{"id":4926,"date":"2017-01-21T02:35:27","date_gmt":"2017-01-21T10:35:27","guid":{"rendered":"http:\/\/earthjay.com\/?p=4926"},"modified":"2017-01-21T02:35:27","modified_gmt":"2017-01-21T10:35:27","slug":"earthquake-report-celebes-sea","status":"publish","type":"post","link":"https:\/\/earthjay.com\/?p=4926","title":{"rendered":"Earthquake Report: Celebes Sea!"},"content":{"rendered":"<p>Catching up on some earthquake reports on a Friday night. This earthquake happened on 2017.01.10 in a region to the west of the Molluca Strait. I have reported on Molucca Strait earthquakes several times before as this is a very seismically active region. To the north and east of the Molucca Strait is a subduction zone, where the Philippine Sea plate (PSP) subducts westward beneath the Sunda plate (SP), forming the Philippine Trench. This M 7.3 earthquake is within the PSP at a depth of about 600 km. Here is the <a href=\"http:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/us10007s9c#executive\" target=\"_blank\" rel=\"noopener\">USGS web page for this earthquake<\/a>.<\/p>\n<ul>\n<li>The Molucca Strait trends north-south due to the east and west vergent, ~north-south striking, thrust faults here. Here are some earthquakes that have happened in the Molucca Strait region. These are #EarthquakeReports that I prepared at the time.<\/li>\n<ul>\n<li>2015.03.17 <a href=\"http:\/\/earthjay.com\/?p=2267\">M 6.2 Molucca Sea<\/a><\/li>\n<li>2014.11.26 <a href=\"http:\/\/earthjay.com\/?p=2051\">M 6.8 Molucca Sea<\/a><\/li>\n<li>2014.11.21 <a href=\"http:\/\/earthjay.com\/?p=2040\">M 6.5 Molucca Sea<\/a><\/li>\n<li>2014.11.15 <a href=\"http:\/\/earthjay.com\/?p=2035\">M 7.1 Molucca Sea<\/a><\/li>\n<\/ul>\n<li>This region has earthquakes like these pretty regularly (monthly). Below are some USGS examples from the last month.<\/li>\n<ul>\n<li>2017-01-14 <a href=\"http:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/us10007t9u#executive\" target=\"_blank\" rel=\"noopener\">M 5.6 &#8211; 119km WNW of Kota Ternate, Indonesia<\/a><\/li>\n<li>2017-01-01 <a href=\"http:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/us10007p3h#executive\" target=\"_blank\" rel=\"noopener\">M 5.5 &#8211; 206km N of Tobelo, Indonesia<\/a><\/li>\n<li>2017-01-01 <a href=\"http:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/us10007p3f#executive\" target=\"_blank\" rel=\"noopener\">M 5.5 &#8211; 219km NNE of Tobelo, Indonesia<\/a><\/li>\n<\/ul>\n<\/ul>\n<p>The PSP subducts westward and has earthquakes deeper than 600 km. These are not subduction zone earthquakes (deeper than 40-50 km max), but are related to deformation within the downgoing plate. (my fingers typed plage instead of plate, which leads me to remember the disease &#8220;the plage&#8221; in Star Trek Voyager. digression aside.). This M 7.3 earthquake appears to be an earthquake like this, within the PSP that is internally deforming.<\/p>\n<ul>\n<li>I placed a moment tensor \/ focal mechanism legend on the poster. There is more material from the USGS web sites about <a href=\"http:\/\/earthquake.usgs.gov\/learn\/glossary\/?term=moment%20tensor\" target=\"_blank\" rel=\"noopener\">moment tensors<\/a> and <a href=\"http:\/\/earthquake.usgs.gov\/learn\/topics\/beachball.php\" target=\"_blank\" rel=\"noopener\">focal mechanisms<\/a> (the beach ball symbols). Both moment tensors and focal mechanisms are solutions to seismologic data that reveal two possible interpretations for fault orientation and sense of motion. One must use other information, like the regional tectonics, to interpret which of the two possibilities is more likely. The moment tensor shows east-west extension, perpendicular to the convergence at this plate boundary. This earthquake is the result of extension in the PSP. <\/li>\n<li>I also include the shaking intensity contours on the map. These use the Modified Mercalli Intensity Scale (MMI; see the legend on the map). This is based upon a computer model estimate of ground motions, different from the &#8220;Did You Feel It?&#8221; estimate of ground motions that is actually based on real observations. The MMI is a qualitative measure of shaking intensity. More on the MMI scale can be found <a href=\"http:\/\/earthquake.usgs.gov\/learn\/topics\/mercalli.php\" target=\"_blank\" rel=\"noopener\">here<\/a> and <a href=\"https:\/\/en.wikipedia.org\/wiki\/Mercalli_intensity_scale\" target=\"_blank\" rel=\"noopener\">here<\/a>. This is based upon a computer model estimate of ground motions, different from the &#8220;Did You Feel It?&#8221; estimate of ground motions that is actually based on real observations.<\/li>\n<li>I include the slab contours plotted (<a href=\"http:\/\/www.agu.org\/pubs\/crossref\/2012\/2011JB008524.shtml\" target=\"_blank\" rel=\"noopener\">Hayes et al., 2012<\/a>), which are contours that represent the depth to the subduction zone fault. These are mostly based upon seismicity. The depths of the earthquakes have considerable error and do not all occur along the subduction zone faults, so these slab contours are simply the best estimate for the location of the fault. Today&#8217;s M 7.2 earthquake is not directly related to the subduction zones in this region (it is genetically related to a spreading ridge), but they do play an important role in the region. <\/li>\n<\/ul>\n<ul>\n<h2>I include some inset figures in the poster below.<\/h2>\n<li>In the upper right corner I include a map showing the seismicity and tectonic plate boundary faults for this region (Smoczyk et al., 2013). Earthquakes are plotted with color representing depth and diameter representing magnitude (see legend). Below the map are two cross-sections (with a legend), C-C&#8217; and D-D.&#8217; Cross section D-D&#8217; is aligned close to where this M 7.3 earthquake occurred. I place a blue star on the map and cross section in the general location of this earthquake epicenter (map) and hypocenter (cross section).<\/li>\n<li>On the left side of the poster I include a small scale (upper panel) and a large scale (bottom panel) view of the regional tectonics (Zahirovic et al., 2014). Plate boundary fault symbology (and other features, like fracture zones) is shown in the legend. I place a blue star on the map in the general location of this earthquake epicenter.<\/li>\n<\/ul>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/20170110_celebes_sea_interpretation.pdf\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/20170110_celebes_sea_interpretation.jpg\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>This is the same poster, but includes earthquakes since 1900 with magnitudes M \u2265 6.5.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/20170110_celebes_sea_interpretation_19002017.pdf\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/20170110_celebes_sea_interpretation_19002017.jpg\" width=\"100%\" alt=\"\" \/><\/a>\n<\/ul>\n<ul>\n<li>Here are maps showing the regional tectonics (Zahirovic et al., 2014). Below I include the text from the original figure caption in blockquote.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_01_A.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_01_A.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nRegional tectonic setting with plate boundaries (MORs\/transforms = black, subduction zones = teethed red) from Bird (2003) and ophiolite belts representing sutures modified from Hutchison (1975) and Baldwin et al. (2012). West Sulawesi basalts are from Polv\u00e9 et al. (1997), fracture zones are from Matthews et al. (2011) and basin outlines are from Hearn et al. (2003). ANI \u2013 Andaman and Nicobar Islands, BD\u2013 Billiton Depression, Ba \u2013 Bangka Island, BI \u2013 Belitung (Billiton) Island, BiS \u2013 Bismarck Sea, BP \u2013 Benham Plateau, CaR \u2013 Caroline Ridge, CS \u2013 Celebes Sea, DG\u2013 Dangerous Grounds, EauR \u2013 Eauripik Ridge, FIN \u2013 Finisterre Terrane, GoT \u2013 Gulf of Thailand, GR\u2013 Gagua Ridge, HAL\u2013 Halmahera, HBa \u2013 Huatung Basin, KB\u2013Ketungau Basin, KP \u2013 Khorat Platform, KT \u2013 Kiilsgaard Trough, LS \u2013 Luconia Shoals, MacB \u2013 Macclesfield Bank, ManTr \u2013 Manus Trench, MaTr \u2013 Mariana Trench, MB\u2013 Melawi Basin, MDB\u2013 Minami Daito Basin, MG\u2013 Mangkalihat, MIN \u2013 Mindoro, MN\u2013 Mawgyi Nappe, MoS \u2013 Molucca Sea, MS\u2013 Makassar Straits, MTr \u2013 Mussau Trench, NGTr \u2013 New Guinea Trench, NI \u2013 Natuna Islands, ODR\u2013 Oki Daito Ridge, OJP \u2013Ontong Java Plateau, OSF \u2013 Owen Stanley Fault, PAL \u2013 Palawan, PhF \u2013 Philippine Fault, PT \u2013 Paternoster Platform, PTr \u2013 Palau Trench, PVB \u2013 Parece Vela Basin, RB \u2013 Reed Bank, RMF\u2013 Ramu-Markham Fault, RRF \u2013 Red River fault, SEM\u2013 Semitau, ShB \u2013 Shikoku Basin, Sol. Sea \u2013 Solomon Sea, SPK \u2013 Sepik, SPT \u2013 Sabah\u2013Palawan Trough, STr \u2013 Sorol Trough, Sul \u2013 Sulawesi, SuS \u2013 Sulu Sea, TPAA\u2013 Torricelli\u2013Prince Alexander Arc, WB\u2013West Burma, WCT\u2013W Caroline Trough, YTr \u2013Yap Trough\n<\/p><\/blockquote>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_01_B.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_01_B.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nRegional tectonic setting of the Philippine Sea plate, Papua New Guinea and the Caroline Plate, following symbology of Fig. 1. The crystallization ages of ophiolites were used to infer oceanic crust age, while the metamorphic age was used to infer collision and obduction. A\u2013 Lagonoy Ophiolite, B \u2013 Calaguas Ophiolite, C \u2013 Dibut Bay Ophiolite, D\u2013 Casiguran Ophiolite, E \u2013 Montalban Ophiolite, F \u2013 Zambales\u2013 Angat Ophiolite, G\u2013 Itogon Ophiolite, H\u2013 Marinduque Basin\/Sibuyan Ophiolite, I \u2013 Mindoro\/Amnay ophiolites, J \u2013 Palawan Ophiolite, K\u2013 Pujada Ophiolite, PUB \u2013 Papuan Ultramafic Belt, COPB \u2013 central ophiolite belt.\n<\/p><\/blockquote>\n<\/ul>\n<ul>\n<li>Here are plots showing the seismic tomographic results from Zahirovic et al. (2014). Basically, the authors use seismic waves in a 3-D geospatial model of the Earth to construct a 3-D model of the spatial variations in seismic velocity throughout the Earth. The concept is the same as that for 3-D Computed Tomography of X-Rays (aka CT-Scans). Their paper discusses a great many more details and they incorporate a broad range of methods in their analyses (including geologic history, topographic\/bathymetric analyses, kinematic reconstructions (reconstructing plate motions over time), paleogeography, gravimetric analyses, and seismic tomography. The 2017.01.10 M 7.3 earthquake happened close to the cross section labeled G-G.&#8217; Below I include the text from the original figure caption in blockquote.<\/li>\n<li>Here these authors present some seismic velocity contoured surfaces (isosurfaces). Basically, each of these blebs represents a 3-dimensional suface that is the same seismic velocity. These surfaces are imaginary (like elevation or topographic contours) because the seismic velocity actually varies in a more continuous manner (like elevation or topography). The color of the blebs is based on depth (see legend).<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_09.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_09.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\n3-D visualization of +0.2% seismic velocity anomaly isosurfaces in MIT-P (top) and +0.9% seismic velocity perturbation in GyPSuM-S (bottom) models. Profiles A to G represent the vertical profiles (see Fig. 10) that capture the convergence and subduction histories of the region since the Cretaceous. Present-day coastlines are translucent grey shades, and present-day plate boundaries are translucent black lines. Slab volumes are colored by their depth, while the light blue color represents the interior surface of these slabs. PSCS \u2013 proto-South China Sea slab.\n<\/p><\/blockquote>\n<li>Here the PSP is labelled as the blue slab &#8220;PSP&#8221; (colder blue slab = higher seismic velocity; warmer red mantle = lower seismic velocity).<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_10.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_10.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nVertical sections from MIT-P (Li et al., 2008) and GyPSuM-S (Simmons et al., 2009) seismic tomography models along profiles A to E (magenta lines). The first-order differences between the P- and S-wave models is that the amplitude of the positive seismic velocity anomalies significantly diminishes away from continental coverage (e.g., dashed lines in profiles A and B). A depth slice at 746 km from MIT-P is provided for reference with super-imposed present-day coastlines and plate boundaries. Interpreted slab sources are labeled: GI-BA= Greater India\u2013Neo-Tethyan back-arc slab, M\/N-T \u2013 Meso- and Neo-Tethyan slabs, W-S \u2013Woyla\u2013Sunda slabs, S \u2013 Sunda slab, PSCS \u2013 proto-South China Sea slab, PAC \u2013 Pacific slab, PMOL\u2013 proto-Molucca slab, PSOL \u2013 proto-Solomon slab, CS \u2013 Caroline slab, PSP \u2013 Philippine Sea Plate slab, S-C = Sulu\u2013Celebes slab.\n<\/p><\/blockquote>\n<li>Finally the authors present two models that incorporate the changes in plate boundary types and vergence through time (see panel with 2 maps an d2 cross-sections).<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_11.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/Zahirovic_etal_2014_The_Cretaceous_and_Cenozoic_tectonic_evolution_of_Southeast_Asia_fig_11.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nEnd-member pre-rift scenarios along northern Gondwana during the latest Jurassic (\u0018155 Ma) rift timing with a triple junction detaching the East Java, West Sulawesi, East Borneo and Mangkalihat from New Guinea driven by north-dipping subduction along the Woyla intra-oceanic arc representing the model implemented in this study (left). Alternatively, these blocks may have originated in the Argo Abyssal Plain (AAP), and a back-arc scenario may have existed along New Guinea (right), similar to the Incertus Arc proposed by Hall (2012). However, if this back-arc spreading did not detach continental blocks, then it may be the source for the proto-Philippine Arc. It is beyond the scope of this study to resolve whether the Mawgyi Nappes on West Burma or the Woyla Terranes on Sumatra contain microcontinental blocks, as it remains a continued source of controversy.We prefer the accretion of buoyant microcontinents in this region in order to account for the closure mechanism of theWoyla back arc in the Late Cretaceous. GAP \u2013 Gascoyne Abyssal Plain, PBE \u2013 proto-Banda Embayment, SNL\u2013 Sikuleh, Natal, Lolotoi and Bengkulu microcontinents. Schematic cross sections approximately follow dashed green line and are modified from Bouilhol et al. (2013). Not to scale.\n<\/p><\/blockquote>\n<\/ul>\n<ul>\n<li>Here are maps showing the regional tectonics (<a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/smoczyk_etal_2013_seismicity_earth_philippine_sea_plate.pdf\" target=\"_blank\" rel=\"noopener\">Smoczyk et al., 2013<\/a>).<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/smoczyk_etal_2013_seismicity_earth_philippine_sea_plate_celebes_sea_map.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/smoczyk_etal_2013_seismicity_earth_philippine_sea_plate_celebes_sea_map.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nAlong its western margin, the Philippine Sea plate is associated with a zone of oblique convergence with the Sunda plate. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to Sulawesi in the south. The tectonic setting of the Philippines is unusual in several respects: it is characterized by opposite-facing subduction systems on its east and west sides; the archipelago is cut by a major transform fault, the Philippine Fault; and the arc complex itself is marked by volcanism, faulting, and high seismic activity. Subduction of the Philippine Sea plate occurs at the eastern margin of the archipelago along the Philippine Trench and its northern extension, the East Luzon Trough. The East Luzon Trough is thought to be an unusual example of a subduction zone in the process of formation, as the Philippine Trench system gradually extends northward (Hamburger and others, 1983).\n<\/p><\/blockquote>\n<\/ul>\n<ul>\n<li>This shows Global Positioning System (GPS) velocities at various locations. These plate motions are represented as vectors in mm\/yr. (see legend) Here note how the vector labeled phil\/eura (for the motion of the PSP relative to the Eurasia plate) is oblique to the plate margin along the Philippine trench (i.e. the PSP is not subducting perpendicular to the megathrust fault). The oblique relative motion seems to lead to strain partitioning, leading to a forearc sliver fault (the Philippine fault, shown in maps above). Below I include the text from the original figure caption in blockquote.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/bock_etal_2003_crustal_motion_gps_indonesia_fig_2.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/bock_etal_2003_crustal_motion_gps_indonesia_fig_2.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nTopographic and tectonic map of the Indonesian archipelago and surrounding region. Labeled, shaded arrows show motion (NUVEL-1A model) of the first-named tectonic plate relative to the second. Solid arrows are velocity vectors derived from GPS surveys from 1991 through 2001, in ITRF2000. For clarity, only a few of the vectors for Sumatra are included. The detailed velocity field for Sumatra is shown in Figure 5. Velocity vector ellipses indicate 2-D 95% confidence levels based on the formal (white noise only) uncertainty estimates. NGT,  ew Guinea Trench; NST, North Sulawesi Trench; SF, Sumatran Fault; TAF, Tarera-Aiduna Fault. Bathymetry [Smith and Sandwell, 1997] in this and all subsequent figures contoured at 2 km intervals\n<\/p><\/blockquote>\n<\/ul>\n<ul>\n<li>Here is a map and cross section presented by Waltham et al. (2008). They use a variety of data sources as a basis for their interpretations (seismic reflection data, gravity data). Note how the Molucca Sea plate subducts both to the west and to the east. Below I include the text from the original figure caption in blockquote.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/waltham_etal_2008_volcanic_arc_oading_fig_02.jpg\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/waltham_etal_2008_volcanic_arc_oading_fig_02.jpg\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\n(A) Location and major tectonic features of the Molucca Sea region. Small, black-fi lled triangles are modern volcanoes. Bathymetric contours are at 200, 2000, 4000, and 6000 m. Large barbed lines are subduction zones, and small barbed lines are thrusts. (B) Cross section across the Halmahera and Sangihe Arcs on section line B. Thrusts on each side of the Molucca Sea are directed outward toward the adjacent arcs, although the subducting Molucca Sea plate dips east beneath Halmahera and west below the Sangihe Arc. (C) Inset is the restored  cross section of the Miocene\u2013Pliocene Weda Bay Basin of SW Halmahera on section line C, fl attened to the Pliocene unconformity, showing estimated thickness of the section\n<\/p><\/blockquote>\n<\/ul>\n<ul>\n<li>Early work done in the region was presented by McCaffrey et al. (1980). Here is a map showing seismic refraction lines that they used to constrain the structures in this region. Below I include the text from the original figure caption in blockquote.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/mccaffrey_etal_1980_molucca_sea_tectonics_fig_02.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/mccaffrey_etal_1980_molucca_sea_tectonics_fig_02.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nMap of the Molucca Sea, eastern Indonesia, showing I~tions of seismic refraction lines (solid straight lines) and gravity traverses (duhed-dotted lines). Thrust faults are shown with teeth on hanging wall. Triangles represent active volcanoes defining the Sangihe and Halmahera magmatic arcs. Isobath interval is 1 km from Mammericks et al. [1976].\n<\/p><\/blockquote>\n<li>Here is a cross section that shows the gravity model they used to interpret this region.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/mccaffrey_etal_1980_molucca_sea_tectonics_fig_12.JPG\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/mccaffrey_etal_1980_molucca_sea_tectonics_fig_12.JPG\" width=\"100%\" alt=\"\" \/><\/a><\/p>\n<blockquote><p>\nGravity model for the central Molucca Sea. (II) Crustal model with layers designated by their density contrasts and refraction control points by open circles and vertical bars. (b) Mantle structure used in modeling the gravity profiles in the central Molucca Sea. Figure 124 fits into the small box at the apex of the inverted-V-ehaped lithosphere. Slab dimensions are controlled by earthquake foci (dots) from Hlltherton 11M Dickinaon [1969J, and mantle densities are taken from Grow 11M Rowin [1975J. The column at the left shows assumed densities for the range of depths between the tick marks. The small v pattern represents oceanic crust, and island arc crust is designated by a short parallel line pattern. East is to the right of the figure.\n<\/p><\/blockquote>\n<\/ul>\n<ul>\n<li>Here is a map with moment tensors plotted for four earthquakes that happened in the Molucca Strait in 2014. Note how they are east-west compressional. This earthquake happened really close to the M 7.1 from earlier (2014\/11\/15). <a href=\"http:\/\/earthjay.com\/?p=2035\">Here<\/a> is my page that has more information about the regional tectonic interpretations. <a href=\"http:\/\/earthquake.usgs.gov\/earthquakes\/eventpage\/usb000t08w#summary\" target=\"_blank\" rel=\"noopener\">Here<\/a> is the USGS page for this M 6.8 earthquake.<\/li>\n<p><a href=\"http:\/\/earthjay.com\/earthquakes\/20141126_halmahera\/20141126_halmahera_illustration.jpg\" target=\"_blank\" rel=\"noopener\"><br \/>\n<img decoding=\"async\" src=\"http:\/\/earthjay.com\/earthquakes\/20141126_halmahera\/20141126_halmahera_illustration.jpg\" width=\"100%\" alt=\"\" \/><\/a>\n<\/ul>\n<h2> <strong>References:<\/strong><\/h2>\n<ul>\n<li>Bock et al., 2003. Crustal motion in Indonesia from Global Positioning System measurements in JGR, v.\/ 108, no. B8, 2367, doi:10.1029\/2001JB000324<\/li>\n<li>Hayes, G.P., Wald, D.J., and Johnson, R.L., 2012. <a href=\"http:\/\/www.agu.org\/pubs\/crossref\/2012\/2011JB008524.shtml\" target=\"_blank\" rel=\"noopener\">Slab1.0: A three-dimensional model of global subduction zone geometries<\/a> in, J. Geophys. Res., 117, B01302, doi:10.1029\/2011JB008524<\/li>\n<li>McCaffrey, R., Silver, E.A., and Raitt, R.W., 1980. Crustal Structure of the Molucca Sea Collision Zone, Indonesia in The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands-Geophysical Monograph 23, p. 161-177.<\/li>\n<li>Smoczyk, G.M., Hayes, G.P., Hamburger, M.W., Benz, H.M., Villase\u00f1or, Antonio, and Furlong, K.P., 2013. <a href=\"http:\/\/earthjay.com\/earthquakes\/20170110_philippines\/smoczyk_etal_2013_seismicity_earth_philippine_sea_plate.pdf\" target=\"_blank\" rel=\"noopener\">Seismicity of the Earth 1900\u20132012 Philippine Sea plate and vicinity: U.S. Geological Survey Open-File Report 2010\u20131083-M<\/a>, 1 sheet, scale 1:10,000,000.<\/li>\n<li>Waltham et al., 2008. <a href=\"http:\/\/specialpapers.gsapubs.org\/content\/436\/11.abstract\" target=\"_blank\" rel=\"noopener\">Basin formation by volcanic arc loading<\/a> in GSA Special Papers 2008, v. 436, p. 11-26.<\/li>\n<li>Zahirovic et al., 2014. The Cretaceous and Cenozoic tectonic evolution of Southeast Asia in Solid Earth, v. 5, p. 227-273, doi:10.5194\/se-5-227-2014.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<div class=\"entry-summary\">\nCatching up on some earthquake reports on a Friday night. This earthquake happened on 2017.01.10 in a region to the west of the Molluca Strait. I have reported on Molucca Strait earthquakes several times before as this is a very&hellip;\n<\/div>\n<div class=\"link-more\"><a href=\"https:\/\/earthjay.com\/?p=4926\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &ldquo;Earthquake Report: Celebes Sea!&rdquo;<\/span>&hellip;<\/a><\/div>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0},"categories":[5,6,7,9,26,27,34],"tags":[],"aioseo_notices":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/earthjay.com\/index.php?rest_route=\/wp\/v2\/posts\/4926"}],"collection":[{"href":"https:\/\/earthjay.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/earthjay.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/earthjay.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/earthjay.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4926"}],"version-history":[{"count":0,"href":"https:\/\/earthjay.com\/index.php?rest_route=\/wp\/v2\/posts\/4926\/revisions"}],"wp:attachment":[{"href":"https:\/\/earthjay.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4926"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/earthjay.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4926"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/earthjay.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4926"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}