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Geologic Map of the Emmons Lake Volcanic Center, Alaska

Scientific Investigations Map 3519
By: , , , , and 
https://doi.org/10.3133/sim3519

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Introduction 

The Emmons Lake volcanic center is a spatially clustered group of stratovolcanoes and calderas in the southwestern part of the Alaska Peninsula, Alaska. The volcanic center is characterized by several ice- and snow-clad stratovolcanoes located within and along the margins of a nested-caldera complex that includes Emmons Lake. A shieldlike ancestral edifice (ancestral Mount Emmons) is truncated by the caldera complex and forms a broad volcanic platform around the center. The main stratovolcanoes of the Emmons Lake volcanic center are Pavlof Sister, Pavlof Volcano, Little Pavlof, Double Crater, Mount Hague, and Mount Emmons. Several small unnamed cinder cones and vents also are located within Emmons Lake volcanic center and on the east flank of Pavlof Volcano. Many of these cones and vents have been the source of the young lava flows that mantle the floor of the caldera. Pavlof Volcano, in the northeastern part of the Emmons Lake volcanic center, is one of the most historically (that is, the past about 300 years) active volcanoes in Alaska, and eruptions from Pavlof Volcano pose the greatest hazards to the region.

Volcanic rocks of the Emmons Lake volcanic center overlie continental and marine sedimentary rocks of chiefly Late Jurassic to early Tertiary age. The oldest rocks in the area are those of the Naknek Formation, consisting of volcaniclastic sandstone, siltstone, and conglomerate of Late Jurassic age. The southern part of the area includes rocks of the Belkofski Formation, a thick sequence of volcaniclastic sandstone, siltstone, and conglomerate of middle Tertiary age. Lava flows, volcanic breccia, and fluvial volcaniclastic rocks of late Miocene age, which unconformably overlie the Belkofski Formation south of the Emmons Lake volcanic center, are primarily exposed on the islands just south of the Alaska Peninsula.

The Emmons Lake volcanic center was affected multiple times by glaciation associated with the glacier expansion that characterized the Quaternary. Glaciation has played a key role in shaping the present-day landscape, and much of the eruptive history of the Emmons Lake volcanic center has involved interactions with glacier ice. Thus, a brief review of the Quaternary glacial history of the area is provided to establish the physical context for Emmons Lake volcanic center eruptive activity.

Suggested Citation

Miller, T.P., Waythomas, C.F., Mangan, M.T., Trusdell, F.A., and Calvert, A.T., 2026, Geologic map of the Emmons Lake volcanic center, Alaska: U.S. Geological Survey Scientific Investigations Map 3519, 1 sheet, scale 1:100,000, pamphlet 59 p., https://doi.org/10.3133/sim3519.

ISSN: 2329-132X (online)

Study Area

Table of Contents

  • Acknowledgments
  • Introduction
  • Geologic Overview of the Emmons Lake Volcanic Center
  • Introduction to the Description of Map Units
  • Description of Map Units
  • References Cited
  • Appendix 1. Argon Geochronology
  • Appendix 2. Whole-Rock Compositions of Volcanic Rocks and Deposits
  • Appendix 3. Radiocarbon Ages
  • Appendix 4. Thin-Section Photographs, Descriptions, and Associated Data
Publication type Report
Publication Subtype USGS Numbered Series
Title Geologic map of the Emmons Lake volcanic center, Alaska
Series title Scientific Investigations Map
Series number 3519
DOI 10.3133/sim3519
Publication Date April 01, 2026
Year Published 2026
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Volcano Science Center
Description Pamphlet: x, 59 p.; 1 Sheet: 49.75 x 31.44 inches; 3 Data Releases
Country United States
State Alaska
Other Geospatial Emmons Lake volcanic center
Scale 100000
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Additional publication details