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A Landmark of Efficiency: Digital Topographic Maps Advance Quickly Across the Nation



A Landmark of Efficiency: Digital Topographic Maps Advance Quickly Across the Nation

Since the first release of the US Topo series of revised digital topographic maps less than 19 months ago, the U.S. Geological Survey (USGS) has published more than 30,800 7.5-minute cells covering more than 50% of the nation’s land area and setting high standards for production efficiency.

“For comparison, the best year the USGS Mapping Program had previously was when we published 2,500 new quadrangle maps in 1972,” said Mark DeMulder, Chief of the USGS National Geospatial Program (NGP). “Now with our digital products, on an annual basis, we’ve exceeded that number by an order of 10.”

For the past 125 years, USGS topographic maps have provided resource managers and the general public with accessible, accurate geographic knowledge for uses that range from recreation to scientific analysis to emergency response.

To meet the need for modern computer-accessible topographic maps that are frequently updated, the USGS established the new US Topo digitally-based national map series. Modeled on the traditional, instantly recognized, paper-based 7.5-minute topographic series, these new maps use the best available government digital data.

A further efficiency gain is that rather than having USGS personnel print, distribute, and store paper copies, the entire US Topo collection is available as digital files and is distributed free of charge, through the Web, via the USGS Store. Digital US Topo map files are designed to be easily printed on demand.

Improved production processes instituted by the USGS National Geospatial Technical Operations Center (NGTOC) will allow the entire contiguous U.S. to be remapped every three years. The USGS is on track to meet this ambitious goal.

In 2009, a developmental product was introduced, a planimetric (no relief) map, called Digital Map – Beta. At the start of 2010, the USGS began adding elevation contours and hydrography (lakes, rivers and streams) and rebranded the map series as US Topo. Currently available US Topo and earlier Digital Map – Beta files are available online.

USGS Newsroom



More information

Parameter Value Description
Magnitude mb The magnitude for the event.
Longitude ° East Decimal degrees longitude. Negative values for western longitudes.
Latitude ° North Decimal degrees latitude. Negative values for southern latitudes.
Depth km Depth of the event in kilometers.
Place Textual description of named geographic region near to the event. This may be a city name, or a Flinn-Engdahl Region name.
Time 1970-01-01 00:00:00 Time when the event occurred. UTC/GMT
Updated 1970-01-01 00:00:00 Time when the event was most recently updated. UTC/GMT
Timezone offset Timezone offset from UTC in minutes at the event epicenter.
Felt The total number of felt reports
CDI The maximum reported intensity for the event.
MMI The maximum estimated instrumental intensity for the event.
Alert Level The alert level from the PAGER earthquake impact scale. Green, Yellow, Orange or Red.
Review Status Indicates whether the event has been reviewed by a human.
Tsunami This flag is set to "1" for large events in oceanic regions and "0" otherwise. The existence or value of this flag does not indicate if a tsunami actually did or will exist.
SIG A number describing how significant the event is. Larger numbers indicate a more significant event.
Network The ID of a data contributor. Identifies the network considered to be the preferred source of information for this event.
Sources A comma-separated list of network contributors.
Number of Stations Used The total number of Number of seismic stations which reported P- and S-arrival times for this earthquake.
Horizontal Distance Horizontal distance from the epicenter to the nearest station (in degrees).
Root Mean Square sec The root-mean-square (RMS) travel time residual, in sec, using all weights.
Azimuthal Gap The largest azimuthal gap between azimuthally adjacent stations (in degrees).
Magnitude Type The method or algorithm used to calculate the preferred magnitude for the event.
Event Type Type of seismic event.
Event ID Id of event.
Event Code An identifying code assigned by, and unique from, the corresponding source for the event.
Event IDS A comma-separated list of event ids that are associated to an event.

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