{"64623":{"#nid":"64623","#data":{"type":"news","title":"Scientists Find Increase in Microearthquakes After Chilean Quake","body":[{"value":"\u003Cp\u003EBy\u0026nbsp;studying\nseismographs from the earthquake that hit Chile last February, earth scientists\nat the Georgia Institute of Technology have found a statistically significant\nincrease of microearthquakes in central California in the first few hours after\nthe main shock. The observation provides an additional support that seismic\nwaves from distant earthquakes could also trigger seismic events on the other\nside of the earth. The results may be found online in the journal \u003Cem\u003EGeophysical\nResearch Letters\u003C\/em\u003E. \u003C\/p\u003E\n\n\n\n\u003Cp\u003EIt\nhas been well known that microearthquakes can be triggered instantaneously by\ndistant earthquakes. However, sometimes the triggered events could occur long\nafter the passage of the direct surface waves that take the shortest path on\nthe earth surface. There are several other explanations out there about how\nsuch delayed triggering occurs. Some involve the redistribution of pore fluids\nand triggered aseismic creep, while others simply consider them as aftershocks\nof the directly triggered events. But the group from Georgia Tech found\nsomething different. \u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cFrom\nour research, we\u2019ve concluded the delayed triggering that occurs in the first\nfew hours after an earthquake could be caused by multiple surface waves\ntraveling back and forth around the earth multiple times,\u201d said Zhigang Peng,\nassistant professor in the School of Earth and Atmospheric Sciences at Georgia\nTech. \u003C\/p\u003E\n\n\n\n\u003Cp\u003EIn a\nprevious paper, also published in \u003Cem\u003EGeophysical Research Letters\u003C\/em\u003E last\nDecember, Peng\u2019s research group found that the direct surface waves of the\nChilean earthquake triggered seismic activity in central California. In this\nnew study, Peng\u2019s group looked beyond the direct surface waves and focused on secondary\nand tertiary waves that return after traveling across the globe multiple times.\nIn addition, they went beyond earthquake information published in the U.S.\nGeological Survey catalog and instead studied the seismographs. \u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cSo\nwhen you look at the events that have been reported in the catalog, you won\u2019t\nsee this effect,\u201d said Peng. \u201cBut if you look at the seismographs, you\u2019ll see\nmany small events and notice that they occurred mostly when those multiple\nsurface waves arrived.\u201d\u003C\/p\u003E\n\n\n\n\u003Cp\u003EPeng\nsaid that the finding is significant because it also suggests that scientists\ncan look beyond the direct surface waves and understand that those later-arriving\nwaves could affect the seismic activity on the other side of the earth. But his\nteam believes that seismic waves circle the globe only for large earthquakes. \u0026nbsp;They are currently examining other\nregions and quakes to see just how widespread this effect is. \u003C\/p\u003E\n\n\u003Cp\u003EPeng\u2019s\nresearch group includes graduate students Chunquan Wu and Chastity Aiken. Their\nresearch was supported by the National Science Foundation.\u003C\/p\u003E\n\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\n\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003E\n\n\nBy\u0026nbsp;studying seismographs from the\nearthquake that hit Chile last February, earth scientists at the Georgia\nInstitute of Technology have found a statistically significant increase of\nmicroearthquakes in central California in the first few hours after the main\nshock. The observation provides an additional support that seismic waves from\ndistant earthquakes could also trigger seismic events on the other side of the\nearth. \u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Results suggests that seismic waves from distant earthquakes could also trigger seismic events on the other side of the earth."}],"uid":"27310","created_gmt":"2011-02-25 09:21:58","changed_gmt":"2016-10-08 03:08:18","author":"David Terraso","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2011-02-25T00:00:00-05:00","iso_date":"2011-02-25T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"groups":[{"id":"1183","name":"Home"}],"categories":[{"id":"154","name":"Environment"}],"keywords":[{"id":"8102","name":"Chile"},{"id":"12120","name":"earthquakes"},{"id":"166926","name":"School of Earth and Atmospheric Sciences"},{"id":"171068","name":"seismic"},{"id":"12122","name":"Zhigang Peng"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003EGeorgia Tech Media Relations\u003C\/strong\u003E\u003Cbr \/\u003ELaura Diamond\u003Cbr \/\u003E\u003Ca href=\u0022mailto:laura.diamond@comm.gatech.edu\u0022\u003Elaura.diamond@comm.gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-894-6016\u003Cbr \/\u003EJason Maderer\u003Cbr \/\u003E\u003Ca href=\u0022mailto:maderer@gatech.edu\u0022\u003Emaderer@gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-660-2926\u003C\/p\u003E","format":"limited_html"}],"email":["david.terraso@comm.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}