Installation.md

@@ -15,13 +15,21 @@ ShakeMap should run on pretty much any modern hardware running Linux or Mac OSX.
 xcode-select --install
 ```
 
-For MacOS users who are running **Mojave (10.14.x)** you may run into additional problems that often manifest as complaints about not finding the limits.h file. At this point all we can offer is for you to have a look at [this thread](https://stackoverflow.com/questions/52509602/cant-compile-c-program-on-a-mac-after-upgrade-to-mojave) and see if something works for you. Some users have had success running:
+**Mojave (10.14.x)**: you may run into additional problems that often manifest as complaints about not finding the limits.h file. At this point all we can offer is for you to have a look at [this thread](https://stackoverflow.com/questions/52509602/cant-compile-c-program-on-a-mac-after-upgrade-to-mojave) and see if something works for you. Some users have had success running:
 
 ```
 open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg
 ```
 
-and performing that install before running the install script.
+and performing that install before running the install.sh script.
+
+**Catalina (10.15.x)**: The steps for 10.14.x, above, will not work. You will need to execute:
+
+```
+export CPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include
+```
+
+before running install.sh. 
 
 # Instructions
 If you are already using conda virtual environments, deactivate before proceeding