DataAnalysis2022/ObsPy/05_Event_metadata.ipynb

{"cells":[{"cell_type":"markdown","metadata":{},"source":["<div style='background-image: url(\"../images/header.svg\") ; padding: 0px ; background-size: cover ; border-radius: 5px ; height: 250px'>\n","    <div style=\"float: right ; margin: 50px ; padding: 20px ; background: rgba(255 , 255 , 255 , 0.7) ; width: 50% ; height: 150px\">\n","        <div style=\"position: relative ; top: 50% ; transform: translatey(-50%)\">\n","            <div style=\"font-size: xx-large ; font-weight: 900 ; color: rgba(0 , 0 , 0 , 0.8) ; line-height: 100%\">ObsPy Tutorial</div>\n","            <div style=\"font-size: large ; padding-top: 20px ; color: rgba(0 , 0 , 0 , 0.5)\">Handling Event Metadata</div>\n","        </div>\n","    </div>\n","</div>"]},{"cell_type":"markdown","metadata":{},"source":["Seismo-Live: http://seismo-live.org\n","\n","##### Authors:\n","* Lion Krischer ([@krischer](https://github.com/krischer))\n","* Tobias Megies ([@megies](https://github.com/megies))\n","---"]},{"cell_type":"markdown","metadata":{},"source":["![](images/obspy_logo_full_524x179px.png)"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["%matplotlib inline\n","import matplotlib.pyplot as plt\n","plt.style.use('ggplot')\n","plt.rcParams['figure.figsize'] = 12, 8"]},{"cell_type":"markdown","metadata":{},"source":["- for event metadata, the de-facto standard is [QuakeML (an xml document structure)](https://quake.ethz.ch/quakeml/)\n","- QuakeML files can be read using **`read_events()`**"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["from obspy import read_events\n","\n","catalog = read_events(\"./data/event_tohoku_with_big_aftershocks.xml\")\n","print(catalog)"]},{"cell_type":"markdown","metadata":{},"source":["- **`read_events()`** function returns a **`Catalog`** object, which is\n","a collection of **`Event`** objects."]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["print(type(catalog))\n","print(type(catalog[0]))"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["event = catalog[0]\n","print(event)"]},{"cell_type":"markdown","metadata":{},"source":["- Event objects are again collections of other resources.\n","- the nested ObsPy Event class structure (Catalog/Event/Origin/Magnitude/FocalMechanism/...) is closely modelled after QuakeML\n","<img src=\"images/Event.svg\" width=90%>"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["print(type(event.origins))\n","print(type(event.origins[0]))\n","print(event.origins[0])"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["print(type(event.magnitudes))\n","print(type(event.magnitudes[0]))\n","print(event.magnitudes[0])"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["# try event.<Tab> to get an idea what \"children\" elements event has"]},{"cell_type":"markdown","metadata":{},"source":["- The Catalog object contains some convenience methods to make\n","working with events easier.\n","- for example, the included events can be filtered with various keys."]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["largest_magnitude_events = catalog.filter(\"magnitude >= 7.8\")\n","print(largest_magnitude_events)"]},{"cell_type":"markdown","metadata":{},"source":["- There is a basic preview plot using the matplotlib basemap module."]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["catalog.plot(projection=\"local\");"]},{"cell_type":"markdown","metadata":{},"source":["- a (modified) Catalog can be output to file (currently there is write support for QuakeML only)"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["largest_magnitude_events.write(\"/tmp/large_events.xml\", format=\"QUAKEML\")\n","!ls -l /tmp/large_events.xml"]},{"cell_type":"markdown","metadata":{},"source":["- the event type classes can be used to build up Events/Catalogs/Picks/.. from scratch in custom processing work flows and to share them with other researchers in the de facto standard format QuakeML"]},{"cell_type":"code","execution_count":null,"metadata":{},"outputs":[],"source":["from obspy import UTCDateTime\n","from obspy.core.event import Catalog, Event, Origin, Magnitude\n","from obspy.geodetics import FlinnEngdahl\n","\n","cat = Catalog()\n","cat.description = \"Just a fictitious toy example catalog built from scratch\"\n","\n","e = Event()\n","e.event_type = \"not existing\"\n","\n","o = Origin()\n","o.time = UTCDateTime(2014, 2, 23, 18, 0, 0)\n","o.latitude = 47.6\n","o.longitude = 12.0\n","o.depth = 10000\n","o.depth_type = \"operator assigned\"\n","o.evaluation_mode = \"manual\"\n","o.evaluation_status = \"preliminary\"\n","o.region = FlinnEngdahl().get_region(o.longitude, o.latitude)\n","\n","m = Magnitude()\n","m.mag = 7.2\n","m.magnitude_type = \"Mw\"\n","\n","m2 = Magnitude()\n","m2.mag = 7.4\n","m2.magnitude_type = \"Ms\"\n","\n","# also included could be: custom picks, amplitude measurements, station magnitudes,\n","# focal mechanisms, moment tensors, ...\n","\n","# make associations, put everything together\n","cat.append(e)\n","e.origins = [o]\n","e.magnitudes = [m, m2]\n","m.origin_id = o.resource_id\n","m2.origin_id = o.resource_id\n","\n","print(cat)\n","cat.write(\"/tmp/my_custom_events.xml\", format=\"QUAKEML\")\n","!cat /tmp/my_custom_events.xml"]}],"metadata":{"kernelspec":{"display_name":"Python 3","language":"python","name":"python3"}},"nbformat":4,"nbformat_minor":2}