jqGrid from USGS geojson data

I'm trying to read and post in a jqGrid a set of earthquakes GeoJSON data extracted from USGS repository. The request is accepted, but displays "Uncaught SyntaxError: Unexpected token" when probably meets the header metadata.

$(function () {
    'use strict';
    $.extend($.jgrid.search, {multipleSearch: true, multipleGroup: true, overlay: 0});
    $('#grid').jqGrid({
        url: 'http://earthquake.usgs.gov/earthquakes/feed/geojson/2.5/week?callback=?',
        datatype: 'json',
        colModel: [
            {name: 'mag', label: 'MAGNITUDO', width: 150, jsonmap: 'properties.mag', sorttype: 'number',
formatter: 'number', formatoptions: {decimalPlaces: 2}},
            {name: 'place', label: 'LOCALITA', width: 150, jsonmap: 'properties.place'},
            {name: 'url', label: 'URL', width: 150, jsonmap: 'properties.url'}
        ],
        toppager: true,
        gridview: true,
        rowList: [10, 20, 50, 10000],
        rowNum: 10,
        jsonReader: {
            root: 'features',
            repeatitems: false
        },
        loadonce: true,
        ignoreCase: true,
        height: 'auto'
    }).jqGrid('navGrid', '#grid_toppager', {add: false, edit: false, del: false})
      .jqGrid('filterToolbar', {stringResult: true, defaultSearch: 'cn', searchOnEnter: false});
    $("#grid_toppager option[value=10000]").text('All');
});

Do you have any solution? Thanks in advance.

I looked in the documentation of geojson and I think I found the reason of the problem. It seems that GeoJSON(P) uses eqfeed_callback as callback name (see here). So I fixed some options of jqGrid which you used to the following:

url: 'http://earthquake.usgs.gov/earthquakes/feed/geojsonp/2.5/week',
datatype: 'jsonp',
postData: '',
ajaxGridOptions: { jsonp: false, jsonpCallback: 'eqfeed_callback', cache: true},

The modified demo works now and display the results like below