Using Strong-Motion Records to Determine the Moment Magnitude Mw of Earthquakes in Taiwan Area

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Project title

Code/計畫編號

NSC99-2116-M019-004

Translated Name/計畫中文名

利用台灣區域強震資料推求台灣地區地震之震矩規模

Project Coordinator/計畫主持人

Yi-Ling Huang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=2147793

Year

2010

Start date/計畫起

01-08-2010

Expected Completion/計畫迄

01-07-2011

Bugetid/研究經費

620千元

ResearchField/研究領域

地球科學
防災工程

"地震觀測資料記錄了地震活動時力的作用與能量的釋放，尤其是近場資料，更是直接近距離的記錄了大部份震源的訊息。台灣區域位處複雜的板塊交界處而地震數量多，測站密度也在相關研究者與部門的努力下傲視全球，近場觀測資料十分豐富，極有潛力嘗試利用近場強地動資料來做震矩規模的估算。一般來說，震矩和震矩規模都是利用遠場體波資料的頻譜計算來求得，近場資料通常不會被考慮用來做這些估算，尤其是大地震的強地動資料，因為不同的波幾乎同時傳入測站被接收、訊號無法分離，導致震矩和頻譜之間無法由一簡單的關係式去描述定義。Delouis 等人於2009 年提出一快速震矩規模計算法，由近場記錄的位移譜去計算震矩規模。這個新方法除了可以有效利台灣密集的近場觀測資料外，因其計算速度比目前常用的震矩規模計算法快許多，可在地震發生後很短的時間內、任何的震源機制資訊都還沒被反演出來前，快速計算出震矩規模。雖然計算速度仍不及氣象局目前的地震早期預警計算速度，但仍很有潛力應用其做為早期預警後的快速再確認估算，對防災工作的準備和調度也可提供更可靠的確認。此外，快速震矩規模的得出也可幫助加速震源反演的估算，並且亦可幫助估算可靠的強地動分佈情形以供防救災工作參考。" "The effects of stress and energy radiation of fault rupture are recorded by earthquake observation, especially in the near-field strong-motion records, the information of source rupture is mainly recorded. Taiwan locates on a very complicated location among plates and induce large amount of earthquakes every year. Seismic array in Taiwan region is dense for research and earthquake protection; the near-field strong-motion data is considerable and well recorded. Those high quality near-field records may provide a good opportunity of estimating moment magnitude MW. Seismic moment and the corresponding moment magnitude MW are classically obtained from the spectrum of far-field body waves; near-field data is generally not used for that purpose. The main limitation is, in near field, different types of wave arrive simultaneously and preventing the definition of a simple relation between the seismic moment and the spectrum, particularly in large earthquake cases. For dealing with that difficulty, Delouis et al. (2009) provides a method for determining moment magnitude MW rapidly. It uses near-field spectra of strong-motion records and compute faster than other methods for estimating MW. The MW can be obtained very soon after occurrence, before any source or focal mechanism inversions have been performed. It may not be fast enough as early warning determination of Central Weather Bureau of Taiwan, but has potential of providing the updated moment magnitude some tens of seconds later. An updated magnitude is not only needed to confirm the first alert and to manage emergency actions but also can perform more advanced seismological analyses, such as fast source inversions and computation of reliable shake maps for reference of protection."

Keyword(s)

震矩規模
強地動
位移譜
震矩
moment magnitude
strong-motion
displacement spectrum
seismic moment

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Using Strong-Motion Records to Determine the Moment Magnitude Mw of Earthquakes in Taiwan Area

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