The light gray area on this map shows the extent of the lidar coverage. The darker gray area shows the extent of the Relative Earthquake Hazard Map of the Portland Metropolitan Region (DOGAMI Interpretive Map Series publication IMS-1) (DOGAMI IMS-1) study, and the gold area shows the extent of the Oregon City Landslide Study (DOGAMI O-06-27). To see the relative earthquake hazard map and landslide map layers, turn on those layers in the Layers tab on the map page.

The default tool is the "Zoom In" tool, so you can immediately start using the map just by using your mouse to draw a box around the area of the map you want to view or by clicking once on a spot on the map. When you change the base imagery, hazards maps layers, or other overlay options, the map redraws automatically.

To display information for the area you are viewing, click on the Map Info and Key tabs.

Read the rest of this Help page to learn more about how to interact with the map.

Use the Layers tab options to select the data layers to display on the map. When you select a layer the map automatically updates. Some users with slower connections may need to wait for layer display to "catch up."

BASE IMAGERY:

You can view and compare the following kinds of imagery:

• Lidar Shaded Topo Relief: Light Detection and Ranging technology offers highly precise terrain modeling data, from which hillshade imagery may be derived; 6-foot resolution. Sources: Puget Sound Lidar Consortium and the City of Oregon City. The lidar base map is ON by default.
• Shaded Topo Relief (DEM): hill shading from 10-meter DEMs (digital elevation model data). Source: USGS.
• Topographic Map (DRG): composite of scanned images of 1:24,000 scale USGS standard topographic map series (digital raster graphics, DRG) of the area. Source: USGS.
• Orthophotos: natural color ortho-rectified digital imagery, 2-foot resolution. Source:  Metro and USDA Farm Service Agency via the Oregon Geospatial Enterprise Office, 2005.

Turning base imagery layers on and off allows you to compare the relative accuracy of various forms of imagery. For more information, read the Background, Metadata, and Disclaimer pages.

PORTLAND AREA RELATIVE EARTHQUAKE HAZARDS STUDY:

Display optional overlays of relative earthquake induced hazard data for the Portland Metro area mapped at 1:62,500 scale. The zones depicted should not be used for any kind of site-specific study or as the sole basis for any type of restrictive or exclusionary policy and may not be accurate at zoom levels greater than 1:62,500.

• Relative Liquefaction Hazard: areas of potential weakening of water saturated sandy soil, creating areas of "quicksand."
• Relative Amplification Hazard: areas of potential increased ground shaking due to soft soil column.
• Relative Slope Instability Hazard: areas of potential slope instability triggered by the shaking of an earthquake.
• Relative Earthquake Hazard: this map is a composite hazard map depicting the relative hazard at any site due to the combination of all three of the above effects. It delineates areas that likely will experience the greatest effects from any earthquake.

These earthquake hazard map layers depict areas that are potentially susceptible to secondary hazards induced by earthquake ground motions. These map layers do not depict areas that more or less susceptible to seismic hazard from earthquakes.

For more information, read the Background, Metadata, and Disclaimer pages.

OREGON CITY LANDSLIDES STUDY:

Display an optional overlay of mapped landslide and debris flow deposits in the Oregon City area mapped at 1:15,000 scale. The map provides a relatively complete inventory of areas of past landslide activity, which in many cases may span hundreds or thousands of years. Not all areas shown on this map are necessarily active landslides.

The data are derived from DOGAMI field mapping and from high-resolution topographic data in the form of a digital elevation model (DEM) derived from light detection and ranging (lidar) surveys conducted by the City of Oregon City. The zones depicted should not be used for any kind of site-specific study or as the sole basis for any type of restrictive or exclusionary policy and may not be accurate at zoom levels greater than 1:15,000.

For more information, read the Background, Metadata, and Disclaimer pages.

OTHER OVERLAYS:

Display optional road and street lines, water features, and tax lot boundaries on the map.

• Roads and Streets: Road and street lines do not appear until you zoom in to at least 1:50,000 scale. To improve image legibility, only certain streets are labeled on this map. Source: Metro November 2006 RLIS Lite data.
• Water Features: River, stream, and ponded water areas. Source: Metro November 2006 RLIS Lite data.
• Tax Lots: Tax lot boundaries do not appear until you zoom in to at least 1:10,000 scale. Sources: Metro November 2006 RLIS Lite data and Columbia County.

The lines and zones depicted should not be used for any kind of site-specific study or as the sole basis for any type of restrictive or exclusionary policy.

For more information, read the Background, Metadata, and Disclaimer pages.

Click on the Tools tab to navigate the map and see information about specific points in the map. When you click on a tool, text appears below to tool to tell you how to use the tool and to remind you which tool is active. It is important to train yourself to look at the current tool before clicking on the map -- you will save yourself lots of frustration if you keep in mind which tool is currently selected.

Zoom In - With this tool selected, click on the map to zoom in and reset the map on the spot where you clicked. To more precisely define the area you want, click and drag (press down the mouse button and hold it down while you drag the mouse) to create an outline of the area you want to see. You can zoom anywhere from 1:517,000 to 1:2,400 scale.

Zoom Out - With this tool selected, click a spot on the map to zoom out and recenter the map on the spot you clicked.

Zoom To Full Extent - With this tool selected, click anywhere on the map. The full map will display.

Zoom To Address/Scale - Use this tool to zoom to an address or scale you select.

For Addresses: The address must be in the mapped area. When you click on the tool, a popup box appears. Type an address or an intersection in the Address field. If the city is not Portland. type the city name in the City field. Click the "Find" button or press the Return key on your keyboard. If only one address is found, the map redisplays zoomed to that address, indicated by a red dot, at a scale of 1:2,400.

If the geocoder finds multiple addresses, another window display showing all the results. Scroll to find the correct address, then click the "Zoom To This Location" link.

For scales: Type a number in the Scale field, then click the "Find" button or press the Return key on your keyboard. Do not put commas in the number. The minimum scale is 1:2400.

Pan - move around the entire map. Press down the mouse button and hold it down while you move the cursor up, down, right, or left. The location map shows where you are.

Zoom To Scale - Click on a number button to zoom to a preset scale:

Download Map Image - Click on "Download Map Image" tool to save a Portable Networks Graphic (.png) formatted file of the current map display that you can print if you have a printer. You can then open the .png file and print it from your browser window or from other applications that can open .png files.

Select the image size and image resolution from the options, then click the "Create Printable Image File" button. A dialog box appears. Choose the application you want to use to open the .png file immediately or choose to save the .png file to your default location for downloaded files.

A red box on the small outline map of the area shows the extent of the large map area. For very small areas the red box changes to a crosshair. You cannot click in the location map to change the large map.

The scale bar provides an approximate scale in miles for the map. To see the map scale, click on the "Location Info" at the bottom left of the map area.

The latitude and longitude coordinates of the current cursor position display at the bottom left of the map window.

Map Info - Click on the Map Info tab in the bottom left of the map area to display the map projection system, the coordinates of the displayed map, and the current scale. To close the tab, click in the tab title area.

Key Tab - Click on the Location Info tab in the bottom left of the map for help understanding the symbology on the map. To close the tab, click on the tab title area.

"Why doesn't the map appear in my browser?"
If the map doesn't display, make sure your browser is JavaScript enabled and, if you are using Internet Explorer, Active X controls are allowed. The map interface has not been tested on all browsers but should work on the most popular browsers.

"How do I zoom to a particular scale?"
Use the "Zoom To" tool or the "Zoom To Address/Scale" tool. See the Help - Tools Tab section.

"How do I save or print a map image?"
Use the "Download Map Image" tool to save and print the currently displayed map image.

"Why doesn't the screen update when I click layers on and off?"
The map contains a lot of data. Sometimes the display needs time to "catch up" to the clicks. If the map will not refresh properly, try resetting the map (click the Reset button in the Tools tab), or refreshing the page, or closing the browser window and then opening the map page again.

"Why are the earthquake hazards layers so pixelated at some scales?"
The IMS-1 map was drawn at a scale of 1:62,500. This pilot lidar map project allows you to zoom to 1:2,400. Layering a 1:62,500 map over an interface zoomed to scales < 1:62,500 will cause the IMS-1 map layers to become pixelated.

"Why do some Clackamas County tax lot boundaries seem misaligned?"
This is a known issue with the RLIS Lite data in that area.