Life Science By Becky Oskin, May 05, 2014 ShortLink
Mile for mile, there are almost as many earthquakes rattling Oklahoma as California this year. This major increase in seismic shaking led to a rare earthquake warning today (May 5) from the U.S. Geological Survey and the Oklahoma Geological Survey.
In a joint statement, the agencies said the risk of a damaging earthquake — one larger than magnitude 5.0 — has significantly increased in central Oklahoma.
Geologists don't know when or where the state's next big earthquake will strike, nor will they put a number on the increased risk. "We haven't seen this before in Oklahoma, so we had some concerns about putting a specific number on the chances of it," Robert Williams, a research geophysicist with the USGS Earthquake Hazards Program in Golden, Colorado, told Live Science. "But we know from other cases around the world that if you have an increasing number of small earthquakes, the chances of a larger one will go up." [Watch 2500+ Oklahoma Earthquakes Since 2012 (Video)]
That's why earthquakes of magnitude 5 and larger are more frequent in states such as California and Alaska, where thousands of smaller temblors hit every year.
This is the first time the USGS has issued an earthquake warning for a state east of the Rockies, Williams said. Such seismic hazard assessments are more typically issued for Western states following large quakes, to warn residents of the risk of damaging aftershocks, he said.
The geological agencies took action after the rate of earthquakes in Oklahoma outpaced that of even California for the first few months of 2014. (California regained the lead in April.) [The 10 Biggest Earthquakes in History]
"The rate of earthquakes increased dramatically in March and April," Williams said. "That alerted us to examine this further and put out this advisory statement."
While Oklahoma's buildings can withstand light earthquakes, the damage from a magnitude-5 temblor could be widespread. Oklahoma's last major earthquake was in November 2011, when a magnitude-5.6 earthquake centered near Prague, Oklahoma, destroyed 14 homes and injured at least two people.
"Building owners and government officials should have a special concern for older, unreinforced brick structures, which are vulnerable to serious damage during sufficient shaking," Bill Leith, a USGS senior science adviser for earthquakes and geologic hazards, said in the joint statement.
While scientists haven't ruled out natural causes for the increase, many researchers suspect the deep injection wells used for the disposal of fracking wastewater could be causing the earthquake activity. Fracking, short for hydraulic fracturing, is a method of extracting oil and gas by cracking open underground rock.
According to the USGS, the number of quakes magnitude-3 and stronger jumped by 50 percent in the past eight months in Oklahoma. Some 183 earthquakes of magnitude 3 or greater struck between October 2013 and April 14, 2014. The state's long-term average from 1978 to 2008 was only two earthquakes of magnitude 3.0 or larger per year.
If the earthquakes are caused by wastewater injection, then the activity could continue or decrease with future changes in well usage in the state.
"We don't know if this earthquake rate is going to continue," Williams said. "It could go to a higher rate or lower, so the increased chances of a damaging quake could change in the future."
5/1/2014 — PACIFIC NORTHWEST MAGMA CHAMBERS “RE-PRESSURIZE” — MT. SAINT HELENS SHOWING RISE
iew of Mt. Saint Helens new magma dome , building along with a rise in the area, and a “re-pressurization” of the magma chambers beneath the area.
SEATTLE (Reuters) - Magma levels are slowly rebuilding inside Mount St. Helens, a volcano in Washington state that erupted in 1980 and killed 57 people, although there was no sign of an impending eruption, U.S. scientists said.
The roughly 8,300-foot volcano erupted in an explosion of hot ash and gas on May 18, 1980, spewing debris over some 230 square miles and causing more than a billion dollars in property damage. Entire forests were crushed and river systems altered in the blast, which began with a 5.2 magnitude earthquake.
"The magma reservoir beneath Mount St. Helens has been slowly re-pressurizing since 2008," the U.S. Geological Survey said in a statement on Wednesday. "It is likely that re-pressurization is caused by (the) arrival of a small amount of additional magma 4 to 8 km (2.5 to 5 miles) beneath the surface."
The USGS, and the Pacific Northwest Seismic Network at University of Washington, closely monitor ground deformation and seismicity at the volcano. This summer, they will also measure its released gases and gravity field, measurements that can be used to monitor subsurface magma and forecast eruptions.
The Pacific Northwests magma chamber reservoirs are “Re-pressurizing” according to a new report released by the USGS.
Summed up, the magma chambers associated with Mt. Saint Helens have been now verified to be building in pressure, causing a rise in the area around the Volcanoes caldera.
“Posted via the USGS Volcano Notification Service (VNS) http://volcanoes.usgs.gov/vns/
Analysis of current behavior at Mount St. Helens indicates that the volcano remains active and is showing signs of long-term uplift and earthquake activity, but there are no signs of impending eruption.
Since the end of the 2004-2008 dome-building eruption at Mount St. Helens, scientists at the USGS Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN) have been monitoring subtle inflation of the ground surface and minor earthquake activity reminiscent of that seen in the years following the 1980-1986 eruptions.
Careful analysis of these two lines of evidence now gives us confidence to say that the magma reservoir beneath Mount St. Helens has been slowly re-pressurizing since 2008.
It is likely that re-pressurization is caused by arrival of a small amount of additional magma 4-8 km (2.5-5 miles) beneath the surface.
This is to be expected while Mount St. Helens is in an active period, as it has been since 1980, and it does not indicate that the volcano is likely to erupt anytime soon.
Re-pressurization of a volcano’s magma reservoir is commonly observed at other volcanoes that have erupted recently, and it can continue for many years without an eruption.
USGS and PNSN are continuing to monitor ground deformation and seismicity at Mount St. Helens. In an effort to learn more about activity beneath the volcano, they will conduct two additional types of measurements this summer.
Surveys will measure the types and amounts of volcanic gases being released, and the strength of the gravity field at the volcano. Both types of measurements are sensitive to changes in the amount or depth of subsurface magma.
The information collected at Mount St. Helens continues to help scientists interpret behaviors at other volcanoes and to improve eruption forecasting capabilities. Additional research results will be posted in USGS Updates, Information Statements, and on the USGS-CVO website.
In a previously planned but related development, an experiment called “Imaging Magma Under St. Helens” (iMUSH) will start this summer and run for the next few years.
The experiment, jointly funded by the National Science Foundation and USGS, is designed to produce a better picture of the magma plumbing system under the volcano. It may also provide new insights into the ongoing re-pressurization process.
The USGS Cascades Volcano Observatory and Pacific Northwest Seismic Network continue to monitor Mount St. Helens and other volcanoes of the Cascade Range for signs of increased unrest.
The likelihood of detecting short-term precursory phenomena before the next eruption at Mount St. Helens is enhanced by the existence of an effective monitoring network established in response to recent eruptions. Efforts are underway to bring networks at other dangerous volcanoes in the Cascade Range up to a similar standard.
The USGS and the Pacific Northwest Seismic Network at University of Washington continue to watch conditions at Mount St. Helens closely.”
After reading the above article from the USGS….
This should be no shock to those of us who have been following the other volcanic events happening over the past few months along the West Coast.
Remember this? Just over 2 weeks ago, on April 14th…… Maybe you missed it … a large plume event from Mt. Rainier and Mt. Adams
Also, lets not forget what we just found out about the Yellowstone volcano.
The magma chambers associated with Yellowstone appear to be “re-pressurizing” as well, the area around Yellowstone has risen by 2 inches in just FOUR months time (since New Years 2014).
Also, in addition to the confirmed Yellowstone rise, and the confirmed Mt. Saint Helens rise …… there have been a series of earthquake swarms occurring along the NW edge of the Craton (Western edge of the Yellowstone Magma chamber) in Idaho.
Is it any wonder these events below are happening along the West Coast at the same time as all of the above?