The Long Valley Caledera and
the Mono Inyo Craters
The Long Valley Caledra and the Mono Inyo Craters are located in an area in
which volcanic eruptions have been occuring for over 3 million years. The caledra
is an eliptical shaped area approximately 10 by 20 miles in size. The caledra
was formed by a volcanic eruption 730,000 years ago, that resulted in the eruption
of 150 cubic miles of volcanic ash and rock. Five miles below the surface of
the caladera there is a partialy molten magma chamber.
Recent activity began in 1978 and interest grew, when in 1980, four magnatiude
six earthquakes occured. The resultant activitiy has brought about an uplift
in the central portion of the caledra.
USGS Long
Valley Caldera Current Condition page
Forest-killing diffuse co2 emission
at mammoth mountain is a sign of magmatic unrest
Earthquake
activity in Long Valley Caldera and Vicinity, updated every half hour
Ground deformation
detection
In the event of increased seismic activity the USGS will set up emergency field headquarters
at the Long Valley Caldera. In the event of a declared watch a message is sent
by USGS to California OES, which is responsible for notifying local authorities.
If The USGS determines that there is a reason for issuing a warning about a
potential eruption the USGS will notify the Governors of California and Nevada
and others who will inform the public.
For more details about USGS's plan see the Long
Valley Caldera Response Plan
Information
on the Long Valley Caldera "Observatory"
Geologic
History of Long Valley Caldera and Vicinity
FACT SHEETS on Long Valley caldera and the Inyo-Mono Craters volcanic complex
For more information about Volcanos see our Volcano Page
For information about earthquakes visit our Earthquake
Center
For information for educators and school administrators visit our Schools
Page
Visit our home page for links to other disaster subjects
Local Links
Information about Bishop
Mammoth Lakes
Newspaper Mammoth Times
Eastern Sierra College
Center
Mammoth Lakes Foundation
White Mountain Research
Station
Inyo National Forrest
Sking Mammoth Mountain
Bishop Internet Service Provider
This page is maintained by The Disaster Center. In the event of a Volcanic
activity this page will be used to provide information about the event. If residents
of the local area have any information which they would like to share with our
site's visitors please send an E-mail to: host@disastercenter.com
Penrose Conference Announcement
Application deadline was January 1, 2000.
Penrose Conference to address Longevity and Dynamics of Rhyolitic Magma
Systems
A Geological Society of America Penrose Conference, "Longevity and Dynamics
of Rhyolitic Magma Systems" will be held June 7-12, 2001, in Mammoth,
California. Mammoth Mountain forms the southwest rim of the Long Valley
caldera, one of three large Quaternary rhyolitic caldera centers in the
United States. Long Valley, a site of recent volcanic unrest, lies at the
heart of current debate over the mechanisms and time scales for the
production, storage, and differentiation of rhyolite magma. Such
information is critical to our understanding of fundamental geologic
problems such as the formation and growth of Earth's continents and
predicting volcanic hazards.
The purpose of the conference is to bring together petrologists,
geochemists, volcanologists and geophysicists actively studying the
generation and evolution of silicic magmas. We hope to try and resolve, or
at least constrain, a number of very important and currently highly topical
issues pertaining to the shallow-crustal evolution of large, typically
caldera-forming, silicic magma bodies. These include:
. What is a magma chamber-a large, long-lived fractionating liquid body or
a "sleepy" crystal mush that gets kicked to life every so often,
re-mobilizing existing material? A related issue is to what degree do
plutons carry-forward, in some integrated way, the expression of this?
. What do crystals really represent-phenocrysts vs. xenocrysts-and what
'memory' do they retain? Related to this issue are questions such as does
crystal growth- and dissolution-zoning reflect protracted fractionation of
a single magma body or remobilization and dispersal of crystal mush during
injection of fresh magma into the subvolcanic system and how do crystals
move in the magma system - or are the crystals effectively static in a
moving magma system?
. What is the efficacy of, and driving forces for, convection/mixing in
silicic magmas? Can crystal disequilibrium features, such as
chemical/isotopic zoning and dissolution surfaces, serve to discriminate
between thermal convection and magma mixing?
. What are the time scales needed to produce large, rhyolitic magma bodies?
Recent work using 40Ar/39Ar, Rb/Sr or U-series isotope data has led to the
suggestion that rhyolite magmas in the Long Valley system are stored,
following differentiation, for long (105-106) time scales. This contention
has been disputed principally on the basis that it would be difficult to
keep a body of magma thermally viable for such long periods, even if
>500km3 volume. Alternative physical models have been proposed, such as
remobilization of juvenile plutons or cumulate materials and ion microprobe
work on zircons has variously upheld or contested the claims for long magma
residence times. A key focus of the meeting will be to evaluate the
different types of data available that bear on ages of magmatic events, and
discuss their interpretations.
A limited number of keynote talks will serve to outline the current state
of knowledge concerning the generation and evolution of large rhyolitic
magma systems, and will set the foundation for evaluation of existing
paradigms, development of new models, and discussion of future research
directions. Most of the meeting will focus on poster sessions and group
discussions. Mid-meeting field trips to selected Bishop Tuff and Sierran
plutonic locations will serve to raise questions concerning limits and
constraints on sampling and interpreting geochemical data from pyroclastic
deposits based on our knowledge of how large silicic systems erupt, links
between plutonic and volcanic environments, and the importance of recharge
and mixing in magma evolution.
The conference is limited to approximately 50 participants to ensure a
'workshop-type' atmosphere focussed on manageable discussions. We
encourage participation of graduate students working on silicic magma
systems; partial student subsidies will be available. The registration
fee, which will include lodging, some meals, field trips, and all other
conference costs except personal incidentals, is not expected to exceed
$750. Information on travel to the conference will be provided in the
letter of invitation.
Co-conveners are: Kurt Knesel, Department of Earth Sciences, University of
Queensland, St Lucia, Brisbane, Qld 4072, Australia,
k.knesel@earth.uq.edu.au, ; George
Bergantz, Department of Geological Sciences, Office Box 351310, University
of Washington, Seattle, WA 98195-1310, USA, bergantz@u.washington.edu,
; Jon Davidson, Department of Earth
and Space Sciences, UCLA, Los Angeles, CA 90095-1567,
davidson@ess.ucla.edu, Website:
http://www.geology.washington.edu/bergantz/penrose-2001.htm
________________________________________
Jon Davidson
Professor of Geology and Geophysics
Department of Earth and Space Sciences
UCLA
Los Angeles
CA 90095-1567