In the early morning hours today, USA time, 11 April 2012 a major magnitude 8.6 MM earthquake hit in the Indian Ocean some 300 kilometers from the western coast of Sumatra triggering a tsunami alert for all countries bordering the basin. To make things worse the hundreds of aftershocks have also included a second major earthquake categorized at 8.2MM magnitude. Both of these major earthquakes have been initially registered at the relatively shallow depths of 23 and 16 kilometers respectively.
These twin seismic shocks of such high magnitudes have undoubtedly raised fears of a repeat of the catastrophe that impacted the same region on 26 December 2004, when an earthquake initially reported to have been of magnitude 8.8MM at a depth of only 30 kilometers generated a major tsunami that caused 200,000+ deaths mainly in Sumatra around the region of Banda Aceh. The earthquake of 2004 is still categorized as a 9.1MM magnitude event based in an analysis of all data, while scientists from the California Institute of Technology rate it at 9.2 MM magnitude.
While we wait for damage reports from today’s Indian Ocean’s earthquakes it is clear that these shocks serve to remind humankind that we inhabit a hazardous planet, where we all are at one time or another vulnerable to the impacts of natural and human-made hazards.
While the Indian Ocean and Sumatra may appear very far away to most of us in the USA, and they indeed are far away places, these natural events of just a few hours ago also bring home the seismic vulnerability of our fifty states. Such vulnerability is illustrated by records maintained by the United States Geologic Survey that show 54 magnitude 3.0 or higher earthquakes have hit somewhere in the United States over the last seven days, including at least one above 5.0 magnitude and five above 4.0 magnitude. Most of these major earthquakes have impacted Alaska and our western states of California, Idaho, Montana, Nevada, Oregon, Utah, Washington and Wyoming. During the same week hundreds of minor earthquakes numerous magnitude ones and twos have affected the same states listed above and several others including Arkansas, Missouri, Oklahoma and Tennessee where at least five earthquakes have hit in the past week. Likewise, Hawaii and Puerto Rico and the U.S. Virgin Islands have been shaking in recent days.
Let these alerts sounded by Mother Nature reminds all of us of the need to be aware of the vulnerability of the communities where we live, and of the need to practice hazard mitigation by incorporating design criteria and other measures into our houses and buildings, which will reduce the potential for damage from recurring earthquakes or other natural hazards such as hurricanes, floods, tornadoes etc. Pay attention! Be prepared!! MITIGATE!!!
Florida has just emerged from one of the wettest Octobers of record, as the state starts to dry-out and pleasant Fall weather takes hold out there in the Atlantic, in the Bermuda Triangle, a cell of low pressure that appeared in early November has been gradually getting organized and stronger as it slowly makes its way toward mainland USA! Late on Monday 7 November this weather system was generating large amounts of rain north of its center over Bermuda and the National Hurricane Center was giving it a high probability (~70%) that it could develop into the next cyclone of the 2011 Atlantic Hurricane season, which has so far generated 17 named storms including six hurricanes.
Could this be Sean, the 18th named storm of the 2011 Atlantic season? Speaking of storm names, as a matter of anecdotal interest, the 2011 list of names for storms is the same that was used in 2005 except for a record five names that were retired from the list because of their strength as major hurricanes and the amount of damage they caused. The retired storm names were Dennis, Katrina, Rita, Stan and Wilma. On the official 2011 list the replacement names are Don, Katia, Rina, Sean and Whitney. These results from the National Hurricane Center preparing six alphabetical lists of twenty names each, which are used in the same order and then repeated, this is why the 2005 list is now being used again in 2011 except for the retirement and replacement of “infamous” storms. So far this year we haven’t had any major and destructive hurricane so if this continues the 2011 list will repeat in 2017 with the same names we have seen this year.
Looking beyond this potential #18 cyclone of 2011 in the Atlantic there are a couple of regions of disturbed weather in the central Atlantic and along a long stretch of ‘Hurricane Alley’, but nothing that shows much potential for further development at least for now. What is quite interesting though, is a cell of stormy weather that is showing potential for further development over the Mediterranean Sea already affecting a vast region from Marseille, France to Genoa, Italy and most of the major islands in the central Mediterranean. Although cyclones and storms are not unusual in that region of the world it is indeed rare to see a storm exhibiting cyclonic characteristics threatening the French Riviera, Monaco and other resorts along the Mediterranean coastline. Please view the composite satellite view below:
Other meteorological hazards that are active on this early days of November 2011 include an area of low pressure and stormy weather in the Arabian Sea., in an area that has seen similar events over the past few weeks. Another cell of disturbed weather with potential for cyclonic development lingers to the east and near the southern extreme of the Indian sub-continent.
Shifting from the ocean-atmosphere environment, there has been quite a bit of ground shaking in Oklahoma over the past week. These seismic events have included a 4.7 magnitude quake on 4 November, and a magnitude 5.7 on 6 November 2011 with an epicenter just 8 km northwest of the town of Prague, and 72 km east of Oklahoma City, located at the rather shallow depth of 5 kilometers. The region of Oklahoma where both these quakes and numerous aftershocks have hit over the last 4 – 5 days has a history of light to moderate seismic activity with most quakes in the 2 -4 magnitude range, with a few 4.5 -6 magnitude earthquakes occasionally occurring. Early reports are of moderate damage, mainly in the form of toppled unreinforced masonry structures, and structural cracks on some buildings. Despite its moderate impact and damage this Oklahoma event is significant because it has taken place near the center of the continental USA not too far from the New Madrid major seismic fault region, where a swarm of earthquakes hit over a three-month period in 1811-1812 that included a possible magnitude 8.0 earthquake. Other major earthquakes have hit this region, including one on Christmas Day 1699 that was written about by early explorers and settlers, and numerous prehistoric events that have left their signatures in the geological record. This whole region is considered a major seismic province capable of triggering major earthquakes in the future.
The map that follows, courtesy of the USGS National Earthquake Information Center [NEIC] shows earthquakes that generated in Oklahoma from 1990 through 2006. Each of the orange circles represents an earthquake, with the size of the circle being proportional to the magnitude of the quake. This record shows most of the recent seismic activity has taken place on in the central-southern portion of the state. This map also shows some prior activity in the region to the east of Oklahoma City where the latest seismic events took place.
Beyond the cyclonic and seismic events looking toward space there is an unfolding space event taking asteroid 2005YU55, a 400 m diameter rock, on a flyby of Earth that will bring it within 325,000 km of our planet and approximately 200,000 km from our Moon on 8 November 2011. This is the closest an asteroid has come to the Earth in more than 30+ years. To put this event in perspective it is important to note that its trajectory will take it between the Earth and the Moon at about 0.85 of the distance between our planet and its satellite, in space terms this is quite close, almost a near-miss. Radar is the main tool used by NASA to track asteroids that come near earth, and in the case of 2005YU55 the radar telescopes in Arecibo and Goldstone have been tracking it for the past 3 days. The image below shows a rendering of the track the asteroid will take as it crosses between the Earth and the Moon’s orbit on 8 November 2011:
These events are just an example of what is typical of the hazardous planet we inhabit, which serves to illustrate the point that humankind lives with risk on an everyday basis. This underscores the need for maintaining a continuous effort of research, public education and outreach, to better understand the natural processes at work on Earth and the natural hazards – sources of potential damage – that may threaten vulnerable communities worldwide, and the need to be prepared and practice hazard mitigation on a constant basis.