm diameter) are mostly confined to the central United States, during boreal spring and summer. And, although increases in moderate hail (≳20-mm diameter) are also found throughout the year, decreases occur over much of the eastern United States in summer. Such decreases result from a projected decrease in convective-storm frequency. Overall, these results suggest that the annual U.S. hail season may begin earlier in the year, be lengthened by more than a week, and exhibit more interannual variability in the future.

Are Active Mid-Plate Fault Zones of the Central United States Interconnected?

1988 ◽  
Vol 59 (4) ◽  
pp. 312-312
Author(s):  
D. B. Slemmons ◽  
A. R. Ramelli
Keyword(s):  
United States ◽  
Active Faults ◽  
Fault Zones ◽  
Eastern United States ◽  
Active Systems ◽  
Kentucky River ◽  
Central United States ◽  
Tectonically Active ◽  
Large Earthquakes ◽  
Epicentral Region

Abstract It is generally assumed that faults in mid-plate regions, such as central and eastern United States (CEUS), unless historically active, are inactive and/or lack a potential for large earthquakes. The Meers fault in Oklahoma, located in an historically aseismic area, is a spectacular exception to this rule. Paleoseismic studies of this fault show that the most recent large event occurred about 1200 years ago, had a magnitude of more that MS = 7 or 7.5, a surface rupture of 40 km length, and several meters of net displacement on a major left-lateral fault (Ramelli and Slemmons, in press). At least four fault zones in other parts of CEUS indicate that the Meers faulting event is not unique, including: (1) New Madrid epicentral region with three events of about MS = 8 in 1811 and 1812 with surface faulting and deformation (Russ, 1982), (2) Washita Valley fault (Cox and VanArsdale, 1986), (3) Kentucky River fault (VanArsdale, 1986), and possibly (4) faulting near Pierre, South Dakota (Nichols and Collins, 1987). Moreover, such midplate active faults are not unique, for there are at last four similar examples of historical seismogenic faulting (McCue and others, 1987) with earthquakes of up to 6.9 magnitude. Most active fault zones can be dearly demonstrated to be parts of branching or interconnected tectonic systems, implying transfer of stress and strain along zones of deformation. We speculate that tectonically active mid-plate fault zones may also be parts of much longer, interconnected active systems, rather than isolated “hot spots” of activity resulting solely from the response of local crustal flaws to a regional stress field.

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