{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:34:12Z","timestamp":1782779652881,"version":"3.54.5"},"reference-count":17,"publisher":"American Geophysical Union (AGU)","issue":"16","license":[{"start":{"date-parts":[[2006,8,24]],"date-time":"2006-08-24T00:00:00Z","timestamp":1156377600000},"content-version":"vor","delay-in-days":23,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Geophysical Research Letters"],"published-print":{"date-parts":[[2006,8]]},"abstract":"<jats:p><jats:italic>Pd<\/jats:italic> is the peak amplitude of displacement in the first three seconds after the arrival of the <jats:italic>P<\/jats:italic> wave. We investigated the attenuation of <jats:italic>Pd<\/jats:italic> with the hypocentral distance <jats:italic>R<\/jats:italic> in southern California as a function of magnitude <jats:italic>M<\/jats:italic>, and obtained the following relationship: log (<jats:italic>P<\/jats:italic><jats:sub><jats:italic>d<\/jats:italic><\/jats:sub>) = \u22123.463 + 0.729 \u00d7 <jats:italic>M<\/jats:italic> \u2212 1.374 \u00d7 log (<jats:italic>R<\/jats:italic>) \u00b1 0.305. Given an earthquake location determined by the <jats:italic>P<\/jats:italic>\u2010wave arrival times at stations close to the epicenter, this relationship can be used to define a so\u2010called \u201c<jats:italic>Pd<\/jats:italic> magnitude\u201d of earthquakes. Our result shows that for earthquakes in southern California the <jats:italic>Pd<\/jats:italic> magnitudes agree with the catalog magnitudes with a standard deviation of 0.18 for events less than magnitude 6.5. Therefore, <jats:italic>Pd<\/jats:italic> is a robust measurement for estimating the magnitudes of earthquakes and has practical application in earthquake early warning systems.<\/jats:p>","DOI":"10.1029\/2006gl026871","type":"journal-article","created":{"date-parts":[[2006,8,23]],"date-time":"2006-08-23T20:08:04Z","timestamp":1156363684000},"source":"Crossref","is-referenced-by-count":273,"title":["Magnitude estimation using the first three seconds P\u2010wave amplitude in earthquake early warning"],"prefix":"10.1029","volume":"33","author":[{"given":"Yih\u2010Min","family":"Wu","sequence":"first","affiliation":[{"name":"Department of Geosciences National Taiwan University  Taipei Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Zhao","sequence":"additional","affiliation":[{"name":"Institute of Earth Sciences Academia Sinica  Taipei Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"13","published-online":{"date-parts":[[2006,8,24]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.1080912"},{"key":"e_1_2_8_3_1","doi-asserted-by":"crossref","first-page":"1521","DOI":"10.1785\/BSSA0680051521","article-title":"Automatic earthquake recognition and timing from single traces","volume":"68","author":"Allen R. 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