UH Hilo Center for Maunakea Stewardship - Research Library

Paleomagnetic data from basaltic lava flows of the northeast rift zone of Mauna Loa volcano, Hawaii

Author:
Champion, Duane E., Lockwood, John P.
Title:
Paleomagnetic data from basaltic lava flows of the northeast rift zone of Mauna Loa volcano, Hawaii
Periodical:
U.S.G.S. Open-file report 98-782
Year:
1998
Subject:
Volcanoes Hawaii Island Earthquakes Hawaii Island Kilauea Volcano Mauna Loa Mauna Kea Lava analysis Volcanic hazard analysis
Summary:
The assessment of volcano hazards to the island of Hawaii from possible eruptions at Kilauea, Mauna Loa, Mauna Kea, and Hualalai volcanoes is a continuing responsibility of the Volcano Hazards Team of the U.S. Geological Survey. That assessment includes the collection of basic earth science information in the form of chemical, physical, and even biological data which are intended to facilitate the evaluation. A volcano hazards assessment revolves centrally around the detailed reconstruction of the history of eruptive activity, and the areal distribution of volcanic eruption products such as lava flows and ash. The list of information collected in this evaluation can include, but is not limited to, identification and mapping of lava flow contacts; geochemical data and petrographic data; geophysical data including gravity, magnetics, and paleomagnetics; absolute age data derived from the rocks (argon-dating, uranium-disequilibrium), from organic material charred or overridden by the flow or ash (14C), and from surface exposure systems (36C1, 26A1, 10Be, 3He, etc.); physical surface characteristics such as glass preservation, roughness, blockiness; degree of soil formation on the flow; and extent and nature of vegetative cover as the ecological system returns to preeruption conditions. Paleomagnetic data are included in this list due to their utility both as the inherent characteristics of a specific lava flow and as a tool for assessing its age relative to other flows. When a basaltic lava flow erupts, moves downhill over the ground surface, and comes to rest and cools, it acquires a thermoremanent magnetization parallel to the geomagnetic field that exists at the time of the eruption. The geomagnetic field is not constant in direction, but instead has a secular variation over time periods of decades to millennia, producing different local magnetic directions that can vary by tens of degrees in both inclination and declination values. Thus, a particular lava flow, with its inherent remanent magnetic direction can be compared to another lava flow with its own remanent direction to see if they are similar. Dissimilar remanent directions are evidence that the compared lava flows are not of the same exact age, while similar directions, when included with other outcrop and geologic data, may indicate that lave flows are of the same age.
URL:
http://pubs.usgs.gov/of/1998/0782/report.pdf
Date:
1998
Collection:
Monographs