Introduction

During the past 40 years, the U.S. Geological Survey has provided the Nation's map users with primary quadrangle map coverage at 1:24,000 scale in the lower 48 States and 1:63,300 scale in Alaska. This

effort has produced about 50,000 separate

maps. By the end of fiscal year 1986, primary

quadrangle maps and related map products

were available for about 92 percent of the country. Completion of initial coverage is scheduled for the beginning of fiscal year

1990.

As the number of areas needing primary coverage has decreased and the need for revised maps and digital cartographic data has increased, the Survey's traditional mapping program has become a program in transition.

Primary Mapping Program

The Primary Mapping Program is designed to provide current and accurate cartographic data to the user community nationwide. To accomplish this objective, the program has two long-range goals: (1) to provide primary cartographic data of standard content, currency, and accuracy to satisfy Federal, State, and local user needs and (2) to provide primary cartographic data in digital form from the National Digital Cartographic Data Base (NDCDB).

To attain these long-range goals and to continue the development of the Survey's digital systems, two special studies were conducted in 1985. One study concerned the programmatic issues of transforming from graphic to primarily digital techniques for map production while coping with a growing need to revise existing maps. The second study concerned the technical aspects of the transition. On the basis of these two studies, an integrated development production plan was adopted to guide

the Geological Survey through the remainder of the century.

Primary Mapping Program Objectives

To provide the Nation with primary cartographic data of standard content, currency, and accuracy, six objectives must be obtained:

1 Complete initial national coverage at the primary map scales by fiscal year 2000. This undertaking will require the completion of 3,200 7.5-minute quadrangles in unmapped areas.

2. Convert 1,500 existing "T-maps" to published 7.5-minute format. T-maps were originally compiled during the 1950's and 1960's at 1:24,000 scale but published at 1:62,500 scale, which was the common map scale at that time. This objective is scheduled for completion in fiscal year 1991.

3. Recompile 5,000 substandard maps so that they reflect the most accurate and current data possible before they are digitized and entered into the NDCDB. This effort is expected to be completed in fiscal year 1999.

4. Recompile 6,280 deficient maps that reflect inappropriate contour intervals and (or) incomplete Public Land Survey System data. The objective is to accomplish recompilation of those data by fiscal year 1997.

consistent with that of standard maps before digitizing. 6. Maintain primary cartographic data already meeting standards of content, currency, and accuracy. About 32,000 of the Survey's primary maps meet these standards and thus can be digitized without revision. The objective is to maintain the primary cartographic data in a 10year cycle of inspection and revision.

are added to the program, and (4) increased emphasis is placed on revision procedures to respond to new user requirements. Because procedures required to complete primary mapping and to convert substandard and deficient maps will be similar to those used to meet current requirements, the skills needed for traditional cartographic operations will remain essentially the same.

$286 million (1985 dollars).

Program Development

As maps are revised, they will be digitized according to user requirements. As figure 1 shows, provisional map conversion will be implemented, but the method of conversion (graphic, digital, or a combination of both) is dependent on advances in digital technology.

Resources devoted to the ongoing revision program will increase as (1) the inventory of existing maps grows through 1989, (2) the deficient maps are corrected through 1999, (3) the maps that lack currency

The Geological Survey has been developing a major new production system, called MARK II, which has as its goal the implementation of advanced automated technologies and production procedures that will satisfy National Mapping Program requirements through the year 2000. At that time, the NDCDB should contain digital data representing the primary map series and other smaller scale series.

The goals for the MARK II effort within the National Mapping Program are to develop and implement specific production capabilities, including the establishment of more effective map revision procedures and improvements in product quality. The production scheme is shown in figure 2.

MARK II Development
Objectives

The development strategy proposed for MARK II addresses its major production capabilities and has the following objectives:

• Development of advanced mass digitization systems, concentrating on the collection of heavily symbolized 1:24,000scale source data.

• Development of improved data verification and testing procedures, concentrating on improved automated data checking. Completion of data standards is included.

• Development of techniques for producing topographic and thematic graphic products from digital data contained in the NDCDB.

• Provision of digital data suitable for analysis and application by geographic information systems and related technologies.

• Development of an improved production management system to efficiently task and track multiple production activities. • Improvement of NDCDB operations and structure to ensure that the data are maintained for optimum use in production.

MARK II System Design

The MARK II effort will result in the implementation of advanced automated technology and production procedures in Geological Survey map production centers. To accomplish this goal and to provide an orderly implementation of newly developed capabilities, the MARK II production system has been divided into four functional components, each under a component manager and designed to handle a specific portion of the production process. Each component has been further subdivided into a series of development modules, currently numbering 48, which consist of a set of defined and assigned tasks.

Data production component.-The data production component deals with all phases of data collection, editing, processing, quality control, and revision before data are entered into the NDCDB. This component is the largest and most complicated portion of the system to be developed. It includes both the development of efficient mass digitization and automatic featurerecognition capabilities for traditional cartographic symbolization and the development of methods for extracting features from imagery. The subsequent introduction of new equipment, software,

By William H. Bakun

In 1985, seismologists from the U.S. Geological Survey and the University of California, Berkeley, forecast that a moderate-sized earthquake of magnitude 6 is likely to occur in the Parkfield area of California within the next several years (1985-93). This forecast was the first to be officially endorsed and accepted by both the National and the California Earthquake Prediction Evaluation Councils. Parkfield lies along the San Andreas fault in a sparsely populated area of the California Coast Ranges 170 to 180 miles from San Francisco, about midway to Los Angeles. Five similar moderate (magnitude 6) earthquakes have occurred on the Parkfield section of the San Andreas fault since 1857. The intervals between earthquakes (in 1881, 1901, 1922, 1934, and 1966) have been remarkably uniform, the mean being 21.9±3.1 years. (Although the 1934 earthquake departed from the regular pattern by occurring a decade too early, the 1966 earthquake conformed to the regular pattern in that the 44-year period between 1922 and 1966 is twice the mean interval.) If the next Parkfield earthquake conforms to the pattern, it will occur before 1993, most probably in early (January) 1988. Figure 1 shows the

1934

epicenters of earthquakes associated with the 1934 and 1966 events.

The Geological Survey established an earthquake prediction experiment at Parkfield to observe the final stages of the process leading up to the predicted earthquake. Four observational networks (seismic, geodetic survey, continuous strain, and creep) are now monitoring the central San Andreas fault near Parkfield (fig. 2). A very dense network of seismograph stations monitors details of seismicity within and near the preparation zone, the region surrounding the epicenter of the 1966 earthquake (see fig. 2). Signals from the seismographs near Parkfield are telemetered continously to the central data-processing facility in Menlo Park, Calif. The signals are automatically and continously monitored by a real-time processor that, within a few minutes, routinely locates earthquakes in central California. Beeper and paging systems have been established to notify the appropriate scientists within minutes of all significant seismicity near the preparation

zone.