https://journal.geophysicsjournal.com/JofG/issue/feed Journal of Geophysics 2022-08-01T00:00:00+00:00 Dr. Mensur Omerbashich editor@geophysicsjournal.com Open Journal Systems <div style="height: 100px;"> <div class="noselect" style="font-size: 0.9em;">The <strong>Journal of Geophysics</strong> (<em>J. Geophys.</em>) is the world's oldest and premier geophysical journal. It publishes research of great importance to geosciences, primarily in any areas of classical (theoretical) geophysics — including planetary physics, geodynamics, tectonophysics, seismology, physical and mathematical geodesy, atmosphere physics, and <a href="/JofG/about#nav-menu">more...</a></div> <p>&nbsp;</p> <div style="text-align: right; margin-top: -30px;"> <p class="responsiveimg3"><img src="/public/site/images/JoGeoph/openbook.png" alt="Journal of Geophysics"><a href="/JofG/about#nav-menu"><img class="flip" src="/public/site/images/JoGeoph/openbook-flip.png" alt="Journal of Geophysics"></a></p> </div> </div> https://journal.geophysicsjournal.com/JofG/article/view/304 Scaling relations for energy magnitudes 2022-06-12T15:10:12+00:00 R. Das ranjit.das@cigiden.cl C. Meneses cmeneses@ucn.cl <p>Homogenizing earthquake catalogs is an effort critical to fundamentally improving seismic studies for next-generation seismology. The preparation of a homogenous earthquake catalog for a seismic region requires scaling relations to convert different magnitude types, like the m<sub>b</sub> and M<sub>s</sub>, to a homogenous magnitude, such as the seismic moment scale, M<sub>wg</sub>, and energy magnitude scale, M<sub>e</sub>. Several recent studies addressed the preparation of homogenized earthquake catalogs, usually involving the estimation of proxies of moment magnitude M<sub>w</sub> from local, M<sub>L</sub>, and teleseismic (M<sub>s</sub> and m<sub>b</sub>) magnitude estimates. Instead of the standard least squares (SLR), most of such studies used the general orthogonal regression (GOR), while some used the Chi-square regression method. Here we critically discuss GOR and Chi-square regression theory and find that both are the same for the linear case — as expected since both stem from the same mathematical concept. Thus to foster an improved understanding of seismicity and seismic hazard, we used GOR methodology and derived global scaling relations individually between body, surface, energy, and seismic moment magnitude scales. For that purpose, we have compiled 13,576 and 13,282 events for M<sub>s</sub> from ISC and NEIC, respectively, m<sub>b</sub> magnitude data for 1,266 events from ISC, 614 events from NEIC, and M<sub>wg</sub> magnitude values for 6,690 events from NEIC and GCMT. We have also derived M<sub>S,ISC</sub>-to-M<sub>e</sub> and M<sub>S,NEIC</sub>-to-M<sub>e</sub> conversion relations in magnitude ranges of 4.7≤M<sub>S,ISC</sub>≤8.0 and 4.5≤M<sub>S,NEIC</sub>≤8.0, respectively. Likewise, we obtained m<sub>b,ISC</sub>-to-M<sub>e</sub> and m<sub>b,NEIC</sub>-to-M<sub>e</sub> conversion relations for ranges of 5.2≤m<sub>b,ISC</sub>≤6.2 and 5.3≤m<sub>b,NEIC</sub>≤6.5. &nbsp;Since the number of data points was insufficient to derive the relations, we considered m<sub>b,NEIC</sub> up to M6.5. &nbsp;Finally, we derived an M<sub>Wg</sub>-to-M<sub>e</sub> conversion relation for the 5.2≤M<sub>w</sub>≤8.2 range of magnitudes with focal depths &lt;70 km. &nbsp;Our scaling relations can be used for homogenizing earthquake catalogs and conducting seismicity and seismic hazard assessment studies with enhanced realism.</p> <p><a href="https://scholar.google.com/scholar?cluster=127838183624783700" target="_blank" rel="noopener"><img class="scholar" title="Google Scholar" src="/public/site/images/JoGeoph/gs.png" alt="Google Scholar"></a> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>ARK</strong>: <a title="ARK Identifier" href="https://n2t.net/ark:/88439/x063005" target="_blank" rel="noopener">https://n2t.net/ark:/88439/x063005</a></p> <p>Permalink: https://geophysicsjournal.com/article/304</p> <p><a target="_blank" rel="noopener"><img class="scholar" title="Copyright Clearance Center" src="/public/site/images/JoGeoph/ccc.png" alt="Copyright Clearance Center"></a> <a title="Copyright Clearance Center" href="https://www.copyright.com/openurl.action?issn=2643-2986&amp;WT.mc.id=Journal%20of%20Geophysics" target="_blank" rel="noopener">Reprints &amp; Permissions</a></p> <p>&nbsp;</p> 2021-03-26T20:33:31+00:00 Copyright (c) https://journal.geophysicsjournal.com/JofG/article/view/313 Detection and mapping of Earth body resonances with continuous GPS 2022-07-29T16:40:16+00:00 M. Omerbashich hm@royalfamily.ba <p>I recently reported temporal proof that M<sub>w</sub>5.6+ strong earthquakes occur due to (as the lithosphere rides on) vast waves of the tidally driven and gravitationally aided 1–72h long-periodic Earth body resonance (EBR). Here I report a methodologically independent spatial proof of EBR, conclusively showing that tremors are not the only earthquake type caused by mechanical resonance: observations of actual EBR waves in solid matter using continuous Global Positioning System (cGPS) and of their triggering M<sub>w</sub>5.6+ earthquakes. Superharmonic resonance periods from the EBR’s 55’–15 days (0.303 mHz–0.7716 μHz) band are thus recoverable in spectra of International Terrestrial Reference Frame (ITRF2014) positional components solved kinematically from 30-s cGPS samplings. The signal is so pure, strong, and stable that even daylong components are constantly periodic at or above 99%-significance, with very high statistical fidelity, ϕ&gt;&gt;12, and ϕ&lt;&lt;12 characterizing overtones or undertones. cGPS stations have diurnal EBR fingerprints: unique sets of ~13–18 EBR frequencies, most clearly formed during ~M<sub>w</sub>6+ quiescence, enabling depiction of EBR orientation for real-time EBR mapping. Furthermore, weeklong component time series reveal complete EBR and expected undertones as the signature of EBR’s companion sympathetic resonances, with very high ϕ&gt;&gt;12. Also, I demonstrate EBR mapping using the Mexico City–Los Angeles–San Francisco cGPS profile alongside a tectonic plate boundary, successfully depicting the preparation phase of the 2020 Puerto Rico M<sub>w</sub>6.4–M<sub>w</sub>6.6 earthquakes sequence. I finish by showing that the EBR triggered the 2019 Ridgecrest M<sub>w</sub>6.4–M<sub>w</sub>7.1 earthquakes sequence. EBR maps can now be produced for seismic prediction/forecasting and unobscuring (decoupling EBR frequencies) from geophysical observables like stress and strain. EBR engulfs the Earth’s crust, forming the <em>resonance wind</em> whose role and incessantness demote mantle convection from the working hypothesis of geophysics and whose applications include geophysical prospecting and detection at all scales and times. A previously unaccounted-for fundamental force of geophysics, the impulsive EBR spans the vastest energy bands, invalidating any previous claims of seismic detections of gravitational wave signals from deep space, such as by the LIGO experiment.</p> <p><a href="https://scholar.google.com/scholar?cluster=998699777037622170" target="_blank" rel="noopener"><img class="scholar" title="Google Scholar" src="/public/site/images/JoGeoph/gs.png" alt="Google Scholar"></a> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>ARK</strong>: <a title="ARK Identifier" href="https://n2t.net/ark:/88439/x073994" target="_blank" rel="noopener">https://n2t.net/ark:/88439/x073994</a></p> <p>Permalink: https://geophysicsjournal.com/article/313</p> <p><a target="_blank" rel="noopener"><img class="scholar" title="Copyright Clearance Center" src="/public/site/images/JoGeoph/ccc.png" alt="Copyright Clearance Center"></a> <a title="Copyright Clearance Center" href="https://www.copyright.com/openurl.action?issn=2643-2986&amp;WT.mc.id=Journal%20of%20Geophysics" target="_blank" rel="noopener">Reprints &amp; Permissions</a></p> <p>&nbsp;</p> 2022-05-14T00:00:00+00:00 Copyright (c)